MadModder
The Shop => Tools => Topic started by: bogstandard on January 12, 2009, 08:01:17 AM
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Now to cheer up Darren.
The private project I am working on has come to a halt while more material and tooling is awaiting delivery. So I am slipping Darrens tiny job in while I have a little time to spare.
This is my first real project to be shown on here, but please bear in mind, my health is still a little fragile, so there might be slight gaps in the posting, and I am a little rusty in the humour department as well, but I will try to keep you entertained.
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DARREN'S BENT LATHE
So now we start.
This is Darren's very poorly lathe, just as he delivered it to my hospital, and I have gathered around a few tools I will use to take it apart.
Just joking of course, the rasp at the front is way too small, I will use my angle grinder instead. The coffee is there to keep me awake.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren1.jpg)
Here is the bit I want for me to work on. It came apart in a couple of minutes, with only a few chunks knocked out of the casting, and a couple of snipped wires (how's your welding and soldering Darren?).
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren2.jpg)
Don't want to get too frivolous here, so I will show you a bit of the technical side.
When Darren first mentioned this lathe, it was to do with the finish of cut he was achieving, it was very poor. It was mentioned that the saddle tightened up as it went along the bed, then slackened off at each end. This is a sure sign of something wrong with the bedway, and when it was delivered, this fact was confirmed with a little checking over with a mic.
So I need to get a more accurate layout of what is happening with the bed. So I duly used the great 24" rule that Ralph had bought me as a gift, and marked out every 3 inches using a paint stick. I then took a micrometer reading at each point and marked it down on the bed. These are thous, and definitely shows that there is a 'bulge' in the centre of the slideways.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren3.jpg)
A check down the reverse side confirmed the same sort of problem, a definite sagging belly, or a bulging top.
This now causes me a great deal of concern. When in the machining stage of this casting did the problem occur? If it was while the top of the bed was being ground, then there is nothing that can be done in my small workshop, my little surface grinder just couldn't cope with the bed length. But if it is as I suspect, and the top of the bed is flat, and it is the underside that is sagging, then there should be no real problems fixing it.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren4.jpg)
So the first job is to get it up onto a known flat surface, level it up, and run a few end to end checks on it.
This is the setup I am using on my mill at present, so that will be stripped down, and the whole lot cleaned off, to see if I can carry out surgery on this sorry little casting.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren5.jpg)
Maybe another posting today, maybe not. Just depends how my power nap goes.
Bogs
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Hi John
Looking forwards to developments.
You can make a fortune fixing ''sagging bellies and bulging tops''
:lol: :lol: :lol: :lol: :lol: :lol:
Cheers
:wave:
Stew
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Are you sure that the hammer is big enough? :lol:
And what's mixed in with the coffee? :lol:
You don't have to answer that Doctor Bogs untill after the patiant has died. :lol: :lol:
OK, now a bit more on serious side.
You know John I think that may be the problem with my Grizzly lathe. I'm going to have to check that some time. There are other problems with it too. So going to keep a close watch on this thread. May need the info for doing mine now that I can put it on the Bridgeport to do the milling if that's what it needs.
You take care of your health. I like it when you write up one of these threads with a bit of humour in them. Always entertaining and informative. :clap: :thumbup:
Bernd
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Now to cheer up Darren.
Bogs
Well I needed cheering up John and that's just the ticket....
You'll have one guaranteed member glued to the show paying full att to how this is done..... :thumbup:
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John
You were remiss in not showing Darren the huge rosebud heating torch you'll be using to "adjust" the bed . :D
Steve
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Steve,
I didn't show him that because of two reasons, the first, I didn't want to scare him too much, and the second, by showing it, would reveal that I really am a raggedy ar**d grease monkey.
Right, I said I might be back with a bit more, but a lot of you will find it totally boring. I spent two hours checking the casting over, just to see what exactly the problem was. Also you must excuse the pics, I can't quite hold steady enough nowadays, but I managed to get enough that weren't too out of focus or shaky to make up a bit of a post.
I popped the casting onto the mill table, and immediately noticed that the whole casting had a twist in it. It was 'rocking' on the machined bases, I measured it and there was roughly a 0.010" (0.25mm) gap under one edge. So I got a 3-2-1 block, put it onto the top faces and checked for rock on there. Sure enough, the block rocked (just like madmodders). The decision now had to be taken whether to carry on or give up and call it a day. So to give it another chance of life, I decided to clamp it down and see what happened.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren6.jpg)
Once clamped down, all rock disappeared on the top faces. So I have decided to give it a reprieve and machine it up, if everything else checks out. This will mean Darren will have to bolt the lathe to a flat section of either 4" thick walled square tube or a length of u-shaped girder. Just to keep the twist under control. Unless of course he can come up with a nice piece of thick Welsh slate to bolt it to.
I suspect that during it's life it has been resting on an uneven surface, and because there is no strength in the drip tray it was bolted to, and only supported on four rubber feet, it has taken on a permanent twist.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren7.jpg)
So out came the trusty Verdict DTI and the casting was set up to 0-0 at either end of the run (my first mistake). I then did a run along the edge and noticed it had a 3 thou dip in the middle. Oh! s**t I thought, it has got an end to end bend in it as well.
So I sat back in my chair, feeling all dejected. After a while a little light appeared above my head, "you stupid bugger Bogs, that isn't a datum face", so can be almost any shape, there are four running datum faces on the casting, and I was measuring the wrong one.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren8.jpg)
So anyway, I decided to check the back face to see if it mirrored the front, but not so, nice and straight (within a thou).
Confidence boosted, I decided to check the main datum running faces.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren9.jpg)
I checked the runout on both angled faces, 0-0.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren10.jpg)
Then the first top face, again 0-0.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren11.jpg)
And the last top face, 0-0. So that proves my initial suspicion, a sagging belly, not a bulging top.
Feeling a lot more confident now. It is fixable.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren12.jpg)
Now I need to see if my original readings with a mic were true. So set the DTI to read the under face at a place that was about 6 thou under the centre reading.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren13.jpg)
Moved to the centre, and sure enough, a six thou sag (you can just make it out on the dial). Now a very happy bogs, theory proved right.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren14.jpg)
So now comes a major decision, machine it on the spot and hope that the casting hasn't been hardened underneath where the jibs run, or mount it onto angle plates and machine it with a known cutter that I know will hack the material off.
I can use the side and face cutter, hoping the material isn't too hard and do it in situ, or use the solid carbide which is guaranteed to work, but will require two more precision setups using angle plates.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren15.jpg)
Decisions, decisions.
My brain hurts (in a Monty Python voice).
Bogs
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Humour? Joking? Bugger it I just went out and bought
the biggest sledge hammer I could find!
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Paul,
It is always better to smile than frown, and once you get to know my (our) quirky little ways, you will soon find out that I (we) always try to make light of a lot of things. Sometimes a little misunderstood, but never too much.
Humour is understood worldwide, and in these times, we need as much as we can get.
Rather than reams of technical jargon, it helps to put a bit of humanity into a post. So I tend to do it as though I am writing a personal account of what I get up to (complete with talking to myself or Bandit).
I think that is why we all get on so well on this site, as long as you don't go over the top and become downright vulgar and abusive, almost anything goes.
Bogs
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Hi John,
That casting does sound to be in bad shape, even to a novice like me.
It's always sat on a good solid surface, but, under the oil pan it has rubber feet.
So it could have twisted to any shape it liked really I guess.
Best I take the feet off then. I would order another bed, but it's likely to be no different from what a couple of peeps have said on here.
That is, it seems I'm not alone with this finish problem..... :(
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Darren,
By the time this has had a few hours spent on it, and if you can get it onto something rigid, it should be a first class machine. Well worth keeping and using.
A new casting would be of no use at all, it would most probably still require reworking to get it something like.
Now that the problem has been found, it will take no time at all to machine up, and I am thoroughly enjoying this little project.
Trust me :lol: :lol:
Bogs
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Darren,
I am thoroughly enjoying this little project.
Trust me :lol: :lol:
Bogs
It's a challenge thing init Bogs.......great when you can conqueror..... :dremel:
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Cool Post!
(I see another tool I think I may need to buy when the paycheck arrives Thursday... <note> add one of those dial indicators that measures sideways..)
PS: I already have a normal? Dial Indicator with a base, for measuring runout and thnigs on Rotary engines when I build them...
PPS: Nice to see I have SOME of the tools I need :P I just was using them for other things. (Vernier Calipers for measuring Thickness of Apex Seals)
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That's our Bogs :smart:
I learned a lot form this man from reading his informative posts.
Eric
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Darren,
Yes it is the challenge that does it.
But I am no super machinist. I just look at the job logically and take my time to find a solution. That is why I show what I do.
It is easy saying do it this way, do it that way, but showing the working out to get the result, is how people learn things.
The machining of the item is the easy part.
Spin,
I have had that DTI for more years than I care to remember, and I use it more than any other tool in my workshop, it has got me out of a lot of little scrapes, where I needed to get in and measure something in an awkward place.
Eric,
Thank you, it is nice to know my little posts help people along their journey.
Bogs
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Hi John
Very interesting :thumbup:. I'm interested on seeing how you machine it straight. I wonder if the twist is due to the casting not beong left long enough to weather, before it was machined, they probibly knock these thing out as quickly as they can.
The casting process leaves residual stresses in the casting that need time to even themselves out, the term weathering comes from the good old days they just left the casting sitting in the foundry yard for a good few months or even years before they used them.
Those 100 year old shash weights you sowed me wouldn't have the same problem they were done moving years ago.
Have Fun
Stew
PS if you need help moving the casting about you know where I am just give me a call.
Stew
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Stew,
That was the reason I got it bolted down to the table, to get it in the same position the bedways were originally machined in. If I can do my bit with it in that position, when it eventually gets taken off, and bolted to something substantial, everything should be spot on. The machining bit is the easy part, getting it into the stable situation it is now in was the worst. I am hoping I can get it to under 0.001" tolerance. The oil film on the bedways should be able to level it out within 0.002", so by going under that, I hope to have good success. The original max difference from my measurements was 0.011" (on the back side of the bed), so anything better than that is a step in the right direction.
Gone are the days when castings are left to 'weather' for up to years at a time, progress is so fast nowadays, three months is a long time, the machine would be well out of 'cutting edge design' before they even started to clean the castings down. They try to use heat to relieve stresses, but that is just like kiln dried wood, crap compared to the old methods of drying out naturally.
The twist could have been caused by almost anything, even the hardening of the slideways could have induced it, we will never know for definite, we can only assume.
I am also hoping that by me taking off a bit of the 'skin', some of the stresses might be relieved, and it may sit a little better when it is free standing.
PS if you need help moving the casting about you know where I am just give me a call
Thanks for the offer, but Mal (SWMBO) is getting rather good at moving things now, just get her into the yoke and chains and she can move mountains. :D
Thank goodness she doesn't read my posts, she would kill me. :wack:
John
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After giving it a long thinking through, I decided that I would give the side/face cutter a go at it, then if that didn't work, I would take the difficult route.
First the problem.
I don't have enough movement on the x axis to do the job in one hit, so two shots will need to be done. But because I am working off the feet bottoms as a datum, if I do a good cleanup between operations and make sure everything is clean, I should be able to keep within my self imposed tolerance of 0.001".
I have decided to go with a slightly smaller cutter to help keep everything a little more rigid.
I also decided, because the rear side had up to 0.011" variation, to actually put cut on of 0.015" (0.4mm) and hope the area can be cleaned up in one quick swipe.
Once the cut was set for height, both z axis' were locked up rigid, and the DRO set to zero. From now until the end of the job, all areas will be cut at this setting.
This pic shows the start of the exercise, and to my great delight, the underside wasn't hard skinned, and gave a nice steady, smooth cut.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren17.jpg)
A shot from the top on the steady creep along the casting.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren18.jpg)
And this is what it looks like from the underside whilst cutting, notice how nice the surface is after being given the treatment by the cutter.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren19.jpg)
You can just about make out the spindle speed, I had it running at 200 RPM. The power feed was set very low and took 25 minutes to travel the half casting distance, overall it took 1 hour to complete both cuts, that included the casting end change.
I could most probably have got away with a much higher speed and feed, but I didn't want to take any chances. You only get one go at it.
I just sat back with a fag and a cup of coffee, while the machine got on with the job.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren20.jpg)
Here is the casting swapped over for the second cut. I set the casting straight longtitudinally by eyeballing the back edge and lining it up with one of the t-slots. That should get it within a couple of thou of being true, and that is close enough for this job, as I do not need to take anything off using the outer edge of the cutter.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren21.jpg)
The finished run, and I have put on an arrow to show the end of the old cut and the start of the new.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren22.jpg)
Here is a close up of the join. It looks rather mismatched, but after measuring all over the area, no detectable mismatch could be found, so no problems on that score.
After checking the whole run length I was delighted to find that my 0.001" tolerance was well within limits.
Punch the air, kiss the dog and after getting all the loose hair out of my mouth, time for a fag and another coffee.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren23.jpg)
I restarted just after lunch, and set up the rear side of the casting, and without changing the height of the cut, the next two cuts were carried out just like the first side. Now starting to sweat, to see if my measurements and calculations were correct, as this was the side with the biggest measured sag error, 0.011".
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren24.jpg)
I needn't have worried, it turned out exactly the same as the other side, except for the very extreme left hand end (1/2"), that had dropped to within 0.002" tolerance. That was accepted by me because that was the thinnest end of all the measurements. In fact, if I had put 1 more thou on the cut, that would also have been within my limits. But it doesn't matter anyway, the saddle should never be needed to go that far back.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren25.jpg)
I did do a slight deviation on the fourth cut. Under where the head sits there was a machined area, to enable a stable flat area for the clamp down bolts. It meant that I had to feed the cutter in to that depth before carrying on to the end.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren26.jpg)
So that is the casting machined up to a good standard, with an added bonus. When I took the clamps off after the final machining run, there was no rock on the casting. Whether it stays that way will only be known in the future.
But, this was only the first part of the job.
As I was discussing this machining exercise with Darren, an article appeared in Model Engineers Workshop, showing how to make and fit tapered jib strips for this very machine. So that will be the topic for the next bit of this post.
I can now stop sweating, and maybe get a bit of sleep tonight.
Bogs
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Rock on John! :headbang:
Eric
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Nowt much I can say...... ::)
By `ek I`m enjoying this project. Thanks John. :thumbup: :bow:
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Eric,
I haven't enjoyed myself like this for many months, it must be the challenge, plus what little adrenalin rush I have left.
It was almost as good as getting a little engine up and running.
SD,
Not many techniques or methods shown in these posts, and of course there are most probably dozens of other ways it could have been done. This version is what I was happy with, and I'm glad you are enjoying it.
This little exercise has shown just how far out of wack these little lathes can be, and still be able to turn materials, not very well, but they do achieve it. I hope by the end of the project, it will be just as accurate, if not better, than a lot of the more expensive machines on the market, with the only thing being expended is a bit of time and a small amount of raw materials.
Looking at the whole process now, I reckon this part of the job could be done in about 3 hours, from running lathe to running lathe.
50% there, the next bit (and adrenalin rush) awaits.
Bogs
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Great Job John
:thumbup:
:wave:
Stew
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Man, I am sooooo jealous of Darren.
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Just how many years of experience do you have Johnjavascript:void(0);
Please keep sharing.
BR
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John,
Nice piece of work. :thumbup: I'm going to have to check my Grizzly lathe. I think it has problems to. But not right now.
Lets see if I understand this. When you took the two cuts you just used your eye ball to line it up parallel ,no indicator or other devise used?
Bernd
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BR
Industry wise, 40+ years.
Me wise, about 50+ years. I was playing about with technical things from a fairly early age.
But machining was only a very small part of it.
Problem solving and lateral thinking is more in my line, plus many years on the tools.
But I never give up learning, if a young sprog comes along and tells me or shows me something I have never come across before, then I will take notice of him/her, just as much as if it was a very experienced person. We all have something to offer.
The problem now is remembering everything, and getting it all passed over before it is all forgotten.
We need to preserve our heritage and skills, before we all turn into a country of shopkeepers, accountants and lawyers.
Bernd,
I did not need to have it any more accurate than a few thou, due to the fact the jib strip face doesn't go all the way back to the main casting body. I just needed a machined area for the narrower jib strip to run on.
When I moved the casting from one end of the table to the other, the cutter was moved out of the way in the Y axis. The casting was then put to the other end of the table, lightly clamped down, and then tapped by hand, so that when eyeballed along one of the machined side edges of the casting, the edge was aligned with one of the edges of the t-nut slots. By aligning by eye over a long length like this, you can usually get to within a few thou of being parallel to the table. But it doesn't work if you are cross eyed. It is better if you can do it with just one eye, I normally take out my glass one, but you could just close one of yours. :borg:
The clamps were then tightened up and the cutter moved back into position for carrying on with the cut.
C-O-C attached to describe by piccy. Once you do it you will wonder what all the fuss was about.
Someone also mentioned about this in a post the other day, but can't for the life of me remember who. It might have been Rog.
Bogs
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Very very nice!
Quite impressive!
(Adds research on a side cutter to the list of "just might need it some day" tooling.)
Watching you measure this reminds me of how I have to measure a Rotor housing on a rotary.
Same basic thing I spose.
THe rotor housing is hourglass shaped (sorta) and it is around 3" thick on one variant of the engines.
The engine is assembled like a dagwood sandwich with long tension bolts.
Thing is.. the aluminum housings that are sandwitched between cast iron.. can compress over time.
Sooo They need measured all around the circumfrence, to make sure thy are within the factory race tolerances. There can be no more than .0023" of variance between measure points.
Junk housing if its out of tolerence. Usually if out of tolerence the chrome liner is worn through on the inside.
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Spin,
A mic and a DTI can become your super efficient eyes and fingers if used correctly. They can show you the most minute detail of a part that just cannot be detected by normal senses, and they very rarely make a mistake.
A side and face cutter is one of those tools that I use to get me out of a scrape now and again. But not essential.
There are other ways I could have used to obtain the same effect. A quickie knock up, upside down flycutter would achieve the same results. You could use a normal flycutter if you can run your machine in reverse.
It is called cat skinning. Many ways of doing the same job.
Bogs
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John that is looking real good I have to say...
You did all that with a slitting saw :lol: learn something new every day, thankfully. Hard bit is hanging on to all these new learnt titbits.
I've had that lathe for over two years, so hopefully the casting has settled somewhat in that time.
Is two years enough? And does breaking the skin cause further stress releases?
Anyways, every time you post further teasers of progress cast a ray of wonder and excitement. It will be interesting how my perception of the machine will alter after abusing using it again
:dremel:
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John,
That's kind of what I thought you had done, but wasn't sure.
The Grizzly has the same kind of bed as what your working on. I'm sure it has some of the same problems. I've had this lathe for almost ten years. I'm sure it's not up to speck.
I've got some interesting things I liked to try to do with this lathe, but that would be :offtopic: .
Bernd
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Darren,
It was a side and face cutter, slightly different to a normal slitting saw. A slitting saw cuts on the circumerence edge, a side and face is as it says. I used the side cutting bit to carry out the machining.
http://en.wikipedia.org/wiki/Milling_cutter
Without knowing what the casting has gone thru during it's life, it is difficult to say whether machining it will cause any changes. You can only hope and assume what will happen. Even some normal materials have wierd reactions when you take the outer skin off. Gauge plate is renowned for bending like a banana if you just machine one side.
I am hoping, by the time I have finished doing all sorts of bits and adjustments to this little treasure, it will act in a completely different way to what you are used to.
Bernd,
Just get your mic and go along the bed as I did initially, no need to strip it down, just in places you can get to. That will show you straight away whether you have the same sort of problems.
Even though these lathes are fairly cheap to buy, it looks like that with a little bit of work, they can be made to be worth their weight in gold.
Bogs
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Sorry John, I was trying to invoke some humor, not my strong point as I'm a tad too dark and dry with it.....or so I'm told :bang:
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Just me Darren, trying to get a bit more info across.
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I was galloping along on a racehorse with this post, then it dropped dead under me.
So I am having to take a couple of days off while I find myself a new set of legs to climb on. Don't worry, the post will soon be up and running again.
So for times like this, I have prepared a little article for you to ponder over. Some of you will have seen this before, but a lot of you will have not.
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While I'm waiting to get onto the next stage, here is a little statement.
MACHINING IS ONLY A STATE OF MIND. :med:
That really means, if you think it can't be done, then you will never be able to do it. :bang:
I am very lucky, and now have a very respectable workshop built up. But that isn't the reason I can machine to a fairly good standard. You have no idea what sort of crappy machines I have had over the years, and I have always been able to achieve what I wanted to do.
Machinery doesn't make a good machinist. You can go out and buy the most expensive bits of kit on the market, but if you don't have the right state of mind, for as long as you have a hole in your a**e, you will never achieve your full potential with your machinery.
Never, ever, be jealous of what other people have. It is a fact of life that a lot of members will never be able to afford everything they really want, so just accept what you have, and use it to it's full potential. DO NOT DROOL over other peoples possessions, especially if you are in your workshop, it tends to make your machines go rusty.
If you can get the job safely mounted on your machine, and have clearance to swing the job or cutter, then you should be able to do a good job of machining it. Never think a job is impossible until you have given it a real good dose of looking at, maybe a few times, from different angles. I can spend hours just looking for a way to achieve something. It is amazing what methods the mind can come up with when it is pushed to the limits.
Reading about it is good, thinking about it is exceptional.
I always use this as an easy example.
My old workshop setup was a 1938 Atlas 10F lathe, restored over the years by myself, and a very early small mill/drill that really should have been looked after a lot better, but again, I upgraded it a little.
So this chappie comes to me and says 'I got a bike frame that I want modding, can you do it'. I told him to bring it along and I would have a looksee. He dragged out of the back of his van what looked to me like a full sized scaffold tower, it was massive. I later found out that he had taken it to a few places before he ended up at my door, they had laughed him out of their shops.
This would be a great swapsie job, I mod the frame, he landscapes my front garden. So out comes the tape measure, a quick call to my mate, and in no time this hunk of steel was on the mill and job done.
I never did get the front garden done, he did a runner. You win some, you lose some. But I did get my own back after a fashion. I had taken some rather critical engine plates and bits off the frame to lighten it up, put them on a shelf and forgot to give them to him when he took the frame away, and with him not coming back, they ended up in my recycle bin, and are now long gone, made into little engines.
On first sight would you have attempted this?
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/7.jpg)
This shot is a bit deceiving, Uncle Bogs was a bit fitter then. The frame was for a full blown chopper, and was almost 7ft long. We dragged the mill into a position where we could use the end of the workbench as an extra support, as the weight of the frame was trying to tip the mill over. The head of the mill was teetering on falling off the top of the column, with 1/4" clearance under the 20mm cutter (fitted later, after this shot was taken). But we did the job, and fairly safely to boot.
Think positive, and never give up on a job unless you can prove it can't be done on your equipment.
Bogs
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As ever, top class work and a great thread ............... thanks John, keep it coming :bow:
CC
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I was galloping along on a racehorse with this post, then it dropped dead under me.
Time to go on a diet, then?
On first sight would you have attempted this?
Not with that crazy looking bastard standing there! :wave:
Nice writeup, looking forward to more.
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Thanks Dave, and welcome home. Hope you are well.
Time to go on a diet, then
Tried it, but didn't enjoy it.
Life wouldn't be worth living without my daily fix of jammy doughnuts, caffiene and nicotine. No matter how bad they are for me. You only have one go at it, so enjoy it while you can. Sh*tting yourself thin and running everywhere just isn't my vision of a happy life. I have done enough and seen enough to last me two lifetimes, so anything from this minute on is a bonus. I am content.
Not with that crazy looking ba**ard standing there
Might look crazy, and can be a real ba**ard at times, but I think you would find that what you see is not what you get. That standing there, is the softest, help anybody, cuddliest teddy bear you would ever meet. At least that's what Bandit says, and he has never lied to me yet.
Bogs
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As always a classic bit of information Bogs.
I have to agree 100 percent with what you said. It's not the machine but the operator.
I got the same about moving the Bridgeport into the basement. "You did that by yourself :jaw: :bugeye: ".
As you said, all it takes is sitting there and studing it. I looked at the machine and figured if one guy can put this together at the factory, then one guy can take it apart and move those parts into the basement. And I did it with out injury to machine or me.
I think one problem people have today is that they are "impatient".
Bernd
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Completely agree with all of the above statements.
I made all my initial car parts, engine mounts, dual thermostat housing, the works... all from a hand file, hacksaw, handheld belt sander, and a electric hand drill.
At this point.. I keep having to re-adjust my mind, and way of thinking because I have the tools to do things.. more efficiently. If not better.
Oh and the bridgeport in the basement. I think I read about that on a different website late one night..
My youngest son and I moved the Series 1 Clone into the garage by ourselves with only a Engine hoist. Man that was scary/dumb. But in the end we had moved it to the end of the trailer, and off onto some boards that smashed to match the contours of the mill base, and ground underneath. Then after realising it wouldnt fit inside whole, the head was removed, and we got the two parts in, and re-assembled. 7 hours for the first part, and 2 more to put it back together.
I enjoy when the more cynical automotive friends of mine poo poo an idea as being impossible before they realise I had already done it, and it was complete. Now they dont nay say so fast. :headbang:
Hope your health smooths out Bogs. Dont know the story, but having various family with health issues. Its a b**ch having to battle the variety of things that can effect us.
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Now, after a bit of a rest after the contract job, I am in a position where I can pick up the bent lathe project. :ddb:
As I said on the last posting bit about it, I am going to fit tapered gibs (jibs) to the saddle, and if all goes well, this will turn it into a very accurate little machine (at least it will be better than it was previously).
I have decided to go with the setup from the mini lathe site, purely because the chap seemed to know a bit more about metals and their weaknesses. The one described in MEW was saying to make the gib strip holders out of aluminium, in my opinion, not the right material.
So anyway, away we go. But please remember, this is how I do things, and for the purists, please stop reading now. :wack:
As always, I like to see just what I am working with, and this was no exception. If I had made the gib holders to the plans, I think I would have had to remake them, as they just wouldn't have fitted. These machines were manufactured by everyone and his dog, so I expected that they wouldn't all be the same, so out came the trusty digivern, my notepad, a couple of bolts and a parallel.
This pic shows the upside down saddle, with the gib strips removed, next to the plans I downloaded. Thank you Rick Kruger for making them available.
http://warhammer.mcc.virginia.edu/ty/7x10/vault/Lathes/7x10-7x12-Projects/TaperedSaddleGibs/
If you read the article, notice the last bit, it seems that Rick is having a bit of a problem with what I fixed in the first bit of this article.
The holes for the gib mounting bolts had large volcano sticky up bits around them, so I went to work so that I could measure everything.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren27.jpg)
The first thing I did was to countersink all the bolt holes and have a bit of a clean up, this will allow everything to be nipped up nice and tight.
The other thing I did was to get out the trusty marker, think about how it was going to be measured, and because it was upside down, I marked everything up so I wouldn't get confused (a very easy thing for me nowadays). The lines on the end are to show the datum ends I will be working with.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren28.jpg)
I am now just going to take some measurements, and explain a little later.
This first one is the length of the saddle. It was within a couple of thou between front and back, so I used this reading for both.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren29.jpg)
Then a couple of bolts were screwed into the first pair of holes, and the measurement noted down. This is a bit of a rough a**sed method, but it will do for this job, as the holdown bolts are a fair amount undersized, and by the time I have drilled clearance holes, there will be plenty to play with. As long as they are within a couple of thou, all will be well with the world. I did the same measurement on the other three pairs of holes and they were noted down.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren30.jpg)
This next one shows how I measured from the datum face to the first hole. I am lucky that I have a pair of magnetic parallels, but you can use almost anything to allow you to measure accurately in a horizontal fashion.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren31.jpg)
To use the data I have obtained, I now need a little more information.
This is the measurement of the mag para (bar).
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren32.jpg)
This is the diameter of the bolts I used (the correct thead for the holes by the way).
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren33.jpg)
So all the data is brought together and worked out using easy equations. These types of equations can be used in all sorts of situations where you need to find centre and edge points. :smart:
Notice the difference between the hole pitches. I would have had to use really large oversized holes to get them all to line up if I had used the original plan dimensions as marked.
It states on the plans that you should really use the dimensions from your measurements. :poke:
So why put dimensions on the plan? :hammer:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren34.jpg)
All my data is then used to make a corrected drawing for me to work to. :thumbup:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren35.jpg)
So now I have a definite, accurate (near enough) and easy to read plan for me to continue. :clap:
So the next post should be where I have raided my recycle boxes to get some material to do the job, got my mill and vice trued up and ready to be used, and started to think about how I am going to carry out the job. :med::coffee:
So out with the notepad again and do a machining routine. :dremel:
John
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I'm going to be watching the next bit carefully.... You never know some of this could make my 9x20 machine better..... It possibly came from the same factory?! :)
Good job your writing on the bottom of that John.... It helps with the photo's as well as your head!! :thumbup: :D
Ralph.
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Bogs,
Thanks for posting this. Very interesting, my Harrison had tapered gibs on the saddle and cross slide (not top though) and have to say you can adjust it superbly.
Nick
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Oh yes, my lack of response should not be taken negatively.
Eyes wide open here taking it all in. Really looking forward to using this machine again. Judging by what I've just purchased I think I'm going to be needing it !!
:lol:
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No worries Darren,
This post isn't really aimed at anyone. If it just helps one other person to fix their lathe, it will all be worth it.
John
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Well if it helps, I picked up one good tip in the last write-up and at the same time realised how messy I am in my slap dash way.... :ddb:
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Darren,
Don't go whipping yourself, you had no way of knowing how far out this machine was going to be. Also this exercise is getting me moving my a**e again, so we are killing two birds with one stone.
Just a little bit more before we get to machining in earnest.
I did a couple more measurements before going any further, and this confirmed that the actual lathe has been made freehand, with no relationship between any measurement. Nothing is in a straight line, the bolt holes vary by about 0.020" on their distance from the machined casting edges. So I have marked up the plans with a guesstimation of something near, and hope that the hole allowances will allow for a good fit. No wonder Darren was having problems setting it up.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren36.jpg)
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren37.jpg)
So I now needed to get some material to do the job. I raided both my stash boxes and recycle bins and found a couple of 1" diameter pieces of an old machine roller and some lengths of hex aluminium bronze. I didn't have enough of any other size to do the job, but with a bit of work these will do fine. In fact the alibronze for the gib strips was my first choice anyway. I have no qualms about turning one shape into another. I just use what is available and make it fit the job.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren38.jpg)
I tried using them like this to see if it would save me some work, but no luck, they kept falling off when I turned it the right way up.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren39.jpg)
So out came my solid carbide shifter and I started to hack metal off. But it was going too slow.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren40.jpg)
So then I wacked the feed and speed up, it came off a lot faster. Don't try this with normal tooling by the way, it will cost you a fortune in new bits. After this face I turned on the flood coolant and went a bit faster. I have no idea what the material is, only to say that it is a bit of tough stuff.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren41.jpg)
So this is the first squarish bit, the other one was done the same way. They are slightly oversized, and will be skimmed up with a flycutter so that they will look a little more presentable.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren42.jpg)
The next part will be to get the gib strips out of the hex, then I will start to plan out the easiest way to get the tapered faces. Methinks a bit of superglue will come into play on that one. One thing I am not going to do, is waste time making the jigplate that they show on the plans.
Bogs
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Cool..... Sparks :bugeye: :headbang:
Looks like you are having fun with your mill John :D
Looking forward to seeing how you do with the alibronze.... That's the same stuff I made a torch out of... Tough to thread!! Still did it though :thumbup:
Next bit tomorrow? :whip:
:lol:
Ralph.
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:) Haha, didn't think they'd work without any machining Bogs, next time check with me first, I could save you trying to catch all those bits of metal rolling around the floor!
:doh:
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Looking forward to seeing how you do with the alibronze....
Oh ye of little faith.
The alibronze machined up like soft butter.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren43.jpg)
Unlike the steel. I said it was tough, made a nice flat on my flycutter in about 1" of cutting.
So I pursuaded it to behave itself with another dose of carbide and some coolant.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren44.jpg)
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren45.jpg)
Basic blanks cut up, ready for the next stage - ALMOST
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren46.jpg)
I popped the steel blanks onto the upturned crosslide, and noticed that the faces on the casting weren't flat, or even horizontal. One step forwards two back.
So out came the measuring gizmos again and a quick check revealed that they were way out, but everything else was spot on. These measurements were all taken from the top of the dovetail on the crosslide.
This really does prove that this lathe was made with a hammer and chisel and a hand drill.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren47.jpg)
I used my paintpen to highlight the problem and you can see how this one angles downwards. The other one was the same, but not as bad.
So everything has to stop until it is put right.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren48.jpg)
I could easily have done this levelling job on the mill, but I decided to use the surface grinder, less setup and cleanup time.
Dress the wheel, drop job onto mag chuck and flip the handle - set up.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren49.jpg)
This is after 8 thou removal, the back one has already cleaned up, but the front still has a long way to go. This shot shows just how far out and uneven this face was. It took another 7 thou to clean it up.
Don't be alarmed by the metal burn marks, this wheel was too soft for the job, it is the one I use for HSS and carbide tooling. A very fine cut took most of it off.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren50.jpg)
Both cleaned up.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren51.jpg)
The parts now sit nicely and squarely on the newly machined faces.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren52.jpg)
So after this little detour, I am now back on track.
I am really enjoying fixing this little sick machine, it is nice to get back into the foray after such a long layoff.
By the time I am finished with it, it should run like a Swiss watch.
Bogs.
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Good grief John....
I've always struggled with this little lathe and frequented a couple of "other" forums with lots of "y's" etc.
I got told that these lathes are little bundles of magic and maybe it was me that was the difficult one..
Anyways, as you know I purchased a Smart & Brown lathe and I do think that is a wonderful machine and a joy to use.
I'm beginning to understand why, now you've shown me what I was comparing it to.... :bugeye:
The surgery looks good, glad you keep finding these problems with it, more problems fixed the better the patient will feel/perform when fully recovered..... :)
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Darren,
This is one thing that definitely had to be put right. The sketch shows an exagerated view if it had been left as it was.
As I have said before, these lathes aren't made by just one company.
It just so happens that yours was made by a little chinaman working in the back of a dimly lit cave, using a pair of sharpened chopsticks and a rock as tools.
Shouldn't be too long now.
John
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The alibronze machined up like soft butter.
So.... How often do you use your mill to slice the butter for your morning toast? :lol:
Never doubted it for more than a minute!! :)
Nice to have the surface grinder handy to make sure your surfaces are flat.... it would have been a right b%$*£r to have to strip it all again ehh?!?
I hope Darren has a good local supplier of jammy douhgnuts? :thumbup:
Looking forward to the rest ( I might have to take a look at my gibs one day???)
Ralph.
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Ralph,
You mean you don't have swarf on toast for breakfast? Shame on you, it is the staple diet for machinists.
It is a shame that this topic is valid only for a specialist market, but I suppose it does show that you should never take anything at face value, and always double check if you are suspecting something out of place.
How many people have done this mod and not got the good results they were expecting, or even failure? I have shown that it isn't such a straightforwards and easy mod as everyone is raving about. It isn't a make it and bolt on job after all.
Mal has taken me off my jammie doughnut diet. I have a major blood test in just over another month, and if the diabetes nurse detects too much sugar, I will be in for a tongue lashing.
Bogs
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Hi John
Great Job you're certainly breathing new live into that lathe. :ddb:
It makes you wunder how they got things that far out I think they must have finished it of by hand on a lynisher :hammer:
Cheers
:wave:
Stew
PS No Donuts this Tuesday then Bandit can still have his doggy chew though
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Stew,
The way the original 'flopabout' gibs strips were fitted, it wouldn't really matter what shape the faces would be. So really on the initial manufacture this area could have been carried out by hand, as you suggest, with a linisher, just to get rid of the casting skin.
Bandit will start to look forwards to your visits if you keep spoiling him like that. :thumbup:
John
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You mean you don't have swarf on toast for breakfast?
No, but the wife had swarf on her foot in the breakfast nook. I caught holy hell for that one!
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It Aint harf painfull when the wife gets swarf in her foot:- they beat hell out of you :hammer: :hammer: :hammer:,
Bin there done it got the scars.
Stew
:wave:
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Doesn't look like much on this one, but I was trying to get another project done at the same time.
So to get up to date.
I got the holes thru the gib holders (what a job, this metal is tough as old boots). They fitted fine, but I had a thought that maybe I could do with a bit of adjustment a little further down the line, so I elongated the holes a little, just in case.
So nothing spectacular here, just bolted on to check the fit.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren53.jpg)
Remember on the last post, where I had to knock a bit of the casting down to get everything level. I now have to alter these blocks to regain the height that I had taken off. So a quickie blue up to show where I wanted to get rid of metal, and back onto the mill with the carbide and suds. Luckily, I had left a fair amount on the blocks depth wise, so no squeeze on any dimensions yet.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren54.jpg)
Doing the pair of blocks took an age. I actually cut them to fit the casting when it was fitted on the lathe, only removing the amount that was really needed for me to get the clearance. I must have had each one on the mill about five times, removing a little at a time.
There is an extra lump to come off the front one to allow for clearance for the gear on the winding handle on the apron, but that will be a wing it job after the gibs are in.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren55.jpg)
A crappy pic here, but it shows the new blocks where they will eventually be fitted. Just a few thou clearance between the blocks and the main lathe casting.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren56.jpg)
I have some calculations to do now, to work out the angle for cutting the tapered lifting ramp. I mentioned before that I did not make the machining jig, I will be doing it in a much easier way and using the blocks themselves as the cutting jig for the gibs.
Now to do the write up of my other little project.
Bogs
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Awesome work....
It makes me cringe at the thought of my lathe.... it was a low dollar lathe. So I will just assume its not quite.. up to tolerence. SO I will use it for what I bought it for.... to learn with. And as I get better, I will simply start budgeting to buy a better made, and or lathe with more functions down the road. Like a gearbox, not "quick" change gears.
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Spin,
Over the last couple of years, the far eastern companies have really got their act together. It was a learning and financing curve that they have gone thru.
You should now find that most engineered stuff coming from the far east has really improved in quality, and the issues I am finding here should not be taken as the norm.
John
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Away we go again.
In the last post I had finished getting the main holders onto the lathe, on this post, I will be machining them to the correct angles to give us easy adjustment.
I have deviated slightly from the plans a little and used a few of my own measurements for the drilling of the adjusting screw holes because I will be making the adjusting screws from scratch, rather than the crappy idea they use for making them out of a crosshead screw.
I have blued up the end and marked where I need the 4mm holes to be. I have also marked where the bottom of the ramp should end up. I mark up like this as a double check, even though I have a DRO on my machine, I always do this as a safety feature.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren57.jpg)
The blocks need to be stood up truly vertical, so this is how I do it.
Shine a light onto the background and all of a sudden the gap shows up very easily.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren58.jpg)
A little light 'persuasion' and the block ends up nice and square to the table.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren59.jpg)
The edge finder is then used to get the edges, and from those, the centre point of the forthcoming hole. When I centre drilled it, I just checked to see that it aligned with my scribe lines.
The tapping size hole (3.3mm diam x 20mm deep) was drilled in each one in turn and then tapped to 4mm, using plenty of high pressure tapping lubricant. I don't normally use a second cut tap, I go from first taper straight to plug (in the UK we use a three set system for tapping, I think in the US, it is only two).
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren60.jpg)
So this is what I ended up with, the holes look slightly mismatched, but that is just the countersink being a little deeper on one.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren61.jpg)
This next bit was the most annoying part of the plans for me, and IMO could have been dispensed with. It is a total waste of material and resources. Plus my method will most probably give more accurate running fits and alignment.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren62.jpg)
So I will now show you how I achieved the same result without the jig.
First off, the block is 3.920" long and requires a 1 degree taper (or something close, the shallower, the better fine adjustment).
A quickie calculation (again using the triangle program), told me a lift at the correct end of 0.068" would give me a 1 deg. ramp.
That is very close to 1/16" (0.0625"). I have some 1.5mm dowel pins (0.058"), so I decided they were close enough and would use them.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren63.jpg)
Now this is where a little 'tricky dicky' comes into play. I wiped the pins on a magnet and they soon became magnetised.
So a bit of plastic tape on the table, stand the blocks on end (the correct way up) and I let the now magnetic pins rest on the tape and stick to the blocks at the same time. A spot of superglue gave them a 'permanent' temporary fix. Have a quick fag, and they could then be handled. Scrape the excess glue off the face that was going to sit on the parallel, and away we go.
BTW, the magnetic trick won't work with non ferrous items (unless you know something we don't), just use the super glue by itself.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren64.jpg)
Tapped down onto the parallel, and the tapered cutaway was gently removed on each block in turn.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren65.jpg)
This shot clearly shows the tapered ramp produced by this method.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren66.jpg)
Here are both blocks machined up, but still in the rough. They need the machining marks and jagged edges cleaning up, then they can be used as the jig for machining the gibs to the correct angle and fit.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren67.jpg)
So that is it for this post, maybe another couple will see it all completed.
Bogs
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Using the glued pins to produce the tapers is inspirational, lots to learn here...like a sine bar...nice
Oh, and you didn't break a tap, on that tough steel too....I need to rethink how I'm tapping stuff.
Power tapping on the lathe goes well for me, hand tapping seems to have a 50/50 chance of success... :(
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Darren,
I try not to break taps down holes, it causes too much work. Not for me, but for my mate who gets them spark eroded out for me.
Everyone breaks a tap occasionally, but a lot of it can be avoided.
Most of the problem is caused by blunt taps. They are not worth resharpening, they are so cheap you should just buy new ones. I buy in bulk for the smaller taps and they are a couple of squid each. Don't even consider the rusty grotty ones you see on car boot sales, unless they are very cheap or for a one off job where buying one isn't an option. They can be dressed up with a stone so you can cut a couple of holes with them but that is about it.
If you know you have a good tap and it is still going tight, step up the drill size by a few thou, most times it will not make much difference in the fit, but will allow you to get the job done in difficult materials.
And as always, the correct lube for the job, not just plain oil if you can help it, but a correct high pressure tapping lubricant. A tin or bottle will last for years and more than pays for itself in not breaking taps.
I have added another file to the downloads section called 'Tapping drill size ranges', but it will not be available until Eric has cleared it.
John
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Hi John,
Thanks for the tips,
My taps don't last long enough to go blunt :bang:
A while ago I bought a job lot of 10 good quality 4mm tap sets (of 3) so 30 in all. I have to admit I'm breaking them at a rate of knots.... :doh:
I will try using a larger drill and I must also try some proper tapping fluid, do you think the right fluid makes all the difference?
Thanks Darren
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Darren,
All oils have their own properties, that is why there are so many about. Cutting oil is designed to withstand the very high pressure of the cutting action, so still leaves a film where all other oils would have dissipated completely. Without something there, you would fail completely, so even engine oil helps.
In all the work I do in a year, if I break half a dozen taps, I think I am doing something wrong. That is all due to tapping clearance and the type of cutting fluid I use.
If you want to buy a tin, I would use a ROCOL product, they are about the best ones that are generally available.
For starting out, this paste is great
http://www.mscjlindustrial.co.uk/ROC-53020B/SEARCH:KEYWORD/product.html
I have an account here, so I don't know if there is a min order, but if you need anything out of the ordinary, this is the place to get it from, they stock almost everything you would require.
I am just about to go out to the shop again, so expect another post later this evening.
John
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John,
We do use three different tpes of taps. It depends on weather we use power tapping or hand tapping. With hand tapping you would first use a taper tap, then a plug tap and then a bottom tap. If I can find the ones I have I'll post a pic of them.
I know of the sine bar method of milling tapers, but never came across your idea of setup in a machine. Only one word to describe that "brilliant". :headbang:
Bernd
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American
Taper, plug, bottom
UK
Taper, secondary, plug
:D
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I think I need to buy some more taps!!
LOL
I have always been single pass tapping!! HA HA HA
Never knew the three different taps were used for the same hole!
Hoookay. Need to go to the garage and add a few taps to the list in sizes I find myself using.
:smart:
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Couple of tips.
[1] I use mainly metric taps but other may differ, I have one machine tap, similar to a second tap per size in an alloy block on the bench going from 3mm to 12mm in a row. at the rear in another row are drill, the ones that line up with the taps are the recommended tapping sizes with dead sizes and clearance sizes inbetween/
saves hunting and it's always in use, easy to move from bench to machine as needed.
Pic later if required.
[2] Tapping fluid, try 25% hydraulic oil or ATF mixed with 75% tricorethelene if you can get it. yes I know it's banned but no one is asking you to drink 10 gallons of the damn stuff, only use a few drops on a tap. You actually need to try this to see just how good it is.
JS.
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There you are lads, and John does it for a living, so it must be good.
Bogs
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Quick question.. I have been using "Rapid Tap" as its what my friends were using.. so I went with what someone else used.
In the experience of you all, Any issues with it?
http://www.barrettdiamond.com/carbide/rapidtap.htm (http://www.barrettdiamond.com/carbide/rapidtap.htm)
Sorry to go :offtopic:
Scott
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You saw last time how easy it was to get the correct taper on the holder part without the use of the jig.
So now I am going to prepare the bronze gib strip, in preparation to cutting the taper on it.
First off, down one corner of each strip I cut a very small chamfer using a 90 degree countersink bit. This is a perfectly acceptable method of doing it, as long as you don't try to remove too much material.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren68.jpg)
The reason for the chamfer is to prevent binding in the very sharp corner of the holder.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren69.jpg)
Now that I am getting close to the end, I marked the parts up so that they would be made as matched pairs, and by doing this, they will always be assembled correctly if ever they are removed.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren70.jpg)
These next four shots are concerned with a major issue I have in the way the original concept of these tapered gibs has been done, and IMHO very bad engineering practices have been used.
Let me explain a little.
The 5" long gib strips run up a tapered slope, and the only thing stopping them twisting to the side is the very small head of the adjusting screw fitting into a running fit slot. The whole gib strip could just as easily move sideways and hit the casting or jam up the whole saddle.
So I have come up with an easy fix.
From the side of the gib strip that sits against the upright side of the holder, and the part of the strip that runs against the slope facing upwards, I measured in 0.150" (half the width of the gib strip).
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren71.jpg)
I then machined along the strip a slot 2mm wide x 1.5mm deep.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren72.jpg)
After that, the holding block was mounted up and I measured 0.150" in from the upright face. Then two 2mm holes were drilled on the tapered slope. The first one was just a bit further in from the end than the depth of the adjusting screw hole and another one, further up the slope, 2.5" away from the first hole. A bit of 2mm rod was stuck in the holes with high strength loctite, then each one was ground down to just below 1.5mm sticking up.
I am sorry for all the mixture of measurements, but I used what was available to hand.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren73.jpg)
After deburring the slots and the tops of the pins, I found that both jibs run perfectly up and down the slope, and there would be no chance of them slipping sideways when mounted on the lathe.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren74.jpg)
So now I was back on track.
In fact, when I first started to plan this job out, I had forseen a problem with holding the gib strips to their holders while I machined them. So I made the strip 0.005" wider than the face they were to run on, 0.305" instead of 0.300".
This is how the solution worked. The two parts were put into the vice, and everything was tapped down onto the parallel. Because the gib strip was wider than the slope, it clamped everything rigidly together in the vice.
It pays to plan ahead.
The extra 5 thou can be left where it is, it will not cause any problems in the future.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren75.jpg)
You can see on this shot how the gib strip sits up at an angle. By cutting it level on the top, I will have a perfect match between tapers, giving me a totally parallel lift on the top face.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren76.jpg)
So with a nice sharp cutter, I wacked up the speed to 1800 and taking cuts of 50 thou, knocked the jib strips down to size. The finishing cut was about 0.002".
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren77.jpg)
A pair of perfectly matched holders and gib strips.
Notice that I have cut away part of the gib strip marking, that will be restamped before assembly.
Unlike in the article and plan write up, I have no problems with twisting or bending of any part. I think that is because I had clamped everything together for final machining.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren78.jpg)
This shot shows the angles produced.
Who needs a machining jig?
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren79.jpg)
Here is the rear bits mounted up ready to be marked for cutting to length.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren80.jpg)
The same for the front.
Remember when I said I would make the holes in the mounting blocks a bit more adjustable. Well it was required. So when final assembly and fitting takes place, I will drill and dowel pin the holders in their final positions.
Not everything can be calculated out, so a bit of built in adjustment comes in handy.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren81.jpg)
So what needs to be done now is, strips cut to length and an adjusting slot machined, adjusting screws to be designed and made and the apron gear cutout to be machined on the front holding block.
These posts make it look like a very long drawn out process, but when you consider the problems and mods I am doing, it has extended it somewhat, plus I am only doing it in short stints of a couple of hours at most. A normal fit like this would only take a good day in the workshop.
Bogs
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A good day for who? :coffee:
Some of us would be still trying to figure out the hows and whys :scratch:
The experience in this thread is shining very brightly and I'm sure many of us are holding out our buckets..... :wave:
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By `ek....... I`m enjoying this project! :clap:
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If it wern't for other comitments I'd be gettin' over there to see this up close and personal.... Oh, and say Hi too John :)
I like the methods.... Who'd have ever thought of the use of the triangle program and little bar idea.... Not me! I'll remember that if I ever need an angle of the sort!
It's gonna be good to see this little lathe cut some metal once re-built :thumbup:
Of course you'll keep us posted?
Ralph.
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Many thanks for the comments lads, but really there is nothing new in there, just old ideas modified to do the job in hand. :dremel:
The round bar to get the angle is only using the sine bar principle, but not as accurate. The actual angle will be a second or two of a degree out, because the bar should really be mounted exactly half of it's diameter, exactly on the corner of the block, but what is a couple of seconds between friends. ::)
The chamfer bit on the corner of the block is only the reverse feature of a vee block. On a vee block they cut a strip along the bottom to relieve the corner, I just took the corner off, problem solved, and it was damned easier than than cutting a relief groove with the block set at 45 degrees. :ddb: :ddb:
It is only because I have many years of fixing machines in my past, that I know what to look for and where problems will arise.
Other people have just as much skill, but in different areas. :smart:
There are many better qualified machinists than me who will do everything by the book and get fantastic results. I threw the book away years ago, and do my own thing, using basic principles and what is knocking about the workshop, and get away with it most times.
Sometimes you have to go down the correct route, most times not. :zap:
John
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Other people have just as much skill, but in different areas. :smart:
There are many better qualified machinists than me who will do everything by the book and get fantastic results. I threw the book away years ago, and do my own thing, using basic principles and what is knocking about the workshop, and get away with it most times.
Sometimes you have to go down the correct route, most times not. :zap:
John
Until retirement, my Oppo was Harry.
I`d had a traditional apprenticeship....... Harry had learned at a small jobbing shop.
He was the ideas man. I was the worker.
For 30+ years, between us, we were devastating.......... :headbang:
He knocked a hole through the wall, as a steady for that extra length bar.
He hung the end of the long fabrication from the crane, while I milled the other end.
Early CNC came along, he was good at maths. Pythagoras. Synophyp. Cosadhyp. Tanopadge.......
Different ideas/ ways, daily.
Eeeee...... I do miss him.......
-
Hi
Harry sounds a real good guy, some of those small jobbing shop do some fantastic work and the men working in them have loads of experience, they have to take on what the market throws at them or they go out of business, working in a big factory with a limited product range you don't get the same exposure. Unfortunately society nowadays just doesn't value them sort of skills.
I'm sounding like a grumpy old man:--- well thinking about it yes I am.
:lol:
Cheers
a Grumpy old b****r
Stew
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As I said earlier if I find my set of taps I'd post a pic. Here they are. Taper on the left, plug in the middle and bottom at the right. These taps are 1/2"-20 NF.
(http://www.kingstonemodeleng.com/Madmodder/taps.jpg)
Bernd
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Bernd,
We use the same taps, but name them slightly different, taper, second cut, plug.
Now on with my post.
I was hoping this would be the last one, but I could only manage about an hour today, so I will show you the results.
This part of the job is a 'wing it' exercise, in other words, make to fit.
Because the new blocks are a lot thicker than the original crappy gib strips, a problem occurs where the gear that runs on the rack for moving the saddle, actually fouls the newly made blocks.
This is from the side.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren82.jpg)
Front shot.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren83.jpg)
By taking the gear off it's spindle, I managed to get the apron bolts in and the spindle almost resting flat on the top of the block.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren84.jpg)
This will do for me to mark out where the cuts need to be.
I run a pencil down the outside of each side of the spindle. I then found the rough middle between the pencil marks, measured the diameter of the small gear, halved it, added 1/16" and marked out from the centre line on both sides.
I thought I had taken pics, but couldn't find them, so the above description will have to do.
Senility is definitely setting in.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren85.jpg)
I checked that the gear clearance was ok either side.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren86.jpg)
Stuck my scriber through the middle of the gear, and held the scriber on the top of the block, and pushed the gear down as far as it would go, and marked it up plus a little bit. It measured up at 0.200" down.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren87.jpg)
I am showing off here, because I had a bull nosed cutter of the right size, but I could just as easily cut out the square recess.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren88.jpg)
Block mounted back onto the saddle.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren89.jpg)
Apron fitted into correct location.
If I must say so myself, it worked out a lot better than I thought it would.
It is about time I had a bit of luck.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren90.jpg)
So the rack was mounted onto the lathe, followed by the above assembly. I put the gibs in position and tried it out.
Looks like we are onto a winning streak.
Bogs
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Nice fit! :thumbup:
Next stop.... Turning?
Ralph.
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Nice fit John!
Eric
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Beautiful!
:headbang:
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Looks great John, can't wait to see what it's like!
Nick
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Thanks lads, it seems to be working out well. :clap:
Next is, cut gibs to length and cut an adjusting slot in them, plus make the adjustings screws.
It is the last bit that will cause most people the problem. :scratch:
You will need a lathe to turn the adjusting screws, and you can't use your lathe because you haven't got adjusting screws.
The perfect catch 22 situation. :doh:
At times like this, you need a friend with a lathe (or make the screws before starting the mod, and hope they fit at the end).
John
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Haha! :scratch:
Do you have any plans for the cross / top slides John or are they acceptable? I'd never come across this type of gib until I got my harrison but have to say, they are so superior to a row of grub screws!
Nick
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Nick,
To modify the top and crosslides is a totally different kettle of fish.
The tapered gibs I am doing just run between two flat surfaces and is all kept in line by the prismatic top to the bed and the groove I put into the bottom of the gib strip, so a very easy mod.
The other two slides work in a different way, to withstand both heavy lifting and sideways forces, they work on a dovetail system. To do this mod on those, requires a dovetail with a slightly tapered lift face on one side, and the casting would most probably need to be machined with a dovetailed tapered slope and a matching tapered angled sided gibs. Most modern machines in larger sizes are now fitted with tapered adjustable gibs, and they are far superior to the normal flat gib types.
If I was doing this mod again, I would most probably do it slightly different, giving much better stability of the gib strip and easier adjustment, based around the normal tapered gib strip method. See C-o-C
John
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Nice one John. That last fix would have taken me more than an hour to complete.
This whole thread has got me thinking I should take my Grizzly apart and check the ways like you show. May just happen sometime.
Thanks for a very informative thread.
Bernd
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Bernd,
I am no superfast machinist, in fact I spend more time looking at the job rather than doing it. But once the decision is made, it gets done.
I think the machining only took about ten minutes at normal machining speeds, so for a normal person, maybe 20 mins all in, and that includes all the measuring and marking out.
I only give timings so people know what to expect, not for boasting. It isn't a race, just take your time, plan and think well ahead, and it should all go smoothly with no unforseen hitches.
I have said before, I look at a job, and have machined it in my head many times before cutter touches metal, I think that is why my recycle bin doesn't fill up very fast.
John
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Here's what I'm saying John, it would have taken me a bit longer for the whole exercise, "Thinking" that is. Haven't had to do it enough to cut the time down. I can machine it in my head to, but I seem to have a bit of a problem when it comes to actually doing the machining. I seem to run into problems then. So by the time I fgure it out a lot more time has gone by. But I'm gaining on it.
A good example is the indexing devise I'm modifying. It's taken me several days to come up with a method of holding the index pin and making a clamping device. I'll explain when I get started on the next part of that project.
Bernd
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Hi Bernd
We all nead thinking time, that's what so great about this game, it keeps you thinking, I'm usualy thinking ahead on two or three projects, my boss is always bol***g me for not listening to here little does she know I'm thinking about how to make something. The big worry is when she say's OK thats agreed too, ho Sh one t what have I just agreed to ????.
:lol:
Keep thinking
Stew
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Stew,
I keep telling mine I'm making jigs and fixtures to build her kitchen cabinets. So far it's worked. She does question why they are made out of steel and are so small. Don't look anyhting like her cabinets. :lol:
I keep thinking what to tell her that I accomplished today. Made jigs and fixtures I say.
Bernd
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You got it all wrong lads. Let them make up your mind for you.
I give mine the choice, either I watch the television and have what I want on, or I go out to the shop.
She can't make me a cup of coffee fast enough, and get me out of the door.
Isn't it nice to be loved?
Bogs
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That's B****y funny John....
Mine would prefer me in the cellar/workshop too.....so she can have the telly would you believe.
As long as you insist on flicking it over when a, Soap, talent show, house program, dancing, singing (insert your own choice here) comes on and watch top gear or CSI or whatever she hates then the workshop is all yours..... :lol:
In reality, you could throw the TV out fo all I care.... :poke:
-
HA HA HA HA
Ya know.. when it was time to build my garage behind the house I held up two sets of plans.
A single car garage...
A 3 Car garage with a STEEP roof. And extra room.
I told her I can build the single car to park the car in, and rent a shop someplace 30 minutes away to WORK on the cars.
It will be cheaper.
OR I can build Gigantor Garage, cost a lot more money.. but I will be out back.
She was perfectly happy to help direct me when I was driving the bulldozer around moving the 20 truckloads of dirt to raise the foundation for the bigger garage.
Now.. Honey Im going to the garage!... 6 or 8 hours later I ask nicely for some sandwiches.. and Im happy. SHe has the house to herself, and can play music and work on her PC doing her graphics stuff.
-
What day is it today?
You guessed it, The dreaded FRIDAY the 13th
First John S bu**ers up his baseplate, now I have a problem. What's the betting, when Darren comes to fit the pipe into the flange, he has cut the wrong size thread.
Anyway, Stew called this afternoon, and after a bit of fat chewing, we went out to the shop to show him how close Darrens' lathe was to being finished. I mentioned that maybe I had seen a problem that I hadn't seen before.
So after Stew had departed, I dragged myself back out into the shop to check things out.
I had already made the adjusting screw blanks, ready for thread cutting and having a screwdriver slot cut into the end.
I had calculated out that I would require an 11mm diameter flange to sit into the slot for pushing/pulling the gib strip up and down the slope. That worked out fine for the operators side, but when I checked the rear, the flange would catch on the casting. So without further ado, I threaded one of the screws, wacked a slot across it, and sure enough, the casting was stopping it being central with the hole. So I gradually reduced the flange size until it just fitted into the hole without touching the casting. See how close the flange is to the casting. It ended up at 8mm diameter.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren91.jpg)
This is the major problem it causes.
As the gib is screwed further into the holder, it rises. As you can see, this isn't all the way in and the flange is almost out of the slot. 11mm is perfect, 8mm is definitely no use.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren92.jpg)
THE SOLUTION
If I blank up the old 4mm hole, and drill and tap a new one roughly in the position shown. Do a little bit of silver soldering on the gib strip to make it look tidy, recut an angled slot acoss the corner and this should work a treat.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren93.jpg)
So much for working to plans.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren94.jpg)
But anyway, today wasn't such a dead loss after all. After I got back from the torture camp (physio), I found a rather large pile of solid tungsten mill cutters waiting for me. Isn't it nice to have friends.
Time for a little share out between visitors.
Bogs
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Hi John
I could tell when you showed me the gib strips there was something niggling you :scratch: blanking the hole off and re-taping should knock :hammer: some good manners into it.
today wasn't such a dead loss after all. After I got back from the torture camp (physio), I found a rather large pile of solid tungsten mill cutters waiting for me. Isn't it nice to have friends.
Time for a little share out between visitors.
John kindly shared some cutters with me and very good cutters they are too Thanks John :thumbup:
-
I am not saying that the plans are wrong, but one set that works with one machine, might not work with another.
I have carried out other work to this lathe, and that might have a bearing on the outcome, but I very much doubt it.
I also repositioned the screw adjusting hole slightly lower (only a very small amount) than shown on the plans, purely to allow a beefier screw to be fitted. That would have some bearing on my problem, but not to the extent I am getting.
So if you are considering this mod, get all your facts and figures first, or leave drilling the hole until the last moment, so you won't encounter the problem I have hit.
I thought I had all points covered, and at the last minute, this jumped up and bit my a**e.
I will now see if my solution works.
Bogs
-
But anyway, today wasn't such a dead loss after all. After I got back from the torture camp (physio), I found a rather large pile of solid tungsten mill cutters waiting for me. Isn't it nice to have friends.
Time for a little share out between visitors.
Bogs
I'm on me way :wave:
Black coffee one good spoon of coffee, one good spoon of sugar. :clap:
JS.
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John,
We are not talking about an artic full here, just a nice pile. By the time they have been shared out, maybe one or two each, for those special little jobs that HSS can't cope with.
Bogs
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Looks like your having fun John :bugeye:
More than a little annoying!! But your fix sounds like it will do the job :thumbup:
I'm sure we will all be waiting to see how it turns out (oh.... is that a pun?? :doh:)
Ralph.
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Ralph,
I can come up with solutions that work rather easily, getting them done at this moment in time is the problem.
I have said that all this could be done in a good day in the shop, and it could, with ease. My problem is getting and staying in the shop for any length of time. I feel absolutely awful because I have taken so long on this project.
Once I get myself sorted (and hope I can be fixed), then little projects like this will end up as a one or two poster.
I have already had the saddle sliding on the gibs, and it was baby's bum. Once they are held in position with the screws, they should be perfect.
John
-
John,
We are not talking about an artic full here, just a nice pile. By the time they have been shared out, maybe one or two each, for those special little jobs that HSS can't cope with.
Bogs
Just a wind up John, Anyway the Donald is still off the road, need to get it MOT'd
JS.
-
I realised that John, but knowing you, you would still just turn up for a free coffee.
Even though it would most probably cost you 30 squid in fuel for the round trip.
John
-
My problem is getting and staying in the shop for any length of time. I feel absolutely awful because I have taken so long on this project.
He John, don't be so silly, it takes what it takes.......besides it's not like I'm a dead duck without it.
Sure looking forward to seeing it again though, but then who wouldn't be :thumbup:
Health is more important, you just make sure that comes first and take it easy...
-
THE FIX
After the fiasco on the last post, I have actually managed to get something done about it.
As you know, I keep all my little offcuts. Well this time they came in very handy. The bits I cut off the ends of the gibs were rough cut up and placed in the jibs to fill up the previously cut slots.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren95.jpg)
A quickie makeshift hearth, a bit of creamy mixed flux and a tiny bit of silver solder. Give it a bit of heat.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren96.jpg)
And you end up with two filled in slots. Not pretty, but they won't come apart. Ali bronze, from previous experience, is an absolute pig to silver solder. But by keeping the heat on a bit longer, I managed to get it to flow.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren97.jpg)
By using the accurate tapers to my advantage, I had no trouble holding the strips to dress down the excess filler blocks.
A few dressing cuts and it was difficult to see where the repair was done.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren98.jpg)
On this shot, by using my taper blocks, I set up my mini vice to hold the strips at the correct angle (45 degs) to cut the new angled slots. As before, I lit up the background to see when everything was spot on.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren99.jpg)
Slots cut, screws nearly finished by putting a slot in the end but the threads still need to be cut, and it is all starting to look promising.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren100.jpg)
This is the rough position for the new holes. The blocks were mounted up as before and the new holes drilled and tapped.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren101.jpg)
All bits now assembled and work a treat.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren102.jpg)
If luck is with me tomorrow, I will get it all assembled and tried out on the lathe. After that is proved, the redundant holes will be filled in and the mounting blocks will be dowel pinned.
Then if all is still OK, I will start on the final assembly and setting up of the lathe. Just got to work out where all the electric string goes, as Darren delivered it partly stripped.
Red to red, black to black, green, haven't a clue.
Bogs
-
Beautiful :clap:
cant wait to see it together!
-
Hi John,
Looking good as always,
I was only telling my mate, of many many yrs, tonight how my little machine is being made into a Swiss watch by an ex Roller engineer.
All came about cos he was talking to a gentleman of the same ilk earlier today, sumut about cars or something .. :scratch:
Anyways, my reason for posting, from memory there's only 3 wires to connect? One goes inside the control box for the speed sensor, a bit fiddly but not too bad.
-
Bravo John. Nice save. :ddb: :ddb:
Usally green goes to "ground", but then in your case who knows it could be another colour that is ground.
Bernd
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I was only joking lads, I have already got the wiring figured.
If it's hangin' loose, just stick it in the nearest open hole and forget about it.
Darren's problem then. :lol:
John
BTW, don't be fooled by the R-R bit. The production line cars, by and large, fitted together nicely, the hand built ones didn't, that is why they had to be hand built.
Bodge it and Dodge it. Purely cosmetic.
-
OHH Minor Derail....
I told the owner of the shop that works on all the Rolls, and has the race shop side I work in..
He is a old school mechanic.. granted he is only mid 40s, but he worked with some very very very very very big names in the automotive workd here in the states. And actually a lot of the cars he ahs maintained go to the one really big show every year. I spose I will leave it at that. BUT... He works on a LOT of older hand built coachwork cars.
Things where everything... EVERYTHING is hand fitted. And makes castings for parts that cant be made anymore, and machines them up in the shop.
Sooooo Talking about that Rolls Carm.. something or other.. and the wonderful fit on the doors.. cough.
He wanted me to mention Italian Coachwork to you.. Figured you would fall over laughing about the fit and finish of it.
(Im clueless sadly.. never having owned any Italian cars)
-
Bodge it and Dodge it. Purely cosmetic.
I worked for a company a while back (Morrison-Knudsen) that refurbished subway cars. These particular cars were for NYC (you've seen them in countless movies), and were known as R-44. They were called that for rail, and being 44 ft. long. The original shells were built in the late 1940's, and that company was no longer around. Anyway, the nominal length of the cars was 44', but we discovered that they actually varied by up to 18" plus or minus! Therefore, all the interior panels, equipment, etc. had to be designed such that it accomodated these variations. The saying in the shop was, "hammer to fit, paint to match".
-
R,
"hammer to fit, paint to match".
That is spot on.
Every single moving panel on the Carmargue had to be 'tweaked to fit'. Doors were different lengths (anything up to about 2") not only between cars, but different sides of the same car. It would take a dozen of us, about 4 weeks to get all the panels, electrics and bumpers (fenders) corrected and fitted to a rolling chassis. Every little job had to be done by hand.
Spin,
Italian bodywork.
The Carmargue was actually designed by Pininfarina, a famous Italian design house.
http://en.wikipedia.org/wiki/Pininfarina#Notable_designs
The white line men had to use up to 1 cwt of lead on the body to get all the necessary sharp edges required to get it to design specs. In some areas the lead was over 1" thick, just to get the bodywork to line up and look right. Even the stainless window frames were tack welded up on each individual car in situ, to make sure they fitted correctly.
But after all that, they looked spectacular and drove perfectly when finished.
John
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There used to be a small vehicle assembly plant in our town and among the products they produced was a particular Ford ute (pickup) from Australia. This was a true ute in that the body panels were welded to make one unit with the chassis etc. They had an assembly jig from the Australian factory but it was distorted so that neither the doors nor the bonnet (hood) could be made to fit. Someone solved the problem by setting steel rings and chains in the floor, they would assemble the whole vehicle then roll it over these fittings, cinch her down then run hydraulic floor jacks under at the critical points. By magic, everything closed perfectly!
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Right, back to the job in hand and no :offtopic: included.
Had a couple of hours in the shop, and as usual when I want to get on and finish the job, another problem rears it's ugly head.
So, I had fitted everything up for first trials and it was looking rather well. Unfortunately, as I was bringing the rear gib to height, it was tightening up, but not up and down, but side to side. After a quick stripdown I notice a small scrape mark on the paintwork. On further inspection, the problem bulge was also on the side of the casting, in the same area as the top one, and the same height, about 0.015" (0.4mm).
This time, it wasn't so bad, I just dropped it in the vice and wacked the material off.
As can be seen, the area that was removed proved that there was a bulge. It didn't matter on the operators side, as that area had already been machined by the factory, and wasn't causing a problem.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren103.jpg)
I was ready to try again, and the gibs were adjusted up.
Just one thing, Darren will never have to worry about a jumping saddle any more. It works perfectly, smooth as silk and free as a bird, with no hint of play anywhere. It will be even better when it is lubed up.
If I was to do it again, or if anyone is contemplating doing this, I would make the holding block and gib strip 0.025" (0.06mm) narrower, make the gib 0.275" wide instead of 0.300" and adjust the holder to suit. This would negate the casting problems I have come across.
Back on track Bogs
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After all this work is it worth skimming the feet of the bed so it will be garanteed to be flat ??? just a thought
peter
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Lookin' good Bog's. :thumbup:
I was looking at the Grizzly today as I was turning the piece of aluminum for my tool holder and noticed how the whole saddle was jumping while it was taking a .05" cut. I got to thinking about what you've done to Darrens lathe. I think a total tear down is in order on this lathe.
But first I need to make some tooling.
Bernd
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Peter,
When I did the first machining steps on the casting, I checked the bed to the feet, and it was spot on.
BTW, when this is done, I have one small private job to do, then I will be showing how to make a tramming tool (nudge, nudge, wink, wink, know what I mean).
Bernd,
The only way that the saddle can jump about is if the operators side gib is not set up correctly. If it is pulled down onto the prismatic shaped bed, it should not be able to wobble about. The back side gib acts to keep it from going up and down under cutting pressure.
Even my lathe has the same method of gib strips as this one used to have, so if it starts to play up, I will fit these type of tapered gibs to it. They really are very easy to adjust, and if made well, unbeatable in the way they operate.
John
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John,
I believe that the jumping is caused by the drive mechinism. It is a very poorly design drive.
The Grizzly doesn't have tapered gibs. This one has straight gibs.
From what I gather that you are saying I could fit taper gibs on the lathe?
Bernd
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Bernd,
If it is the same gib style as Darren's, then sure, with a bit of measuring up, tapered gibs can be fitted.
All they do is basically sit in a block that mounts in the original gib position using the original mounting holes. I only machined up the saddle because it had not been machined up correctly in the first place.
BTW, 0.100" is a standard depth of cut in steel and up to 0.250" in ali or brass on my machine. Take no prisoners.
I am just doing a job now that goes from 1/2" down to 5/32". Two rough cuts and one final. I am making some spare adjusting bolts for Darren if ever they are needed.
Not actually for Darren, but his lathe. He's not yet bionic. :lol:
John
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Rather than babbling on and spouting bulls**t, here is a little vid to keep you going.
If I feel up to it, tomorrow I will finish the lathe off and give it a run, to see if this mod has cured the crappy finish problems.
John
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Ohhhh Verrry Nice!
I think its time to check my lathe and see how much slop it has.. and see if its adjustable.. or if I need to start planning for something along these lines LOL.
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Nice vid John.
That sure looks smooth. A lathe that can have the saddle moved like that without any real effort is a joy to have. :thumbup:
Darren I'm jealous. :wave:
Bernd
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...... So when do I get my saddle booked in John :dremel: :lol:
I like the look of this.... And I'll get to inspect it in 2 days :thumbup: Unless you have it back together and tested by then and Darren is there like a shot to take it away and start dirtying all it up!! ::)
I'll make sure I give it a thorough going over ..... So I can replicate it, between this post and the seeing it in person, I think when I'm feeling brave and foolhardy all at the same time I can have a go :)
Nice vid, tells us all what we need to know.... Except the web address :doh: ..... Maybe in the description? ..
:ddb:
Ralph.
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Nice! Can't wait to see it in action. This I hope would fix the issue. Now all Darren needs to do is replace the headstock bearings (maybe?) I saw that mod on the interweb somewhere. Nice Job John! I may be inspired to do this mod come summer.
Eric
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Thanks lads,
If the lathe casting hadn't been so bent, bulging and twisted, and knowing what I do now, this mod would have been a piece of cake.
The position of the adjusting screws work, but in hindsight, the correct position would be between the two. But it works, so job done. If it is cleaned and lubed up regularly, the gibs shouldn't need resetting for years, and as it is, once the machining marks are bedded in over use, it will only get better, still a mite tight.
Ralph, I put a new name on it. Might attract a few more twisted members. :borg:. But this post has already had a load of hits, and I don't think that is all from the collective having a look.
We will soon be hitting the magic 200.
I don't have the time or patience at the moment to embed a load of text or music, so just a quickie.
So now, every part of the lathe is going to be set up to perfection (well, so it works right), and we will then see if we have made a good precision lathe out of a cheapo Chinese lump.
John
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Hi guys,
I can't view the video at .. erm .. on this computer :hammer: :doh: but it sounds like you've done a great job Bogs.
With taper roller bearings in the headstock it should be a great little machine.
Nick
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Nick,
The original bearings are staying in there. Nothing on the jobsheet about doing that mod.
Darren should be quite capable of doing it, if and when needed.
But I do have high hopes for the machine as it is.
John
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Already done the taper bearings some time ago. When the lathe was fairly new the plastic gears inside the headstock sheared. Did you notice they are now metal John? I hope they are still there :lol:
I put them in hoping it may help to improve the finish I was getting. Didn't make a tad of difference...
Never noticed the head adjusting screws for lining the head back up? Newbie alert :wave:
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Darren,
Yes, the gears are still there :lol:
I am in fact a bit annoyed. I have done a parts count, and there is nothing left over except for the redundant gib strip bits.
I normally get a few left over extras to put in my parts boxes.
I have got the leadscrew working as good as it will ever get, it is slightly out of alignment and bent, I managed to get everything aligned so that just by hand turning the leadscrew the saddle was moving nicely. The whole saddle area has been built up and adjusted.
I feel like burning a bit of midnight oil, so I think I will go out and align the head up while it is all quiet. Then connect up the electric string, turn on the wiggly amps, and see what happens.
John
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That's me awake for the night..... :D
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You can go and get a bit of shuteye now Darren. :med:
As usual, I have hit a last minute hitch. Why can't things go right for a change? :bang:
But this time, I caught it straight away. I had set everything up to clock up the spindle and at the end of the silver steel bar I got runout well over what my DTI could measure. A quick check showed the chuck was wobbling about like a drunken Scotsman. :scratch:
So the chuck was unbolted and given a good dose of looking at and a service while it was stripped down, not much wrong there. :thumbup:
This pic shows the lathe with the electrics still hanging off, as it wasn't worth doing if the head casting had to be shimmed up.
This shows my DTI setup, by having it on the saddle, I can move it easily between the x and y axis.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren104.jpg)
So while the chuck was off, I wacked a new 3MT centre up the spout and dropped the DTI on it, to check the runout. 0.0002", not even worth bothering about, a film of oil or a speck of dirt up the spout could cause that. :clap:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren105.jpg)
So the DTI was switched to check the runout on the backplate. It found the problem straight away. 0.0025" runout, no wonder it was wobbling about at the end of the test rod. It was tried on other areas of the plate, with the same sort of results. :doh:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren106.jpg)
So I have now decided, first thing in the morning, I will get the electrics on :zap: and skim the backplate level, and hope that the head is true, otherwise I will have to take the electrics off again if major movement is required. I think I might just wack in a saddle lock while I'm at it, :dremel: it will only take a couple of minutes, and will definitely be needed if I am skimming across the face of the backplate.
This lathe has to be finished tomorrow morning, as I have a private rush job waiting in the wings that will take a couple of days, and Ralph is calling tomorrow afternoon. Maybe I can get him to take a vid of the lathe in action. :poke:
So out comes the sledgehammer and angle grinder again. I have to use a bit of brute force to get the 6" nail hole thru the saddle for the lock.
:lol:
Bogs
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So this will finally be the last technical post about putting Darrens lathe to rights. :clap:
I left it last night with the backplate requiring skimming. Normally a dead easy job, but not on this type of lathe, it has no saddle lock, so the facing cut could end up any shape as the tool tip was pushed out of line by cutting forces.
So the first bit is how I cured the problem. I fitted an easy to do and use saddle lock. :dremel:
After rooting thru my racks, I found the ideal bit to do the job, an 8mm steel bolt with a fitted brass tip. It isn't necessary to use a bolt the same as this, you could drop say a 6mm long slug of close fitting brass rod down the hole and screw a bolt down onto the top of it. :thumbup:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren107.jpg)
So I found a position for the lock bolt to go. About half way across the tailstock slide, and positioned so that the adjusting grub screws for the cross slide would miss the bolt head, no matter what position the bolt head would end up at. I chose this rail because I thought that the tailstock should never reach the area that this bolt will be working in.
So I just then put in a good centre, but make sure you don't break thru the saddle, you will end up drilling the bed. :hammer:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren108.jpg)
After removing the leadscrew end support, I was able to slide the saddle so that it just overhung the back of the bed far enough so that I could drill right thru the saddle. The saddle was drilled and then tapped out to fit the bolt. You need to be careful that the hole is drilled truly vertical, if needs be, get someone to watch you while you are drilling and to tell you if you are going off square. :poke:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren109.jpg)
So saddle run back up the bed, leadscrew support bracket fitted and adjusted and the bolt fitted into the hole.
It only takes a light nip up to get the saddle locked solid. Another successful job, time to carry on. :beer:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren110.jpg)
To cut a long story short, I got all the electrics in and then run the machine up. It was working very intermittently, sometime power, sometimes not. The problem was found just after Ralph arrived. A loose connection in the interlock block hanging at the back of the machine. :zap:
So I could then carry on. Saddle was locked up, and the face was blued up to show me what was going on while I cleaned it up. Ralph was looking over my shoulder, and he commented on how much it was out.
Ignore the blue ring in the middle, that is a recess. If you look at the left hand side, the face is nearly cleaned up, whilst opposite to it, there was hardly any removed. I carried on until I had a clean face all the way across.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren111.jpg)
So the face cleaned up, ready for the chuck to be remounted.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren112.jpg)
I couldn't wait, so chucked up a lump of 3/4" hex and in low gear ratio put a cut on of 0.100", speed 800, pushed down of the leadscrew feed and took a cut. I wasn't happy with the finish, so tried it again, same thing.
Then it clicked, this was a mini lathe, not mine, plus it was doing an interupted cut. So a cut on of 50 thou, and things started to improve. I eventually ended up at a 25 thou cut, and was almost happy with the finish.
The problems Darren had been having have now disappeared. :ddb:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren113.jpg)
So I flipped the bar round in the chuck, locked up the saddle and hand fed across the end. Not too bad, and I am sure I could improve on it with a bit more use of the machine.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren114.jpg)
So I now thought I would have another go at improving the finish, so changed over to high ratio (this will give a finer feed).
Usual 50 thou for rough cuts, and a final of 5 thou.
Now happy with the results.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren115.jpg)
Now for the bad news. On checking over the chuck, it has a built in runout of about 2 thou. This is about normal for a generic chuck like this. :(
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren116.jpg)
Not much I can do about it. :scratch:
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren117.jpg)
I have just one other issue, the machine is cutting slightly tapered, so tomorrow that will be fitted in during a private job I have to do, it just requires a small tweak on head alignment, a quickie tap with a sledgehammer might just do it.
So Darren, your lathe is ready to pick up after tomorrow.
Everyone else. If Darren hasn't contacted me in the next four weeks, I will have for sale a one user refurbished lathe.
I fly out tonight, to a secret location in the Bahamas for a five week holiday. :lol:
Very happy Bogs
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Ralph was looking over my shoulder, and he commented on how much it was out.
He was.... and did! :)
Good to see that it now cuts pretty much the way it should :thumbup:
Go easy with that sledge hammer John..... Maybe use the 2lb ball pein instead? :hammer:
Darren,
I can't quite remember how bad it was the first time I saw it there on Johns bench? (memory ain't what it used to be) But, the saddle runs as smooth as the proverbial baby bum! (Never quite understood that one?!) :headbang:
Your going to be happy with the end result :D
Ralph.
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"Very happy Bogs".
I`m not surprised!
What a crackin` posting this has been! :clap:
Thanks John, for showing & telling....... I`ve thoroughly enjoyed every word & pic. :thumbup:
David.
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You have given us all a wonderful insight covering many aspects John. I'm sure that sincerely applies to all of us whether new to the game or not.
Each post has been very clear and informative keeping us riveted to the show for the following installment.
Sad to see it come to an end in a way, but of course I'm personally bouncing up and down... :)
I know "Pat's on Backs" are not allowed, been told off for it before,
Tough..!! That's a wicked result from a :ddb:. Who'd have thought it could have been so far out yet still usable. (well ok only just)
I'll make the arraignments, be good to have a chin wag again at the same time. Not quite the strangers this time.... :wave:
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Ralph,
But, the saddle runs as smooth as the proverbial baby bum! (Never quite understood that one?!)
Smooth as a baby's bum. Silky.
Opposite of most probably what yours is, that would be called 'rough ar**d'. :lol:
I did enjoy your visit though, it is nice to talk to someone who answers back in a legible language, rather than just 'woof, woof'.
Bandit is good, but is limited a bit on his vocabulary.
David,
I am very pleased you enjoyed the long post, and thank you for the comments.
I hope it has given an insight into how things can be achieved, and that little challenges can occur at every corner, and have to be put right before the journey can continue.
We got from A to B, but had to detour thru X,Y & Z to get there.
Darren,
Who'd have thought it could have been so far out yet still usable.
People can adapt and make use of even the most feeble and badly adjusted machines, and produce some outstanding work.
The word 'adapt' is crucial. If a machine can be made to allow the user to not have to adapt to it's little foibles, and having to fight with it to produce what is needed, then a more relaxed and happier experience can be achieved.
Not quite the strangers this time....
I never class anyone as a stranger, just someone I have never met in person before. That little belief has got me in and out of a few sticky situations at times, from looking down the barrel of an Arabian muzzle loader, to being towed across the desert in a landrover by a pair of camels. But hey!, you only pass this way once, so make the best use of it.
I will look forwards to our next meeting.
Was it all worth it?
To me, yes.
It got me back up and running again after a long layoff, and I enjoyed every minute of the challenges.
It is after all only a mini lathe, and only so much can be done to it to make it a more precise machine. It will never compete with much more expensive and larger machines. But it is now performing to it's maximum potential, just by doing a couple of mods, and a lot of hacking and tweaking.
Accept what it is, and take it from there. :med:
John
Sorry lads, looks like the lathe auction is off. Darren still wants it. :ddb: :ddb: :ddb:
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Very nice thread John. I've grown a set of brass monkies now that I see how easy it is to get one of these sows ear lathes turned into a silk purse. The Grizzly is definatley going to get a rebuild, the question is "when".
Agin thanks for a very wonderful and informative thread. It's encouraged me to try the same on my lathe.
Oh, and Ralph if your reading this, that link to the guys lathe was a great inspiration too. Thanks.
Bernd
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Bernd,
Glad you enjoyed it, and hope that it has encouraged a few people to try out a few of the things.
The saddle lock especially, that only took about half an hour, and totally transforms the way the machine can face off.
Don't worry, one day you will find you don't have anything to do, then you can try doing a few of the fixes on your Grizzly.
I have dozens of projects in the pipeline, just hope I have the time and will to carry them all out.
John
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Excellent thread John!!
Thanks for sharing the work with us.. it has been enlightening.
Can I suggest we sticky this? SO its something of a reference? SO many start with a less expensive lathe.. and some of the things you discovered, and repaired may help others wandering through the forum.
:)
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Superb thread as usual John! I now have another page of modifications to do to my mini!!
Re: The chuck runout, I saw this article about grinding the chuck jaws when I first bought my lathe http://mini-lathe.org.uk/true_the_chuck.shtml (http://mini-lathe.org.uk/true_the_chuck.shtml).
What are the pro's and con's of doing this, is it worth my while as I have about the same run out on my machine.
Great to see you firing on all cylinders again :thumbup:
David
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Excellent read John.
Just realised last night that my cheapo chinese mill has tapered gib strips on all axis too ... probably made wrongly mind you :hammer: but it's still pretty smooth!
Nick
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David,
The general consensus amongst 'people in the know' is NOT to grind chuck jaws as it only puts it right in the position that the jaws are in at the time of the grind.
On much larger chucks, growing runout doesn't rear it's ugly head due to them having a lot more 'meat'. The scolls are much larger on a larger chuck and don't 'bend' as much when tightening down hard. A small chuck can be easily bent internally if the jaws are overtightened. It isn't the jaws that are out, it is usually the scroll or the followers on the back of the jaws that have come to grief.
In fact, if you think about it, if you do grind the jaws, when they are moved to a different position, they just might be worse than they were in the first place.
I do grind independant four jaws, but they are removed from the chuck first and each one is reground to be perfectly square on the gripping face, this is because they do distort and wear over time, as unlike a three jaw, you can get immense differences in holding pressures applied on each jaw due to the way things are held and adjusted.
BTW still only firing on two cylinders of a V8, but the gearbox is OK.
Nick,
Now the far eastern makers are getting their act together, things like tapered gibs are starting to become standard on a lot of the new models now. In a few more years, they will have everything perfected, and the quality will shoot up. We are actually starting to see it the the quality of tooling, a few years ago you wouldn't have touched it. Now you can buy with the confidence of knowing that it will do a very acceptable job. The machines are going the same way.
Look what happened to Japan, cheap tat to begin with, now world leaders in quality. At the moment Taiwan seems to be the leader of the up and coming pack, with China and India coming a very close second. In fact on larger and more expensive machine tools, they are already up with the best of them. What we see and buy is only in the bottom 10%.
John
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Thanks for that John, I had a feeling that article wasn't telling the whole story, I'm glad I held off from doing it now
David
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I just couldn't stop playing with the damned thing, and rather than leaving the post in a bit of limbo, plus my conscience had got to me, saying that I couldn't really do anything with the chuck.
At the end of this post is a little vid, please read the text first before playing, as it will make a lot more sense.
I had already got the head sorted, but because of doing this next bit, I redid the head, and I will show what I got up to.
First off, the chuck. It had around 2 thou runout, which really is about normal for this sort of chuck. But I thought I should be able to reduce that to a more acceptable level, just by using a technique I have shown you before.
A bit of rough bar was mounted into the collet chuck. Even though this chuck has no detectable runout, I still turned the bar down to make it truly concentric.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren118.jpg)
The suspect lathe chuck was mounted onto the new arbor and the back face checked for runout. It was a fair bit out, so it was as usual, blued up.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren119.jpg)
The chuck was then cleaned up on the back face until the blue was all gone.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren120.jpg)
Everything was cleaned down and the chuck refitted on the lathe. The runout was checked, then the chuck was remounted into the next set of holes. The check and change was carried out on all three possible mounting combinations. I then chose the best reading and mounted the chuck in that position. The backplate and chuck were both pop marked, so if the chuck is ever removed, it can be remounted back in the same position.
The first part of the vid relates to the results obtained.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren121.jpg)
This part now covers my realigning of the head. Because I had redone the chuck, the head settings were now no longer valid.
So the first thing I did was to change the two rear head holdown cap screws for a pair of hex head bolts. When I had set it up before, the motor had to be removed each time so that the cap screws could be slackened, so taking about 15mins to reshim each time. Having to do that half a dozen times is no joke. Now the cap screws have been replaced, that time drops to 5mins, because the motor can be left in position.
The lathe was cutting tapered, getting larger the further away from the chuck, not a lot, more of an annoyance. If you turned a long bar between centres, it would become an issue
So using cooking foil (0.001" thickness) folded over to make a shim pack, I inserted one pack onto the rear face of the prism bed.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren122.jpg)
And another onto the front face. This effectively kicks the head over in the direction I want to go. After four attempts, using different shim packs, I had it rather good.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren123.jpg)
Outboard end.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren124.jpg)
Inboard end. Spot on, no taper at all.
(http://i202.photobucket.com/albums/aa102/bogstandard_photos/Darren125.jpg)
If you now watch the vid, it will show the results.
So that really is it.
Bogs
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I'd better get round yours pretty quick John.....
Otherwise It'll be CNC'd next and you'll get nothing else done !!! :lol:
Yes, you did show us how to center a chuck before, but I'd never have made the connection and done it on a full sized chuck.
Oh don't laugh, I can just hear you from here, yes, yes it's only a piddly lil' diddy chuck :poke:
Joking aside, that lathe is looking like a pretty darn accurate machine now.
I'd better stop using it for grinding and polishing :jaw: That was about where it had been resigned to for a while.
Good job I have a polishing machine, must do a post on that sometime.
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Darren,
It is actually a nice little lathe. Never having used one before, I can now see why it is so popular.
As long as people realise its limitations as to size and weight it will cut, then it does the job admirably.
Don't worry, that is now definitely it. I will clean it down (including my bench, which is covered in brass swarf) and get the covers back on and it will be ready for you.
Leave yourself a couple of hours free, and we can have a look at doing a bit of machining.
John
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Very nice. I see what I am doing this summer. Thanks for the tips and inspiration John!
Eric
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A good rest (making stuff!) well earned I think John.
Good to see it is all running sweetly.
Darren you lucky ...... We'd better see some well turned work from you and this little beauty soon (well the next 6-8 months anyway) :)
Ralph.
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This posting just got even better. :clap:
THANK YOU John...... :thumbup:
David.
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David,
Some of the purists would scream if they saw what I had done in this last part. The shimming should have gone a lot deeper and setting nose up/down as well, and they would burst into flames with rage at the way I treated the chuck.
It all depends what you want out of a lathe. With a LOT more time and effort, it really could be made absolutely perfect.
But what I have done is made the lathe cut as accurate as possible, by just a couple of easy to do things.
I haven't even played with the tailstock, that will be up to Darren to put back on centre. A fairly easy job if he wants to do it.
I have already shown how that is done somewhere else.
Just remember, this is the way I do things, it might not be right, but it gets the job done.
John
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Nice one John :thumbup:
Wounderful bit of work. :clap: :clap: :clap:
Cheers
:wave:
Stew
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But what I have done is made the lathe cut as accurate as possible, by just a couple of easy to do things.
John
Well I wouldn't quite say easy, depends on who you are :clap:
Ralph,
Expect this baby to be showing its talents quite soon as I have a small job just waiting for it's return.
But I'm sure many other projects will follow :dremel:
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Excellent as always John,
GRIZZLY LATHE, look out because here I come to rebuild you. :D
Your an insperation John.
Bernd
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Hi All,
I thought I might revive this thread, 'cos it's so darn good AND because I have spent the afternoon measuring and skimming the underside of the ways on my mini-lathe which is the same as Darren's.
In my case I had a taper end to end of .24mm :hammer: which I have suspected for a long time. The good news for me is that I can't detect any sag or twist in the bed at all, the bad news is that I had to reset the bed on my milling table 6 times to skim the full length both sides because my mill is MUCH smaller than John's :scratch: but with a bit of jiggery-pockery I managed get the transitions between cuts just right with a nice finish using a Glanze form tool mounted upside down in a flycutter with the mill in reverse.
I was feeling pretty pleased that I had managed to get the taper down to .07mm end-to-end with no lumps and bumps but now I'm having second thoughts........ What tolerance should I work to?
BTW I dont know what posessed me to start this, I am way out of my comfort zone here. :doh:
David TS
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David,
I would leave the main casting as it is now, because with your setup, I don't think you would be able to get it any closer. Besides, that is a very reasonable figure to have over such a length.
You will find any other tweaking much easier because everything is so much smaller.
If what you say is correct, you could stop at almost any point, and know that you have already made a significant improvement.
Well done indeed.
John
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Thanks John,
I had worked myself up into a bit of a lather about it but you have put my mind at rest, as you say certainly a significant improvement.
Looking at the weather forecast I cant see me doing much proper work tomorrow so I may have a go at your tapered gibs mod I can feel the symptoms of :proj: creeping up on me ::)
David TS
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David,
All I would do is wrap a bit of something like 240 or 400 W&D paper around a square edged flat bar and spend a few minutes just rubbing up and down each slideway, plenty of thin oil as well, where you have machined, just to blend together any transition machining marks. Other than that, you should be ready to go.
Before doing any machining on the saddle, make your carriers and tapered jibs first, leaving a little bit extra on the carriers height and width to give you something to fiddle with. Then if you do get into a pickle, you can always revert back to the old jibs.
John
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John,
Yup sounds like a good idea, the last thing I want to do is back myself into a corner and end up with a pile of scrap. I would say that I will take it slowly but I only have 2 speeds: dead slow and stop.
David TS
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Bloomin ek David,
That's pretty good going considering you feel out of depth. In fact that's pretty good going all round.
0.07mm = 0.0027559" or 2.8 thou over 24"
Usable working area is 12", so that's 1.4 thou. And we are only talking about the gib tightness not ways to the spindle accuracy.
Besides, you need somewhere for the oil to sit.
:clap: :clap: :clap:
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Excellent, David. You've got me interested in trying this.
Got any pics of your work? Did you happen to do this on a mini-mill?
Mike
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If you are going to show any more, could I suggest that you raise a new topic. Then David will get all the recognition for it, rather than just being an add on to my post, where it will most probably get lost over time.
John
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New thread started, I really need a hug right now. Is it wrong to love a tool so much? as much as this little lathe is a bit wobbly and dare I say inaccurate I am extremely attached to it/her, she is my first you know :lol:
Mike, nope not doing it on a Mini-mini mill this is a similar machine to mine
(http://lh4.ggpht.com/_v5iriLjrHis/SvLw99bmSKI/AAAAAAAAAEc/rHDIY1fQ9EM/s800/XJ20.jpg)
Darren
Thanks, I had to put on my brown trousers and bicycle clips when I started cutting but overall I'm pleased with progress so far.
David TS
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Joking aside, that lathe is looking like a pretty darn accurate machine now.
Darren:
I have gone through much of the same experience that you have with your machine.
My machine wasn't so much bulged in the middle as it had a 0.017" difference in bed thickness from HS end to TS end in the front and 0.014" thickness, in the other direction of course, in the back.
After fixing that, I found that the saddle gib mounting plates needed adjustment by about 0.006" and the saddle/bed contact area was out as well.
Fortunately the cross-slide was perpendicular so that wasn't an issue but this thread doesn't mention if you had any trouble aligning the tailstock.
I cannot get my tailstock aligned well to the spindle and there seems to be some problems with trying to adjust it. http://www.robobits.com/realbull/tailstock.html has some pictures. There are no pictures of your tailstock in the thread. Is yours the same design as mine?
I'm curious if you had any additional problems?
I'm also wondering what the serial number stamped in your lathe is? Our lathes appear identical and are about the same vintage. The number stamped on mine is 033. I'm wondering if perhaps you and I were the lucky receipients of the first few machines that came off a fairly new assembly line in the Far East.
Kevin
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I just finished reading this entire thread and it was inspirational.(Now to take mine mini out of the box). :coffee:
I'm assuming that there are no further updates to Darren's lathe.(?).
Darren Harris
Staten Island, New York.
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I broke a tooth on a change wheel trying to cut a 6tpi thread ..... does that count as an upgrade :lol:
No, no further upgrades were found necessary, congrats on your new joy toy :clap:
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I just finished reading this entire thread. Very good information. I happen to have... three of these beasties... don't ask me why. So, whatever fixes there are, I get to multiply by three.
I've been looking into this carriage gib problem for some time. I started gathering materials to make the tapered gibs, but after reading about gibs in Machine Tool Reconditioning, I thought I had a simpler solution. It's not as elegant as the tapered gib, but it might do the job while being quicker.
Has anyone investigate making loose-fitting gibs? This is where the gib bracket is fixed to the carriage, and a series of adjusting screws press the gibs against the underside of the ways. This design would automatically compensate for any angle of the carriage at the mounting point, and the relative angle of the underside of the ways. I'm thinking of using 1/4 brass for the gibs ('cause I have it) and making the gib brackets out of standard size steel stock and shims, stacked up and drilled to create the proper form. Unfortunately, to adjust the front gibs, the apron would have to be removed. Once fitted and worn in a bit, they probably wouldn't have to be adjusted for years.
Any thoughts?
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Simpler still, I use shims and haven't looked back.
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Shims work! But if the lathe is not flat on the bottom of the ways. Your carriage is going to be loose in spots. You can scrape and fit the tappered gibs and its a whole lot better! Unless bogs is your neighbor. :D :dremel: Also some lathes are pretty straight from the factory.
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With regard to "loose gibs", I've made and fit two extra cross slides to one of my lathes, a ten inch Logan lathe of 1948 vintage. The cross slides were for using the lathe to mill, were castings bought from Metal Lathe accessories, and were machined mostly on a bench mill, with the second one machined on the lathe its self. They were designed to use a gib with half a dozen gib screws to adjust it, and I used eighth by half inch hot rolled steel, clamped in the dovetail of the cross slides with small C-clamps to machine the angle on each edge, and a light sanding on both sides with some 320 wet or dry paper, to remove the mill scale. They are about fifteen or more years old, haven't been adjusted since the first few months of wear, and are slick moving, with no play, and no discernable wear at all, on a lathe used daily for every kind of work repairing old machinery and engines.
I've rebuilt a few mills and lathes with tapered gibs, and while the concept is "better engineering", in the big picture, it has little real value over "loose gibs" for the home shop, in my opinion. The last time I refit a tapered gib, it was on a milling table that weighed about two tons, was about twelve feet long and three wide, and I rolled it over with a fork lift. The workers had long used up the designed in usable adjustment of the x-axis gib, but kept going for more, and managed to get enough more that the table pulled the gib over its adjusting screw shoulder, lock the table to the knee, and required a come along to pull the table back out, free the gib, and allow the table to be removed. I got a week's pay for repairing that gib, the table, and putting a new notch in the gib, and making a new gib screw, after scraping both the table dovetail flat and straight, and the tapered gib flat and straight. They'd have saved half the cost if they had brought it to me before they jammed it, and had the machine back in service in a day or two instead of over a week. Unless I'm replacing a tapered gib already in place and working, I always go with the "loose gib" and get good service out of it, completely satisfactory in all regards. :bugeye: :thumbup: mad jack