Another new project... a QCTP (Quick Change Toolpost)

[jim]

another excellent write up!

i really am impressed with your work. ignorance is bliss, but also gets the job done!!


as we say at work, if it gets the job done its ok!

[AdeV]

another excellent write up!

i really am impressed with your work. ignorance is bliss, but also gets the job done!!


as we say at work, if it gets the job done its ok!

Thanks Jim, it's nice to know that my muddling along is appreciated 

I have to say, my ongoing improvements are almost entirely down to the help & encouragement I receive on this site, so, in short: 

 

[Trion]

Your QCTP is beginning to look very good!

Regarding your issue when setting the shaft up in the v-blocks. Would it not be possible to set a DI / DTI to the tapered surface, run the X-axis back and forth and adjust the part until you got no dial movement? Just asking because I don't have such a fancy digital angle gauge.. yet

[madjackghengis]

Hi Ade, I keep a starret level on my mill table, it has two bubbles at right angles, and is pretty accurate matching up bubbles pretty close with my machine level, and I often use a level to get a piece in the vise close enough for regular kind of work, like putting a handle on a tool post.  As to dimensions of a large tool block, I suggest you find one you feel is the right size, lay a couple of dowel pins in the female dovetail, use an appropriate sized adjustable parallel to tighten up the dowel pins (they need to be about two thirds the depth of the dovetail slot for accuracy), and measure off the parallel, and use the same pins and parallel when you make your slots.  I'd suggest making a "master slot" blank, and use it for testing all your future tool holders, to keep from creeping larger or smaller, incrementally.  By the way, you can braze a piece of high speed steel onto a bar of steel, and then grind it to a good shape and dimension for boring, and get a good boring tool, capable of good sized cuts, with little problems with chatter as long as your relief and clearance angles are good, and it sharpens up, right on the machine with a touch up stone, if you stone it every time you use it.  I'm busy ignoring having "only" half a dozen tool holders, and changing out tools left and right.  Maybe when I get my 12 inch shaper up and running, I'll make a gang of tool holders.   Keep up the good work, Ade, mad jack

[AdeV]

Your QCTP is beginning to look very good!

Regarding your issue when setting the shaft up in the v-blocks. Would it not be possible to set a DI / DTI to the tapered surface, run the X-axis back and forth and adjust the part until you got no dial movement? Just asking because I don't have such a fancy digital angle gauge.. yet

Trion, thanks! If my lowly QCTP looks even slightly as good as your Sajo mill (once you've finished it), then I truly will be a happy bunny. As for using a DTI - yes, that would work just fine. It would probably take quite a while to get it spot on, although TBH I think you can get away with a whole chunk of inaccuracy because it's threaded, and slop in the threads will take up any error.

[AdeV]

Hi Ade, I keep a starret level on my mill table, it has two bubbles at right angles, and is pretty accurate matching up bubbles pretty close with my machine level, and I often use a level to get a piece in the vise close enough for regular kind of work, like putting a handle on a tool post.  

Another cool idea, I like it   It wouldn't work on my mill, unfortunately, as mine's at least 1/2 a bubble off level... Looks like I'll be shimming it some time soon...

As to dimensions of a large tool block, I suggest you find one you feel is the right size, lay a couple of dowel pins in the female dovetail, use an appropriate sized adjustable parallel to tighten up the dowel pins (they need to be about two thirds the depth of the dovetail slot for accuracy), and measure off the parallel, and use the same pins and parallel when you make your slots.  I'd suggest making a "master slot" blank, and use it for testing all your future tool holders, to keep from creeping larger or smaller, incrementally.

It's the finding one that's the issue... Anyway, I've given up trying to match an existing one, and am going with my own dovetail size (2" root x 0.5" depth), In fact, I'm about to go out & cut the first one...

[AdeV]

Tonight's write up will be a little brief, as it's late o'clock, I'm starving hungry, and swarf isn't edible unfortunately. 

Today, I worked some more on the main body. First job was to cut one of the long sides down to the top of the dovetail:



18mm roughing cutter, pushing it until it produced nasty burny blue chips. Then, since the mill wasn't complaining, I carried on. I only got burnt once worth a mention...

Once the holder was milled to exactly 4.010".... erm, OK, approx 4", I turned it 90^o in the vice, and used the edge finder to locate a corner. Next job, rough cut away the material either side of the dovetail:



Same cutter, same colour chips. Lots of smoke. Mmmmm, smoke. The shallow groove was a reference cut to make sure the dovetail is the right width, and that I'm cutting in the right place. I was.... so the non-dovetail portion was taken down another 0.500".

Then, load my newfangled 1.25" dovetail cutter (a snip at £20 from Chronos - hardly worth keeping sharp at that price), and get cutting. This is a miserable operation on my mill; I've got some wear in the dog clutch in the top, so it clatters like a bugger at slow RPMs, unless I use my fingers to keep a bit of resistance on the quill. I think what's happening is, as a flute clears a chip, the cutter sort of springs round, until the next flute engaged which slows it down, then the dog clutch catches up with a BANG; repeat 200 times per minute and it gets quite boring quite quickly... Yet another "must fix it" job...

ANYWAY, I did manage to take one photo; this is the second to last cut & is much easier on the cutter than the previous cuts, hence having a spare hand to run the camera:



Once the dovetails were cut to size, I used a deburring tool to mill a small 45^o chamfer on the top edge, then a brief whizz round with the file just to deburr & soften the edges slightly.

Last job tonight, I don't bl**dy believe it, YET MORE SLOTTING!



Using the 1/4" cutter (as I happen to have a 1/4" radiusing tool which will radius the pistons just right). The cutter moaned if I tried to take anything more than 0.100" at any more than a glacial feed rate. This got old very quickly, so I slapped in a 6mm roughing cutter & chopped the piece out in one fell swoop. Yeah, it smoked at me, but it got the job done. Then, back in with the 1/4" mill to tidy up the edges. A bit more faffing with the file, and here's the result:



Starting to actually look like something now....

I have a lot of machine marks to clean up. Not looking forward to that job...

Tomorrow, I will try to finish the other dovetail, then I just have a bit of work to do on the underside of the body and I can move on to some other parts...

Question: I've made the cam out of 303 stainless steel: What material would you, gentle reader, recommend for the pistons? I'm wondering if it's worth avoiding S/S to avoid galling, and I'm thinking maybe brass or phospher bronze might be an option?

[madjackghengis]

Hi Ade, were I me, which I am, I'd use a piece of aluminum bronze if I had one laying around, stainless does gall easily, particularly 303, and the aluminum bronze is about as hard a bronze as you get, and would probably give the best bearing surface for the eccentric.  It's probably going to be turned a few dozen times at least, I'd say.  Worth taking account for some friction.  I expect once you've got a few tool holders, you'll be as well off as if you bought them, and from then on, all the ones you make, will be as if you'd bought the original post, so you didn't lose much of anything in not finding dimensions.  I looked through my catalogs, and books, and didn't find any reference with dimensions of the dovetail in any of them.  As long as it's big enough, it'll get you through the day.  I think that spline issue would about drive me crazy, my tractor was doing that a few years ago, ended up having to make a new clutch for the PTO so it'd stay engaged and cut.  One of these days I'm going to buy a few roughing cutters, I keep reading about people using them, and they sound like a good piece of gear.  Looking good so far  mad jack

[AdeV]

Hi Ade, were I me, which I am, I'd use a piece of aluminum bronze if I had one laying around, stainless does gall easily, particularly 303, and the aluminum bronze is about as hard a bronze as you get, and would probably give the best bearing surface for the eccentric.  It's probably going to be turned a few dozen times at least, I'd say.  Worth taking account for some friction. 

Well, I didn't have any lying about (I only have a lump of brass, but that's earmarked for a different project), luckily my metal merchant had some kicking around. It's not cheap though - £40+vat for a 4" length of 2.25" bar! Still, that gives me loads to make the pistons with, & some left over for future projects.

As for the pistons, the more I look at it, the less I like the rectangular shape, I think I'd prefer a squarer piston, to give better side-to-side support. I also need to figure out how to make the pistons stay inside the unit; I'm thinking a small flange on the back, and an appropriately recessed area inside the bore (I have to cut a recess, otherwise I'd never get the cam sleeve in...

I expect once you've got a few tool holders, you'll be as well off as if you bought them, and from then on, all the ones you make, will be as if you'd bought the original post, so you didn't lose much of anything in not finding dimensions.  I looked through my catalogs, and books, and didn't find any reference with dimensions of the dovetail in any of them.  As long as it's big enough, it'll get you through the day. 

I think you're right; I still need to make the holders; not sure if I just bite the bullet & buy some steel to make a stack of them, or whether to make 1 from ali first... choices choices... I'd better finish the main toolpost first, lots to do on that yet.

I think that spline issue would about drive me crazy, my tractor was doing that a few years ago, ended up having to make a new clutch for the PTO so it'd stay engaged and cut.  One of these days I'm going to buy a few roughing cutters, I keep reading about people using them, and they sound like a good piece of gear.  Looking good so far  mad jack

You're right, the clattering just sounds so wrong, so bad, that I really ought to do something about it. I can usually avoid it by setting my cuts up carefully, and by equally careful speed/feed rates. If I keep the cut aggressive, it tends not to clatter...

I can highly recommend the roughing cutters, they're great for rapid removal. The surface finish from the side of the cutter is dreadful, but then it IS a roughing cutter. The end cut can be pretty smooth, certainly little worse than my best endmills.

[AdeV]

I've not abandoned this project... but it took 2 days to cut the 2nd dovetail: Day 1 to bulk-remove material to dimension, Day 2 to rough the dovetails, cut them properly, then cut the hole for the piston. There's no action shots, because they look the same as before. When roughing the material off, I had to stop every 0.200" to let the block cool from "FMTH" to merely toasty...

So, here's the result:





As you can see, I've gone for the bigger square piston rather than the tall thin one. I obviously still need to open out the original hole, I ran out of time tonight. I've also had a little go at draw filing on the first dovetail, hence the slightly odd appearance of the marks. A bit more time & it should look loverly.


Finally tonight, a little light relief.....

How does one transfer oil from the big can to the little can, without spilling any, when you've not got a handy assistant to hold the funnel?



Answer tomorrow...

[DMIOM]

.....How does one transfer oil from the big can to the little can, without spilling any, when you've not got a handy assistant to hold the funnel? ......

One possibility - have a look in the corner of the workshop and find a large billet of aluminium that happens to have a tapered interior, and several oil-drain holes in it; dangle the said billet overhanging the edge of the mill table, fill the sump with oil and catch the run-off in the small can?  

Dave 

[andyf]

.....How does one transfer oil from the big can to the little can, without spilling any, when you've not got a handy assistant to hold the funnel? ......

 
I bet you've found a foot or two of plastic tube to use as a siphon.

Andy

[Colh]

Hi Ade

I had exactly the same problem - 20 litre drum near full with cutting oil needed to be put into a small oil can.

Went to the local auto parts shop and bought a cheap diff/gear box oil pump - like a big syringe with a plasic hose.

Have been following your thread as a QCTP is the next project on my list. 

Where did you get the plans or are you making it up as you go?

Have to work out the best dimensions to fit my lathe - Hercus 260 (Australian version of a Southbend/Boxford) with 11/16in or 18mm from top slide to centre height.

Will post photos of my workshop soon.

regards  Col

[AdeV]

Hi Col, welcome aboard the cube  Assimilation is guaranteed... but you get to make your own hardware 

My QCTP is loosely based on this one: http://homepage3.nifty.com/amigos/qctp/qctp-e.htm, but I'm pretty much winging it with the dimensions - I aimed to have a similar block size to my existing 4-position toolpost. I always wanted 2 dovetails, so I can mount boring bars & turning tools without turning the toolpost. There are no drawings, as I've not yet done any...

My centre height from the top of the cross slide is 1.750" (about 44.5mm), the toolpost is about 3.5" high currently, although I have an extra 1/2" base to add to that yet; I've noticed that when I add the base, the centre point will be below the bottom of the toolpost piston; so I may try to take a bit more off the base block yet to compensate for that.

[Rob.Wilson]

Cracking Job Adev 

Been watching with interest  as i need to make a QCTP for my Cub lathe 


Keep it up 


Rob 

[AdeV]

Cheers Rob - much appreciated... I need encouragement after today... it was one of those "2 steps forward, 1 step back" days in the workshop 

First job was to enlarge the first piston hole to be the same size as the other one (1.400" square). This went OK-ish... oddly, the same setup as I used yesterday (6mm roughing cutter, followed by 1/4" end mill) didn't work; the roughing cutter over-cut. I've no idea why, the only possible explanation I can think of is; the 1/4" collet I was using yesterday has stripped its threads, so I was using a different collet. Maybe the old one had some runout or something. Anyway, the result is, the 1/4" end mill didn't do anything useful to the finish, so I'll have to be a bit careful with that piston.


Anyway, on with the show... I've been pondering for some time how I would retain the pistons within the body of the QCTP. The only solution I've seen is a fellow madmodder's (sorry, I forget who) idea of drilling up through the base & screwing in a pin which sticks into the body of the piston, thus retaining it. Whilst I can see how that works, It doesn't seem very elegant to me. So, I figured I wanted something a bit neater. Then.... inspiration! I have a "Quillmaster" for my Bridgeport, which allows me to mill inside of things. So, a bit of fiddling later (including shortening a 3/16" end mill so the whole kaboodle will fit inside the main bore):



And then, having lined everything up & dialled it in using the "bump" method (bump the cutter into the work, call that near as damnit 0.000" + 1/2 cutter width), and got ready to take the first cut.... a thought occurred. Anyone who knows me will probably slap their forehead & groan at this point, because it's bound to get more complicated... Today is no exception 

I decided that, this would make a very ugly flange. It would be nearly 1/2" deep at the edges, yet only a few thou at the centre. This offends my sense of symmetry - the flange should be the same thickness all the way around. And.... it can be! All I need to do is mount the block on my dividing head, and I can cut the flange on a curve! The only problem is, the dividing head has a fairly small 3-jaw chuck on it, and I really don't want to disturb it. The chuck is too small to grip the outside edges of the block (and besides, they'd be off-centre), and is too big to grab the inside edges of the small hole in the bottom; and I can't use the big hole 'cos I need that to get the Quillmaster in....


....so I spent the rest of the evening making a mandrel to hold the body in the dividing head.... After much cursing and one (luckily minor) toolcrash:



I don't have a decent 60^o threading tool, so rather than try to cut a threaded stub, instead I drilled it with a handy 0.435" drill & tapped it 1/2" UNC - to match my milling machine mounting kit. The threaded stub is the shortest stud in my kit, screwed in as far as I could get it. The flange bolt also comes with the kit. When it's all put together:



It then sits nicely in the dividing head:



The only issue - visible in the 2nd photo - is that line about 1/2 way down the main diameter. After the tool crash (more of a hard tool bump really), the mandrel was knocked slightly off-centre. After some colourful cursing, I re-dialed it in as best I could, but I couldn't quite get it exactly bob on. So, after finishing the 1" bore (which goes into the QCTP body), I took just enough thousandths to ensure the mandrel would run true in the dividing head. Unfortunately, I couldn't reach the last inch or so, due to the chuck, and guess what - yep, the dividing head jaws are deep enough to grip on the slightly off-centre (larger) diameter. Agh! I'll have to pop it back in the lathe & take another cut to narrow the back diameter just enough that the trued diameter is being gripped. THEN I can use the Quillmaster!


Finally, the answer to the oil question... Dave is remarkably close, really...

Firstly, one cannot just pour oil into the funnel. If you go too slow, the oil all dribbles down the big barrel, and you're there forever.
If you go quick enough not to spill oil down the barrel, then the funnel fills up & tips over, dumping at least a pint of oil on the floor. Don't ask
me how I know this. Similarly, finding a corner is no good, as the funnel will ALWAYS tip out of the corner, even if that seems to be physically
impossible. Lastly, even if you find a way to support the top of the funnel, as long as it's resting on the oil can, it will form a perfect seal
which prevents the funnel from draining in anything less than 3 weeks. Again, don't ask me how I know this.

So, I had a chat with Heath Robinson, and he suggested this:



Funnel is held in an old brake disc, supported between the Comedy Bandsaw and the Bin of Paper Towel Death. The oil can is sitting on a can of old paint,
another project in the making, and finally my ER32 collet set, to bring it up to the perfect height. I can now fill the oil can in just a few seconds, with
as good as no spillage whatsoever, result!!!

Naturally, the very next day, the brake disc fell off its perch, scattering everything far & wide as it fell.... Ho hum, such is life...

[Baldrocker]

Hi Adev
I only have a Falcon left front disc brake, will that fit? (Don't be rude)
BR

[AdeV]

 

Damn Quillmaster wouldn't go far enough into the bore before it hit the thread in the arbor; so I would only be able to cut the flange 1/2 way down the sides of the piston - no good! So, I spent a good hour pondering, turning down a nut to 1/2 it's original depth, cutting a shorter piece of threaded stud, and modifying a large washer (needed a bigger hole), the end result of which is...... I got within 3/16ths (the cutter width, approx) of being able to cut the flange on the bottom edge, but no further! Aaargh!

Faced with the prospect of trying to lose another 3/16" off the nut/washer combo (impractical, I fear, there won't be enough nut left to grip properly), I decided enough was enough. So, I did a bunch of draw filing, which is surprisingly hard work - unless I'm doing it wrong, and have now called it a night.

I may yet give up on the Quillmaster & flange route; Instead, I'm thinking of making the piston holes (and the pistons themselves, obviously) tapered, so they'll go in the holes from the inside, but can't pass all the way through. The other option is to find another way to clamp the block onto the dividing head...

Hmmm.... 

[Rob.Wilson]

Ade

I now have tool envy    cool bit of kit you av there (quill master) 

Rob  

[AdeV]

Rob - I got it at quite a reasonable price (I thought) too - only £85 (they seem to go for £150+ on ePay); however, so far all its done is take up space in a cupboard... it's gone back away now, 'cos I'm going to part-taper the pistons instead, MUCH easier than tring to make the quillmaster work. Ah well, I'm sure it'll earn its keep one day, even if it's on eBay...

Only a bit of machine time tonight; I put the block back in the lathe to cut the underside recess (the toolpost will ride on a base, this will allow it to rotate without falling off & causing the baby jesus to cry). The base is a separate section of 1/2" plate which also needs some work...

So, anyway, here it is: Misuse of a boring bar #1 (but hey, it's currently the best facing/turning/cutting tool I have...):



Gotta love power feed 

Then, as the lathe seem to be cutting particularly well tonight, I took the skimmiest of skim cuts off the bottom, partly to get it dead nuts flat relative to the top (I'm not convinced it matters, but what the heck), but mainly to make an impression on those machine marks that the mill left:



I took about 0.006" off in total, in 3 passes (yawn).

Then, over to the filing bench, I spent the next 2 hours draw filing various sides. Even that didn't get rid of ALL of the machine marks, but I'm hoping the metal blacking will cover a lot of sins...

More tomorrow 

[Brass_Machine]

Ade,

It's looking good! That is going to be one QCTP you can be very proud of.

Eric

[AdeV]

I hope so Eric, it's certainly taking long enough! 

Speaking of which.... a nice long day in the workshop, albeit with a couple of trips out to break the day up a bit...

First, I thought I'd show you the results of my draw filing efforts... Here's what we started with, at about midday:



Plenty of marks, pits, ridges & so forth. After about 1/2 hour - with the occasional pause to wipe my fevered brow, it's surprisingly sweaty work this draw filing business - with the coarse file, here's where we're up to:



Almost there, just a few bits at the bottom middle, and some faint lines where the file dug in - then bounced, damnit, all the way down the left hand side of the block. Another ~30 mins of effort, first with the fine file, then with some 120-grit wet&dry (with cutting oil lube):



As you can see, there's still one mar left, but life is too short, I'd still be filing that out now...

Repeat the above for the top edge, then a quick skim of the dovetails, and it's time to move on...

First, I parted off a chunk of my super-expensive Aluminium Bronze - the piece in the picture represents just under £10's worth of metal (2.25" diameter). This was a bit of a bum-puckering task, the first time I've parted anything off under power. Not realising just how tough this metal is, I just plunged in with my sticky-outiest HSS parting tool. It smoked like mad, but cut cleanly, turning about £1 of metal into swarf...



Next, onto the mill to convert it into a square. Man this stuff is tough, mild steel is a doddle by comparison. Max depth of cut: 0.025" per pass; lucky I'm not building the body out of this stuff, I'd be there forever! Anyway, once it was cut square and to dimensions, and the top/bottom edges skimmed to flat, it's time to radius the corners:



You can see where I got over-confident and ballsed up the first one, I went 0.025" too deep with the cutter. It's 1/4" radius, not 1/2"! 

Soon:



As usual, I've not got anywhere near as far as I'd hoped (I was hoping to have both pistons finished & to have made a start on the base, but, no such luck). So anyway, here's a couple of glamour shots:



The piston currently sticks out about 0.113" when it should really be flush; so that's a job for tomorrow. Maximum movement for 1 rotation of the cam is about 0.150", plenty I reckon. What I'd call "normal" movement (i.e. handle fully back to handle where I'd expect it to be) is about 0.050", that should be OK, so long as I can make my toolholders fairly accurately.

And what post would be complete without an arse shot?




 

Looks good, though, doesn't it? Even if I do say so myself....

[Rob.Wilson]

I would say so to Ade ,,,,,,,,,,, very nice 

We all day days were we dont get as much done as we thought we would   


Rob 

[raynerd]

Looking bloody brill!! Well impressed!! 

[Trion]

Still looking very impressing, I'm looking forward to seeing it mounted on the lathe!