Author Topic: Ball or Radius cutter  (Read 34070 times)

Offline MadNick

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Ball or Radius cutter
« on: December 18, 2011, 03:12:28 PM »
Evening,

Ive had a busy afternoon - after messing around with some designs for the past few weeks I finally made a start.

The raw materials -



The first step was to drill the mounting holes for the base of the cutter. Unusually my lathe does not have the usual T-Slot arrangement for the cross-slide. Instead I have this -



I carefully double checked my measurements, set up the work in the vertical miller and got rolling. Now, im not going to blame the X scale on my DRO but the four holes I ended up drilling were out, way out.

After checking over the X scale I realised it seemed to 'stall' halfway along - a quick adjustment and it was working correctly. Just to be sure I thought I would try some test cuts on a piece of scrap rather than using another decent piece of steel. I needed to be certain about the distance between centres on the cross-slide mounting holes. I measured up again, using the diameter of the head of the bolt this time rather than their diameter at the thread and got a slightly different set of numbers -  I did a test cut -



Offered up to the cross-slide this was a perfect fit so I setup mark 2 of the base and drilled using the measurements proven on the scrap -



This was a perfect fit on the cross-slide and I was extremely pleased with my effort. Taking time to THINK, measure and check after the first ballsup had paid off.

I need to rework my design as I hadnt factored the diameter of the bolt heads into the diameter for the turret. Ill either countersink these, cut the bolt head back a bit or a combination of both - this is when the T-Slot setup for a cross-slide really helps.

Its easy to forget that 80% of this type of thing is measuring, considering and setting up - only 20% is spent actually doing anything.

Nick


Offline saw

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Re: Ball or Radius cutter
« Reply #1 on: December 18, 2011, 03:45:06 PM »
Good start, this will be an interesting project.  :thumbup:
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Re: Ball or Radius cutter
« Reply #2 on: December 18, 2011, 03:58:52 PM »
Looks like your off to a good start Nick  :thumbup:

Nothing better than a satisfying afternoon in the shop  :dremel:

Rob   

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Re: Ball or Radius cutter
« Reply #3 on: December 18, 2011, 04:54:00 PM »
Hi Nick  :wave:

 I've lost count of the times I've miss-calculated things.... Often resulting in a re-design  :borg:  There are literally hundreds! :lol:   

I can tell you these tools are fun to use and make all sorts of interesting shapes possible. I use mine for a huge portion of my "styling" work. I quite simply, love the thing!

Not having seen your design thread yet, I just thought I'd ask while I'm here. What cutting tip you're fitting?
I only ask because I have details about double ended inserts that might fit your requirements?

I would always go with a concave and convex cutting toolpost as it opens up the versatility of the tool.

As said, not seen your design... I'll look after and you might have already answered that?



Looking forward to seeing your progress  :thumbup:






Ralph.
I know what I know and need to know more!!!

Offline MadNick

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Re: Ball or Radius cutter
« Reply #4 on: December 20, 2011, 03:34:13 PM »
Evening,

Not much pysically produced today but my learning has improved tenfold.

It was time to countersink the 4 bolt holes on the base. Realising that I didnt have a datum nor two square adjacent edges I was in trouble right from the start and just couldnt get the piece lined back the same position I had it yesterday - needless to say the countersink effort I made using a knackered 3/4" slot drill was unsuccessful and produced a far from concentric result. I tried to recover with a boring bar which worked but by the time the holes were concentric they were too big and looked stupid.

I decided to get the hacksaw out, start again and not make the same mistakes.

After hacksawing another approximate sized block of steel I clamped and faced one edge in the vertical mill parallel to a 'good' side. Realising that each of the 4 holes was going to need piloting, intermediate and then final drill, intermediate and then full countersink I made sure the piece was square to the milling head on the side I faced earlier and at 90 degrees on both X and Y to the head. Neither hell nor high water was going to make me remove the piece from the clamps until all drill/mill operations were complete.

I did my stuff.





It needs finishing and squaring off but I have produced exactly what I was after and worked to a level of accuracy I am happy with.

The lessons learnt today?

1. Spend as much time as needed to setup the piece
2. Make a note of your datum, preferably a corner of the piece rather than the centre of a hole(!)
3. Work out what operations are needed and try to do them all while the piece is clamped in position
4. Make sure all your tools are in the same place - I used a knackered slot drill when I had a brand new, unused one in another cupboard

I know this is probably 'old hat' to some of the pro's out there but i'm sure it will be of use to other beginners.

Nick

@Ralph, thanks for your comments. I bought a double-ended tip from the local toolshop for 1. It 'looks like' one for use with steel. Either way I intended to use a double ended one because then I can just spin the toolpost round to a cut concave radius and vice versa.

Offline DaveH

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Re: Ball or Radius cutter
« Reply #5 on: December 20, 2011, 04:05:35 PM »
Nick,

It looks good to me - Well done :thumbup: :clap:

 :beer:
DaveH
(Ex Leicester, Thurmaston, Ashby De La Zouch.)

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Re: Ball or Radius cutter
« Reply #6 on: December 20, 2011, 09:06:14 PM »
Morning Nick,

Sounds like you're learning a few valuable lessons the hard way! Been there, still do that  :doh: 

I'd like to say it doesn't happen all that often but I'd be lying! I can plan a job for hours and draw it out, make a list of operations and run it through in my head over and over....often re-arranging the order more than once to aid tool swaps, clamping variants etc and I'll still screw it up! Not too often now. But after 4-5 years you'd think I'd have learned!?  :scratch:

Happily you have the end result. The base you wanted to make.... Personally I'd run the next few (centre hole and recess? ) processes over in my head, all the time thinking "will that work, will I be able to hold it to do the next part and can the machine do what I'm thinking of?"

Then I would probably do what I do and end up making the next part fit the bit I did wrong  :lol:

Seriously though.... The order etc is how I personally do it.  As said, doesn't always work... But it gives me a fighting chance!



That is a serious looking baseplate you have there too! How many steps are you putting in for the turret? I suppose I should be patient and wait and see like everyone else?  :)



Could you throw in the tip with one of your next photo's? Someone will be able to identify it I'm sure? You'll need replacements one day!


Hope that's not too rambly... it's early and my head goes a bit funny after 01:30!  :loco:  :lol:





Ralph.

I know what I know and need to know more!!!

Offline MadNick

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Re: Ball or Radius cutter
« Reply #7 on: December 21, 2011, 01:04:02 PM »
Evening Ralph!

Thanks for your thought provoking comments :)

Quote
That is a serious looking baseplate you have there too

Thats because I am into big balls ;) In all seriousness I think Im heading down the path of the over-engineered solution - that base plate is big enough to use as an anchor!

Its time to rethink my design and see if I can come up with something a little more elegant :)

Quote
Could you throw in the tip with one of your next photo's? Someone will be able to identify it I'm sure? You'll need replacements one day!

Good sales pitch lol, ill get one for you for next time :)

Nick

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Re: Ball or Radius cutter
« Reply #8 on: December 21, 2011, 08:35:50 PM »
Nick,

Over engineered... No such thing. Merely engineered differently to other versions  :borg:  :)

Elegance... My first and only ball turner is all square edges and rough as a bears asterisk!
Admittedly I went a little over the top with the mini version.... But that wasn't for me.


Sales pitch... Not from me. Unless you are up in the north of Wales/west Cheshire and need a garage door?  :ddb:  (before and after pictures available on request  :lol:  True though!)

Just knowing that I've gone through 8 or so tips. You might need spares?




Have fun! If you want any help...useful or otherwise we will always try  :mmr:





Ralph.
I know what I know and need to know more!!!

Offline jiihoo

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Re: Ball or Radius cutter
« Reply #9 on: December 22, 2011, 07:49:27 AM »
Hi Nick,

You can use one of these to pick up any hole location with reasonable accuracy:
http://littlemachineshop.com/products/product_view.php?ProductID=1240&category=
or the center finder from this set:
http://www.chronos.ltd.uk/acatalog/Edge___Centre_Finding_Tools.html#aEFS.

If a little less accuracy is enough, just sharpen the end of a 12 mm rod to a 60 degree angle in the lathe and chuck that in the drill chuck or collet on your mill. It is a lot easier to point with that than a drill bit.

I am watching this thread with interest.

Cheers,

Jari

Offline MadNick

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Re: Ball or Radius cutter
« Reply #10 on: December 23, 2011, 03:59:54 PM »
Thanks for the support fellas.

I made a fresh start on my more elegant solution and fabricated the following using some 1/2" plate I had knocking around -



As you can see I used a boring bar to cut the recess for the centre gently, gently and plenty of collant gave quite a decent cut and square edge - I was pleased with it anyway.

Having purchased some thrust washers I really wanted to see if I could come up with a slightly different solution to everyone else



The washers fit really nicely into the recess that I bored out -



Onto my question. You see the lump of ali in the second picture well I want to use that to make the turret with - its exactly the same length as per my requirements but needs to be taken down from 75mm diameter to 56mm, wants a step putting into it and a 10mm hole drilling and tapping to locate it to the the base.

How would I do this please as I am unable to turn the diameter down the whole length of the piece whilst its in the chuck.

Nick

Offline adamriley

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Re: Ball or Radius cutter
« Reply #11 on: December 23, 2011, 06:19:34 PM »
Hello Nick, I recognise that lathe...
Is it a Barker?
I have one too, so will be watching this thread with great interest...


Adam.
« Last Edit: December 24, 2011, 03:17:57 AM by adamriley »

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Re: Ball or Radius cutter
« Reply #12 on: December 23, 2011, 08:12:05 PM »
Nick,

In answer to your question (well, my answer anyway)  If you are putting the 10mm hole through the centre then you can make a simple arbour to hold the turret while you machine it.

Use a bar, as chunky as will fit well into the jaws on your lathe and be smaller than the diameter you wish to turn the turret to. make a section of it the same dia as the hole through your turret and then make a thread on the end of that so you can hold the turret on with a nut.

Or a threaded hole all the way through just screw the turret on and start machining. (you might want to centre drill it and use a live centre for support?)

If you were not making the hole all the way through then a threaded hole for a 10mm thread on an arbour would work too, just make sure the arbour has enough meat for the turret to butt upto when screwed on. (larger dia arbour helps for stability without a tailstock centre for support...)

This next bit might sound obvious but I have to say it. Keep the turret on the arbour as close to the chuck as possible to prevent undue flex and subsequent uneven/tapered finishes.   


If you need a crap-o-cad to aid in my ramblings then I'll sort that in the morning. Getting sleepy! (just proof read this and edited it 5 times... my brian is faulty this time of night!)



Looks like you have a plan anyway....  :thumbup:




Have fun,



Ralph.
I know what I know and need to know more!!!

Offline MadNick

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Re: Ball or Radius cutter
« Reply #13 on: December 23, 2011, 09:36:06 PM »
Ralph,

Thanks again for your help. I was pretty certain that an arbor was the answer - I suppose that in this case I would want to use a blind hole although cant see why I am unable to use a threaded bar the whole length of the turret.

Ill have another crack at this tomorrow and see what I can produce.

@Adam - good spot and yes it is a Barker, quite rare apparently. I keep wanting to strip it down for a refurbish and a coat of paint but it feels like I need to buy another lathe first in case anything needs to be made - does yours have the original top slide?

Nick

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Re: Ball or Radius cutter
« Reply #14 on: December 24, 2011, 02:55:05 AM »
The blind hole on mine is used to set the tension between the turret and the base.

You make the fixing screw too long and then fully tighten it, check the play in it, remove the screw and file/emery off a little from the end. Then repeat until there is a full range of movement and no discernible play felt (feel is the only way to set these up IMO. )


Right.... Xmas shopping here I come!  :loco:    :lol:  Luckily only 2-3 little things from one shop left to buy  :ddb: 




Hope that today's endeavours go to plan  :dremel:  (I'm in my workshop later trying to make a few other Xmas gifts before 15:00! Wish me luck  :borg:)






Ralph.
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Offline adamriley

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Re: Ball or Radius cutter
« Reply #15 on: December 24, 2011, 03:00:32 AM »
Nick, I have the original topslide. The nut has more backlash than I care to admit though...
The lathe, at present, is original other than the 3 phase motor I've fitted, and the QCTP I'll be fitting next week.
I cannot for the life of me though figure out the backgear system.
Unfortunately I'm missing a LOT of the changewheels, and no 4 jaw chuck.
I might have to try turning a backplate at some time in the near future, and picking up a chuck.
Have you done any mods to the lathe at all?

Adam.

Offline MadNick

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Re: Ball or Radius cutter
« Reply #16 on: December 24, 2011, 08:34:03 AM »
Afternoon,

Ive spent the morning making lots of tinsel out of ali.

Ralph's arbor suggestion in use -



The turret fitted -



I am really pleased with the results - the mandrel really made it all work for me.

Re the countersunk bolt to supply tension between the base and the Turret - the one I have is clearly too short, looks like ill have to wait until after Christmas now but I will try your suggested method of making it fit. In the meantime I can start on the toolpost and swivel arm.

It would be great to get it working before I return to work when my freetime will be siginificantly reduced.

Adam, have PMed you about the Barker.

Merry Christmas everyone.

Nick

Offline 75Plus

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Re: Ball or Radius cutter
« Reply #17 on: December 24, 2011, 09:58:21 AM »
Nick, do not forget that you need to keep swarf out of the thrust bearing.

Joe

Offline MadNick

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Re: Ball or Radius cutter
« Reply #18 on: December 25, 2011, 05:41:22 AM »
Thanks Joe,

Im working on a collar for that :)

Nice bike BTW - is that you?

Nick

Offline 75Plus

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Re: Ball or Radius cutter
« Reply #19 on: December 25, 2011, 10:26:00 AM »
  :offtopic:

 Yep, that's me. The bike was a 1952 Harley 45 cu. in. flathead. The picture was taken in 1956. A lot of water has passed under the bridge since then.

Joe

Offline MadNick

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Re: Ball or Radius cutter
« Reply #20 on: December 27, 2011, 12:37:15 PM »
Evening,

Back on topic ;)

I cut the toolpost out this afternoon -



Theres quite a lot of work in this part alone. I need to profile the upright to sit just behind the cutting tip on both sides, machine a slot down the side to accomodate the fixing screws and work out how to machine a recess for the tool to reside in.

Then of course it has to be a nice tight fit in the slot that I am yet to machine in the turret - I might do that tomorrow.

Nick

Offline philf

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Re: Ball or Radius cutter
« Reply #21 on: December 27, 2011, 12:57:26 PM »
Nick,

Before you cut the pocket for the insert have a look at http://mikesworkshop.weebly.com/ball-turner.html

When I eventually get round to making one I'll certainly incorporate his ideas.

Cheers.

Phil.
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Offline DaveH

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Re: Ball or Radius cutter
« Reply #22 on: December 27, 2011, 01:07:14 PM »
Looking good Nick  :thumbup:  :thumbup:  :thumbup:
 :beer:
DaveH
(Ex Leicester, Thurmaston, Ashby De La Zouch.)

Offline MadNick

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Re: Ball or Radius cutter
« Reply #23 on: December 27, 2011, 02:42:50 PM »
Thanks for the support :)

@philf how many ways can there be to make the same thing?!

Nick

Offline Bert

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Re: Ball or Radius cutter
« Reply #24 on: December 27, 2011, 04:11:33 PM »
Hi all


  Simple answer!  If 10 people are making the same thing......10 different ways!!!

Regards....bert