machining small object washer sized

Hi,
I would like to machine a small object using my lathe, basically I have
an object thats 2p coin sized and I would like to half its thickness
using a lathe.
I struggling to hold the workpiece in the chuck to any degree of
accuracy so that I can machine to the edges.
Can anybody suggest the best way to hold something like this?
Thanks
David
Reply to
googlinggoogler
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Hello David, Yes,...superglue the object on to a larger piece of material, then true that up in the chuck and face off to whatever tkickness you require, the object can then be removed using a thin blade between object and backing material. Works for me every time. All the best for now, John.
snipped-for-privacy@hotmail.com wrote:
Reply to
john.morton22
You want to make a double headed 2p piece? Why not be a bit more ambitious, try a £2 coin?
Cheers Tim
Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service
Reply to
Tim Leech
Tim, Would be interested to see that done, how would he hide the join especially as the copper coins of today are steel with a copper coating. Pass a magnet over some coins and see what happens.
Martin P
Tim Leech wrote:
Reply to
Campingstoveman
The £5 coin is made from cupro-nickel, and is an almost-perfect blank for the 36mm turbine wheel-and-blades in a small turbopumped rocket engine. Except it costs £5, of course!! A chap I know in Canada uses nickels (for teeny rockets).
[running in 80% oxygen at 700K and 1,400 psi]
Reply to
Peter Fairbrother
Yea its for a double sided 2p coin,
I wanted to get my technique correct before destroying loads of =A32 coins, I tried filing down and then ringing them together and that kinda works but its messed up but the join and gluing although they hold together well just rung together.
I like the superglue idea, will give that a go.
I've heard that the center of a =A32 can be punched out, and therefore the join wouldnt be noticable as it would be hiden, which is why I wanted to use one.
If that isnt the case it will still be easy to machine out the centers and replace them.
thanks for the advice guys,=20
David
Reply to
googlinggoogler
There are two main ways.
1) Soft jaws bored to the required depth. I use mine all the time for holding washer type workpieces. 2) Glueing the object to something larger that you can hold or directly to a backplate.
There is a third way if the front edges of the jaws on your 3 jaw chuck are sharp enough to grip properly on their end mm which is to mount a backstop inside the spindle which the workpiece can be pushed up against.
Reply to
Dave Baker
David wrote ............
Yes, David, the centres can certainly be pushed out - I know that when these first came into circulation there were at least three with the centres reversed! :)
Mike
Reply to
Mike Whittome
I use something called a wax chuck. It uses sealing wax on a faceplate. Heat everything up till warm and carefully position your work, you can't take great cuts, but it doesn't hurt if you trim the wax during machining. Very easy to use, very quick, and re-usable, I believe it was a watchmakers dodge, though my mentor taught me.
Joules
Reply to
Joules
I was taught the same thing, but using shellac instead of sealing wax. Shellac traces will dissolve in meths to leave the object clean.
Peter
Reply to
orrerymaker
Most glues break down when heated; if you have trouble getting the coin off with a blade, a gentle blowtorching to above 150-200'C will help. Less likely to mar the copper coin face.
There's also a trick to making perfect double-faced coins. I'm not going to reveal it, but I'm sure it's somewhere to be found on the net...
cheers Guy
Reply to
Guy Griffin
We all like secrets, don't we? Anyway it intrigued me enough to make me think about it.
I guess the problem is to disguise the join on the edge. So how about reducing the thickness of one coin in the middle only, leaving the thin rim around the edge to full thickness? Reduce the other coin to half thickness and reduce diameter to fit a close in the recess made in the first one. Pop one into the other and the join won't show. Superglue should be enough to hold it. I'm assuming that most (all?) coins have the narrow raised rim around the edge.
Henry (Trying to contribute for a change!)
Reply to
Dragon
Hi,
I would like to machine a small object using my lathe, basically I have an object thats 2p coin sized and I would like to half its thickness using a lathe.
I struggling to hold the workpiece in the chuck to any degree of accuracy so that I can machine to the edges.
Can anybody suggest the best way to hold something like this?
Thanks
DavidHi,
I would like to machine a small object using my lathe, basically I have an object thats 2p coin sized and I would like to half its thickness using a lathe.
I struggling to hold the workpiece in the chuck to any degree of accuracy so that I can machine to the edges.
Can anybody suggest the best way to hold something like this?
Thanks
DavidHi,
I would like to machine a small object using my lathe, basically I have an object thats 2p coin sized and I would like to half its thickness using a lathe.
I struggling to hold the workpiece in the chuck to any degree of accuracy so that I can machine to the edges.
Can anybody suggest the best way to hold something like this?
Thanks
David
Reply to
James Lugsden
Don't ask, but I can tell you that this technique works very well! (In olden days 'defacing the coin of the realm' was a serious offence)
Peter
Reply to
orrerymaker
Hi Regarding the washer making, I used to make shovepennys for my local pub and ended u= p making sets for 5-6 pubs. This may be ok if you are making a few . =
I used a piece of Gas Barrel about 6" long of suitable diameter
I first chucked it up and turned a suitable recess for the coin/washer Then I hacksawe= d down length ways for 2 or so inches each cut 90=C2=BA to each other ( four cuts). I cut o= f the remainder of the tube 0.5 " from the end of the cuts. Then I re-fitted into the chuck A four Jaw concentric chuck would be useful if not make= only 3 cuts at 120=C2=BA, for a 3 jaw chuck, on replacing it in the tightened chuck I re s= kimed the recess then inserted. I could have a batch run of 10 or so coins. but if i took i= t out it would need re-skimming. You could also use a meaty jubilee clip to crimp the cuts to grip the coins.This will de= pend on the strength of the jubilee clip if the hold is sucessful. Good luck. Mal.
Reply to
Malcolm Ewing
Oh yes, Mal again, while turning down shovepennys I intended to make a holder out of 1.25" Gas Barrel it was simple. 3"" 0f tube one wide cut of 3 mm wide 2"" long along the length of the tube bore a hole 1" from the end use a bolt and nut or tap one side and use a allen bolt. with the uncut end of the tube in the Chuck turn a recess to hold the coin/washer insert the washer and away you go, you will need to re-true the end every time you remove the tube from the chuck. Mal
Reply to
Malcolm Ewing

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