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
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:
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
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:
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]
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
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.
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
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
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
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!)
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
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.
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
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