Smooth off one side of a coin?

GTJC460 · Nov 11, 2015

I would do like doc...KISS!

Use some CA glue to glue the coin to a piece of wood dowel. Then hit it on an 80 grit belt sander. Should make quick work of it. If the dowel isn't warped it'll act a "truing " fixture

peteb · Nov 11, 2015

Use double sided tape and tape to a precision ground steel flat then go to machine shop and surface grind carefully. If the tape is good (apply pressure to insure flatness) they will not move laterally and are easily removed with alcohol.
I remove background material with a 1/8" or 1/16" end mill on .010 niobium, to a depth of .002 in platinum or sterling with this rig which is nothing more than 2 6"x8" granite surface plates, the bottom fixed and the top one floats while the cutter rides on an extended micrometer head. The precision milling head is mounted on an old chop saw frame. Hope this helps.

bartelfitzneel · Nov 11, 2015

I am very curious as to how these methods work out. I would like to smooth one side of coin so I can load it into a shotgun to make dies. Much like this:
https://books.google.com/books?id=x...Ch34XAkb#v=onepage&q=shotgun coin die&f=false

Sam · Nov 11, 2015

Thanks for suggestions and offers to help.

This took just a couple of minutes on the Powerhone starting with a Gator 320 wheel and ending with a 600 grit. Then a few swipes on some wet or dry sandpaper. I held the coin down with my fingertip and it slipped off a couple of times but it went pretty smoothly and I was able to maintain consistent thickness.

This is a Roosevelt silver dime for practice. I'll get some Mercury, Barber, or seated Liberty dimes on eBay.

JOEYS CARVED ART · Nov 11, 2015

That's exactly how I do it, I just hold it down with my finger, it doesn't get too hot if you keep it at a decent speed and yes it does fly off every now and again but after you do several you get the hang of it. I hold it on the lap before I start the machine that way you don't have to worry about putting flat spots on any angles but the flat face. Great job Sam!
Joey

Brian Marshall · Nov 11, 2015

Pretty much the same as I do...

Might wanna add in a dop stick and save your finger tips, plus there will very likely be no slips if you use one...

Chop up a wooden dowel of a slightly undersized diameter to 3" lengths and get hold of some lapidary cement. It's cheap and reusable.

Add a small mason jar of alcohol for cleaning up any particles that remain after you knock 'em off with a rawhide mallet. Or you can put them in the freezer to release 'em.

Brian

Marrinan · Nov 11, 2015

Sam, Some years ago I sent you a coin clamp along with one of my X Y axis six by six microscope centering fixtures jigs. Each on the four coin holders is exactly half the thickness of the coin it holds. Jig was designed originally to make two headed coins. You have never mentioned using either the 6 inch centering jig or the coin holders. The coin holders were designed for exactly what you want to do if they are not in the scrape bin. Fred

Brian Marshall · Nov 11, 2015

I have both of those from you Fred. But I never thought of using the coin fixture as the holder for this particular purpose...

Guess if there's a next time, I'll have to remember to give it a try. Easier than dopping 'em!

Brian

Sam · Nov 11, 2015

Marrinan said:
Sam, Some years ago I sent you a coin clamp along with one of my X Y axis six by six microscope centering fixtures jigs. Each on the four coin holders is exactly half the thickness of the coin it holds. Jig was designed originally to make two headed coins. You have never mentioned using either the 6 inch centering jig or the coin holders. The coin holders were designed for exactly what you want to do if they are not in the scrape bin. Fred

Yep, I have 'em here in my tool cabinet, Fred.

Brian: The only thing I'd worry about with a dop stick is keeping the coin flat on the lap. I've not tried it though, but I will.

Brian Marshall · Nov 11, 2015

Maybe I forgot one small detail? I am slowly spinning the dop stick between my thumb and forefinger, choked up close to the coin, not out at the end of the stick... you can "feel" the flat.

If you really like the fingertip way - then get yourself some of those rubber fingertips we used to use for engraving to keep the calluses down.

Back before swittching over to silicone fuel line tubing 10 or 15 years ago... Office supply would have 'em.

Not only give you a better non-slip grip, but insulate a bit of the heat if you get the coin warm.

But yeah, since Fred's fixture is a flat bar only 1/4" to 3/8" thick (can't remember for sure) it might be the better way to go?

Only thing I see with using it is that you won't be able to see the coin while grinding it... with a dop you have more visisbility.

Dunno 'till I try it. Got none to do right now.

Brian

thughes · Nov 11, 2015

Sam,
A piece of double stick tape on the coin takes care of the finger slip-off issue. at least it's worked for me on similar stuff.

Todd

Sam · Nov 11, 2015

thughes said:
Sam,
A piece of double stick tape on the coin takes care of the finger slip-off issue. at least it's worked for me on similar stuff.

Todd

There's a good idea! Thanks Todd!

oiseau metal arts · Nov 11, 2015

doesn't using the lathes and power hones loose the silver you grind off?
thatll add up quickly after a while.

JOEYS CARVED ART · Nov 11, 2015

That double-sided tape trick sounds like a good idea, I'm gonna try that the next time. Thanks for the tip!!
Joey

Ron Spokovich · Nov 11, 2015

As 'oiseau metal arts' said, the metal loss would add up over a period of time, depending on how many coins you do. When I did my stuff on the jeweler's lathe, with the razor sharp tooling, I merely picked up the stringers with tweezers or fingers, and put such into a little jar or vial. Properly cut, minimal finishing remains, with minimal finishing required.

Sam · Nov 12, 2015

Ron Spokovich said:
As 'oiseau metal arts' said, the metal loss would add up over a period of time, depending on how many coins you do. When I did my stuff on the jeweler's lathe, with the razor sharp tooling, I merely picked up the stringers with tweezers or fingers, and put such into a little jar or vial. Properly cut, minimal finishing remains, with minimal finishing required.

A lathe would be the ideal way. You can preserve the rim and recover the shavings.

Brian Marshall · Nov 12, 2015

I am surprised that you DON'T have a watchmakers lathe Sam? Just to pet once in a while as you walk by.

It's also a cool tool to add statistics and credibility to the "Coolness Chart"...

Brian

Sam · Nov 12, 2015

Brian Marshall said:
I am surprised that you DON'T have a watchmakers lathe Sam? Just to pet once in a while as you walk by.

It's also a cool tool to add statistics and credibility to the "Coolness Chart"...

Brian

You're right Brian. I'd love to have one and this might be a good excuse to buy one

Brian Marshall · Nov 12, 2015

Not many people could pay for one in pennies, nickels, dimes, or quarters... few dozen of the right coins ought to buy you the best available?

B.

RDP · Nov 13, 2015

Here is one to look for Sam,

https://www.youtube.com/watch?v=Y1bvyFG3hWM

but I think you may need a bit more than a few dozen coins to buy it,

Richard.

Smooth off one side of a coin?

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