here's a weird one. I've got a client who's wanting me to help him
work out the manufacturing aspects of making custom coin holders.
I would skip all the other ideas and go straight for the ring
roller. The reason is this, a basic ring roller is a very inexpensive
design, for the dimensions you want it is well within the
capabilities of compression of a ring roller and the advantage is
that all you would have to do is purchase standard strip, or if you
buy enough, they could probably cut custom at a reasonable price.
Now if you don’t mind, lets look at your problem a little deeper;
All measurements are with used coins out of my can and a
non-calibrated electronic caliper and double stacking my glasses to
see contact points, for the sake of completeness, my glasses are a
1.75 and a 2.25 pair of readers.
24.19 mm Dia.
22.33 mm inside at bevel
23.33 mm at top of outer bevel
1.69 mm thick at edge
A standard US Quarter has an overall diameter of about 24.19 mm with
a variance of .04mm. The inside dimension edge to edge is about 22.33
mm and bevel to bevel is 23.33 leaving an actual grip surface of
about.93 to.88 mm or a rim variance of about.05mm. The beveled edge
on a quarter is ~ 0.43 mm wide. The thickness of the edge of a
quarter is about 1.69 mm overall.
17.91 mm Outer diameter
15.81 mm Inner diameter dif/2 = 1.05 mm lip width
17.09 mm inner edge at the bevel/2 = 0.41 bevel width
1.36 mm thickness
Snagging some coins from the wife’s collection, I do not see a whole
lot of difference in construction except ours seem to be the only
ones with the outer bevel, I don’t know what she did with the
As you do not say what this will be used for,.25 mm in a static
display with 30 gauge would hold, if it is to worn our used, I would
go with a minimum of.6mm depression and 26 to 22 gauge or more.
I think you may be over estimating the difficulty of holding the
strip as it goes through the roller, I think a simple bracketed slide
guide would be sufficient for the tensions and materials you are
using and more than likely you will be using spooled material to feed
I would suggest that you not make the roller square, if you do the
metal will want to stick to the form, and at higher speeds this can
be a real disaster. I do not know what the modulus of elasticity for
silver is, so you will have to experiment a little for that value.
This will affect how deep the channel will have to be in forming for
a given depth of the final channel. It should be easy to calculate
the displacement of the groove into the channel width you are looking
to make, again, do not use square corners or sides, it ‘will’ stick,
I think 3 degrees was what was used, a over should not be a problem.
Hope this helps