*********Oh and note... sharp edges of the holes can cut through thread, (*****************
Buy a little thing called a "countersink" at any industrial supply - like where you'd buy the drills.

I haven't seen the link Cliff, but I'm betting it refers to a tool something like this:

www.contenti.com/products/...0-057.html

As luck would have it, I've never seen such a tool, but I do use a little pair of 6 inch Vice Grips now and then (to hold small items while drilling using a drill press)

My $.02.

Drilling and deburring holes through coins can be accomplished in a number of ways, some of which are quite tedious.

1) Hand drill (or pin vise) + pliers (preferably locking) + jewelers files (for deburring) <-- very slow and tedious

2) Power drill or Dremel tool + pliers <-- still slow and tedious, but better than #1

3) Drill press + clamping device (either pliers, watch vise or custom jig) <-- faster, potentially more accurate

Personally I would choose #3 because I already have tools required. I might build a jig, but would be more inlined to buy one b/c they don't seem to be too pricey and I collect tools.

I would stay away from "gang drilling" and stick to one coin at a time b/c I've found that the torque of drilling usually causes problems no matter how clever I try to be in stacking round blanks together and then clamping the result for drilling. I'm not saying that a jig like the one Wil suggests could never work, I'm just saying that I've tried similar setups in the past with mixed results.

A while back, a girlfriend wanted me to drill some Morrocan brass coins as charms for her bracelet.
Not wanting to invest a whole lot in specialized equipment for the sake of doing a handful of coins, I devised a cheap effective way. And this uses some tools that people usualy may have around the home.
First get a centerpunch and hammer a dimple into each coin where you want the hole to be. This so the drill bit does not wander and scratch up the coin whist starting the hole. Presumably the hole is to be at the top of the design so that the face or design or writing or whatever hangs straight up. This has to be done individually for each coin, and by hand.
Then get a pair of large Visegrips adjustable clamps and glue bits of leather to its jaws. The leather facing prevents scratching or defacing the coin design. Clamp the coin to the edge of a board. IF you need to then clamp the board to the edge of a table. Then drill using hardened metal drillbits, such as are suitable for metalwork. After having completed the holes you may want to use a larger sized drillbit to bevel the rough hole edges so that they are smoothed.

Another nice effect is to wire brush the coins to bring out a nice luster.


I fail to see the advantage of utilizing a positioning jig in that each coin has to be eyeballed and punched and clamped iand drilled ndividually.