I am thinking of gluing a stack of coins from my own country and then have them drilled a big hole in the stack - like the stack of coin gaff.

My question is - after the gluing part is done, and when the drilling start, will the coins come apart? if so, what kind of glue is recommended for sticking coins together. Any other suggested method?

Your assistance is appreciated. Thanks!

I have always used epoxy for stuff like this, but the new polyurethane glues such as Pro-Bond or Gorilla Glue should also work well. Be sure to follow the instructions, clamp tightly, and don't apply too much adhesive, or cleanup could be a problem.

As for separation while drilling, this is always an issue, but if you start with a small bit, firmly clamp the work, lubricate the hole as you go, and use a light, even pressure with the drill press (don't try this with a handheld drill) I think you will be fine.

If you can find it, "JB Weld" is made specifically for metal and can be used to re-anchor engine components to an engine block. The compound can be machined and ground for smoothness and as we know that can generate quite a bit of heat which is generally hazardous to other forms of epoxies.

FWIW

Cheers!

Might it be better to drill them separately and THEN glue them together?

Whay not take them to a jeweler and ask them to solder the coins together?

Yep, clitonmagnus is on the right track. Epoxy, clamp and drill while clamped. Do not try to drill them separately because you'll never get the hole exactly the same for each one and you'll have rough edges. Finish off the centre with a round file (not the one you put your rubbish in).

Thanks for all the advises. I'll try it out and see what comes out. It is the drilling after the gluing that worries me. Experience will teach me, I guess. Thanks again.

If you clamp the coins in a drill press vice and use a sharp drill bit you should not have a problem. For best results I would use a little oil while drilling.

Thanks, Remote Guy, I'll remember the oiling too. Really appreciate the tips from everyone.

Did you think of the exact size of hole you intend to drill (weight of the gimmick at the end)?

I would stack them before drilling because sometimes tear-out may be a problem.
Drilling incrementally larger holes is suggested, using oil as a coolant. The heat of large bit may break them apart if you don't.
PC 11 available at many stores, is 3 times better the JB weld. It takes a day to cure but is top notch.
I'd still rather see them silver soldered though.
The best suggestion is, spend 10 dollars to have a machine shop make the hole with a lathe then you can stop the drilling at the depth you plan. They can do it in ten minutes, you may take over an hour depending on how big the hole is and you may possibly mar the edges of the stack unless using the correct vice or collet.

Thanks, Jay Leslie. If it does not work out for me, I may as well get a machine shop to get it done for me.

James,

If you are familiar with a jewelers saw, you could drill a small hole and saw out the desired diameter needed.

As far as gluing or soldering the coins together, you might consider using pins or rivets so the coins can have some natural movement, but not come apart.

Drill two holes only part way through the underside of the top coin; one hole for the pivot pin and one for the stop pin. Then silver solder the pins in the holes.

The rest of the coins will have the centers removed either by sawing, drilling or turning on a lathe; with an additional hole corresponding with the pivot pin, large enough to allow movement of the stack. The other pin will be just inside the large center hole to restrict the pivot so not to expose the secret.

The pivot pin hole in the bottom coin will need a countersink so the hammered end of the pivot pin will be recessed, so the stack will sit flat on the table surface. Wile peening the pivot pin you will need to place a shim between two coins in the stack, so the coins can move once the shim is removed.

I know this is some what more complicated but I believe the results would be worth the effort.


Tom

Thanks, Tom, excellent tip. I did not think of the coins being able to move which is more realistic. I'll give it a try and see how it goes.

How about getting some Danish coins? - they already have a hole through the middle.

I'm using them here as they are so different from the coins in the Gulf. Audiences seem to think they are magic coins.

How big are the holes, for those Danish coins?

Using an epoxy or Gorilla glue on coins seems to be too hard of a smooth surface against the cured epoxy, even if you rough it up a bit.

If you encounter a change of temperature, the differing speeds of temperature change for the coin and the glob of epoxy may invite a full separation of the pieces, leaving you in a bind.

I prefer something more flexible and forgiving, I suggest E6000 or Shoe-Goo. Just much more flexible and less likely for a full unattachment at one time.

JF

James Tong

Sorry for lateness of the post, forgot to check back last week

Holes in Danish coins vary between 4.5mm and 5mm

Many are worn as necklaces with a leather throng through

I find that the country of the coin, and the metals used, makes a difference in how I can hole it. I have used a large rotary punch in a machine shop for many coins with good success. One pull of the lever and the hole is done. If the hole is large compared to the size of the coin you might need a backing piece of metal to keep it from buckling or binding. Use of oil here is also a good thing. The machine shop guys will help here, and it is faster- at least for me, than clamping and drilling.
After being holed, it is pretty easy to solder pin, or glue up the stack.
k