Thread: Cap maker

Proving I do something else other than talk about dust here's a project I knocked up this weekend. It's a cap maker for a gun. It turns pieces of aluminium can into small dimples that a tiny bit of detonator is put into to act as a blank for a bit of black powder tomfoolery.

The one on the right is the one I was copying from, the one on the left is the one I made. The little caps these make are on the table in front


Here's what the inside looks like.

The allen bolt acts as the inner former while the spiked punch pierces the aluminium and wraps it around the former.

the al sheet goes in the slot here and the punch is whacked down.

I don't have access to 'detonator' but I can legally purchase powder for reloading, would this work?

Be careful, you might get shut down by the fun police.....

Is it still possible to buy the old school paper roll caps anymore?.

Originally Posted by Graziano

Is it still possible to buy the old school paper roll caps anymore?.

I have heard about some people using these ally shells as holders for old school caps by cutting up 2-3 caps and putting them inside these little ally shells.

Originally Posted by Gerbilsquasher

I don't have access to 'detonator' but I can legally purchase powder for reloading, would this work?

I believe not.

Usual warnings about playing with explosives. Depending on the can, you may get fragmentation when the fulminating compound goes off - eye protection advised. Missing finger nails - or whole fingers - are your problem.

You can still buy proper, annealed copper pistol & rifle caps, lovingly made by German Fauleins at RWS (they go thru a truck load of beer every day - its not that exciting).

Hi Bob ,
It appears you have a charcoal burner!
The commercial model of this same tool was available in the seventies for use in making percussion caps that fired muzzle loading blackpowder firearms.

The cap was placed over a nipple attached to the firearm's lock and struck by a cocked serpentine hammer thus igniting the blackpowder in the guns chamber and firing (usually) a patched ball.

Aluminium sheet from soft drink and beer cans was used.The tool was a Forster Tap'O Cap and indeed each cap was fired by a couple of cap gun caps.

Used as intended they are quite safe but I'd be inclined not to mess around with fulminate compounds for safety reasons.

A nice little project.

Grahame

Cheers Graeme,

Thanks for the info.
The unit is not for me. It's for a relative who is in a black powder club.
I believe he'll be loading the fulminate into the caps at his club.

Cheers
Bob

If you feed the cap maker with dead soft annealed sheet, does it make a neat wrinkle free cap?.

Originally Posted by Graziano

If you feed the cap maker with dead soft annealed sheet, does it make a neat wrinkle free cap?.

I doubt the punch and former are fitted well enough to do this. The punch I made has 8 points that pierce and cut the ally circle which results in 8 folds, which means that the resulting cap is not as neat as the 10 fold cap the original produces. the reason I used 8 points was that it is easy to divide a circle up into 8 sections but I will now remake the punch with 10 points and do the divisions on my small rotary table.

Does anyone have an idea how the punch and die could be fitted to create a wrinkle free cap?

Bob, to go wrinkle free you have to draw the cap.
Typically to do that you will need to clamp the material (that is, sandwich it between two plates) and then push a punch into it. The sandwich bit is the trickiest, as the material needs to be clamped just tight enough that it can be drawn into the recess by the punch without being so tightly clamped that the material will yield.
A search on a term like "deep drawing" will probably bring up a few pages that will give you a few ideas.

Michael

I remember years ago while doing a Tech coarse, we went on an excursion to see how AA batteries were made at Union Carbide. My recollection is a bit vague, but they were punching a small disc of zinc with a mechanical system that made the zinc, when struck, form a tube around the punch. OK I know zinc is soft and they may have introduced heat as well but may be you could try a larger disc over the correct sized hole to give you a wrinkle free cap. I have also seen pipe caps being made. From 25mm X 25mm square right up to 100mm diameter (both square and round caps for finishing fence posts). they were thumped into the finished state with a 90 tonne press and they were doing about 2 per second out of flat galv sheet steel.
have you ever put a coke can into a broaching press and place just so and have the can's top get pushed down into the rest of the can and you end up with the writing on the can, on the outside as well as on the inside, but the can is only half as high as it was when you started. the bloke who was demonstrating could only get about a 25% success rate. Most of the time the can would just squash flat

I'm imagining a tool like those plier type leather hole punches, that clamps the sheet between the fixed jaw and spring loaded moving jaw and as it squeezes further pushes a pin into a loose fitting hole to draw the cap and then shears of the rim of the cap from the sheet with a close fitting base of the pin. Keep in mind I have no idea of how sheet metal drawing works, maybe a quick and dirty prototype pin and socket hit with a hammer would test it out, would need hardened parts I imagine.