SpudFiles

I bet that this would work nicely to make a hybrid cartridge that will take high mixes



that is a gudgeon pin from a Earth mover it is made from 20MnCr5 steel and is seamless of coarse

you could probably get a wheelbarrow full of them from places that repairs those big earth movers for the price of a couple of beers, or you can get them from the scrap yard, just walk up to the owner and hand him a six pack and ask if it would be ok to look for a few odd chunks of steel.

Since it is made from high quality steel I would bet that you could make a pretty high mix cartridge. I am going to let the other speculate on how high mix you would be able to get in there cause I am still pretty clueless on hybrids

I think I want to make a mini hybrid from this one

Is that a metric caliper? If so, my calculated burst pressure is 136,500psi.

So, 1365x... Effectively 320x butane/propane, because of liquification.

I'd use it for a 20mm receiver, and make brass cartridges... and a bolt...

Where did you get this one?

correct it is a metric caliper I got that specific one from a mechanic who fixes bulldozers but you will find plenty of those at the scrap yards or shops that fixes those tipes of engines. After seeing your estimated burst pressure you got me inspired to make a high mix mini

Hmm... Glued up my prototype now to let it cure.



Also considering doing a piston hybrid cartridge, but that would e in the distant future

UPDATE- bollocks the pvc cement didnt really work may have tofind some more.

Heimo wrote:I bet that this would work nicely to make a hybrid cartridge that will take high mixes

Not if you wanted the cartridge ejecting, it would knock out anyone standing next to you...

the pvc cement didn't really work may have to find some more.

... or discover the joys of epoxy adhesive

I made a cartridge and a barrel/breech, it will need another 24 hours to cure though as it's bloody cold and it's too big to fit in the oven. I'm very confident it will blow back succesfully, I've learnt a lot since I last gave this idea a go. With a 40mm O/D cartridge there's almost 2lbs of force on it for every 1 psi so it should have more than enough energy to push back a bolt spring and overcome the friction of the other cartridges from the magazine.

I'm also using thinner walled PVC tubing for the body which is also shorter than my previous attempts, so the all-up weight of the cartridge should be lower.

Another worry I had with my previous attempts was that since the cartridges were coaxial, I wouldn't be able to centre the mouth of the cartridge with the breech, since I work with very basic tools. The simple solution to this was to wrap a section of barrel material with strips of tape until it reached the diameter of the cartridge body, this is a neat and simple way to get a perfectly centred cartridge every time.

The plan now is the make sure the cartridge works and blows back smoothly, then proceed with the construction of a suitable sprung bolt with ignitor contacts together with an ejection mechanism along these conceptual lines.

I would love to use epoxy.

Unfortunately no money to buy it. In a couple weeks im going to buy alot, but as for now, not happening.

What calibre doyou plan on using? 1.25"???

Hopefully i can get it reglued up today (fingers crossed)

JDP12 wrote:What calibre do you plan on using? 1.25"?

It's 0.75" calibre, which will give me the possibility of using 12 gauge wads. The cartridge body itself is 1.575" O/D, 1.417" I/D and 6" long.

nice.

Should get a fair bit of force out of it to eject it like you said.

I'm testing a slightly smaller one- 1.050" ~~ ID and a .75" barrel.

but I need glue first damm!t

I'm thinking of building a combustion cartridge prototype too. How is your progress jack? Any new pictures or videos?

Prototype here, I stopped working on this project though due to disappointing power.