Different Burst Disk holder ?

[Rob748]

Well Im putting together my biggest advanced combustion cannon, its a 4 inch chamber about 24 inches long, with a 10 foot barrel for a .8:1 ratio. I bought the threaded end coupler and a ball valve, just need to get from a 4-2 in reducer to the 1.5 inch ball valve. This costed me $22 so I didnt have enough money for unions, so I bought these threaded coupler things, the ones that people use to screw barrels on and off. I had an idea, I put aluminum foil over the threads ( 3 layers ) and threaded the barrel back on, and it went on all the way. Is this a method of using a burst disk ?

[Radiation]

There's no way a standard combustion will blast through 3 layer foil. And your idea will yield nothing but threads that chew though your burst disk losing it's air tightness.

[Rob748]

Im sorry, its a advanced..... 3 layers should only be around 50 psi. I think it would be able to clear it. Hgdt says there will be 106 psi built in the chamber so im betting there will be atleast 50 being built. And the threads thing, its airtight, I cant blow air past it. and I tried till my face went red. I guess Im just going to have to get $50 and show you guys when its complete. O and wehn I say advanced.

4 in* 26 inch chamber ( it got longer with the couplers)
2 in* 120 inch barrel
7 gap spark strip- a spark per every 3 inches
Metered Mapp or Propane
92mm Brushless fan running on 12 volts or 9 volts
Barrel Connectors which I used foil over the threads to make a burst disk and it works
Electronic Gas sparker

[inonickname]

He's talking about a union. Yes it will work. Do the threaded connectors flare out, and it has an o-ring seal.

As a point of note: your lungs generate around 2 psi, but if it's a union then it will probably be airtight anyway.

[Rob748]

I dont think its a union actually. ahah i used a male adapter and a female adapter, I wrapped the alluminum over the male adapter and screwed it into the female....hehehehehe ..... lol and I already have the spark strip built, my idea was that if 3 sparks is good then more is better giving more of a "detonation" instead of spots in the chamber that take up time to burn. I figured it would be more boom then fwoof, lol and no im not saying three isnt good, I just think if u can distribute more sparks farther down the chamber all the more chance of never having a misfire and having more explositivity. Im still complicating on using dual fans, Havent you guys ever put your face into the chamber when the fan is on to feel the air that its pushing ? Well on 12 volts I can barely feel the breese and I mean barely, And I know two fans would be all the better in flow wise and ventilation terms

[jmeyer1022]

I think hes just talking about a male/female clean-out for barrel swaps such, as shown here:

[youtube][/youtube]

Anyways, I think it will work. 7 gaps is overkill and a half though. stick to 2-3 tops on a spark strip.

[Rob748]

Hey Jmeyer I think ur work is excellent and I love ur cannon, mines being built like urs just a bit smaller at 301.6 ci

[starman]

I guess Im just going to have to get $50 and show you guys when its complete.

$50?? How about just a few photos of this thing you're building?

[Rob748]

Im going to have photos tommorow if I can borrow a friends camera. Ive already spent 40 on this..... 4 inch pvc parts are expensive, the total price of this gun is about $110

[jmeyer1022]

Rob, that's not mine all credit to Verboten he roams the forums time to time I just think his videos are useful and often relate to peoples build ideas, I have 2" piston pneumatic and a small 3" advanced combustion I plan on redoing into a 4".

[inonickname]

Oh ok, it should work but if doesn't, get one of these:



Dirt cheap, o ring seal, easy to screw together, available in a huge range of sizes, PVC, cast iron, abs, poly..what ever you want.

Good luck

[starman]

Im going to have photos tommorow if I can borrow a friends camera. Ive already spent 40 on this..... 4 inch pvc parts are expensive, the total price of this gun is about $110

Decent advanced combustion's costs will add up. Don't be surprised if you aren't finished spending money yet.

[psycix]

You can use an union, but for faster reloading, use a cam-lock.

There's no way a standard combustion will blast through 3 layer foil.

There is.
You could blast through thousand layers, if the diameter is large enough.

[Rob748]

Yeah I know this thing could blast through 3 layers cause I have a mini that blasted through 3 layers .5 inch in diamter...... you probably wont belive it but it did as it blew in half lmao. BUT it did go through.