I believe the primary reason for multiple ignition points is to create multiple flame fronts inside the chamber during ignition, which theoretically deceases the time required to achieve peak pressure and helps to ensure complete combustion. However, I'd bet that the difference is only a few ...

As others have pointed out, make sure the chamber is serviceable so you can adjust spark gaps or fans or etc... if needed.

I accomplished this by attaching the reducer at the "back end" of the chamber (farthest from the barrel, where my vent valve is located) with six carriage bolts instead of glue ...

A very similar system has been used (with a 3-way valve, sometimes a 3-way solenoid valve) on several cannons to great success. Some people have even created a "one-touch meter". So yes, your idea works perfectly. Unfortunately, it's not new - but it's still a great idea.

Nice rendering, by the way ...

Alright- here's a sketch of what I have in mind. To fuel, I'd meter in the appropriate amount of propane Then, I'd port the proper amount of air, allowing the pressure gauge to find the pressure for the whole chamber. Is this correct? (also, forgive me for continously finding something to ask about ...

I think it merits some research into rather or not clear primer is acceptable for applications involving pressurized pipe. Assuming the clear primer is rated the same as the purple primer (likely being the exact same stuff but without the purple dye) then I see no problem with it.

Having said that ...

Very cool - I like the simplicity and effectiveness. Nice work.

Once you have the design all finalized, I'd suggest adding a handle (or maybe just a forward grip on the bottom of the "stick") and rudimentary sights.

I noticed you were careful to keep it pointed "downrange" while cocking it (and I ...

Awesome gun! Great build, looks like you really researched it and took your time.

Mind providing us some details on how you rifled the barrel? How did you achieve a steady rate of twist?

Peace,
Pete Zaria.

POLAND_SPUD wrote:done... it seems that everything works fine now
thx

No problem. Have a good one.

Peace,
Pete Zaria.

Run HiJackThis again (no logfile required this time) and check the boxes for the following lines:

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://wyborcza.biz/biznes/0,0.html?p=005 (unless you actually wanted that for your homepage)

R3 - URLSearchHook: UrlSearchHook Class ...

Downlad HiJackThis: http://download.cnet.com/Trend-Micro-HijackThis/3000-8022_4-10227353.html

Once you download and open it, do "Scan system and save a log file."

Then post the logfile here and I'll tell you whats wrong.

After that, try ComboFix: http://www.bleepingcomputer.com/combofix/how-to ...

Edit: Sorry, didn't realize I was kicking up a dead thread until after I posted. My bad.

...otherwise the mix behind the piston could POSSIBLY ignite, forcing the valve closed and possibly causing your chamber to explode. at the very least, your rubber sealing face will be trashed, as well as ...

I know that sch is not a pressure rating, I was wondering the minimum pressure rating I should use if I decide to make this. I will not be using any burst disks or pistons, just a simple combustion with low propane mixture fuel.

For a non-hybrid combustion, ABS pipe is one of the best choices ...

I wouldn't trust it. Advanced metered propane combustions can generate in excess of 120 psi. If it were me, it is at least sch 40 for that.
"Sch40" has nothing to do with the pressure rating. All it means is that all Sch40 parts will fit together properly.

Yes, and no... Although Sch40 doesn't ...

In the pic you posted, the gauge is reading well north of 500psi, and I know fridge compressors are capable of more.
No, his gage is reading 200 psi.... Which is "well north" of 500 kPa. More like 1300ish, actually.

Whoops, you're absolutely right, I didn't notice the kPa marking. Good call ...

I don't think a propane tank is safe at those pressures.
i don't know where you got the idea i was going to be using extremely high pressure from.

In the pic you posted, the gauge is reading well north of 500psi, and I know fridge compressors are capable of more.

As long as reasonable caution ...