Spudgun won't ignite even with blowing into chamber

Tijn_416cs · Fri Mar 04, 2016 10:48 am

My friend and I recently made a spudgun around 4 feet long give or take, using a little piezo electric ignitor from a lighter, we tried the proppelants: butane, axe body spray, and alcohol, and it just take around ~25 sprays and retries to get it to ignite, we tried blowing into the combustion chamber and using an air compressor, and cleaning the chamber out.
Tl:dr Spudgun won't ignite, even though trying all the tricks, please help

matti · Fri Mar 04, 2016 12:13 pm

What's the chamber size and how much fuel are you spraying in there? If the ignition is installed ok and it gives a spark then the problem is probably bad mix in the chamber.

You could try syringe for fueling, there is even some how to videos for that, I will post then if I find them. I think JSR is the one who has done some tests with syringe fueling, do some research here.

EDIT: here is the link for syringe fueling how to:

Fri Mar 04, 2016 1:15 pm

Hi Tijn

you need to know that in Holland a combustion launcher is concidered an illegal firearm.
That alone should be reason enough to switch to pneumatics.

Tenminste...als je slim bent...

Tijn_416cs · Sat Mar 05, 2016 5:02 am

I know that it's illegal, it was my friends idea and it's his spudgun. I tried gettig him to use co2/hpa, but he likes fire apparently sooo...
By the way, would a 5 inch by 1 inch combustion chamber with a lighter ignitor and a 9 inch barrel with diameter of 6.03mm be able to shoot an airsoft bb at around 300 fps or more?
Thanks or the replies

matti · Sat Mar 05, 2016 7:09 am

Tijn_416cs wrote:I know that it's illegal, it was my friends idea and it's his spudgun. I tried gettig him to use co2/hpa, but he likes fire apparently sooo...
By the way, would a 5 inch by 1 inch combustion chamber with a lighter ignitor and a 9 inch barrel with diameter of 6.03mm be able to shoot an airsoft bb at around 300 fps or more?
Thanks or the replies

I second what BTB said, even if it's your friends gun. And anyway, I would advise you to go pneumatic if your thinking about BB gun, or anything in that size. For a reliable combustion you would need some sort of fuel meter and battery etc. and for a cannon that size, it's just not worth it because pneumatic would make it so much simpler and even more compact. You can use 12gram Co2 capsules /paintball bottles or bicycle pump for power source.

Tijn_416cs · Sun Mar 06, 2016 8:20 am

Thanks Matti, I am switching to pneumatics for the bb gun, as for my friend, his cannon almost exploded yesterday and he got some minor burns on his hands, but he still wants to persue the combustion gun. for the BB gun I was thinking having either a 12g co2 capsule or cheapo coke bottle at 130 psi, then having it set up like Airsource->Valve to small air compartment that has just enough pressure to propell BB->air compressorpistol-> barrel with magazine. so you need to open the valve to the air compartment that will run at the same pressure, just lesser volume, then close the valve once the compartment is filled and under enough pressure for it to shoot, I can pull the trigger on the air compressor pistol to let through the air and shoot. If you have any idea's or complaints about the system I am thinkig off, That I could use to make a better system please let me know, Thanks.

matti · Sun Mar 06, 2016 3:08 pm

Tijn_416cs wrote:Thanks Matti, I am switching to pneumatics for the bb gun, as for my friend, his cannon almost exploded yesterday and he got some minor burns on his hands, but he still wants to persue the combustion gun. for the BB gun I was thinking having either a 12g co2 capsule or cheapo coke bottle at 130 psi, then having it set up like Airsource->Valve to small air compartment that has just enough pressure to propell BB->air compressorpistol-> barrel with magazine. so you need to open the valve to the air compartment that will run at the same pressure, just lesser volume, then close the valve once the compartment is filled and under enough pressure for it to shoot, I can pull the trigger on the air compressor pistol to let through the air and shoot. If you have any idea's or complaints about the system I am thinkig off, That I could use to make a better system please let me know, Thanks.

You could do some research on hammer valves and make a hammervalve that only releases small amout of air from the chamber. That way you don't need two chambers and you don't need to fill the smaller one after each shot.