The piston is done, I just have to work on the front and back sealing faces now. Heres a photo of the piston At very low pressure (10-20 psi) you can't hold the piston in, it seems like it will work well. The piston is also very light, so it should actuate fast. Do you think the threaded rod will ha...

Yeah I would have used the lathe if I had a long enough boring bar.
I have got about halfway doing the piston, it seems to be sealing well :bounce:

Hi mate,
I used a file and sand paper to remove the seam, then I honed it with a drill engine reamer

Hi, That video is awesome, I never thought the simple slingshot was so powerful. For measuring the speed I used a Go Pro hero 3 black, on wvga resolution (240 fps). The length scale was a length of 4 inch PVC pipe with tape 1 meter apart, then I just counted the frames to travel 1 meter. The ball be...

This is going to be one serious gun if this thing works.
The piston would be over 65 mm across.
BTW the piston would be welded not fittings. And I have a lathe

Here she is The chamber is a lpg bottle (holds about 6 liter) I let it off one day for an adrenaline hit, the sun had just gone down and the air was quite moist ( you know how sound travels further), anyway you could hear the shockwave traveling up the paddock for about 5-10 second. The sound was un...

Yeah it will almost go through 3/4 inch ply wood
I wouldn't like it aimed at me.

Here is my other combustion cannon, mainly for bird scaring.
I have had this shooting 25 mm steel balls at 240 m/s

Thanks for the info mate, I will look into it.

Hi Mark
I don't have any access to some aluminum bar stock so, I was wondering if steel pipe with two end caps would be ok ?

Hi, Thanks for replying so quickly, The fuel I hope to use for this gun is Propane. My other guns have been just combustion, my electrolyser cell doesn't produce high pressures, and I don't!! Want to compress hydrogen and oxygen mix....BOOM The piston material will be steel hopefully if I can find t...

G'day everyone, I am building my first hybrid, its made out of 90 mm ID x 8 mm wall steel pipe. I want to use a piston valve, I've already had one attempt, but I figured out what went wrong, I made the piston smaller than the sealing face and it can't overcome the force holding it shut. Here's some ...

Hi everyone
just wondering if any of you have some info on the burn rate of hydrogen oxygen mix (as produced from water), it is supposed to be 1000 times petrol ?

Ok,
Ha ha...electrolyser could do it, but you would need substantial materials, eg stainless everything.
Regards burning_water

Thanks DYI,
I am glad you like it.
What sort of pressures have you been using on your setup ?