Add what was missing to get the valve closed automatically. It works correctly, luckily. The valve closes when you let in compressed air and the pilot depressurizes immediately after firing. The dosing system that I am testing needs to be able to decompress to measure the right amount of butane, it ...

That's beautiful man. That's the kind of project where if you just have to enjoy the fabrication process itself. The shooting is the icing on the cake Nice work!

Welcome to the forum! After investigating hybrids for a short while, I found Larda's Electro-Thermal gun and instantly wanted to build one. So, here's my first attempt at a design for one, subject to much How come you discounted hybrids? From what I remember of Larda's work, his hybrid was signific...

How much pressure are you going for? What will you be shooting out of it and what velocity are you going for? If the answer is "maximum power to shoot a bullet-like thing", then there's really only one formula I can think of that makes sense: 4140 (or similar strength alloy), burst disc, big bottles...

Project update. 8-) I built the hybrid's wooden stock, I think it looked nice. I also finished everything about the machine itself. In the photos you can see the parts, the .25 caliber barrel, the bolt system, the piston valve with automatic pilot opening and closing of the pilot, which I described ...

Here's something a little unusual that I acquired a while back, it took me some time to play with it as I needed to make an adapter for a new chamber and it's only recently that I was able to cut non-standard threads on the lathe. I bought this one without any accessories and with an air reservoir t...

Sorry to go to the sewers, and divert the topic of the publication a bit. ;) No need to apologize, I'm here for the humor as much as I am for the ballistics ;) How finely have you tried adjusting the distance between the barrel and valve body? The problem struck me while looking at the photos, if y...

I gave the balanced valve a go and was able to raise firing pressure to 1100 psi. Some initial testing: https://youtu.be/FnSsZp7-18M Best velocity recorded was 774 fps for 59.3 ft lbs, around 50% more than the maximum for the conventional valve. I was a little conservative with the diameter of the b...

Damage video just to wrap things up, this thing is a lot of fun!

Got it finished, my homemades chrono shows 140 fps for it and 115 fps for my Ceda S in comparison. To charge and load is two seperate actions but is no problem.

Fantastic shooting area you have there! Yes, once I get the gun mobile and aimable I can do whatever I want. I plan on getting it up to 40x mixes once its more practical, and more if nothing has failed yet. Depends on how much pressure I can get before ignition with a spark gap becomes impractical....

I was contemplating about making a coaxial type air cannon design but I had a thought about the pressure rating. We know that certain pipes has been factory tested to withstand a certain amount of pressure inside of it. But what if that pressure is being applied outside of it? That's basically what'...

See link with external pressure ratings for PVC. They call it "critical collapse" pressure ratings. You can compare the critical collapse rating with the internal pressure rating. Critical collapse ratings: https://www.usplastic.com/knowledgebase/article.aspx?contentkey=777 Compare those figures to ...

What do you mean by buying an air tank and punching holes through it? Making a PVC cannon this large makes me especially uncomfortable.

After an 8 year hiatus... I figured I'd give some closure to what happened to MFIC. Long story short, she had a short but eventuful career. I eventually finished her, lost subsequent build photos along with MFIC herself in my divorce that happened 3 months after my last post here. I'll try to give a...