I built it! A potato cannon using a Humphrey 3/4" QEV to aluminum camlocks for both the chamber and the barrel. Not pictured is the detachable blow off gauge/pressure valve. Whole system is rated for 150 PSI. Pictured with the 1.5 inch barrel attached, and the 2" barrel alongside. Thoughts?

https://preview.redd.it/pnriyo6thsxd1.jpg?width=3072&format=pjpg&auto=webp&s=963156ccbd9acb199d17e45140a101d3c5b93ac3

https://preview.redd.it/figren6thsxd1.jpg?width=3072&format=pjpg&auto=webp&s=0b5527ea87419d3a24e963bc528e8dd360cdd82c

https://preview.redd.it/9wvnxn6thsxd1.jpg?width=4080&format=pjpg&auto=webp&s=07aef5688454f3c89c6fe285319700fb5342c5ba

Wondering if my idea for a sabot will work A potato cut into 4 pieces and a hole drilled in a bbq skewer in the centre

Any ideas about using some kind of valve that automatically shuts off the air pressure to the reservoir when it hits a certain psi? So you don't have to monitor the pressure manually when reloading? Already searched the reddit to see if it's been brought up before (potentially searched the wrong keywords. For context, making a prop pirate/Naval cannon so I don't want a big pressure gauge sticking out the top and I want loading/firing to look quick and period accurate. I've looked at regulators for spray guns but not sure that's the right piece for the job

I made it out of random pieces I had in my basement

1/2 diameter barrel 1-1/2 diameter combustion chamber

I am in the process of receiving the fittings for a compressed air potato cannon that will feature the following:

Camlock swappable barrels

Camlock swappable chambers

A swappable blow off valve/pressure gauge system

3/4" high flow QEV

An air fill system capable of being set up for Schrader (bike tire), air hose (automotive), or (if properly regulated, I have the parts list for that too) fill off of an HPA tank.

Not counting the 10 foot sections of PVC I intend to pick up locally, based on my vendors and choices for materials, it's about $250 for the fittings, valves, and parts (with shipping) for the US.

Would this subreddit be interested in a break down, links, reasoning for parts, etc.?

It’s producing a spark on the inside but it just won’t light the fuel

I only got it to work about once without out any projectile in it

I'm looking at making an Flak88mm style potato cannon with shell ejection. I've got everything figured out apart from the fuel for the spud, the idea is to fire a couple spuds in quick succession but I need the fuel to not evaporate/deteriorate over a 5-10 minute period. Any recommendations ? I'm in the UK if that helps

https://us.docs.wps.com/module/common/aiGuide?sid=sIL_TjIWFApOvp7cG&v=v2#1726673792639

Long time builder, but looking to really up my game. I am looking at making a hybrid cannon, completely portable, and ideally not burst disk fired for reloading reasons. Barrel length/size TBD, but so far my rough theory is:

HPA Carbon fiber 80 CI paintball tank at 4500 PSI

Fed into an adjustable regulator, that does approximately 800 PSI, 600 PSI, and 400 PSI.

Fed into high pressure 3 way valve to a air chamber of steel sched 40, maybe 1.25 inch in diameter, for about 10 CI of volume

Other side of the cannon has a camping propane tank, with regulator to reduce it to 30 PSI (I see tanks come at 125 PSI, and I want to leave room for multiple shots), with again, a roughly 10 CI chamber of Sched 40 steel and a 3 way valve.

To a combustion chamber of sched 40 steel, probably 4 inches in diameter, probably a foot long.

Now burst disk is easiest trigger method, but I have concerns with barrel seal and the ability to reload/swap barrels for various rounds (using an 8 foot barrel muffles sound a bit more than a 4 foot, but sometimes you just need that 4 foot 4 inch wide rain of 5 pound sack of baby potatoes on a field)

Anyone familiar with, or have any theories on using an electrically triggered QEV that dumps into a barrel with a taser ignition 2 inches from the QEV?

In theory, you'd hold the trigger, and it would first turn on the taser, keep the spark arcing for the duration of the trigger hold, and then half a second later dump the QEV resulting in a 3.6 atmosphere stoichiometric combustion that would feed both into the chamber and barrel at some frankly ungodly pressure.

Obviously, chambers/pressures/QEVs can be adjusted, but the idea of igniting a gas being dumped out of a 1" QEV through a taser spark arc at least 1" in length.... thoughts?

The non complex version of this is everything up to the air tank side, probably just into schedule 40 PVC for a chamber, but sized in air chamber/tank chamber for 100 PSI at 800PSI in the air chamber, reducing pressure as you adjust downward. Barrel swaps at that point are easy, and the trigger could literally just a blowgun valve out the back T of the input for the QEV.

Hello this is my second post on this sub I am wondering how big should I make the combustion chamber the barrel is six feet. Second question how could I make a proper APFSDS round. The barrel is 1.5 Inch wide I'm just wondering what the best projectile is. Apologies for the low-quality photo. This is the shroud. I'm planning on using 3-D modelled it myself.

So, the beloved PVC is always the go to, and seeing as part of our shop makes well seals, I have access to it. That being said, machinist by profession. Saw someone years ago on YouTube weld one up out of aluminum using a screw in retained cap for building fuel cells. Wondering if the experienced members here know if aluminum would hold up to continued acetylene use or if I should go stainless or chrome moly.

I recently made a potato cannon, and since it's illegal to fire it in a park, I'm forced to use my small backyard in the suburbs. The issue is that the cannon produces noise levels of up to 90 dB. Do you have any ideas on how to reduce this noise?

I'm looking for an igniter where my son can be at least a few feet away from the cannon. But, most of the igniters use the body of the BBQ grill as a common, so they only have one wire. Is there anything off-the-shelf that has two wires to the sparker?

I use a 2 inch barrel, 3 inch combustion chamber (aussie hairspray) cannon, ignited by an electric candle lighter. It works about half the time, and was wondering what I could do to improve reliability?

I posted a picture of the gun on my profile if anyone is curious.

Size comparison, the orange ball is a 6 mm airsoft bb, which should be the projectile

What about a single shot bolt or breach action with rifled rounds for accuracy

I recently Made my first Mini Potato gun. Unfortunately the back lid exploded and was a ticking time bomb. I’d like to make something similar just safer. Anyone know of any household items I can use. I can get PVC but I do not have my license so I would have to ride my bike. I also saw someone make a gun out of a pill bottle. Is that strong enough? Thanks.

I have a combustion based potato cannon and was thinking I could get more consistency if instead of having a screw acting as a stop for the ammo, I instead put a 1 way check valve in between the combustion chamber and the barrel.

Ive tried looking on google and youtube but have never seen anyone try or recommend using a check valve.

Some other benefits I see are being able to load smaller items into the barrel or things that dont give a perfect seal in the tube and not having to worry about things falling into the combustion chamber.

The only real problem I see it being is accidentally putting the check valve on the wrong way.