Keep in mind that the material strength for material strength for cheap steel is on the order of 32ksi, not 9ksi like you were using. That said, a lot comes down on how it is welded.

I think welder duty cycles are usually spec'ed per 10 minutes.

So a 50% duty cycle means weld for 5 minutes, then cool for 5.

I would say as long as the tank is rated for the peak combustion presssure, go for it.


I would use flashback arrestors just in case, and be conscious of which direction the burst disk on the pb tank is pointed (ie. not at you)

Well I made my canon have a tire valve for propane injection. And I was wondering if I can pumpe extra air in too to Mix the air. But if it isn't too much of a deal ill just shot it without a fan. If it doesn't work ill cut the camber off and put in a fan and add a coupler with a screw on cap in th...

marginally legal compared to any modern centrefire. I presume you mean "marginally lethal". Depends in whose hands I guess, an accurate 22 with scope and suppressor is not to be taken lightly . Ironically, I own a .22lr rifle that was considered 'less lethal' for riot control purposes in Russia. Al...

It looks like they re-used some of your footage as well. Specifically, shooting the dummy with the hoodie on and loading the various different projectiles.

I don't think they would significantly weaken the pipe. In fact, by cold working the copper, you will actually work harden it. Of course, kinks will concentrate stress. The outside of the bend will be thinner, and so will experience slightly less stress. I think you would be save if you took the rec...

I will say that the angle formed by the holes/flutes on the die will have a significant impact on its cutting ability, as will their surface finish. You may also consider 'drilling' the swarf holes with an center cutting endmill (after spot drilling to guide it), rather than finishing with a drill b...

That data is for a constant chamber size, with variable barrel. If you have a fixed barrel length (like have a maximum overall length and an over/under design, I think the optimal ratio is closer to 2:1 (larger chamber). The general rule is that the bigger the chamber, the more powerful, but with qu...

Probably. Although, in my area, propane is at least ten times cheaper than butane. The big flame from a propane torch will also heat the pipes MUCH faster.

i took a golf ball to the forehead at about 100-115 psi, i dont remeber exactly but surprisingly it didnt hurt, but im glad i didnt loose an eye similar story, though i was trying to chip a golfball on to my lawn, 5 swings later and a couple of centimetres deeper into the ground i decided to belt i...

If I recall, 30 degrees is above the critical point of oxygen, so you will have an EXTREMELY high pressure. Tens of thousands of PSI would not surprise me. You could find the number of moles of O2 in 1 L of liquid oxygen and use pv=nRt, but that would tend to overestimate the pressure.

Where did you get that magazine well (part that the magazine fits into)? Did you buy it or make it?

Great work!

As I remember, Autodesk CFD doesn't simulate compressible fluids.

Casio ex-f1 offers the highest resolution AND framerates, but it is now discontinued and, iirc, sells for quite a lot of money. Like ~$2k.

If you're feeling ambitions, you could try making one.


Alternatively, find a used one