jackssmirkingrevenge wrote: ↑

Sat Mar 18, 2023 9:04 am

Sometimes building tools and jigs is half the fun :D

And the other half is doing it again when you realise you've buggered something up :)

You need the entire system to be filled with water, or as close as you can get to that. Then connect the grease gun and pump grease in. Doesn't matter that it's not water, or that it's not miscible, all you need is something incompressible. Tear down and clean up afterwards.

Nice machine, and nice result.

For hydrotesting, cheap hand actuated grease guns generally go up to about 400 bar, used one for some hydroforming experiments a while back. The hardest bit is fittings, and managing to get a gauge in circuit.

Fuck off, spamcunt.

About the only way you're really going to get an idea of muzzle energy is to run it through a chronograph, or if you don't have access to one, shoot into a ballistic pendulum. The latter is very easy to set up; with a mobile phone as camera ad some calculations you can get some very accurate results...

Boyle's Law. Not Susan Boyle. For a given mass of confined gas at constant temperature, pressure multiplied by volume will be constant. So for a starting state at pressure P₁ with chamber volume V₁, and a compressed state P₂ with final chamber volume V₂ : P₁V₁ = P₂V₂ This gets combined with Charles'...

Haha no. bought the inverter to run the mill, which is 380v three phase, it turned up and the documentation said it could run 4 separate motors (one at a time, obvs). The mill has a 2 speed dahlander motor, so effectively 2 motors, and the lathe also has a 2 speed dahlander motor, so 2 more motors, ...

Glad to hear it was something simple. I would have left the resistor on a start capacitor, as it will live with charge on it - it's a shock hazard. there's also the risk of more arcing on the centrifugal switch as it switches, which could mean more wear and tear. It's no biggie, though, just be very...

You think it's bad here? Try getting involved in making pulsejets :P "the death of the forum" has been ongoing for a while, with several technologies vying to take its place. All sorts of gamifyng and the like, and it pulls users from forums with glitz and pizzaz, but the problem as I see it is that...

I like that idea, Hector.

There's a few people on here with machine tools (I'm one), maybe some community machining of specific parts? Maybe a design for a specific high performance hammer valve, something like that?

Quite. And to be honest, the addition of the little "thumbs up" icon at the top of every post does little to help. Gamification of social interaction, it fucking sucks.

jackssmirkingrevenge wrote: ↑

Fri Sep 16, 2022 10:51 am

I don't suppose there's a way for PCGUY to automatically update all the broken links?

I've been through this before, and frankly, it's an awful lot of work and a proper pain in the rear to do correctly.

With a standard hammer valve the hammer has to open *and hold open* the entire valve that's going to be used to flow the air you're using for propulsion. As pressure and bore size go up, you'll need more and more hammer force to open the valve. A QEV + hammer valve reduces the hammer force required ...

That's not entirely true, as I understand it Users with unverified accounts may only post videos less than 15 minutes long. Verified accounts can post videos up to 12 hours long. The cynic in me says it's nothing to do with reducing the amount of time people spend on the site, as that would be utter...