the bottle is actualy steel That's a good sign. Steel is far more resilient than aluminium. so it is has a working pressure of 1800 psi- 124 bar.... No, it *had* a rated working pressure of 1800psi, for CO2 only, in March 2001 when it was last hydrotested. Not sure what the acceptable period betwee...

Good question. The force being applied to the barrel will be compression, rather than tensile, and PVC (like many materials) is stronger in that respect. Tensile strength of rigid PVC, 34 … 62 MPa, Compressive strength 55 … 89. So in that respect, you're probably OK. However. These figures are signi...

Nice. Comme dit hector, le cuivre ne risque pas d'aimer cette utilisation. Tube acier sans soudure Ø20, ep2 te donnera Øint de 16mm, ce n'est pas trop cher - https://lamtechno.com/tube-acier-de-precision-e235n-rond-sans-soudure-cintrable/90-381-tube-acier-sans-soudure-cintrable-diametre-20.html#/23-...

Norguns wrote: ↑

Sat Mar 27, 2021 11:56 am

I get what you are saying, I might not get any real velocity gain from it. That being said, the entry fee for evacuating the air from the barrel is low on my setup and i might play with it at a later time.

You owe it to yourself to try :)

It's been a while that I've been looking for a smallish milling machine to go with my smallish lathe(s). Yes, I am aware that the chinese make some fairly capable small milling machines. But I simply don't like them. Horrible yucky plastic tat. Id far rather something made of great big chunks of cas...

So, spent some time stripping down a bit. Managed to unblock the tooling and the Z axis, (hooray for hand winches), loking at the scraping marks on the slideways and gibs I thought to myself "that's been rescraped", but given the way the gibs fit, I'd be surprised if it's done many hours from new. D...

> Obviously the downside is the spring isn't variable so a different spring would be needed for a given mix.

A threaded boss at the rear can increase or reduce preload on the spring within a certain range, although this will also reduce spring travel.

But it's pretty damn next level.

At a guess, that can's gonna be super thin, which would make modding it pretty difficult. I'd be more tempted to look at a discarded 60l oxygen canister or maybe a fire extinguisher CO2 recharge canister. Rather than modifying a canister, try talking to a local machinist, see if they can make up a t...

Not sure if there was air in the line behind the water, but an interesting result. Definitely, he was pressurising with gas. So there was all the stored pressure of the gas in the line to deal with. Best way to do it is with a grease gun, they go up to stupid pressures (I've done hydroforming with ...

Bearing in mind that I know bugger all about 3d printing apart from what Ive read on line, I think I'd probably be a bit worried about the housing splitting along the lines between layers. Otherwise, it looks proper good and very much the kind of thing I'd machine.

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 ...

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.

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?