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by mrfoo
Fri Aug 28, 2020 11:28 am
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Re: Full auto airsoft pistol

Video or it didn't happen :)
by mrfoo
Mon Sep 07, 2020 1:44 am
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Re: Let's talk nerf blasters

I could always make my own, but it would be too powerful and might kill someone, so that idea is out.
I thought that was the idea?

Seriously, though, 150 bucks for a (high performance, admittedly) plastic toy gun? Tha fukk? I'd be far more inclined to try the nexus pro.
by mrfoo
Wed Oct 21, 2020 12:26 am
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Re: Concerning video of a Piston Valve Cannon bursting

There's a lot of mass in a 3" piston, and PVC is fragile. The break at the barrel end was clean and exactly at the stress riser where the reducer meets the valve body, looks like shock fracture rather than pressure rupture. Lesson to learn - don't do that. At 2:00 or so, he says "That's not funny. I...
by mrfoo
Mon Oct 26, 2020 6:52 am
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Re: JSR's workshop chronicles

Nice, a much cleaner setup than my workshop. Hell, even your rustic stock stand is cleaner than my workshop :) I like your mill vice. Watch out with the LEDs, depending on the type they have a strobe effect that can make spinning things appear to be still, or jut simply give you a headache if you're...
by mrfoo
Tue Nov 17, 2020 1:20 pm
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Re: JSR's workshop chronicles

Hey, that's not totally cheap shit throwaway stuff, it'll probably be more than OK. Wedge style is a good call. Watch out for chatter, a QCTP brings the tool out away from the topslide, effectively it's hanging out in the void, any slop in your gibs will show itself here, particularly if you're doin...
by mrfoo
Wed Nov 18, 2020 3:28 pm
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Re: JSR's workshop chronicles

It is certainly true that, where what you're making doesn't have to interface with some other precision part, you don't ultimately care about exact dimensions. However, you do care about fit, and that requires measurement. Take the example of a sliding fit, sub 10mm piston in bore, not uncommon in w...
by mrfoo
Wed Dec 16, 2020 6:42 am
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Re: JSR's workshop chronicles

Neat. Yeah, hand-cranking is the safest way to go, but it's properly slow. The next one is to thread away from the chuck, for normal threads that means mounting the tool upside down and running the spindle backwards.
by mrfoo
Mon Dec 28, 2020 5:16 am
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Re: stainless steel tube burst pressure

There's also the question of how it's capped, etc etc. Pressure vessels aren't, perhaps, rocket surgery, but there's still a lot of hard theory involved, and major consequences if you get it wrong. The only way to be sure, without putting yourself in danger, is hydrostatic testing. Fill it *complete...
by mrfoo
Thu Dec 31, 2020 11:28 am
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Re: about accuracy

I dont think you actually Google the magnus effect? Its not the "aerodynamic" effect. It's absolutely aerodynamic, and I didn't need to google it. Higher education in physics will do that for you :) What would you suggest as a mechanism for the magnus effect other than aerodynamics? Unicorn farts, ...
by mrfoo
Thu Dec 31, 2020 12:26 pm
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Re: I got some questions.

To a certain extent, you'll always be pumping water in, unless you live somewhere with absolutely 0% humidity. You're also adding water vapour through combustion, as you note. After combustion, the pressure in your chamber goes to its maximum, and then reduces as the projectile (if any) is pushed do...
by mrfoo
Thu Jan 07, 2021 3:57 am
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Re: 4,2 mm pipe for 4.5 ammo

farcticox1 wrote:
Wed Jan 06, 2021 5:19 pm
I guess an old rifled barrel would be the answer, but I think that's kind of cheating :?
Rifling buttons are cheap on aliexpress. Just saying, like.
by mrfoo
Fri Jan 29, 2021 12:21 pm
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Re: Multi Shots out of 100psi Tank

Well that's bad advice. I let people know I was thinking of the children and I ended up on a shortlist.
by mrfoo
Fri Feb 19, 2021 11:48 am
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Re: co2 tank to fill with air

Avoid beating off in public. It'll get you on a list. Sorry, that was a cheap joke. An aluminium tank can only, AIUI, be rated up to 3000 psi. That's around 200 bar, and the absolute maximum safe rating, tank direct from the factory, you can possibly expect. However, liquid CO2 only requires a bit m...
by mrfoo
Fri Feb 26, 2021 12:57 pm
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Re: Which side do we like the User Information on?

I guess the verdict's in ;) Yep. With over a hundred views, only 4 people expressed a definite opinion. 2 more (myself included) stated that they didn't care (an option, in fact, which should have been "I couldn't care less", another case of overpondian mutilation of the beloved mother tongue), and...