Search found 206 matches

by mrfoo
Wed Jan 13, 2021 6:37 am
Forum: BB, Airsoft, and Pellet Guns
Topic: 4,2 mm pipe for 4.5 ammo
Replies: 14
Views: 403

Re: 4,2 mm pipe for 4.5 ammo

Hah, fuel filter.

Ironically, an off the shelf oil filter, intended to be used as such, might well do a better job. For example,



27dB is 512 times quieter.
by mrfoo
Thu Jan 07, 2021 3:58 pm
Forum: BB, Airsoft, and Pellet Guns
Topic: 4,2 mm pipe for 4.5 ammo
Replies: 14
Views: 403

Re: 4,2 mm pipe for 4.5 ammo

No, I understood that, I was suggesting a possible other approach. Crimping should work, as you suggest, use a mandrel of the desired size inside to avoid going too small. You can put a significant amount of pressure on with a drill chuck, but if it doesn't work you might look into finding someone w...
by mrfoo
Thu Jan 07, 2021 1:00 pm
Forum: BB, Airsoft, and Pellet Guns
Topic: 4,2 mm pipe for 4.5 ammo
Replies: 14
Views: 403

Re: 4,2 mm pipe for 4.5 ammo

Totally stupid idea, maybe, for use of bbs... What if you were to bend the barrel down slightly, right at the start by the breech? Would that perhaps force a consistent contact between bb and the top of the barrel, effectively guarantee a hopup effect even with the extra speed you're generating? A b...
by mrfoo
Thu Jan 07, 2021 3:57 am
Forum: BB, Airsoft, and Pellet Guns
Topic: 4,2 mm pipe for 4.5 ammo
Replies: 14
Views: 403

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
Wed Jan 06, 2021 12:13 pm
Forum: BB, Airsoft, and Pellet Guns
Topic: 4,2 mm pipe for 4.5 ammo
Replies: 14
Views: 403

Re: 4,2 mm pipe for 4.5 ammo

How about using a reamer? in brass you could probably ream from 4.2 to 4.5 without steps, or pick up an adjustable reamer and use that.
by mrfoo
Fri Jan 01, 2021 9:24 am
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 71
Views: 13065

Re: JSR's workshop chronicles

jackssmirkingrevenge wrote:
Fri Jan 01, 2021 6:25 am
I have to say that after being the bane of my machining existence for many years cutting threads is a real pleasure now!
Nice result!
by mrfoo
Fri Jan 01, 2021 4:59 am
Forum: General How-To & Discussion
Topic: about accuracy
Replies: 29
Views: 492

Re: about accuracy

Doesn't it? 🙂 No, it doesn't. It indicates an inability to correctly express oneself. Text is perfectly capable of conveying emotion and intent; there's a whole section of the arts dedicated to it. It's been around for a while, you might have heard of it. It's called "literature". You'll perhaps al...
by mrfoo
Thu Dec 31, 2020 12:36 pm
Forum: General How-To & Discussion
Topic: about accuracy
Replies: 29
Views: 492

Re: about accuracy

PracticallySane wrote:
Thu Dec 31, 2020 11:49 am
I will concede though, it doesn't seem like you are worried about the proper science, rather that your opinion is fact.
PracticallySane wrote:
Thu Dec 31, 2020 11:51 am
I do want to reiterate though. I mean no disrespect.
Really. Because putting a smiley on the end makes it all so much more polite.

Happy new year.
by mrfoo
Thu Dec 31, 2020 12:26 pm
Forum: Hybrid Cannons
Topic: I got some questions.
Replies: 35
Views: 1402

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 Dec 31, 2020 11:28 am
Forum: General How-To & Discussion
Topic: about accuracy
Replies: 29
Views: 492

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 8:47 am
Forum: General How-To & Discussion
Topic: about accuracy
Replies: 29
Views: 492

Re: about accuracy

I wasn't suggesting he should use a rifled barrel*, I thought that was fairly clear. What's important is imparting a known and consistent spin on the projectile such that the aerodynamic effects can be compensated for. A hop up does this by imparting backspin on the projectile, using the aerodynamic...
by mrfoo
Thu Dec 31, 2020 2:43 am
Forum: General How-To & Discussion
Topic: about accuracy
Replies: 29
Views: 492

Re: about accuracy

Is there anything different? Quite a lot, going through the list above :) I'm no expert on bbs, but something with a smoothbore barrel and no other "gizmo" to ensure reliable, repeatable spin of the bb is going to result in random or more-or-less random spin, and thus bbs wandering off anywhere the...
by mrfoo
Tue Dec 29, 2020 4:41 pm
Forum: General How-To & Discussion
Topic: stainless steel tube burst pressure
Replies: 24
Views: 489

Re: stainless steel tube burst pressure

Welds are a risk. Firstly, the weld itself is an unknown quantity. Next is the alloying of the base material(s) and any filler used, which leaves another unknown. Hydrogen absorption into the weld puddle is another risk. Without subsequent heat treatments (for which the welds themselves pretty much ...
by mrfoo
Mon Dec 28, 2020 5:16 am
Forum: General How-To & Discussion
Topic: stainless steel tube burst pressure
Replies: 24
Views: 489

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
Wed Dec 23, 2020 2:43 am
Forum: General How-To & Discussion
Topic: JSR's workshop chronicles
Replies: 71
Views: 13065

Re: JSR's workshop chronicles

Yay! Nice results. Threading is hard to get right. Is the threaded piece in the foreground 2 pieces stacked on one another, or is it camera distortion that makes it look - ummm - "bent"? Meanwhile, and polluting your thread a bit (sorry) but it's a workshop thing, my surface plate is getting there. ...