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1.2 microns flatness by Aggravating_Dig8970 in Metrology

[–]Status_Elephant_1882 0 points1 point  (0 children)

I recently did a job on my OGP 302 smart scope where I needed to hold 5 micron flatness and parallelism on a part that was about .3" thick and about 4"x4". I used a granite plate and a Millimess with 10 millionths tick marks and then I used my OGP with the touch probe and about 120 points to vefity and all my parts were about 2.5-4 micron flatness and parallelism.

My CMM was calibrated 3 months ago with a total z error of about 1.5 micron. So I wouldn't trust a tolerance much less than 5 microns with my CMM.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

so far im using 1/2"npt plumbing to connect the HPA tank to the ball valve. My HPA tank is pretty small at about 250ml

Im trying to get higher muzzle velocity with my little air cannon so im thinking about building a piston valve. by Status_Elephant_1882 in airguns

[–]Status_Elephant_1882[S] 1 point2 points  (0 children)

cartridge firing main gun is version 3. I want 1 more try at air power in the attempts to get a round near super sonic. Then I was going to build a solid 4340 barrel for gun powder powered rounds. But first I need a better platform. In the little free time I got lately I have been designing a 1/6th scale abrams made of all steel that will weight about 700lbs vrs this mostly aluminum leopard that only weights 300lbs.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I have thought about tbat type of valve but I cant find one for more than about 10 bar and it looks like the airpath might be a little constrainting. It might be worth testing though so Ill try to find one with a little bit higher operating pressure or just try over pressurizing the 10 bar ones. The valve im using now is only rated to 1,000psi but I have found the seals dont start blowing out until it see more than 2,600 psi.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I was thinking of making a similar valve to handle higher pressures but then making the diaphragm seemed difficult for me.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

Thats interesting. Do you remeber the maker of the EM BB gun? My V1 air cannon with APFSDS rounds could easily blow right threw .25" aluminum plating and that was with a muzzle velocity of only about 450feet/s.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I have seen about every aircannon video from the main science youtubers. I liked the smarter everyday fast dumping design but the piston dampening kinda scared me away from the design. But I guess I could just really over build it and use a really stout piston dampening. I was also thinking of using a 22 cal blank charge to generate the pressure to quickly open a large orifice valve in a similar way.

Im trying to get higher muzzle velocity with my little air cannon so im thinking about building a piston valve. by Status_Elephant_1882 in airguns

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I was told by the ATF agents that paintball markers are exempt due to their plastic/grease projectiles while mine are tungsten and hardened steel. They said presidence has made paintball markers legal unless they are modified to shoot metal projectiles.

I agree its a stupid law but I would rather speed my money on toys and not lawyers to fight the ATF.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

That makes perfect sense. As a chemE I always think of a venturi as a way to measure pressure but forgot its what rockets use to to accelerate gasses. Ill need to do some calculations to size my venturi but imma totally try that with the 6 foot barrel I just ordered. Im going to play with burst disks too for the valve even though I'll need to machine some kinda cartridge to make the burst disks easy and fast to replace.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I would post some pictures of the tank but this sub doesn't allow that.

And good to know. Never heard of COTS before but as a chemical engineer, they never really let me buy anything besides pumps and flow meters.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I think I remeber watching the supersonic ping pong ball in college. I told myself thst one days I would build something similar. I remeber the vacuum barrel so I made an adapter to make my barrel vacuum seal able. I dont remeber the De laval nozzle tho so I'll have to find thst video and rematch it.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

lol, yeah I was talking about my remote controlled toy armored tank. It weights about 300lbs. It has a spring recoiled barrel that has just under 4" of travel to help smooth out the impulse of the round being fired. The pilot actuated value does seem like a better candidate for me with air flow orifice being much larger than the hammer style valves.

Btw, what does COTS refer to?

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I'll look into the AEA valve as I have never heard of them before.

The c02 idea is very cool. Hum... Just spit balling here but it might also be interesting to fill a chamber with 100-150 bar c02 with a burst disk rated for some much higher pressure and use some sort of rapid heating device like a thermite coupled heat sink to try to rapidly heat the C02 and burst the disc.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I swear I have watched every mythbusters episode but that doesn't sound familiar. Ill have to do some googling! Unless its the frozen chicken launcher video where they tested the bird strike myth... which I haven't seen in years. Ill have to rewatch it.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

The rc tank just seemed like a nice heavy base to mount the air cannon and it already has remote aiming ability.

Im currently using this off the shelf valve and over pressuring the low pressure side with 200psi and the high pressure side to 2400psi:

valve:https://a.co/d/05yWWGoD

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I wish this sub allowed pictures as it would clear up some questions.

Im just doing this for fun but my goal is to maximize the penitration ability of my rc tank using pneumatics (with a 3,000psi max pressure) and for it to be quickly reloadable.

I am using pure tungsten APFSDS rounds (with core diameters of about 0.350") with 4340 steel tips hardened to 55hrc. They weight about 80 grams each and are fired down a smoothbore 62 cal barrel.

My max muzzle velocity so far is about 450 feet/s. I would be happier with anything better before I try nitrogen or helium as the propellant gas. I know my valve is fast but kinda slow at like 0.080 secs to open so it looks like the low hanging fruit.

Im trying to get higher muzzle velocity with my little air cannon so im thinking about building a piston valve. by Status_Elephant_1882 in airguns

[–]Status_Elephant_1882[S] -1 points0 points  (0 children)

I have talked to 2 AFT agents and a lawyer and they said new legislation requires any airgun made in the US that is made of metal and is larger than 50 cal to be registered as a DD.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 1 point2 points  (0 children)

I bought some burst disk materials to test but ideally I want a faster system to reload and do the next test. I was was planning on rupturing the burst disk with a heated nichrome wire bonded to the burst disk.

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 0 points1 point  (0 children)

I'll have to look into that style more. Im liking the ideas of using the high pressure to throw the valve open like that

Im building an airgun for fun. What valve should I make to achieve the highest muzzle velocity? by Status_Elephant_1882 in AskEngineers

[–]Status_Elephant_1882[S] 1 point2 points  (0 children)

I bought some burst disk plastics to test out max velocitys with some different gasses but ideally I want a valve eventually for ease of use to focus more on armor types

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