Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
The seat diameter is 2.5cm (1"), and the total piston area is 4.5cm (1 9/16")
That is not a major difference.
With some mods, I will give this a try this weekend though, and tell you how it works.
Do not look back, and grieve over the past, for it is gone;
Do not be troubled about the future, for it has not yet come;
Live life in the present, and make it so beautiful that it will be worth remembering.
It looks like it has a lot of promise, looking forward to your results
As to my own power tests, you're going to have to wait a bit longer as the air spring has (unsurprisingly, given it's just a syringe tube) sprung a leak and in the process of sealing it I too the opportunity to reinforce the whole section. Sadly this means that the piston will no longer be visible but at least I'll be able to test it without fear of breaking it. Also, the fact that the syringe tube sides will be supported means they can't bulge out under pressure and therefore the seal will be less likely to leak.
Instead of using a syringe tube, what about getting a cheap 120PSI bike stirrup pump, and hack a small section off the metal tube and use the piston from the pump for the piston in this? Then you just need to epoxy it to whatever.
Just means it could take a few hundred PSI no problem. I'm not sure about the size ratio between a piece of that tube and the syringe you're using, the bike pump tube might give you more volume then you want.
A valid suggestion, in that case however you'd have to use a coil spring, as the pump piston will only seal one way. As an air spring my prototype only needs around 15 psi of pre-pressurisation, I doubt it rises much more than that when the piston actuates. In any case, it's got a layer epoxy around it now, plus PVC pipe which can take at least 400 psi, so in around 24 hours we should be good for testing
NNNNNICE!!!
I just love it how it goes daka-daka-daka instead of braaaap. I'd send you a cookie if I knew where you live.
Once you're done with playing with epoxy and finish tweaking n experimenting with full auto valves so that you have researched all the aspects of it; I think I'll build myself a machined one out of steel or aluminum running at about 30 bar.
BTW, where did your laz0r soundz go? xD
Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!
Address it to the "Epoxy Batcave" and it's bound to find its way here
where did your laz0r soundz go? xD
Interesting that you should mention that - I think it's an indicator of the high flow, in that the air is not as restricted. I can get the sound by putting my finger over the port.
Still a lot of tweaking to find the ideal pressure in the air spring and flow from the compressor but we'll get there, what's more important though right now to get me to finish it is MOAR POWER!. I'll hook up a barrel this evening and try single shots to get an idea.
With this oneI had got a maximum of 2 ft/lbs with lead pellets for a single shot, this is about similar for the maximum I got for an individual shot with my ball-valve BBMG so not really very inspirational. If it can put a lead pellet through the bottom of a soup tin though, I'll be a happy man watch this space.
Had a play with the reinforced prototype fixed to a 36 inch long 6mm barrel firing single shots and here are some average velocity results:
0.25g airsoft BBs: around 460 feet per second
Standard 16 grain 0.22 airgun pellets: around 280 feet per second
Modified16 grain 0.22 airgun pellets: around 330 feet per second
That's just under 4 ft/lbs for the last projectile, not out of this world it will be impressive on full auto and in the meantime, enough to give you a decent damage video with single shots through the bottom of a soup tin:
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Here's the unit in operation, note how the pressure on the shock-pump gauge (attached to the air spring) peaks with each shot as the piston compresses the air behind it.
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Out of interest, I tried a couple of shots with the modded pellets but filling the air spring to 30 psi and opening the schrader to fire, velocity was around 345 feet per second so I know the setup is tweaked reasonably well.
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