SpudFiles

...will have to get this done before the West Point Fall Scenario Game, comin up quick ~Sept 20. i'm getting an ASCO 3/4" for the final build (published Cv 10.5 !!!!!)

those are Deltrols (3/4" and 1/4") in the pic below.

some specs for the new build are captioned with the picture.

the WhumpGun that came out of the work i described in this thread and earlier in this one worked out great, but i had to run it at much higher pressure (~85 psi) because of the smaller chamber, which had the unforseen side-effects of (i suspect) making the foam rockets deform in the barrel and accuracy was nowhere near what i was seeing with the earlier prototype.

hence the search for a larger cheap, light metal for the chamber. in asking around for small sections of 2" or 3" copper pipe, i was directed to P&T Surplus in Kingston, NY.
kid in a candy store. don't need to say more

p.s. 2 ft of thin-wall 3" dia. copper pipe sells for $90+ on McMaster.com right now. argh! 2 little feet!
at P&T, the 20" piece of aluminum barstock set me back a whole $6 . i'll go back to get more different pieces to protect the critical portions (trigger linkage, mainly), and maybe even a shroud for over the ASCO, as well as something for a sight rail.

will try to post details of my build over the next few weeks...

That is bloody groovy mate. Good luck with your up-coming game :thumbright:

Wow thats nice, what are the black strips tape ? i would use hose clamps they might hold it all together better. And is that a paint ball gun handle ?

thanks!

the black strips are temporary - grip tape like for hockey sticks. comes off easy. that is there only to hold the pieces together for initial fitting. btw, it is very comfortable to hold - the way the bottle hangs off the bar, along with the back end of the bar, makes for a great shoulder stock.

for the final build, all the parts will be bolted together, mainly to the aluminum bar. since that's the pressure chamber, all penetrations will have to be sealed.

hose clamps or other ghetto straps won't even be necessary. (although they will be on the Fernco barrel coupler to hold it on one end and adjust the friction/seal for the sliding end.

the barrel will pass thru two plastic electric conduit hangars i picked up from Lowes. better pics of them in this thread. they're the grey pieces that the barrel passes thru (and also clamp onto the chamber on that prototype).

friction of the barrel sliding through them can be controlled by how tight you do the mounting screws. plus, it's plastic and i can sand the inside if i need/want (they're saw-toothed on the inside circumference, and the points of the teeth contact the barrel, so would be easy to uniformly sand little bit off the tips).

for the pressure chamber/body, the aluminum is not too thick (~0.125 in), but will definitely hold screws. i'll tap the threads & seal them with loctite and maybe silicone too. or, i could use thin hard rubber washers, but i think i'll get good seals with sealants.

the ends i'll seal off with thicker plate set inside, held by setscrews from outside, and silicone or other (better?) sealant. could even use epoxy, but i'd like to be able to take it apart. also have easy reinforcement method planned if one plate doesn't work.

setting the plates inside allows me to inset a little but more to protect the overpressure blowoff valve (they're touchy crawling thru the brush ), which i'll drill & tap one of the endplates for. threaded hole for the chamber pressure gage can be drilled & tapped anywhere on the body, or on the other endplate, similarly inset for protection.

however, i'm going to keep the front end clean, in fact i'll probably inset the seal plate, fill the end with epoxy, then contour it with a grinder.

btw, i'll use an 80 psi safety blowoff.

for the valve, i'll drill & tap 3/4" NPT threads right into the top of the alum chamber. might even trim off the ends of the close-nipple hanging down into the chamber to minimize entrance loss (i'll check the books to see even how much it would buy me before i bother).

and yup, that's a gripframe off an autococker. i'd like a single-trigger, tho (not a fan of double triggers). looking for a stock Automag gripframe...

one awesome thing about this is that all the metal is aluminum - looks like i'll get to learn how to annodize! probably end up just painting it, tho.

as i found with the blooper, the trigger will be the trickiest/hardest part, but i have idea there...

Just be careful because (you probably already know) pressure chambers with corners don't hold pressure as well as pressure chambers that are cylindrical.

It probably won't be an issue since you are using 60 PSI, but it is still something you should keep in mind.

Is the grip actualy working for the piloting or is it disguising a regular valve ?

I was tempted, quite a few times, to use the grip from my Smart Parts ION with the board and the pilot solenoid on a piston valve.
Would be able to fire in Semi/full-auto and even three round burst.