Expansion Chamber Rebuild Help

[Toestr]

Yep I see it. The hole in the top just isn't big enough to get a hex key down there and I'd rather not drill it.

[scottieb]

Way down inside, through the top, you'll find a hex head slot stick the Allen key down there and loosen. It will come apart.

[Toestr]

Necro!

How about this one? I believe it's a Bob Long/Benchmark. I'm pretty sure I see a socket cap screw down in there through the top but the hole isn't big enough to get an appropriately sized hex key through. There's also a seam at the top that's probably loctited together but I haven't been able to get a good hold of the top to unscrew it.

[Cunha]

The o rings don’t need to do much in those things so you can almost get by wrapping dental floss around the o ring slot haha.

i love those air America ones

[Cunha]

Yeah me too.

[Toestr]

Hehe thread resurrection time. I got the AA one apart. Olsson is correct, it is just a sleeve over the core. I wrapped the ASA threads in a piece of rubber hose and threw it in a vise. It came apart with quite a bit of difficulty. Then I pressed it upside down against a table and the sleeve slid off.

I have no idea why it wouldn't slide apart with the bottom on. Its only function is to keep the sleeve from flying off the bottom when pressurized.

Here is a picture for those interested. I expected it to have all urethane orings instead of the Buna. The Tippmann one was the same way.

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[MrBarraclough]

Going to have to try that.

[Olsson]

Then your next step would be to screw it into a vertical asa - or any asa you can fit it into - and see if you can twist the outer shell further than the Thumper threads into the asa. If that is possible, the outer shell is a loose press fit. If not, it's either just stuck over age hardened o-rings, or I may very well be wrong. I will of course never fess up to actually being wrong, and will delete this comment accordingly.

[Toestr]

Got the Tippmann one apart. Three it in a pot of boiling water and it came apart super easily from between the knurled sections. Looks like the threads had... green loctite on them.

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[MrBarraclough]

The Tippmann, or whatever the knurled one is, should be modular, with threading between each segment. My buddy had one on his Automag back in the day, but with one more knurled segment thrown in. After we resurrected his mag from our 20 year hiatus, his expansion chamber started leaking between the bottom segment and the first knurled segment. I took it off his marker and was able to unscrew all of the sections with some strap wrenches...except for the leaking threads. Of-effing-course. Those would turn maybe 1/8th and then stop. So I'm pretty sure all segments were threaded, but I suspect those threads were galled (or maybe just jammed with petrified o-ring). My "solution" was to put it all back together and use multiple applications of green Loctite (the thin, penetrating stuff). Have not tested it, though, as we reconfigured the air lines to bypass the vertical ASA since we use HPA now.

So it is now a rather heavy foregrip, or at least it would be, except that my old ANS Phase II expansion chamber which I had swapped in as a temporary replacement now appears to be stuck in his vertical ASA.

But anyway, each segment in that expansion chamber is shaped like a flattened, inverted cone with a hole tapped towards the edge. Imagine the baffles from a firearm suppressor but without center holes. The only way to machine that is segment by segment, hence they are modular.

[MrBarraclough]

Similar design to the ANS Phase II expansion chamber, then.

[EvilCreature]

Okay, I will go into the crawl space and find this tonight (hopefully)

[Toestr]

I can't see a seam above the knurling on the Tippmann.

I turned the Thumper upsidedown and pushed on the sleeve as hard as possible and it wouldn't move.

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[Dusty Bottoms]

that will be awesome if your right. I have one of these on a Minimag and I thought it was press fit together and couldn't be disassembled if it started leaking.

[Olsson]

If I remember correctly, the Thumper doesn't have any threads for you to loosen. It is a press fit outer sleeve over an inner frame with o-rings. So you're spinning that entire frame, when you're trying to open it. Put the Thumper upside down, hold on to the outer shell, and try to wiggle it downwards. It will most probably loosen, albeit slowly.

I had one of those years ago, and it took me quite some time to figure it out as well.