^good to know!
as to "turning off" the internal reg... it's a matter off putting something behind it to stop movement. I forget exactly the length of my little nub of delrin I used, but it worked well.
I theorize: how the internal reg on a thumper works:
Okay, so, the reg piston:
Bottom-most o-ring is the reg piston face o-ring; the other two are what I will call the spool valve/off o-rings
One o-ring acts as a piston face, and a spring behind that applying a certain amount of force. You also have two small seals that act as basically a little spool/off valve. As pressurized gas is applied to the large seal/piston face, the spool/off valve eventually catches the input (input and output are both between large seal and first of the small seals; once the piston has, against the force of the spring, traveled a certain distance, the input it shut off, trapped between the two small seals). The more you adjust the spring, say clockwise, the more pressure required to move the piston/turn it off, so the higher the regs output pressure would be. And vice versa, if you lower the spring tension by screwing the adjuster out, counterclockwise, you decrease the pressure needed to move the piston. It works because, when the input is caught between the two small seals on the piston, it's the spring holding it back, against the force of a certain amount of air (the decreased, reg's output pressure) - the more your increase the force required to move the spring, the more the air pressure needs to increase to hold it in equalibrium. Before the two small seals shut off the input, the input is supply the air. But once the air pressure reaches a certain amount - i.e. moves the piston face a certain amount, so that the input gets trapped between the small seals - the input is shut off and therefore only a certain volume/pressure of air is allowed to pass through the reg...
Off the top of my head I don't know of any other reg designs like this. It is ingenious in its simplicity. Of course, I haven't had much luck with it, but still. Very cool design.
If you all didn't quite understand what I was trying to communicate, I don't blame you.
Pictures of course would be ideal, but I'll at least try and get some sort of hand drawn diagram setup.
Now, what I think we really need, is to get someone with mod/admin privileges to condense some of this newfound info on getting thumpers to work well into the first post (or maybe that of the other thumper thread)?
EDIT: This would have been SO much easier if I had any CAD program on this computer... Anyways, this should make things easier to understand.
The diagram on the left illustrates the position of the reg piston when marker is NOT PRESSURIZED. The one of the right illustrates what the piston looks like when the marker IS pressurized. Enjoi!
Now, it should be more obvious, that an easy way to disable to internal reg on a Thumper is by putting a bit of delrin (or whatever) rod where the spring would be. You want the reg piston from moving, thus keeping it from closing off the input. I had also forgot to mention that, beside adding that spacer to prevent much movement, I also removed the middle o-rings. Only the middle o-ring can be removed, otherwise, by removing the ones on either end of the reg piston, you'll create a leak (i.e. neither end of the reg piston housing is seal with anything but those two o-rings).
Disclaimer: I'm not perfect. If this isn't how the reg piston works, well, I hope someone will point that out.
EDIT: After a bit more thought with some wine this evening, I've come to the conclusion that, indeed, with quality o-rings (of the proper durometer/material/size) a good polish and a more reasonable input pressure (say, less than 600psi, but not less than 350psi absolute min - keep in mind the marker needs 200-300psi to operate, or at least this seems to be the case), the internal reg could work quite well. If I get a chance to work at a polishing wheel or borrow a dremel and proper head, I'll have to try this. Now, I just wish I knew more about o-ring durometer and material qualities in terms of what works best with CO2 vs HPA at described pressures, and with what lubes...