Balanced UnBalanced Piston

[jackssmirkingrevenge]

Any chance of finding the right size tube to use between the o-rings? Short sections of tube sanded square using the drill press

This is another way of doing it, the APS airsoft shotgun cartridge does this in a similar way:

[airatomic]

JSR, thats a cool option. Can you draw up a quick diagram on the internal working of the CAM 870?

MrFoo, thank you for the long long explaination. I wished to have more complete tools to do all that. But the tools I have are basics, and a lot of the fabrications I did were just out of the box. Very ghetto or macgyver style, so to speak.

Here are some options:

1)

Place matching metal washers (in yellow) around the o-rings, before casting in fiberglass resin once again. That should give "cleaner" edges when its cure.


2)

3way_slide3.jpg (9.78 KiB) Viewed 2444 times

Cut out matching spacers (in red) from metal or nylon blocks, epoxy them between the o-rings. This provides even "cleaner" edges. Only concern is how strong the epoxied spacers will be, as the pressure (psi) increases. If I do this, I will drill in some screws to the body of the spacers from outside to make it more solid and safe.



While pondering the above, I played around with the following:

and

for

Attempting to make a 3-way ball valve. Similar to the slide valve's objective.


Thats before I went to check the internals of a ball valve, and assumed that the teflon shield covered the entire internal. When it was not so; only around the ball valve's 2 exits. The tiny screw epoxied to the body was to shield the hole I made earlier to fix the problems, but the hole through the shiny ball cannot be fixed already, obviously.

Still, it was a good experience.

[jackssmirkingrevenge]

JSR, thats a cool option. Can you draw up a quick diagram on the internal working of the CAM 870?

The CAM 870 operating mechanism is virtually identical to your typical pump action firearm (click image for non-medieval gifv):



The cartridge is a simple balanced spool that is knocked open by a hammer striking a firing pin, here are some more detailed images of the internals:









The small hole in the spool is for filling purposes, when fired the gas flows around the grooved portion.

Place matching metal washers (in yellow) around the o-rings, before casting in fiberglass resin once again. That should give "cleaner" edges when its cure.

I don't think the washers are needed, this is an unnecessary complication. O-rings used directly should work just as well provided that they are not slack on the mandrel when casting.

[airatomic]

Thanks for photos effort, JSR.

I keep wondering how the intermal of the spool looks like. Both ends of the spool got hole, and it seems to be a tunnel from one end to the other. There is a hole on the body at the end of one side. In which case, how can it be a balanced spool? How does it work when infilling it with compressed air, and storing it in this manner?

Having a diagram of the spool's internal will making things clearer, i think.

[jackssmirkingrevenge]

Here's a diagram, should be clearer now. The cavity in the rear of the spool is not open to the chamber, it just anchors the spool in the fill rig while pressurizing.

[airatomic]

Thats much clearer. Thanks for diagram, JSR. That's quick. The legend lives on.

Now this is a clever alternative to my previous one. I like the part where you can service the internals. Lets see if i can fabricate something similar. Without the mess of casting.

Turning this into a slide trigger requires some thoughts. The incoming air from the chamber is from one end. Piloting it goes the opposite end. Hmm..