Creating a non-permament seal on the end of my chamber

[Blitz]

So I've reached an important step in the construction of my upcoming cannon.

For a chamber in an over-under design of a pneumatic, you typically have a cap on one end, and the valve at the other (or elbows leading to it). This is fine and dandy, because there is usually no need to access the interior of the chamber. For a combustion, this isn't always the case. Where the cap would go on a pneumatic, some sort of access is beneficial for many reasons such as venting and maintenance of the interior parts. So what's typically used? Plugs and female adapters, right?

The issue here, is my chamber is 6" in diameter. Female adapters are around, but nothing simple is available to plug that up (And please do not refer me to part 9102K335 on McMaster, because I only want to use pressure-rated components)

So barring that, can anyone think of a graceful method of being able to seal that end off, while being able to remove it at will?

What I want to avoid is reducing the ID. An advantage of a 6" cdiameter chamber is being able to service the insidies more easily and I plan on taking advantage of this by making a small platform/rail where I will mount my fans and ignition source, and if I reudced this to 4", that wouldn't be possible without modifying my fans heavily, which I want to avoid!

Flange?

[ALIHISGREAT]

well a flange is an external rib or rim around the outside of something so i can't see how that would help but yeah i know what you mean and it would probably be the best option unless you have the facilities to make your own metal 'plug'?

[psycix]

A thick sheet/cillindrical block wich is shoved in and held with bolts trough the chamber wall?

[jrrdw]

A flange may be the way to go. Once fixed to the chamber you can bolt on a piece of flat PVC with a o-ring/gasket to seal the end. This way will allow access to the chamber when needed.

[JDP12]

yep i'm gonna say a flange as well.

[jimmy101]

A flange would work but I don't think they are usually pressure rated.

I would go with what psycix said. Perhaps a piece of 3/4" MDF bolted into the end of the chamber. I believe DR used a similar method for his basketball gun.

I wonder if there is a way to cut the plug to the proper size using a router and flush trimming bit? It would be easy to cut the plug to the same OD as the pipe but you want the disk to be the ID of the pipe.

[Blitz]

Some nice thoughts thrown around here, thanks guys! The flange method seems easier... but what DR did to his basketball cannon certainly looks nicer. The OD of most of these flanges exceed 10" in diameter.

I don't see how that'd be a problem jimmy, I think that'd be worth investigating and I'll certainly do that. Thanks for the link.