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An idea I had for making canisters a lot easier - use polished stainless tube and bungs in the end. The bungs are two pieces of acetal with a circular groove around the edge that is slightly smaller than the O ring that fits in the groove. Pop the bung into the end of the tubing and tighten the cap head allen screws - fully tightening them gives about 30% compression on the O ring.

Pictures below show the end bung cap for an 80mm stainless tube


The end cap

Stainless fitting in the centre is used to align the two parts but also gives the ability to attach a fitting bracket to the end cap

Five stainless 6mm cap head allen screws are used to compress the O ring

It is probably a bit over-engineered; could get away without an alignment fitting and probably without as many allen screws

Fitted into the end of a piece of 80mm polished stainless tubing

Using end bungs would mean that canisters could easily be made in standard sizes - say 63mm & 80mm, because that the sizes of stainless tube I happen to have - and then the canister body is just cut to length from the tubing

This should be long enough for any battery - its a meter long canister!

For the top end cap the allen cap heads would be smaller, probably 3mm, and there would be no alignment bolt so that a cable gland and switch could be fitted.

Once I’ve made a prototype top end cap I’ll update this page