Looking to ask He Who Shall Not Be Named

[george]

Hello and Thanks for your Time.

A LONG time ago, it was posted somewhere that if you wanted to make your own end caps, you could use not epoxy but a two part liquid used to cast parts so you could make multiples of them.

What I was thinking of using was Car Bondo, used for car body repair. My questions are; If I use it how much larger should I make the End Cap to deal with drying/shrinkage and is there cracking? Is it water proof? What I planned on doing is make it at least an inch larger diameter so I can turn it on my lathe and put in the grove for the o ring. Also what is used to prevent it, the wet bondo paste from sticking to the larger mold. I was going to use a larger piece of pvc pipe as the mold for the bondo plugs. Do you think Bondo is strong enough for this End Cap use with constant installing/removing?

What do you think and also some of the material you have access to I don`t here in Canada, could you please tell me of the general products or what industry they are from so I can try to match them here.

Thank you for Your Sharing Your Wisdom with me.

George

[Subculture]

Polyester filler is the last stuff I would use for endcaps. Brittle, shrinks like the blazes, and isn't waterproof. To release resins from a plastic or wooden mould you need to either wax the mould, apply PVA or use one of those fancy mould release sprays which cost an arm and a leg.

For one-off endcaps, or even small batch work, there's no need to cast at all, just turn them from sheet stock- lexan, PVC or acrylic make excellent endcaps. Here in the UK, WTC's by OTW and Sheerline use that method. The result looks very neat, and if you purchase offcuts (sign makers, ebay etc.), the cost is very low.

Casting them like Dave does makes sense if you're going into batch production.

Finally you can get all the resins in Canada, a quick google brought up several links of online vendors in your part of the World.

[KevinMc]

A LONG time ago, it was posted somewhere that if you wanted to make your own end caps, you could use not epoxy but a two part liquid used to cast parts so you could make multiples of them.

Modellers Choice in Hamilton carries Alumalite, that's the two-part casting resin you're looking for. Having said that I agree with Andy that unless you have a need to make many it's less work to turn off what you need, especially since you have a lathe at your disposal. Large diameter PVC works great for end caps.

[Kazzer]

I can't imagine why anyone would say you couldn't use epoxy to cast end-caps, unless they were thinking of using a paste grade material. You'd need a liquid 'engine oil viscosity' material so it would pour into the mold. It would have little, if any, shrinkage. but the mold would be the problem, undercutting the O-ring groove, would snag in a solid mold, so you'd need to make it from RTV rubber. For a one-off, I'd agree that you'd be better off simply turning one up on a lathe.