Hi. I have built a nice little twin pump vacuum plant out of bits and pieces for very cheap on account there are about 8 pumps under my bench at work. I have sat 2 double pumps on an old 40L compressor tank. And will add in some control. The pumps reach a good strong vacuum and much much more than the high vollume dust extractor type I have seen being used.

Looking at a fixture design to machine alloy. I am about to cut a groove out of a piece of alloy for my fixture, for my o-ring to sit in. I have bought about 5 sizes of O ring material from 2.5mmm up to 4mm.

Hey so wondering what kind of stick-out the o-ring should have? Ie 3mm o-ring material, I am thinking I will machine a groove say 3.05mm wide by, at a guess, 2mm deep to give a 1mm stick-out seal. But is that too much or not enough? I have seen a sandpaper trick so perhaps 1mm is not enough.

It would be good to hear what others have done before I start experimenting. Thanks in advance