Fusor Forums

Yeah, brand new brass swagelock works fine and fairly new brass swagelock is OK. I wouldn't subject it to vibration or too much thermal cycling though.

Plus there are fully compatible and just as good swagelock imitations commonly available from McMaster or even Amazon at much lower prices. Especially when made of brass, for combination with 50 cents a foot hand bendable copper tubing from local hardware store.

You can also use o-rings and backwards ferrules to turn swagelock into poor man's ultratorr fittings. This would function as the dismountable tube fitting we need. This or VCO fittings are preferable if high temperature or UHV is not needed.

It may be possible to pick up large "garbage" assemblies of VCR from semiconductor business surplus and cut them up.

VCO fittings are not used for high temp or high vacuum.

Swagelok new or old is fine for high vibration no matter what material you use. Brass is cheap and stainless is corrosion resistant. There are also steel and aluminum versions out there plus a couple exotic metals.

I have reused a lot of VCR stuff, just did on the gas manifold on my big system. The big thing about VCR is you are going to need a orbital welder ideally or at least a tig machine to weld the fittings on, there is no simple way to make new assemblies with VCR.

Why not silver brazing?

Silver brazing is fine as long as you are sure you have cadmium free rod. The problem is the internals can be very dirty and oxidized and it is going to be a real pain to clean it up. So for larger stuff it is fine or for stuff like water cooling lines inside the chamber. It is also used for connecting chunks of copper together since it takes a heck of a lot to tig weld copper, especially big chunks.

Standard "Swagelok" fittings (the crimp ferrules) are really only meant for one or two uses with every day fluids like, say, a refrigerator condensor. They can be pressed into use for vacuum, but expect to hit problems if retightened more then once or twice. Maximum performance in the 1E-5 ish Torr range. Swagelok the company also makes so called VCR fittings which are actually designed for vacuum service using a metal-to-metal seal by compressing a disposable copper gasket between stainless flanges. The gasket is fully disposable/replaceble and costs about 5 cents. These fittings will outperform any pump the amatuer is likely to use. They cost about the same as standard 'swagelok' fittings. They can be purchased directly through your local swagelok dealer or secondhand through ebay. One drawback is they are more likely to require brazing/soldering but this can easily be done with a $5 homedepot propane torch and silver brazing rod. If you are brazing, shock cooling with water is a good method to break up the flux residue. A simple wire brush works in a pinch. Sandblasting is usually the best solution. Really, you only care about cleaning the vacuum facing side. The hard to reach bits will be inside the water channel and not enough to be a concern for amatuer fusors.