rx7locost wrote:
I'm interested in seeing how you achieved getting things colder than liquid Nitrogen. I thought that a public sharing would be better than a PM. Can you expound?
Sorry, I was half asleep when I wrote that. It should have read farenheit, and I don't know the precise temperature it reaches, but it is seriously cold - enough to shrink the overall diameter of a .827" hardened steel bearing by more than .017". I got the -200 degrees figure from charts on the shrinkage-from-cooling of hardened steel, as that much was required to attain the reduction in size I required. Since I got a greater degree of shrinkage than I'd expected (and even hoped for), well, that's where the estimate of the cooling came from. The point is...it works.
And, since you ask, my method is to buy a can of "Dust-Off" (or similar) from an office supply store. Attach the straw, invert the can, spray the part to be shrunk with the liquid that issues from the can for several seconds until it is uniformly solid white in color. Do NOT touch the part with exposed flesh, for obvious reasons. I repeat the cold-soak again after 30 seconds or so to ensure the part is uniformly cold. I also spray the tool I'm using to place the part in position, so as to not make a spot of relative heat at some point on the part. Also, try not to breathe the stuff - it's probably not good for you.
I've successfully used this method on such things as removing a press-fit barrel on a rifle, steel bolts seized into alloy engine blocks, etc. In each case, heat (from, say, oxyacetylene) was not an option.
_________________
Scratch building, at continental-drift speed, a custom McSoreley-design framed, dual-Weber 45DCOE carburated, Zetec-engined, ridiculously fast money pit.
http://zetec7.webs.com/