I recognize a few names on this post from other forums. Hi guys!
The talk about sand blasting is interesting...sounds like it might make a great stretching tool.....since I never use sand blasting, I haven't given much thought to its effects..stretching and work-hardening. A shrinking disc will work on large areas, but on a low crown panel, you may need to prop the metal out to shrink it without it popping in on you. As far as which side of the metal is stretched or shrunk, I don't think of it that way. It does not matter which side you apply shrink, or which side you hit with a hammer other than the convenience of access, or to bump the metal in a certain direction, which has nothing to do with stretching or shrinking. You can figure out whether shrinking or stretching is required by taking a template of the curve up and down and another front to back from the other side of the car. You need to read the panel in both directions to see if it is low or high. It is easy to get a false read if you don't check this in both directions as you work. Sometimes you might have to smooth with a hammer and dolly and shrinking disc just to read the panel, and then proceed to stretch up low spots, or shrink down highs, or both.
I've used a sauce pan lid, the bottom of a small stainless pitcher, a clogged up scotch brite pad on a sanding disc backup pad to shrink...they all work, but a shrinking disc takes the cake. If you see steam when you quench, you are shrinking. No need to change the color of the metal. You can shrink down huge bulges, or tiny little areas. Lately I've been playing with a low crowned disc (think very shallow hubcap) which seems to work even better than a flat one. It works in shallow reverses, and on flat panels where a flat disc is problematic, and it also works on regular crowned panels.
Oil cans are relatively easy to fix once you realize you can shrink and stretch at will without worrying, because you can always correct an over-stretch, or over-shrink.
By the way, the how to make a shrinking disc article was by Paul on the metalmeet site.
Last edited by John Kelly; 12-02-2004 at 06:56 AM.