by Roland Wilhelmy
I have heated and quenched it a few times and
can tell very little difference. Do I just keep
on? How much can it change?
I would think the heating would expand it, the
cooling would shrink it, but how could it shrink
it back enough?"
"I'm doing some body work and have a
stretched area of metal. I understand that
to shrink the metal, you heat it up to a dull
red glow, then quench it with cold water soaked
rags. Repeat as necessary.
I have heated and quenched it a few times and can tell very little difference. Do I just keep on? How much can it change?
I would think the heating would expand it, the cooling would shrink it, but how could it shrink it back enough?"
What I am going to say is based on my experience. Your experience may be different. If you want to make steel hard and even brittle, just heat it red hot and quench it with water or a blast of compressed air. In the process you may get some shrinkage, too.
If what you want to do is shrink some sheet metal you need to identify the stretched spots and shrink them. If there is a larger area, then you have to shrink it one small spot at a time. You can cold shrink or hot shrink. Hot shrinking involves heating a small area gently and tapping it with a hammer against a block of wood (not metal) or just letting it cool slowly. The shrinking occurs when the spot gets hot and wants to swell but the metal around it holds it in place, so that spot gets thicker. Or it bows out, which is why tapping it down carefully and very gently with a hammer helps keep it in line and thickening. Stretching metal makes it thinner. Shrinking it makes it thicker. You can cold shrink, but it is easier on edges where you can gather some metal into a "pucker" and then hammer it into itself. Again you use a metal hammer and a wooden dolly or vice versa. It helps if you hold good thoughts in your mind while you do this ;-).
If you want to see a video of how it is done, you can order one titled "Shrinking Magic" by Kent White (aka the Tin Man). If you're serious about body metal work he is one guy you need to know about.
P. O. Box 429
North San Juan CA 95960
Phone: (916) 292-3506
They have catalogs and stuff, too.
The usual disclaimers apply to Shrinking Magic. I bought a copy and like it. I learned a lot of stuff from it. That's all.