Re: Shrinking Dents

Posted by Marco on April 29, 1998 at 11:44:08

In Reply to: Shrinking Dents
posted by Bob Bidonde on April 29, 1998 at 05:03:34

Bob,
Now that Glen and Bob did all the dirty work (typing) and offered good advice, I can add just a little. Shrinking is done only if still required after dent removal as described by Glen. Never use heat as an aid in dent removal, it will only make things worse. If you do need heat I don't know of a single fuel torch that will provide either the heat or control required.
If you find you must resort to heat shrinking DON'T USE WATER! Use a small tip on the torch and heat a small spot (smaller than a dime) cherry red. As you heat, The metal will draw towards the hot spot and you will see the metal rise towards the heat source. Quickly hand off the torch and hammer and dolly using Glen's "work around" method, which works the metal into the hot spot. The final impacts are at the center. You must use the direct contact method with the hammer and dolly which requires a light touch. The dolly is held lightly on the back side so that it bounces away easily with a light impact from the hammer.
If you are comfortable and effective with a hammer and dolly, the only real art to this practice is knowing when remaining problems are caused by over shrinking (which is often). The tendency is to keep chasing high spots surrounding the original shrink, when all that is usually required is a little hammer and dolly work at the original shrink to relax (expand) the metal slightly. One shrink can effect a fairly large area.
As mentioned earlier, follow Glen's advise and most if not all your dents will retract to an acceptable level. If you must shrink, get some junk to practice on. You will be amazed at how much the metal will draw from even the smallest shrink. Without a great deal of experience DON'T shrink near an unreinforced edge (such as near the hood latches). The metal will draw from the edge and expand the other direction.
Good luck,
Marco

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