A bench-mounted shrinking machine is a great tool for many metalworking tasks, and they are reasonably priced. Read how this tool can be used to “tighten up” a defect on the edge of a hood.
Q.
First, I have enjoyed your column and videos for years. Great help!
I have a 1953 Chevy truck with a high spot on the back of the hood. I am sure you have seen these, and it has a raw edge, with no hem or reinforcement. There is a small high spot that runs about 2 inches along the edge and protrudes about 1 1/2 inches into the hood. It’s essentially “U” shaped with the legs of the “U” on the hood edge and it has the “oil can” effect when pushed on.
With help from your videos and writings, I have become fairly proficient at hammer and dolly work. I have trepidation on working this dent out because of its fragile nature, and the fact I can’t fill any imperfections after I am done because it’s on a raw edge.
Do you have a suggestion about how to fix this? I am just not sure where to start. Any suggestion would be very helpful.
Joe Warner
Via the Internet
A.
I’m very glad you enjoy my columns!
Probably the best way to deal with the type of damage your hood has is by using a mechanical shrinker, right on the edge of the panel. These machines are quite easy to use, and they do a great job of shrinking, or “gathering” metal right on an edge. Work slowly here, and check your progress as you go. The jaw depth for most shrinkers is 1 inch, but they do affect the metal a little outside of the area touched by the jaws. If you are lucky, this tool might do everything you need, and shrink the metal that is 1 1/2 inches in from the edge, too. Even if the shrinking machine doesn’t do the job completely, you should be able to get the edge of the hood just where you want it, and if there is still a bulge inboard from the edge, you can use heat to shrink that area. The heat shrinking can be done with an oxy-acetylene torch.
The reason I don’t recommend using heat from the start is that the normal shrinking process isn’t very efficient on metal edges. When you heat a section of metal that’s not close to an edge, there are several things working for you. The hot metal is expanding out against the cooler metal surrounding it, and the constricting force generated by this “donut” of cooler metal will help to shrink the hot spot. Of course, if you carefully hammer off-dolly on metal when it’s hot, it will shrink even more. As I have said many times before, I don’t recommend quenching hot metal with either water or a blast of compressed air when shrinking with a torch, since the rapid cooling will harden the metal.
Unfortunately, this “normal” shrinking process doesn’t work nearly as well on an edge because there is a “bite” missing from the donut, and the constricting forces are greatly diminished.
Another method for removing a bulge in the metal (again, away from an edge) is by using a shrinking disc. This tool creates heat from friction and it is a quite effective tool for removing bulges and high spots in sheetmetal panels. When using a shrinking disc, you DO have to quench the metal to get the maximum benefit from the tool.
Try this out, and let me know if you’re still having problems.
You can email your questions to Professor Hammer at covell@cruzio.com, or mail to: Covell Creative Metalworking, 106 Airport Blvd. Ste. 105, Freedom, CA 95019; you’ll receive a personal reply! Ron Covell has made many DVDs on metalworking, and he offers an ongoing series of workshops across the nation. Check them out online at covell.biz, or call for a current schedule of workshops and a free catalog of DVDs. Phone (800) 747-4631, or (831) 768-0705. You’ll also enjoy Ron’s YouTube channel; youtube.com/user/covellron.
The post Professor Hammer’s Metalworking Tips appeared first on Hot Rod Network.