Anyone know how to shrink metal? I got some 14 or 16 guage tin on an old tailgate on my Future Fordernational that has the oil can effect. I have been hammer and dollying the dents out of it for about a week, and it is getting closer to straight, but still is warped, and oil can popping.

I would like to avoid cutting it if I can, I was once told the way the do it for the military is to cut Xs in them, and then weld them back shut, and when they cool down, they would shrink to tighten.

Any other tricks you can suggest?

any advice will be appreciated.

 

heat followed by dry ice is one method. Need enough heat to relax the metal. And i found Wal-mart now sells dry ice.

 

Couple of methods...

If you have a torch, heat a dime size spot to cherry red, then cool quickly using compressed air. go slow and only try one or two spots, then dolly it out, its easy to over do it with heat but its also the quickest way to get er done.

Another way is a shrinking hammer, one that has a waffle serration on the striking head, but you must back it up with a dolly. easier to under do than over do.

Ive heard of other people shrinking using a uni spotter, the kind that welds the copper nails on so you can pull dents, basically weld the nail on, then cut it off, you only need the heat from the process to do the actual shrinking, ive heard this works, its somewhat slow if you need to shrink a large area though.

hope this helps

 

Do you mind explaining to me the term dolly it out? I don't want to screw this up too bad.

 

well after heating then quickly cooling, the spot that you just heated should have shrunk...meaning it will be lower than the surrounding sheet metal, kinda like a low spot, at which point you work it with hammer and dolly. usually the spots that need shrunk are the ridges or high spots around the area that had the dent.

 

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I do know what a dolly is, I do have one,and have been using it. I was just wondering about technique. I didn't understand the reasoning behind needing to use it after the shrinking, I didn't realize that it would warp the area around the heated area. But thanks for your input. ; )

 

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Its on 14 guage metal, and I only have a little benzene torche, I would think it would take alot of effort to screw it up with that. Also I am not out much if I ruin this one. its in need of replacement so it would be a good article to practice on.

 

Big flat panels without curves are the worst, any panel that has a compound curve is a lot easier to work!

Go slow work one or two spots at a time, (remember DIME size) and eventually you'll get that oil can effect gone.

Also the older thicker sheetmetal is a lot more forgiving.

you can do it

 

Ranger93 has the info that I'm familiar with Curtis. To heat the dime spots I think most folks would use an acetylene torch. I'm not sure that the little propane jobs will do it. He also mentioned the shrinking hammer. You can probably get one ordered through an auto parts store, or maybe Harbor Freight has them. I'll be in Salina later in the week and check. If I find one I can pick it up and we can share.

I also have a book on hammer and dollying on sheet metal that I would loan you. I'll see if I can find it tonight.

Way to go on trying the metal work. I've done some playing around with it and the better half even asked me to take a dent out of a silver tea pot she picked up at an auction. It even worked.

I have a bunch of old fenders with dents. Maybe I can bring some hammers and dollys to a gtg and let folks play. I'm not a auto body person, but do like to try my hand at some of this stuff.

 

Heres a more detailed version of the same thing...

Lots of controversy surrounds heat shrinking, yet I've successfully used this process for 40+ years. It not only makes a damaged panel repairable (and can save a job from totaling out), but it's also a less invasive repair.

By Mike West

The Tools
The tools you need for the shrinking operation include:

Oxy-acetylene torch. Use a small tip. This could be a 000 or 00, depending on your set, or a 1 or 2. You want a small neutral flame that you can control.
Air blower with an on/off button or a lever for fast on/off action.
Smooth-faced body hammer. The hammer should be a quality, smooth, well-maintained body hammer with no nicks or gouges. You’ll be working on cherry red metal, so you don’t want to damage the metal with a poor quality hammer. Do not use a “so called” shrinking hammer or rough-faced hammer for this procedure. You’ll damage the surface and defeat your purpose.
Heel, toe or other dolly that has a good flat surface to it.
Device to hold your torch safely while you’re doing the hammering operation. I use a jack stand with a trim panel pry tool clamped to it to hold my torch.


The Process
I’ve always felt that if you understand the physics or chemistry of a process, it helps you achieve successful results — probably because you actually understand what you’re doing.

Metal that’s stretched is thinner than it was originally. You want to make it thicker again, thereby lowering the high or stretched area to its original contour. To do this, you’ll heat a high spot of the stretched steel about the size of a dime or a quarter to a cherry red color and then hammer immediately and rapidly around the hot spot, while “backing up” the area with a flat-sided dolly, lightly held on the back side.

Do not hit directly on the hot spot, since this will only stretch it. What you’re actually doing is driving the molecules into the hot, more fluid or liquid spot, thereby thickening it.

Also keep in mind that if you use a shrinking hammer...do it without heat. so you may not need one at all.

 

Very good discription, now if I just had a torch and some experience.

 

jimmie, stop spamming this topic.

 

Ahhh, but experience only comes from trying and learning, go for it!