Howdy HAMB I have torch shrunk stretched panels before- the usual routine is to raise a spot with the heat, quick hammer & dolly it down a little in a circle around the hot spot, then hit it with a wet rag to shrink it down or even better the air nozzle leaves the metal a little better looking than the water. I have to shrink some spots with no access for a dolly. Should I still give it a little gentle love with a body hammer off dolly? Or just let the cold air do its work? What worked for you? Thanks! Radar
Yeah for sure- finesse is good sometimes but this is a floor panel that’s under the bench seat. I would bust out the disc for more like exterior body work that shows. I just need to suck this panel tight before I never see it again. Don’t want any chance of it popping and banging as the exhaust warms things up or the body flexes. Really I could probably leave it alone but I would know it’s there!
An old trick I was taught years ago at college when I did my trade was to use a brazing rod in a stick welder, drag it across the panel and it will arc, spark and shrink the metal. I haven't tried this for years however the teacher was an old school metal man in a dust coat and knew his stuff. We were even taught how to repair / weld pot metal parts.
Interesting. I have tig but figured ox/a would be the easiest way to quickly put some heat in the metal
You only need to give it a love tap if it "rises up" in the middle of your hot spot. If it does, tap it down with a hammer. Just heat it up in small spots and it should shrink and accomplish what you need. It may not take but 1 or 2.
Figured it would work with just heat and cold air but never tried. Just got home from work- tomorrow is my day off (wrenching day!) so I’ll be wheeling out the torch in the morning with a little less doubt clouding my purpose. Thanks!
A stud welder like used for pulling dents can also be used for shrinking. It can also be a little easier to use around flammables.
Easy to control heat time on thin metal also. I've done far more shrinking with the stud gun than pulling.
You guys are good. I'm a pathetic looser when it comes to stuff like this. I had a nice 63 Olds Starfire with a grapefruit size indent in the 1/4 panel. My buddy and club member Cliff and I decided to fix it one day. We were able to access the back side of the dent through the trunk and we used heavy hands and big hammers to knock it out and we stretched it terribly. We used a torch to heat and quench the oil canned area. We tried it over and over, heating a bigger and bigger area and quenching with a big wet towel. When it got to basketball size, the metal finally cracked! We stopped and now the car needed a 1/4 panel. I now have a buddy [not Cliff] who does this stuff for me. If I'm in his shop he won't allow me to pick up a hammer....
When I heat shrink I don't let it get hot enough to raise, I try not to let it change color. If I see blue then I think I've overheated. I heat, hit with damp rag and if you see steam then you are shrinking.
He ( @mgtstumpy ) is talking about using a stick welder not an electric torch. An old Lincoln buzz box will work for what he is describing. I have never tried it myself but you can rest assured that I will. We used to heat a spot and rub ice or dry ice on it. Probably not anything that teach at one of those hot shot schools but that works too.
When I was in body class 40 years ago the instructor showed us how to get "oil can" out of a hood. He used Oxy-acetylene to heat the area by moving the torch in circular motion starting at the center and going larger and larger to about a two to three inch circle. Making it just turning red in the center and pulled the torch away and put a wet towel on it. You could hear it pop tight and the "oil can" was no longer a problem. If you've never done it or seen it I would recommend trying it on a scrap or unwanted piece before doing it on the car.
If one has the time, you can do a much nicer job if you don't quench. No water, no air, just let it cool. No traumatic changes to the metal structure, and pretty hard to over-shrink things also. It does require patience.
You can play around with dry ice or the duster stuff that comes in a can, with good results I have been told by a couple paintless dent repair guys.
On floor pans I just use a 2x4 and a big hammer and give it a few good hits around the perimeter of the floor pan.
Do you have a nail gun? I have used a nail gun without a nail to shrink it can be a very controlled shrink with far less heat than a gas torch.
Lemme help you get found. My ‘54 dodge pickup had a soggy rusty floor in the cab so I cut it out and made a nice strong frame for the floor. Then I made the floor mostly out of three panels of 16g. The parts you step on are bead rolled and rosette welded to the frame. They came out flat and really strong. The big rectangular piece that makes the top of the bench seat pedestal doesn’t have any frame underneath it, just all around the edge. Nobody will ever step there. I knew that I got a little happy with the bead roller and it wasn’t dead flat but I didn’t care so much because it will never be seen under there and I figured welding it in might stretch it tight. Well it didn’t and now it has a nice big oil can in it that is painfully obvious while I roll around in there welding in the firewall. I could probably leave it and it’d be fine but when you drive things warm up and move around and I want to suck it down a little tighter. It isneasy to address now, harder later. I have an ox/a torch, mig, tig/dc stick, but I don’t have four foot long arms with an extra elbow. I almost always work alone and only beg help when absolutely necessary. I was taught to shrink an oilcan with a little hammer & dolly work around the heat and never tried it without and wanted to see if it had a shot at coming out ok. If it doesn’t shrink down flat it will at least harden and tighten it a little and that can only be a good thing. I posted because my mind was spinning around this operation and I was worried it might be a bad idea. Of course when I wheeled my torches out this morning my oxygen regulator diaphragm stuck or ruptured so I worked on other stuff and ordered a new one. I understood what he meant about using an AC stick as a short circuit metal warmer instead of loading fluxed consumable rods in the stinger but tig seems like a more modern way to introduce heat with a clean electrical arc? Tig and stick are kinda first cousins right? Basically the same process I don’t know why the tig couldn’t be used to introduce heat without enough amps to make a puddle. I’ll report back whenever I get a chance to get out there. Clear as mud? Radar
It went pretty good. I got in the groove fixing the pan that will be hidden under the seat then fixed the one little spot on the passenger side. I definitely needed the hammer!
Nicely done. I’ve never used a dolly. I was taught to use a torch, hammer only and wet rag. Been successful for 35 years, so it must work. I’ve also used the nail gun method and it works well also. I teach all my students the same method and they are all successful fixing oil canned metal, and believe me, they can really stretch metal when learning to straighten dents.
""I understood what he meant about using an AC stick as a short circuit metal warmer instead of loading fluxed consumable rods in the stinger but tig seems like a more modern way to introduce heat with a clean electrical arc? "" If you make an arc you will most surely make a hole...Ground the rod to the metal until area is suitably hot enough..I never did any large areas but I only heated a dime size area and quenched..
I've tried shrinking with a torch and a rag, but I'm not skilled enough to have real success. However, I have a shrinking disc and I used it and a wet rag on my Model A Hood Tops and it kinda made it "dummy proof". I just popped the oil canned areas up with my hand, then put in the ear plugs and rand the disc over the high spots, then quenched with a rag. The disc would really warm up the metal high spots, but not get it glowing like a torch would (hence low skill lever required).
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