ok i have noticed that on the older steel used in 55 ford trucks that the steel puckers up around a dent,, and this can be very frustrating when trying to fix a dent ,, but a friend suggested heat shrinking it,, so i guess my??? is is this a good idea,, will it work?????????? and how exactly would i do it?????? any help would be greatly app.

 

If it is "puckering up" around the dent then you are probably over working the metal and stretching it (making it thinner)........your friend is right, you need to learn to shrink

You need to bring the metal in towards the centre of the high to try and restore the metal to it's original thickness.

Two basic ways of shrinking:

Use a "slapper" on and off dolly on the high spots to reduce the "fullness" of the metal ie cold shrinking

This is a difficult skill to learn

And/or

Use heat and hammer/dolly work to shrink the highs

The later is probably easier to learn so lets cover that......but it helps a LOT if you have an assistant



Adjust your oxy to a neutral flame.

Working from around the edges of the high spot and moving inwards heat up a spot the size of a dime untill the centre JUST goes red.

Hand the tourch to the assistant and QUICKLY work the heated area with the hammer and dolly as you would a crown dent

Quench the area with a wet rag or a blast of compressed air

Repeat, working around the high and inward to the centre

SOMETIMES a group of bigger shrinks in the centre is all that is needed, but it's a skill knowing when.....To start with do lots of small shrinks working from the outside in

If you don't have an assistant make a stand for the torch to sit on while you work the heated area.......shuting it down and restarting it is just too time consuming.

You could go and buy a shrinking disk for a body grinder, this is a replacement for the torch and may negate the requirement for an assistant.

Mark

 

thanks for the info halfdone,, im thinking that the shrinking disc may be the way to go,, but then again maybe not ,,ive never had any luck with em,, but time has passed since i tried em,, so maybe it will work this time thanks again for the info

 

jsut another way to shrink the good metal in the old body panels, you can also use a slapping file wich is a file bent kind of in a s shape that you slap against the meatal in the area of the stretch and work the slaps in toward the center of the stretched area. als o when you shrink with heat or cold shrink you should use a shrinking hammer wich has a serated head that draws the maetal in toward the center of the stretched area thus thickening the area you streched by overworking it . ( just a not shirinking does not work on the new high carbon steel panels of the late model cars it removes the carbon and the strength form the pannel, it works on the older pannels because they were made from a low carbon base sheet metal which is why they are so much thicker than todays body pannels they needed this thickness to get the same amount of strength ) hope this was of help

 

ok,, i have tried to heat shrink the area but it seems that all im doin is making it bigger,, so what am i doin wrong,, im thinking that im not getting it hot enuff,., but i dont know how hot to get it,, and man its getting frustrating,,it seems like whenever i fix an area all im doin is creating another,, any help would be app.

 

The nice thing about the shrink disk is that it only heats the high areas. Once you have hammer-and-dollied the area out as close as you can make it, then the disk heats up any high areas and you cool it with a wet rag. I used mine in a couple of spots and then sold it after it sat on the shelf for a year with no potential projects in sight. The kit came with a video and I got to talk to the supplier/demonstrator at Hot August Nights which was very helpful. Good luck, Jag

 

I HIGHLY recommend getting Ron Covell's "Basic metalworking techniques" video or dvd. He covers all that you are asking about and more and a video is worth SO MUCH more than still pictures or words. My wife just gave me a copy for my birthday and I learned a lot from it already! It really helps to see and hear what on dolly and off dolly hammering means and especially what it sounds like, how hard he hits the metal to shape or smooth it etc as he works on restoring a 1932 Morgan.
PS they repeatedly emphasised NOT cooling the panel with water or air when demonstrating heat shrinking.

 

ok sorry you sometimes forget the tiny details when you have been doing something, when you heat the metal you use a feathered flame on the torch called a carbonizing flame, then you heat the metal to a cherry red color in a small circular motion about the size of a quater when it is hot enough you will know cause the stretched metal will rise up and form a little bump ( the bump's size depending on how stretched the metal is ) then in a circular motion working from the outside edge of the heated area you hit the metal in towards the center in a circular motion ( either using a shrinking hammer or a shrinking dolly, once you get in to the center you hit the center down with one hit and then let it cool naturally, i hope this helps and i agree with axracer a video is much easier to learn by than written word,

 

yes you only want to gently tap the hump down flat not pound on it, so you don't restretch the metal.

 

I used a hand torch with Mapp Gas on my 51 front fenders. They were all smashed down and they were oil-canned. I just worked around the permiter in a smaller circle till the oil-canning went away and it was where I wanted it. My not have been the best heating source. But as we use to say went running sand buggies (you have to run what you brung). Besure to wear a good glove on the hand on the underside as the hot undercoating really burns.