Is it shrunk or streched

[jdss]

I removed the heater blower motor from my firewall and welded up the hole(about a 6inch hole). also welded up the two smaller holes were the heater hoses go in.Now there is and oil can dent just to the side of were the blower motor was.I don't know if it is shrunk or stretched.Or how to fix it if it's even possible...Any thoughts??

[John Kelly]

If it was straight before you started welding, then it is only shrunk from the welding. You need to stretch the weld, and perhaps a little of the metal to the sides of the weld where it has turned blue. Make sure you have removed the weld crown on front and back so you don't mark up your dolly too much.

John www.ghiaspecialties.com

[jdss]

Sorry it took me so long to reply.I went to a football party, they lost :(.. Anyway If I understand you correctly I should put a dolly on the back side and hammer on the otherside. but where? just where the weld bead is or out farther? how hard do you hit it?

[John Kelly]

It takes practice to get a feel for it. Weld some scrap pieces together and start using a hammer and dolly on them. If your dolly matches the curve (or flat)of the panel, and your hammer head is fairly flat it takes more effort to stretch. I like to use a small headed hammer or a slightly crowned hammer and a dolly that matches whatever curve there is. The small contact area between the hammer and dolly makes it easier to stretch. Do just the weld, then check the flow between the pieces with a flat machinist's ruler to see if you need to stretch right next to the weld as well. You will fine the blue area has shrunk.

John www.ghiaspecialties.com

[v2cad]

jdss

I just did the same to my Firebird along with filling the cutout that the heater box went through. You would think that with all that welding something would need to be streched, but I was able to get everything pretty flat using the shrinking disk. (Which I got from John Kelly, thanks John, it worked great!)

J. Clear

http://www.metalmeet.com/photopost/data/3403/22Firewall.JPG

[John Kelly]

Hi J.

Glad you like the disc...just about my favorite tool. I'm guessing you may have just evened out the shrinking...perhaps you have a little less overall shape in the panel now than it would have had using other methods....or maybe your whole car is just a little smaller than before (insert smily emoticon).

John www.ghiaspecialties.com

[Kerry Pinkerton]

I FOUND IT!

I used Dutchs shrinking disk on Bennets truck and was SOLD. What an amazing tool. Unfortunately I could not find mine. I was about to order another from John when I looked in one last place and there it was! YEA!

It's interesting as I do metalshaping demos at shows how often shrinking in side a panel comes up. I don't have power to run the shrinking disk but will make a sample panel that shows before and after of how it works.

[jdss]

Just thought I would give an update on my progress.I tryed to stretch around were I welded in the patches but ended up with two oil can dents.So I figured it was stretched to far.I never did it before but I got out the gas torch and did my best attempt at shrinking.What I did , and I have know idea if it's the right way,is use a very small flame and heatup a spot until it just starts to turn red.Then i removed the torch and cooled the spot with a wet rag.I did this in about six spots and the oil can dents went away.Now the panel isn't perfectly flat but it's way way better than it was. :D Thanks All for the help....

[John Kelly]

Glad you got it! Next time you shrink with a torch, try heating to no hotter than blue...maybe even a little cooler, especially if you are going to quench. This will help you keep from getting hard spots where you have shrunk.

John www.ghiaspecialties.com

[cyberrodder]

I just what to add to this thread as for oil canning. I had a scenario where I was welding a roof of my 37chev together (still have more :( ) but I had a series of nasty oil canning's I found the this piece of information priceless, pretty much followed it to a T and got rid of all the oil canning I had, I have performed so many fixes lately I could spot the problem pretty much straight away and resolve it rather quickly rather than second guessing.


// Oil Can Dent.

An oil can dent is caused by stretched or shrunken area of metal on your panel. This will pull to the next strongest curve in the panel. You have to restretch or shrink the area originally damaged and not touch the oilcan area at all to repair it.This always confuses the beginner because he will try to work the oilcan and it will never go away unless you repair the source problem. Dutch


cyber

Mt Macedon
Australia

[jdss]

Thanks for the reply Cyber.I guess the hard part is deciding if its shrunk or stretched.So far I've learned that welding only shrinks it.If you hammer on it it stretches. :?: