Repairing "Oilcans"

[Stanw3]

I'm working the nose on my 66 bus. It had been pushed in pretty good - I've beat back out fairly straight and am ready to start skimming it with el Bondo - BUT - I have an "oilcan"effect on both sides of the middle seam - where the largest area of sheet metal is. On my 61 that has never been hit or worked there is some of the same thing so maybe it can't be eliminated??? My concern is if I lay a thin layer of bondo over it will it crack and break out the first time someone leans against the nose?

How can I eliminate the oilcan effect all together?

Thanks!
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Sanborn7

www.facebook.com/Sanborn7

[lonslo]

The bondo will crack in time. You need to heat shrink the surounding area till it cherry red with a torch and cool it off with direct contact with a wet towel.

[Stanw3]

do I heat the center of the oilcan area or the perimeter of it?

Thanks
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Sanborn7

www.facebook.com/Sanborn7

[diy570]

start at the highest, most raised spot first. only heat small amounts at a time. do not heat it up past cherry red or you could start melting. a good rule of thumb is to heat an area the size of the face of a body hammer. once you heat it up, tap around the area lightly with your hammer to concentrate the metal. then you cool it with your rag. move on to the next highest spot. patience is key!

[lonslo]

sorry i forgot to tell you about tapping it w/a hammer.

[John Kelly]

Torch shrinking is a difficult skill to learn. It deforms the metal by expansion and then contraction to shrink. It is best to use a torch very sparingly. Do not heat to red hot. It is not necessary, and creates a harder local area. Heat small spots to just below blue heat, or to blue at the highest. Then quench with a wet rag. Make sure the panel is totally cool before shrinking more. You must use a hammer and dolly to smooth the surface, before and after.

A better and easier way to shrink sheet metal is a shrinking disc:

http://allshops.org/cgi-bin/community/communityalbums.cgi?action=openalbum&albumid=9980121727059

And:

http://allshops.org/cgi-bin/community/communityalbums.cgi?action=openalbum&albumid=9980124046566

Here is an article that might help a little (scroll down):

http://clubs.hemmings.com/clubsites/chevylist/tech/hammerwelding.htm

John www.ghiaspecialties.com

[diy570]

ive been meaning to check out a shrinking disc. ive heard about them, but never seen them in action.

[John Kelly]

They work extremely well. There is a short video of me using one of the type I make for sale...click the link, and scroll down to video downloads, then click on shrinking disc:

http://metalshapers.org/101/index.shtml

John www.ghiaspecialties.com

[Stanw3]

John -

Does the disk simply attach to a normal grinder???
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Sanborn7

www.facebook.com/Sanborn7

[Stanw3]

just watched yhe video - I see it now.
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Sanborn7

www.facebook.com/Sanborn7

[zimblewinder]

Hey Stan , thought Id throw in my 5c worth since I just did my nose over too. It had some really hard folds because it had been damaged, kicked out, and damaged again Id say. Anyway... the shrinking disc it the ants pants!!!! I have never done panel work with just a heavy ball piened hammer before but thats all I used with the shrinking disc and a bucket and sponge and its now original shape and baby butt smoothe. I thought youd like an opinion on one of these from someone other than the maker. Believe me its as good as he says!!! (PS thanks John , very happy with it)
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58Euro 23 343208 The Ultimate Zimblewinder Machine.
59 mango standard
Wanted- splash pan supports, og pressed bumper coach bolts, ivory blaupunkt knobs (early), armrest alloy strips, NOS door mechanism