oilcan on flat area, help!

[666frisco]

Hi guys,

So I have been welding up this 39 chev truck cab chop. For the most part the weld went smooth except for a large oilcan on the passenger end of the rear window. Now there is some weld in this area but I have taken it down to the thickness of metal from both sides and I have good access with a hammer from both sides. I have a shrink disc and using it I was able to remove a lot of the problem but it got to a point where it stopped shrinking the problem area.

I still have a oilcan and I wanted to ask for some advice on getting the remaining oilcan out.

The area should be flat so it really stands out.

I'll get a close photo today and post it so you have a better look at what im up against.

Thanks guys

Dan.

[666frisco]

http://4.bp.blogspot.com/-APX903uhtN...214_125316.jpg

[oldgoaly]

Hi Dan!

So you got yourself a little extra metal..... the quick answer is tap from the inside so it pops out then go over it with your shrink disc. The disc takes multiple passes, heat / cool cycles, it is not fast like a torch but is easier to control in some ways. There are some things that can give you problems, is the panel really flat? Many parts were made convex to the exterior to be stronger and resist dents and dings. Also have your welds been dressed out ( plannished smooth) Also was there any damage before? this can give you headaches as the metal work hardens where you need to work it. Oil canning can be a real pain in the butt! So don't give up, just take your time, you will get it! tt

[Bill Gibson]

I'm thinking that if you welded it and just ground the weld down, then the weld HAZ has shrunk. That will make the patch itself bulge out, but it will pull the surrounding metal toward the patch. If it is popping back in easily, then you probably need to stretch the weld area. That should level the patch and push the surrounding metal back out. I think tt is correct that it needs an almost imperceptible convex (low crown) to make it hold it's shape.

[Strum]

I am hardly an expert compared to most people on here, but I'll give you my 2 cents anyway. When you use the shrinking disc on this area, you are likley stretching it inward as you run over it. This would cause it not to shrink. Have someone hold out lightly on the oil can area from the inside with a soft object and give it a try. I also agree with Bill about the cause of your problem. I would try what he said first.

[humandurk]

mioght be a little off topic. but does anyone have a video of how to use a doughnut dolly in this kind of instance?

never mind, did my own searching! seems like a neat tool!

[jlrussell4]

I'm thinking you folks are wanting to shrink an area that was caused by shrink from welding. Unless something else was done to the panel that we haven't heard about, start by stretching the weld area.

[anders nørgaard]

Originally Posted by jlrussell4

I'm thinking you folks are wanting to shrink an area that was caused by shrink from welding. Unless something else was done to the panel that we haven't heard about, start by stretching the weld area.

I think you're right Buddy!

I think THIS is what causes the void/curve



The red line/curve has got a shorter radius than the yellow ones. The sheet shrunk in the red area. Using the shrinking disc will increase the shrink.

Stretch the red line on dolly and you'll be good!

[Carbuilder]

I agree it needs to be streched. What I do in spots like that is mark the outer edges of the low area with a sharpe then start my hammer or slap & dolly stretching from the out side in a circular pattern work in to the center. I prefer a sliding slap motion. A lot of times I will slightly over stretch so I can finish it with a shrink disc. Just my thoughts.

[larry mullen]

dan
good advice on your oilcan problem on above posts. Ive got a forty chevy truck , considering chopping it , How much did you chop yours ?
can you post a side view picture ?
thanks Larry