[chas350]

oil canning/sheetmetal buckle

I am welding on cab corners on a 71 k10. After butt welding it on, the rear flat area had a section where the pieces did not line up perfectly even, so like a dummy, instead of leaving it, I put some more weld there. After grinding down and hammering the weld, I have a buckle that pops in and out. I figured all the hammer doly work stretched the metal out so I did some shrinking work in the area, several times. The buckle is firmer and smaller but still there.
What can I do, short of some relief slits and rewelding again (more carefully) to fix this?
Prior to this problem my panel welding was good, darn it, I knew this was working to well to last!
thanks for any help!

 

[Fast Eddie D]

Keep shrinking it.

I don't have a shrinking disk, but I hear great things about them. I avoid shrinking as much as possible, would rather stretch the metal, but in a situation like this it's unavoidable.

I have had some success by heating up metal slowly with a propane torch, and quenching it quickly. If you shrink it a little too much, you know what to do.

 

[Silverback]

I've tried the whole 'red hot propane torch/wet towel thing' and wasn't that impressed... but it was on newer sheet metal and I was wondering if I might have had some alloy/hardening issues and other stuff affecting the results. I also tried a similiar setup that I believe was sold by matco or snapon as an addon to a mig welder that basically was a copper tip without the wire feed to do the same thing, create a red hot spot where you want it... again, it worked but I wasn't impressed.

As far as a shrinking disk, I made my own (had some scrap stainless sheet, taped a 7" cutting wheel on it and traced it with my plasma cutter, making a perfect disk with the hole in the right place. I sanded off any slag off the cut surfaces and then found a pot in the kitchen that was slightly smaller than the disk and had a piece of MDF that was slightly smaller then that, put the whole assembly on my press (pot, disk and then MDF) and pressed them together putting a crown in the disk/bending the edges back.

I have to say that works absolutely incredibly well for shrinking while making the most hideous screeching noise....

 

[chas350]

Screeching noise, thats funny. sounds like you put your thinking cap on for that idea!

I do have a shrinking disc and it works wonders, but the problem is, its like a 6" wide recessed section, so its tough to optimize a 9" disc on it.
I used an old 3" flap disc that was worn and not really cutting on an angle die grinder and this heated the metal real quick for shrinking, I also tried a small butane micro torch, they both worked but I still have the buckle/oil can effect.
Should I keep trying to shrink it?
Anybody else have an idea?

 

[Mike H]

Shrinking it more should get the oil can out. I use an oxy accl. torch with a 0 tip to get it hot fast then quench it with an old towel. You have to do it in several small spots to get a big issue taken care of.

 

[chas350]

Shrinking it more should get the oil can out. I use an oxy accl. torch with a 0 tip to get it hot fast then quench it with an old towel. You have to do it in several small spots to get a big issue taken care of.

Hey Mike, how hot should it be?

 

[Mike H]

I get about a dime size red then quench it then move about an inch or so away then do it again till I get the results I am looking for. I hammer and dolly the raised spots out and see if the oil can is gone.


To keep the shrinking disk from squeeling put some bar soap on it and keep a little water and soap in a spray bottle on the surface to keep things lubed. It will keep the disk from galling to the metal you are heating with it.

 

[chas350]

I get about a dime size red then quench it then move about an inch or so away then do it again till I get the results I am looking for. I hammer and dolly the raised spots out and see if the oil can is gone.


To keep the shrinking disk from squeeling put some bar soap on it and keep a little water and soap in a spray bottle on the surface to keep things lubed. It will keep the disk from galling to the metal you are heating with it.

Ok, that sounds a bit more intense than I was working it, going to try your method and see if I can win. At this point I am almost afraid to hammer/dolly anymore for fear of stretching more.
Can a s disc make enough heat with soap on it?

 

[Mike H]

The founder of metal meet shows using soap for the galling in his DVD and the watter should steam when you have enough heat.

You will have to hammer and dolly the shrink out of it because it pulls up quite a bit when you heat it with a torch but you only take about 50% of the shrink back out with the hammer and dolly. So it takes a little bit to get the desired result but the filler is minimum when you are done.

 

[Silverback]

You know, I've found a lot of mentions of using a hammer/dolly to do this with a torch, and I found that it was necessary when I tried it with a torch (again, I tried a largish map torch, I found that propane couldn't direct enough heat in a small enough area to get results, I'd be shocked if a little butane mini torch could), but with the shrinking disk I was in a spot that I really coudn't back up my work with a dolly but found that it once you got the metal moving it worked without the hammer/dolly, that I could just hit it wherever it got too tight.

 

[chas350]

You know, I've found a lot of mentions of using a hammer/dolly to do this with a torch, and I found that it was necessary when I tried it with a torch (again, I tried a largish map torch, I found that propane couldn't direct enough heat in a small enough area to get results, I'd be shocked if a little butane mini torch could), but with the shrinking disk I was in a spot that I really coudn't back up my work with a dolly but found that it once you got the metal moving it worked without the hammer/dolly, that I could just hit it wherever it got too tight.

When you say "I could just hit it wherever it got to tight" do you mean with a hammer only? Actually, I am not understanding your technique, are you talking about working metal with a hammer/dolley and shrinking with a torch? Sorry, a little slow here tonite :]