Welding dent

[Vinnie]

Hey folks,

Though my welding skills are slowly improving I did discover a dent caused by my welding. See attached picture. I guess I used too much heat there afterall...

To me it looks like the weld is pulling the metal due to shrinking. What would be the best way to get the dent to pop out again? A logical solution would be to make the weld put less tension on the sheetmetal above it but how?

Any ideas?

Thanks,

Vincent.

 

[Carolina_Mountain_Mustangs]

Do you hammer your welds before you grind them? In a difficult place for sure you cannot get to the inside probably. They to make shrinking body hammers if it is an oil can situation that pops in and out.

You might go online and look at some video on heat shrinking the metal back. We have lots of places here that do the hail damage repair and they have the tools to get into the tight places. You might look for one there. They call it paintless repair here sometimes.

 

[Don C]

You can get a paintless dent puller that uses glued on buttons, or weld studs to the low area and use a hammer puller, or drill holes in the low area and use a hook to pull the area.

Search results for: 'dent puller kit' (eastwood.com)

 

[Vinnie]

I can pull it out with a suction cup but it pops back inwards when released.

I did not hammer the welds before grinding. Should I? Why so? In this case I can hardly get behind the weld.

 

[Stanglover]

Well Vinnie, I'm no body man, but I have had experience working metal. I hand built steel air cleaner prototypes for many years. Basically what's happening here is you have stretched the metal by over heating the weld. Dressing the welds with an appropriate body hammer and dolly will even the joint area, but the oil canning need to be shrunken out. This can be done by pin point heating a spot to red heat, then using a hammer and dolly, hammer the high (red hot) spot back, then cool it with a rag and water, continue this until the oil canning is removed. This takes practice and a load of patience. What happens is when you heat metal in that way, the spot will actually shrink slightly and as you go, slowly shrink the entire area. There are "shrinking discs" you can get to use on a drill, but I've not used one to say exactly how. Basically, keep your heat lower and don't try to do too much at a time. 

Good luck, hope that helps, but I'm sure there are experienced body guys here who can explain better than I.

 

[turtle5353]

If it’s oil canning, I have had good luck with drilling a hole or two in center of oil can. 1/4” hole will do. Then weld the hole shut and cool it quickly with a wet rag.  That should shrink it and tighten up the metal. 

 

[Carolina_Mountain_Mustangs]

The hammering of the weld just expands it. The weld always shrinks more than the raw material. A few taps with hammer expands the metal. That is why blasting warps metal like tiny hammers hitting the metal on one side expands it and causes oil can.
I see those guys on Forged in Fire trying to fix a warped blade and they end up breaking it. In Tool & Die you add a 1/4" thick hardened back up plate under die sections with buttons and small inserts to prevent hammering into the soft die shoe. When you harden they always warp. I would sit for hours with ball peen hammer taking the warp out before grinding. Slight small peens expand the metal and you push the warp out. It is sort an art form for sure. I am sure if anyone will catch on you will.

 

[Vinnie]

The hammering of the weld just expands it. The weld always shrinks more than the raw material. A few taps with hammer expands the metal. That is why blasting warps metal like tiny hammers hitting the metal on one side expands it and causes oil can.
I see those guys on Forged in Fire trying to fix a warped blade and they end up breaking it. In Tool & Die you add a 1/4" thick hardened back up plate under die sections with buttons and small inserts to prevent hammering into the soft die shoe. When you harden they always warp. I would sit for hours with ball peen hammer taking the warp out before grinding. Slight small peens expand the metal and you push the warp out. It is sort an art form for sure. I am sure if anyone will catch on you will.

Learned a new word! First I thought "Whose small peens is he talkin' about?" But google told me it's the thin side of the hammer head, opposite the flat head. And suddenly your story makes sense and the world is a better place once more

I have to remove door and quarterwindow weatherstips this weekend and then see if I can get something behind that dent.

Thanks for your explanation!

V.

 

[Carolina_Mountain_Mustangs]

Sometimes translations do not got right. I use to laught at signs in China. The translation just does not come out right.
Yes you move the metal on one side to expand the other side and take the warp out. I am not an expert for sure but I have spent hours getting parts back flat with a hammer and dial indicator.
It is same with a body panel. Hammer, Dolly, English wheel all form the metal. You can take a junk piece and make it like new with time and patience.

 

[Don C]

About shrinking disks:

Easy Shrink Metal Shrinking Disc Kit, 4-1/2 inch (trick-tools.com)

 

[Vinnie]

I think too much shrinking (in the weld) is causing this flat spot. So I don't think I need to shrink anything, actually need to expand the weld. I haven't had time to do so yet though...

 

[Carolina_Mountain_Mustangs]

You should always hammer your weld after you do a short section. It does shrink due to the thicker section of the weld. Hammer and dolly every inch.

 

[Vinnie]

Well, finally I got to working on this dent. Had to buy myself a flat dolly first because there's another panel behind the dent (on a coupe anyway) with only half an inch in between. So this little friend went in between:



And then I hammered down on the welds beneath the dent for a while. After a while the dent started to get less and less but not totally gone. But as soon as I pointed my heatgun on it it popped out completely and it's gone