Hammer welding

[arandall]

Does anyone have any insight into how to do hammer welds for auto-body work?
My understanding of it is that it is a butt-weld, generally MIG'd, which is subsequently hammered flat when the weld is cold. Is that correct? And if so, don't you need access to the back of the weld to hold a dolly for backing? This is quite often impossible when adding patch panels into a car's bodywork. Addittionally, doesn't the hammering stretch the metal?

Thanks,
Art R.

[matteh99]

I have heard that you can hammer on TIG welds easier than MIG welds. But I haven't tried it.

[junes]

Real hammer welding is done by heating the metal then hammering them together. Most people hammer weld pannels after they weld them. It shouldn't matter what process was use to weld it's the wire that makes the difference. Hammering should streach the weld a little but usually after welding there is shrinkage so they kind of negate each other when done right. You do also need a dolly on the back side.

[arandall]

Junes:
Thanks.
That's kinda what I thought - it should be done hot shouldn't it?

Cheers,
Art R.

[junes]

Hot as you can get it.

[itsmecord]

Anyone have photo's of the finished product ?

[Kiwimike]

Hammer the weld with the ball end of a ball pein hammer with a dolly behind it. It doesn't have to be a hard hit, just a tap. After all the finish you are looking for is a flattened weld that you don't have to use the flap disc grinder on aggressively.
You can use this method to stretch the metal and to shrink it use a wet rag.

[tigqk]

When I was in Auto Body Technology it was a part of the program to be able to hammer weld or you would not pass the course, this was oh about 25 years ago.The two reasons for hammer welding was to repair a panel without ever knowing their was ever a splice and normalizing.In first year we were given an 18 by 18 inch panel 18 gauge that was raised to a high crown the had to be shrunk down to low crown within a cigarette paper tolerance, their was a template to go by like the racers use.It would also normalize the weld and remove all distortion from welding heat.If you know how to shrink with a torch down to dime size shrinks, and I suppose you can use a tig to do it also you can control your metal anyway and do anything to it.I would not advise using a ball peen hammer but a large faced body hammer and large face dolly, snapon makes the best of both and everyone uses them.You want to weld your weldment about and inch or less then place the dolly behind and strike the weld to flatten it, then off dolly any rolls in the sheet metal pushing up lowspots hard and hammering down highspots.Usaully if you weld it nicely grinding is not required but if you see to much fill it is ok to grind it down.When tig welding steel and sheet metal I make my own filler rod from .030 filler rod 4 feet folded back upon itself and spun with a drill into a spiral and your filler rod is the right size, Heat your weld to red hot and hammer down and repeat.It should also be known that welding HSS steel structural components red hot is warrantee voiding, so this is for panels all HSS should be spot welded and normalized by hammering on dolly.