Hammer Welding

Ok, I am a very inexperienced welder. I asked this question on another thread, but figured I'd start a new thread on the subject.... The comment was made by a couple of rodders that they keep cold water ready when welding sheet metal to cool the welds to avoid distortion and warpage.

I have never done this - I usually run a bead about 3/4" to 1" and let it cool. I then clean it up w/ a grinder. That usually turns into a disaster because I either grind off surrounding good metal leaving a gouged area or when I grind out the weld flush, I find pin holes exposed that weren't effectively penetrated. I then end up rewelding the area several more times getting the pin holes filled in.

So on the subject of hammer welding - I have never done it. In my case, I could easily hammer the 3/4 to 1" bead before it cools, right? Doesn't this take care of the shrinkage ?? You can't cool the weld w/ water and hammer weld can you??

I would like some experienced brain waves here - what's the proper way to do this (say I'm welding the roof back after a chop or I'm doing a pancake on my trunk lid) ??

better stay away from the hammer right now with your luck lately

Welds shrink. When you hammer the weld, you stretch it out and also relieve stress. You should not cool it with water. Do a short weld, hammer, and move to another area and do another short weld. Keep skipping around and dont get things too hot.

As far as grinding, I have several grinders and sanders that I switch around on depending what I am doing. You really should use a grinder and wheel that you have good control over so you dont grind the steel you are trying to weld. You should only grind the weld.

I like a flex wheel that I use on one of my 4 inch grinders. It will say "flex" on the label. It is a softer way of grinding. The wheels go fast, but it doesnt take off and grind grooves in the good stuff..... too often. Some people use the cut-off wheel as a grinder. I do that too sometimes.

Good luck, we're all counting on you.

Hey Wrecker - thanks for pointing that out !!! I'm not worried - I still have 9 fingers I can screw up ! HAW, HAW, HAW !!!

Mad Dog - thanks for the info. That's what I was thinking. Where do you get hammers and dollies? - the ones I've seen are expensive.

Anyone know of a good site that may have some video on hammer welding?

I am really thinking about finding a community college to take a class - I would like to get better w/ the MIG, learn some TIG and that God forsaken stick..

A thicker cut off wheel is your best bet on sheet metal.I would keep the welds smaller than what you doing.Keep them to a 1/2 inch instead.

As soon as your done welding.Back that weld up with a dolly and hammer it lightly.It needs to be done while hot.

I also use a spray bottle with water if I am not hammer welding.It will cool the metal.But the beads must stay small and in incuments spaced aprart.

The pin holes that yopu are seeing are contamination in the weld.The metal needs to be clean.Grind the area well with a light wheel and you will be ok after.

Use disks that are not too agressive.That way you metal wont get too hot.Grinding metal also will warp with the heat it creates.

I would recommend small 3" roloc disks that will fit a small air angle grinder.

I would use 60,80 and then finer grits to grind down welds.Dont use 24,36 or those real coarser grits as they make a real mess of the metal.

Also you can get flap wheels that are real good to. You can put on your 4" grinder.Just keep the grits to the finer ones and your metal finishing will be a much better quality.

When grinding down the welds keeps the machine flat to the weld and dont try to do the whole thing at once.Skip around and it will be a cleaner job when done and the metal wont warp.

I hope this helps.

These guys are good.

Like 35Master said, some people use water. I dont, maybe I will try it. I am still learning (in leaps and bounds, everyday).

I got my best hammers and dollies from my dad. They sat in my toolbox for years and I never used them. Now I use them all the time. I have seen them cheap at harbor freight (I hate that store) and I have just made some myself. It takes some cutting with a torch and then some grinding, but its not too hard. Make all kinds of shapes.

goto and regester here http://www.metalmeet.com/

You will find all you need to know and a thousand times more. I have learned a ton at Metalmeet.

Hey thanks guys - Maddog, good idea on making the dollies - I just figured it was a piece of "specialized metal" that I should acquire by emptying my wallet....

35, I will try the thick cut off wheel and flex wheel - never tried those. I let my welds air cool - takes long time - I will try the water on non-hammer.

I am welding old sheet metal that is very clean on the outside, but still has rust inside (interior part of car) - I presume that is where the problem w/ the porosity is coming from ??? Do you guys clean both sides - seems hard to do (if not impossible) in a lot of situations.

I do skip around while grinding and pay attention to heat build-up pretty carefully. I do use a pretty aggressive disk - like a 36 grit - I think it is the flap you're referencing. It is essentially a 4.5" flat disc w/ flaps of grit that lay flat and overlap each other, right?? I have good luck w/ the "flap" disc, but it is usually this 4.5" grinder that gets me in trouble - I can't get close enough to see all that is going on.

Not sure if I understand the 3" roloc - I have the air angle grinder w/ the flat 2" discs I believe - they just have course grit covering the face. I presume that's what you refer to as a roloc (I'll do a web search on that....). I do have better control w/ the smaller air grinder.

I think I just get too much in a hurry and don't bother to go finer on grit when I get closer to the base metal - by the time I'm done, I've gouged out the metal.

So how much do you hammer a weld ? How do you know when you're done? Can you correct porosity problems by hammering out a weld?

Also any help locating hammer and dolly would be appreciated.

Thanks for the expert brain waves guys. Appreciate the knowledge transfer.

wrecker55 said:

better stay away from the hammer right now with your luck lately

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Ouch... er... probably good advice for now!

I just slammed my bad finger in the door.... give me a minute.....

Boy, that smart.... so can one of you guys post 2 pictures?? #1 being the hammer you typically use to hammer weld and #2 the dolly you normally use to hammer weld ??

I'd like to see the shapes - I found a lot of junk on flea-bay. Is Martin a good brand??

I dont have pictures right now, but plenty on metalmeet.

The idea is to smash the weld between the dolly and the hammer. Not making enough contact with the sheetmetal to bend or distort it.

You can use any hammer that you can hit the weld with and any dolly that backs up the weld. The different shapes are for getting into kooky places, or on folds or bends or in a rounded area. Often times the hammer will not have a perfectly flat face (sometimes it will) but will be convex (a slight dome) on the head.

You will see after a few smacks that it"s not gonna get any better if you keep hitting it. Remember, you are just trying to stretch out the shrink a little bit. You are not hammering it flat.

ok, that makes sense. I am ready to smash some metal - I just found another trunk lid that I want to pancake for my '49 so I will start honing my skills again as soon as I get my finger healed up....

You guys probably already know about it, but the Miller Welding site is pretty good - they have a forum similar to this.

Site is www.millerwelds.com/resources. In the "online community" on the right side of the page there is a forum titled "welding discussions". Good stuff out there.

An important question regarding the hammer welding subject and welding sheet metal in general. What do you experts use to weld sheet metal and when you're hammer welding a panel? Are you using O/A, Mig, Tig or what? I perused some other forums and saw a lot of O/A hammer welding, comments that Mig was very difficult to hammer weld, etc. Consequently, I briefly tried hammer welding w/ my Mig and was not that pleased w/ the outcome.

Any feedback or help appreciated. Thanks

O/A is the way.

Bonehead said:

O/A is the way.

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Bonehead, so what type of rod do you use, tip size, and flame ?? Again, a newbie here asking the questions.....

I use a very small tip, as far as rod goes... I hate to say it because most guys go and buy rod from the welding store. But, at auction, I picked up a bunch of the wire they use to make those little flags to mark utility lines with. It has a little spring to it, (better than bailing wire anyway). You won't need much filler rod here, as you mostly pull the corner off of the patch panel.

(Okay, now the guys who are die hard buy it at the store welders, can jump on this post.)

as i recall im pretty sure you CANT hammer weld a mig weld because its a hardened weld, but u CAN do it with the tig or oxy/actelyn since its a soft weld. if the metal is moving or warping on you your getting it way to hot. when mig welding sheetmetal your supposed to do 1 tac weld about every 3 inches and jump around so u can lock down all the sides and keep it from moving out of place, and after its tac welded in "stitch" weld it by doing about 3 or 4 tacs on one spot then move about 5inches away and repeat and if its a small panel only do a few spots and let it cool down. i usually have a air blower close by to cool down the welds so i can weld a panel in faster.

Bandit, so when you stitch with a Mig, do you have distortion problems? And is it easily to grind out?? I have worked inner rusted panels, but never on exterior panels, so I have tacked the panel, but haven't started finish welding.....

I'm still on the learning curve for MIG, but seems to me keeping it from distorting is all about patients. I just welded the bob on my 63 last week and would hit it till it felt very warm then let it cool to luke warm before going at it again - quick when it's 20 degrees out. Didn't notice any warpage. Same when grinding - don't let it heat up - skip around and take breaks. Have another job going that you can go at while the metal cools - keeps me from getting impatient. Wish I could get a more consistent bead though - less grinding, but hey, I am gettin' better.