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Discussion Starter #1
I need to repair a battery apron and a floor pan on my '70 vert. I'd like to butt weld in repair panels, but everything I hear says using a MIG welder can cause warpage of the panels. The solution is "stitch welding."
Eastwoods sells a stitch welder to work on your MIG set-up. Any onetry this device, or anything like it, and how well did it work? Better options?

Carl
 

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I can't answer your question on the stitch welder but I believe that the warpage problem is mainly directed to the outer sheet metal. Quarters, fenders etc. are long straight thin panels and are subject to warpage due to the high heat of welding. IMO, a fender apron (with the fender removed)and floor pan would be fine to repair with a mig welder.

Scott
 

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Is this is that attachment you use on an electric welder that you use a trigger to drop, make an arc, then lift the rod using the trigger to kind of like spot weld metal?
Practice, practice befroe you put it to real use.
 

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I'm not a welder other then small stuff. Any welder will cause warping if done wrong. MIG welders are very popular with the auto crowd. The trick is to move around and in short bursts. Basically what stich welding is pulsing the power on/off. This allows some cooling between welds minimizing warping. With arc welding you can do the same to an extent called a "whipping" IIRC, when I took a welding night course many years ago. What you're doing is to twist your wrist to pull the rod out of the weld momentatily. Years ago I welded in a small patch panel I made (nothing fancy) to go behind the rear wheel on my old work van. At the time I didn't have a mig welder but did had a AC Lincoln arc welder. With a very small rod, and the lowest setting I was able to arc weld the panel in with no warping or blowing holes in it. I moved around from one spot to another, avoiding too much time in one spot to minimize excess heat and warpage. As scottstang said, it wasn't flat, had a slight curve in it for strentgh. Again, my repair wasn't anything special, it was very simple, really didn't care too much what it looked like as it was an old truck and I wanted to "fix" the rust hole. Basically what I'm saying it wasn't too hard to do with a little practice.

You could rent a MIG welder or buy one. You'd be suprised at just how much you'll use it! The key is practice, practic, practice.
 

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The stitch welder they sell as an attachment to a MIG is snake oil, according to a couple of welding shops I've talked with, who said that stitch welding with a MIG is a technique, skipping around and making short, small "spot welds" that will eventually all connect to form a continous weld.
--Kyle
 

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Unless they've added something new to their catalog the stitch welder Eastwood sells attaches to an arc welder, not a MIG. It is not the same as the spot weld attachment either. The stitch welder tries to correct the warping and burn through problem associated with using an arc welder on sheet metal that sometimes happens from poor technique or trying to make too long of a continous bead which adds to the heat build up in the piece you're welding. From what I've been told the heat isn't as big a problem with MIG or TIG units because of the flow of gas over the weld area with these units. However, warping can happen with thinner sheet metal with any type of welder simply because of the heat necessary for the weld, so if you already have a MIG just get some scrap sheets to practice on before welding the repair part to the car and keep the beads short to avoid putting too much heat in the metal. You might want to try Eastwoods butt weld clamps too. They hold the panels in correct alignment and at the proper gap to make an even and level repair. Personally, I'd prefer overlapping the panels instead of a butt weld. With an overlapped panel you can flange the lower metal so the new part lays flush, then the weld on the top side can be ground smooth without compromising the strength of the repair and you get an invisible repair after painting.
 

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Discussion Starter #7
I guess that answers my question, just practice with the MIG before trying the panels, and skip around the edge when welding. I've gotten decent with my MIG, but I've learned that any trick I can get my hands on would help (I don't even want to think what my welds would look like without the auto-darkening helmet :) ) Since I'll have scrap from the cut peices, I'll just use them for practice. Here's hoping I get it right!

Carl
 

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you can use a mig, but have to be very carful. i used a mig with everything on my car, and had no warpage probelms. if you tack weld the spot and skip an inch or two, then tack again, continue this along the panel, then go back and continue this until you have a full weld. it takes a little while, but it works and looks good. 1/4 panels are the hardest, floors arent too bad, i welded my floors and battery apron myself.
 

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Just use a normal MIG welder, with the smallest wire yours takes (0.0023" I believe), and make sure you are using shielding gas (not flux core). Practice a lot before hand. You want good welds that look the same on both sides of the panel (even though you are welding just one side). A good weld is on the verge of all the metal dripping onto the ground, but ISNT. This way, the weld is going completely throught he metal.

You will want to do this in small increments, maybe 1/2" long stitches spaced out, keeping the panel heating to a minimum.
 
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