Newbie here attempting my first chop. This was mig welded. I tried to hammer and dolly some but it didn’t seem to lay the weld down much at all so I took to sanding. I can get one side of the weld smooth but the other created a “fold”. It’s a 1/16” or less. I’m going to skim coat with filler, but will this fold or crease cause a problem with paint? I stopped sanding because I started to get a groove. B7994297-0EE4-4EED-A73C-DE6B2E9D3923 by settoon3 posted Jun 26, 2021 at 6:23 AM EC22AC20-BE5B-4668-A7F2-7E63E212D01E by settoon3 posted Jun 26, 2021 at 6:23 AM BAD11E12-DA29-43DC-BB49-9AF72C5A2C39 by settoon3 posted Jun 26, 2021 at 6:23 AM
I can't see much detail with the pictures but I will say with MIG welding you can over work the weld. The welds are harder that the metal they are on. If you remove to much of the weld there is a risk of the weld cracking and if you leave to much it might show up in your paint work. TIG is much better for but welds on sheet metal because the weld is not harder than the metal being welded, this allows the weld to be worked with the sheet metal it's on. I would leave some weld showing by not removing all to the point that it's flush.
When mig welding this metal, try switching over to ER70S2 wire - you've likely got ER70S6 which is very common, the S2 wire is softer and behaves like a tig weld. At least you care enough to do some nice welds, great start
Times 2 on the 70S2 wire. When we first started to box all our own rails for our chassis business we were using 70S6 and we were going thru a lot of grinding discs. went to the softer wire and it laid in the groove better, ground easier and left a better finish. Never had any customer complaints that the welds broke. I would assume it's the same on sheet metal.
When using the mig welder, did you weld continuous weld runs, or spot welds, weld in different areas along the weld area, then let it cool before spot welding more of the area. The continuous runs, cause warp-age due to heat build up, and the weld is then harder to grind down to surface grade.
Before I bought my tig I always used mig, But I started out 50 years ago in high school with a torch . Used to do hammer welding. If you have a small tip torch , heat an area of the weld about an inch at a time and hammer on dolly to flatten the weld while still red .Work it a little at a time and let it cool slowly. It is time consuming and it will still requier some filler work but the panels will be more uniform and you won't thin the surronding metal by grinding to much. Larry
All spot welded moving around, looking down the panels I don’t feel I have any warp. Larry, you’re the second person to mention heading with a torch before using the dolly. I’ll give that a try on some areas and see how it goes. If it cracks a few years from now I guess I’ll just go 1/2” lower.. lol
You are doing fine. I don't like to grind off more than 1/2 the weld because it weakens it. A little filler will take care of any unevenness.
Also keep in mind on the next one ,whether you gas, mig or tig. Panishing the welds on dolly while they are still hot helps to flatten the welds and minamizes distortion. Thats how we learn , practice and more practice! Larry
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