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I try and skip around while welding patch panels, but can never seem to get a clean, "can't tell its been done" finish, the kind like you see on "Rides", and American Hot Rod. I've got a old Miller Millermatic 200, and a new 180SD. I've try 'em both with the same results. (Almost) What am I doing wrong?
Reply:there's 2 things to keep in mind. first - they dont show their mistakes, second - they dont show their secrets. their mistakes are that whole big bin that they have that is nothing but practice parts - that is - the ones that would have been used if they had worked out right, but they really just taught somebody that their idea would not work. we all have some of those. the more you try, the more you will learn, and the more mistakes you will have. experience comes from trying stuff and trying stuff results in some successes and some failures. if you ever find a way to change that - count me in- we'll make a few billion before they catch up to us.their secrets are not really so much secrets as thay are things that many experienced hands don't discuss unless they know the other guy might know something they want to learn about. Ive noticed that many shop techniques that they use on these TV shows will very often create more scrap parts than they should because they dont always work out just right for the novice, but they dont have to show you their winning method and all their backup techniques, just the results.most everybody who has worked with sheetmetal and tried to weld it has wound up with a much bigger HAZ than they really wanted. techniques for limiting the HAZ are legion, but a few are the fundamentals. first - keep the heat input very small ( this says - use mig for starting out - on steel, set it up to run correctly on some scrap, work quickly and be very careful to cool the work quite often, learn how to cool your work quickly and properly before it scorches and warps, lay out your work so that it doesnt have a big HAZ , and learn how to shrink-raise- or swell the parts that need it afterwards, if you happened to miss the mark a tad. ) none of these techniques are impossibly hard, just that each one takes some thought and preparation. same procedure goes for TIG and stick, as much as you can. using a gas torch - there is usually a failrly big HAZ so you have to learn to set the work up just right to deal with it. torch welding is best done where the HAZ is not a problem, altho I have seen some good hands do body panels with this too. it still took a good deal of dolly and sander work to get it to look just right.same for materials and techniques. learn about heat control paste, using heatsinks ( copper backups for welding holes shut, threaded steel or copper parts for controlling heat flow into a heat-treated or specially finished part needing to be protected from HAZ etc. many shops use heat control paste and water soaked rags and sponges to control heat in panels when doing the patching work. this isnt always a one-man operation so let's not think that you just set it up and go lay the bead- often it takes a number of burns and each needs to be set up - executed quickly -and then cooled down so the heat doesnt migrate to other areas and cause warps, etc. making the perfect patch is a misnomer for the welding operation. this patch is usually the result of good prep, good layout and clamping of both the work and the patch pieces, practiced smooth and quick welding technique, good after-treatment like bringing the warp-down areas back up flush, selecting the right materials to maintain softness in the weld area so that it can be worked with the metalworking tools, and the good finishing techniques to make the area look like it was never stretched or shrunk. its not really magic, its just a lot to learn.Last edited by lucywalker; 11-30-2004 at 06:48 PM.
Reply:I can't comment on the TIG, since I have yet to master it. In theory, that should be the way to go, but it takes years of practice to become really good.Mig on the other hand, I can give you a few ideas. And I agree with lucywalker, they don't show you their mistakes. And keep in mind they show you months of work in an hour.With a Miller 200, are you using .023" wire? The 023" will bring your low end down, melt faster, and flow in nicer than a .030 or .035. DO NOT RUSH IT!!! I talked to a writer for an automotive magazine - real hands on guy. He would put down one tack weld, maybe 2 or 3 depending on big the panel is, walk away, come back 20 or 30 minutes later when he could put his hand on the panel, and then do the same thing. It would literally take him hours to weld it in, but he minimized warpage and distortion.
Reply:Use Harris Twenty Guage cored wire AND gas and skip your weld around, grind down and it's a lot easier than .023.024 solid wire... |
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发表于 2021-9-1 01:02:29