Welding burn thru
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A quick hint: sometimes porosity is not a shortage of shielding gas. On the older stuff we work on, it could be contamination on the backside of the metal being welded. As the metal melts, it also brings forward rust, undercoat, and such, from the inside surface. Try cleaning the backside of the seam before welding, if possible.
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The area is in behind the rear tail light. There is factory bracing back there that doesn't allow me good access. I was able to treat my weld beads from the front but the back is a different story. Because I'm not perfect and rewelded some spots the finished surface in the rear is not smooth. It would be difficult to sand or scuff although I will try. I can however reach with a brush so coating it will have to do. I think I will coat with epoxy then resin and then paint at least a couple layers of our version of Rustoleum, called Tremclad. The face side of course epoxy then fillar. |
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After I cut the metal out I was able to reach in and prep the back side pretty good. After patching I can only reach in thru the tail light opening. Tricky getting tools and hands all at once back there. |
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So I was just wondering about welding wire. So I've read a few times that mig welding makes the dots or beads hard? Meaning harder to planish, cracks when dollied. Is there not a different makeup of welding wire you can get that would make the result beads softer? More copper or something softer in make up perhaps? Maybe a stupid question...but what the hey!
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Jimmy
Yes their are other filler wires to use. If you have been doing your research on this web sight you would have read about my choice for Auto metal..... READ. IF you can get to the back side clean it to bare metal Treat with EPOXY only! front and back Then cover with a Fiberglass filler front and back and leave it alone Then move on. Brush or spray it doesn't matter. DO not try wonder gimmicks or treatments stick to what works clean bare metal epoxy and fiberglass filler. your patch will work fine as long as you use that. Practice your welding try different wires Try different techniques try Gas welding its cheap to get into, read a lot and Practice! A LOT! go to junk yard get some old hoods or fenders cut them up weld em back together. You will get their NO it will not happen in one project or over nite! I been doing this **** for a very long time It takes time, it takes practice, it takes money! Dennis B.
A&P Mechanic, FCC General radio Telephone Operator Line Maintenance A&P Mechanic and MOC Tech specialist. |
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Got it. Epoxy first then fiberglass. I'm on the right track. Thx Dennis. I'll probably stay with the mig for now. I am practicing a lot...I think. I have what I call my donor cab that I rob sheet metal from. It's all stripped and walnut shelled. Been welding on it, cutting holes in it and then welding them up. It's a learning experience that I'm enjoying. I'm going to look into different wires in the next few days. I appreciate all your guy's experience and knowledge. I'm in the construction biz. People ask me how to 'build' things. I roll my eyes lol. So I know your thoughts when I throw out those newb questions! ![]() |
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I was on the Eastwood site, checking out new tools and what not, and came across this Magnetic Welding Copper Backer. Comes in different sizes depending on what your doing. https://www.eastwood.com/welders/clamps-tools.html?p=2
Thought this could be good idea for guys like me that tend to burn thru too often. Any thoughts? |
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It does work to a point, BUT if you look at back side afterwards you'll see why I don't care for using the Technique (Its a Bandaid for poor welding technique in my opinion.) Have I done it ? YUP! Do I do it any more? No not if I can help it their are just better ways. One being : Use a Step drill bit to clean up the Hole nice a round, then using a Punch tool Punch out a similar size of steel Plug fit it to hole then weld the Plug in as a Patch. Punch tool : https://www.amazon.com/Capri-Tools-CP21 ... s9dHJ1ZQ== Step drill: https://www.amazon.com/Drill-Titanium-C ... s9dHJ1ZQ== The Punch tool I show above is just a elcheapo their are Many many mfg of these types of Punches in all kinds of sizes. I have and use Two different Roper Whitney Punches. I have had good luck with them they stay sharp and punch clean holes. I credit and thank Chevman for this Technique! Dennis B.
A&P Mechanic, FCC General radio Telephone Operator Line Maintenance A&P Mechanic and MOC Tech specialist. |
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Got it Dennis, thx again. It's great hearing from you guys that give awesome suggestions based on your years of experience!
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So a little update. I've done a small patch repair. Went relatively well. Had a small burn thru but managed to fill it without a lot of drama lol. Unfortunately now I must of had a little too much heat going because I have some distortion going on. The worst is at the body line. I can't really get back there to dolly it because of the inside box curves down there. Any thoughts? I'm curious about my welding. Obviously applied too much heat? I used air to cool the area but maybe too much or should have let it cool naturally? Did a light check from behind and found some pinholes that I've welded up already, so I'm happy with that. Although I will remove all the original paint eventually and spray with epoxy, could I at least treat the patch with epoxy so I could apply some filler? I understand it's better to seal the metal then apply the filler after. The backside I will clean up and treat right away with epoxy.
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