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Mig welding sheet-metal**
This thread was originally posted on the old site. The original thread with photos can be found here:
http://allmetalshaping.forumsdot.com....php?f=11&t=23 Please make all new posts for this thread on the new site...that is HERE. We will be working to get the photos moved over. I think learning how to weld sheet metal properly is one of the most important things to learn. Until recently acquiring a tig welder, I had to mig weld my panels because the mig was the only welder I had. A mig weld is a much more brittle weld and over hammering will lead into a cracked weld. However it is possible to produce a nice piece using your mig welder. Here is a fender I mig welded. 20080426_2.JPG I think if you are using a mig it is key to have the panel fitting perfectly first, to reduce the need of extensive hammering. Don't ask me how I know . I will show you the method I used for welding the fender,on some scrap pieces of metal. I start off by tacking in 3/4 inch increments. 20081018_27.JPG I start in the center of the panel and work outward alternating sides with each tack. After every two or three tacks,I grind down the proud of the weld,using a cut-off wheel. 20081018_28.JPG Next I will re-stretch the HAZ of the weld (heat effected zone) This is the blued area around the weld. All I do is using the dolly on method I give each tack a few light hits with my body hammer. On dolly stretches metal off dolly shrinks metal. 20081018_30.JPG Now that I have the panel all tacked in place, I start filling in between the 3/4 inch tacks. 20081018_39.JPG After I fill in the weld I grind down the proud of the weld and re-stretch the Haz of the weld the same as I have shown with the tacks.When welding between the tacks I still start in the center and alternate sides. When welding in I place a tack let off of the stinger then I lay another tack 1/2 on the previous tack and so on and so on.When placing each tack you have to almost burn through before letting off of the stinger.This is to insure a full penetration weld.This will take some getting used to.Here is a picture of the back side of the weld. 20081018_31.JPG Here is a picture of the panel welded up. 20081018_42.JPG I also welded a panel up using the same principals except I did not re-stretch the haz of the weld.Here is the result. 20081018_48.JPG I think it is pretty obvious which method works better. This is just the method I found to work the best for me, I would love to see other methods if you do it differently. _________________ Johnny Arial |
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