Welding sheet metal panels without warping

Discussion in 'General foundry chat' started by Zapins, Sep 13, 2019.

  1. Zapins

    Zapins Silver

    I've been wondering about how is the best way to weld sheet metal panels without having them bacon up and warp? Is there a trick? Especially in projects that need to be continuously welded to seal it liquid tight.
  2. Peedee

    Peedee Silver

    Some peeps use heatsinks, slabs of copper behind the welds, in any case a series of spot tacks, ground flat and follow through with the finish weld. There will be many more extremely more experienced people follow this with better suggestions but I thought I'd start the ball rolling...
  3. Jason

    Jason Gold Banner Member

    Peedee is right. I cut 3/4" copper pipe lengthwise and open it up and flatten it out. Clamped on the back, it makes a good heat sink. I also use 1inch aluminum cnc blanks too. The trick is always controlling heat input. And that is best done by travel speed. Ya didnt mention process, mig would be king there for the inexperienced like us. TIG can put a lot of heat into a piece if you are not careful.
  4. Melterskelter

    Melterskelter Silver

    I had to tig long seams in sheet metal quite a few times making my muller, flasks, furnace parts, etc. Yes, it is challenging. I did use some sort of backup at the seams to prevent burn-through, but did not expect that to control warping. To prevent warping it is important to get the the pieces clamped into position and make many many tacks. I’d start by dividing the seam length into thirds and take near middle and far. Then midway between those tacks and then midway between those tacks and so on. If you just start welding without a lot of tacks, metal expansion due to localized heating forces potato chip. Once I have tacks every couple inches, I make the seam weld. Works pretty well.

    Here is a source of better formation than I can give and more advanced techniques .:

    Last edited: Sep 14, 2019
    Jason likes this.
  5. ESC

    ESC Silver Banner Member

    The Willys body is .024" sheet metal and was welded with oxy/acetelene. Lots of tack welds and filler rod of the same gage.
  6. Zapins

    Zapins Silver

    Well this will be with tig. I'm thinking of making a slurry mixer from SS 308 or maybe 316. And it needs to be round and flat on the bottom or the wall and floor scrapers won't work right.

    I am also partially asking because I mig welded my kiln together and when I put the side panels on there was a lot of deformation and the sides aren't that even especially on the top where the vent hole is. Not sure what happened there as I raced it every 4 inches and welded small 2 to 3 inch sections at a time to try prevent over heating.
  7. Melterskelter

    Melterskelter Silver

    Getting how “round” is necessary? Like there is roundish and then there is round. Spring loading scrapers might overcome a lot of issues with being somewhat out of round. I would think it would be very difficult to maintain better than +/- 1/8” on a two foot diameter cylinder, for instance. But springs would compensate easily.

  8. Zapins

    Zapins Silver

    Yeah 1/8" would be ok. I'm more concerned that the floor or the barrel will bacon up and cause it not to rotate correctly.

    I also need to figure out how to have the base spin around on a large bearing or rail system. Something like a lazy susan. Screenshot_20190429-030859_Chrome.jpg
  9. Petee716

    Petee716 Silver Banner Member

    I've learned my lesson the hard way more than once and I'm sure I'll learn it again. I've been able to correct warping somewhat by reheating the area red hot with a torch and letting it cool. It seems to relieve the stress. But as they say, an ounce of prevention is worth a pound of cure, especially when the cure is just "ok".

  10. Melterskelter

    Melterskelter Silver

  11. Jason

    Jason Gold Banner Member

    Ever see inside a Dryer or washer machine??? I picture a barrel sitting inside a frame and riding on 4 tires. Same for the top half. Motor off the side and a 6foot long belt wrapped around it attached to a pulley. Easier when you can wave your hands. Find something online you like and bassackwards enginenerd it.

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