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Welding virgin - Butt or Lap?

Discussion in 'Modified Alpine' started by V6 Mark, Feb 2, 2011.

  1. V6 Mark

    V6 Mark Donation Time

    No it's not an Adult Entertainment DVD title...

    I'm assessing the body repairs needed on my car before I make progress with the V6 install. It needs several panel repairs (sills, wheel arch, radiator surround,lower wings). I'm wondering whether you experienceg guys would recommend I attempt to Butt weld or use a joggler to create a recess and lap weld the joins between new and old metal?

    Any other advice would be very much appreciated!!!
  2. jumpinjan

    jumpinjan Bronze Level Sponsor

    If you do a butt weld, it will burn through using a MIG. If you can roll a jog into your base metal, that would be the best...if you can do it. I usually, spot weld a strip (about 1"-3/4" wide) centered on the butt joint, and then weld the butt joint. I get a nice MIG weld doing it in that way.
  3. tony perrett

    tony perrett Gold Level Sponsor

    When I welded a new floor into my Vespa Sprint I bought a joggler and made a lap weld. One advantage of this method is that the panels can be aligned and held together with a few pop rivets whilst the welding is being done, the rivets then being drilled out and the holes plug welded.
  4. bashby

    bashby Donation Time

    You can butt-weld with a MIG, I found it can be easier if you place a copper spoon behind the area as it will help, burn-thru is quick and an RPA. The thinner it is the harder it is IMHO and I am no welder and know it it is a practiced skill and art. First thing someone told me when they found I had purchased an LBC was " so, you know how to weld?"
  5. sunalp

    sunalp Platinum Level Sponsor

    As far as rust prevention, butt welding is the way to go. If you lap weld you have to make sure the "other" side is protected from moisture as it will get behind the panel and it will eventually rust. I butt welded almost my entire Alpine . When you butt weld it makes the patch part of the panel you are repairing, and if done correctly, there is no seam for moisture to get behind.

  6. MikeH

    MikeH Platinum Level Sponsor

  7. weaselkeeper

    weaselkeeper Silver Level Sponsor

    I had to do a lot of welding on my rust bucket and I'm getting close to being done with the welder. I've butt welded all external body panels. I also used the strip method described by jumpinjan to back up a joint in areas where apprearance on the backside wasn't a factor, like the floor that will be undercoated anyway or a fender patch that will be closed in. I've also used the joggler pliers to build in the step. All depended on the area and access I had. For an external panel with a curve, the joggler might further distort the metal and your body guy will have more work.

    I lap welded most of the floor panels and trunk panels (had to replace every single piece of floor/trunk/baggage shelf). Remind me why I started this project? I used a combo of clecos and sheet metal screws to close the lap gap. Some areas, I just welded an edge seam especially around the widened trans tunnel. Others, I drilled holes in the top piece of the lap and spot welded going back to fill the holes used by screws/clecos. I also used weld through primer on closed/lapped areas, but don't feel I got as clean a weld. Had some splatter.

    For the butt welds, I left a very small gap between the parts for the filler to flow into and got a better weld than if the parts fit tight together. Where possible, I used a high intesity light behind the piece to check my work. Once ground smooth, I occasionally found a pin hole to close that I would have missed otherwise.

    Choose a small diameter wire! Copper certainly helps to back up a butt weld or behind a hole you want to close as bashby noted to keep blowout to a minimum. Copper dissapates heat quickly. I mady my own by going to the plumbing store, getting some copper pipe, smashing the end flat and shaping it to fit the area I was working. 2cts.

    Good luck and let us know how its going.
  8. afssanders

    afssanders Donation Time

    Depending on your experience with the welder, type of welder you have, if you can get behind it to straighten it out after it warps and if you have a stud gun with a shrinking die all play apart in how it should be welded. The other thing I've noticed is when using a offset tool is that area can show up after all is done and painted. The reason for this is that area is quite a bit thicker and expands differently then the surrounding area, but I am a extremely picky person when it comes to finishes, so most won't notice this. I've seen area on my own car that are affected by body support under the panels on a warm summer day.
    There are many areas on my car that were hammer welded and areas that were overlapped and a couple that were butt welded with the wire feed. Back welded really. It's where a guy stitches it and lays another bead about an inch long and welds to the previous weld. It keeps the heat down and allows for a nice bead that penetrates without blasting a hole through. It's important to get good penetration when butt welding with the wire feed. Ive seen a lot of welds come back and haunt people after their project was finished , because they didn't weld it good enough and then they made matters worse by sanding it so much it cracked. Also make sure you're using .023 wire.
    For the most part on a Sunbeam there aren't too many areas where a guy can't get behind it after welding and shoot some type of epoxy primer and or undercoating on it. This is probably the most important thing a guy can do if he expects it to last and not come back and haunt him. Also pack the weld with water proof body filler after sanding it down a bit and sandblasting it. Don't use that duraglass as a filler just as a insurance policy. Waterproof muds shrink a lot. Where a quality filler won't.
    It's hard to give good advise without knowing what a guy is capable of and specific areas that need attention. Practice if you haven't, lay a bead or two on the metal you plan on patching. Set your welder up right before even stiking a arc.
  9. MikeH

    MikeH Platinum Level Sponsor

  10. V6 Mark

    V6 Mark Donation Time

    OOOh I like those MikeH

    I think on balance (whilst I need more practise first) I'll attempt the butt welds

    I'll keep you posted

    I'm waiting for quotes for the required panels from Sunbeam Spares Company over here in the UK. Its run by a guy called Brian Postle - I used to live fairly close to him and he actually came to look at my car with me before I bought it - some 12 years ago -- when it was still bright and shiny. Although the hardtop was a POS and I had to drive the car home with one hand holding onto the roof to prevent the whole thing from flying off! haaha happy memories.

    Hope 2011 will be the year of its rebirth - its been off the road for about 5 years now - scary how quick the years are flying by now!!
  11. tony perrett

    tony perrett Gold Level Sponsor

    The butt weld clamps are available from Frost, here in UK at £14.30 for a set of 5.
  12. V6 Mark

    V6 Mark Donation Time

    Thanks Tony

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