77 Type LT Budget Build

Discussion in 'Project Progress' started by ZerroHalfcup, Apr 3, 2019.

  1. Scott51

    Scott51 Veteran Member

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    Took me ages to get the hang of plug welds.:confused:

    It's a little hard to tell from the pics but try spending some more time cleaning everything to 'white metal' including both mating surfaces and a larger area around your welds. If stuff is burning off as you're welding it's potentially contaminating your weld and you.

    After trying all kinds of weld-thru primers I found the copper type from upol and proform to be the best, the others all mucked with the weld, even after using a dull spot weld drill bit to clean it off the lower surface exposed by each hole.

    The real ah-ha moment though was turning up the MIG amperage and wire feed speed higher than you'd normally have it for butt or lap welding 18G. If your welder has one of those handy charts of recommended settings try going up one. Strike the arc in the centre of the hole and swirl the puddle around the edge until it flows out and closes up The surrounding metal will lift as the weld cools so tap it down with a piece of pipe while things are still warm (use it like a hole punch around the outside of the plug weld).

    With a bit of practice you'll be able to get a flat or slightly dished weld that doesn't need any grinding, but if none of this makes any sense check out https://www.jalopyjournal.com/forum/threads/55-210-wagon-progress.788490/page-24#post-11953692
     
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  2. ZerroHalfcup

    ZerroHalfcup Member

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    Couple questions, any good recommendations for resources on what "white metal" should look like? Also, best tools or methods for cleaning it? I skimmed through that jalopyjournal link and I'm definitely bookmarking that to read through in detail later. Any other articles, threads, books or resources you would recommend I am completely open to.

    I've been using a wire wheel to get everything off the surface until it looks like bare metal, then using non-chlorinated brake cleaner to wipe it off. After letting that sit for a bit and completely dry, I went to welding. I did figure out the second time that turning up the amperage and wire feed, it worked much better. I also drilled wider holes. The metal underneath I hit with some weld through primer but I'll have to give that copper stuff a shot. Makes sense that it would work better if it actually has copper in it.

    I'm sure it may be my technique and lack of experience with a welder but I'll try going from the inside out next time and cleaning the area a little better. I have one more plug weld I need to do at the bottom of the toe board at the rocker so I'll give it a shot on that one.
     
  3. Scott51

    Scott51 Veteran Member

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    sorry technically 'white metal' is a white or silvery alloy but in this context it's just really clean metal, so clean it looks like a white or silvery alloy. :)

    Wire wheels are ok for stripping paint and rust but they kind of burnish the metal and leave a residue, which is why it looks dark grey. For the purposes of welding, a roloc wheel, strip-it disc or even some 120-180g sandpaper is the way to go, and if the area is dirty or greasy, clean it before you start wire wheeling, grinding etc.

    For plug welding, drill or punch 5/16" holes and be sure to clean off the weld through primer on the areas exposed by the holes (I know, why do they call it weld-thru if you can't weld through it right?) A dull spot weld drill bit or one of those long narrow drill mounted wire brushes does the trick.

    In terms of other resources check out John Kelly, Wray Schelin, Ron Covell, Ron Fournier, http://www.allmetalshaping.com/ and https://www.autobody101.com/ I'll probably think of some others later
     
  4. ZerroHalfcup

    ZerroHalfcup Member

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    That's what I assumed about white metal but just wanted to clarify. I've got some strip-it disc so I'll give those a try instead.

    That may be another part of my problem, I welded directly to the weld-thru primer under the impression it was made to weld through. I have a spot weld bit and I like that a lot better than the previous smaller bit I used on the first try.

    Thanks again for the help, I'll check those people and websites out as well.
     

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