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Thread: Stitch welding tips?

  1. #1
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    Stitch welding tips?

    Hey everyone,

    I am working on stitch welding the engine bay on an E36 and having a heck of a time with it. I'm a decent welder, but everything comes out looking like a 6 year old did it with it a harbor freight box. I am sure my issue is the seam sealer. I've wire wheeled, than wire wheeled more, then acetone wiped, then mapp gassed, then acetone wiped again but every weld just explodes and looks like I forgot to turn the gas on.

    Does anyone have any tricks for this? Right now I am convinced the only way to have this come out looking decent is to chem dip the chassis first, but that is not practical on this build.

    Thanks!

  2. #2
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    I'd bet some form of seam sealer is in every seam in the car.

  3. #3
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    Try the hot tack stacking method, where you use more voltage than you normally would and do a TIG-like stacking of dimes (quick zap, move to the leading edge of the tack, repeat). Once you get at least one or two decent ones in place, it usually goes much better when you have a clean tack to stack on top of so you can stop and clean off the crap that gets boiled out ahead - you'll get enough heat into the metal to where it starts cooking off a bit ahead of where you are, so you can clean it off and have a good go of it for the next while and keep an eye on it. If you just run a bead, things will get so hot that even if where you are welding is fairly clean, the crap burning ahead will be outgassing so hard that it will interfere with your shielding gas.

  4. #4
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    Quote Originally Posted by TheJuggernaut View Post
    Try the hot tack stacking method, where you use more voltage than you normally would and do a TIG-like stacking of dimes (quick zap, move to the leading edge of the tack, repeat). Once you get at least one or two decent ones in place, it usually goes much better when you have a clean tack to stack on top of so you can stop and clean off the crap that gets boiled out ahead - you'll get enough heat into the metal to where it starts cooking off a bit ahead of where you are, so you can clean it off and have a good go of it for the next while and keep an eye on it. If you just run a bead, things will get so hot that even if where you are welding is fairly clean, the crap burning ahead will be outgassing so hard that it will interfere with your shielding gas.
    This is basically what I was doing, but I was trying to catch the second tack while the first one was still red and keep that rhythm for about 10 tacks. I'll try pausing between tacks and wire brushing again. Thanks!

  5. #5
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    Quote Originally Posted by Novablue454 View Post
    This is basically what I was doing, but I was trying to catch the second tack while the first one was still red and keep that rhythm for about 10 tacks. I'll try pausing between tacks and wire brushing again. Thanks!
    Cool, yeah the idea is try to get as little heat radiating out and cooking the shit as possible, and letting the current tack cool also gives you a good idea of what you're in for on the next one - if things are smoking hard, stop and hit the next inch or two with a brush. Let us know how it goes!

  6. #6
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    Yeah, I would also like to know what will be the result, I am a beginner and still a lot of things to learn. Welding is not such an easy job I thought before. It requires a lot of practice and knowledge to make a decent work. My father was welding a lot of times his old car, but I could only see the final result, because he didn't let me watch the process to not hurt my eyes. I wanna buy a new welding apron for myself after I found a list of 10 best https://afterpaints.com/best-welding-apron-reviews/, but not sure which one to choose, what do you guys think would be the best choice?
    Last edited by Keithfoxy; 12-30-2020 at 03:57 PM.

  7. #7
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    Trick is to have a good wire size from my experience. .25 or .30 and keep the voltage low. Wire speed low so that you almost stub out. Almost as if you would as an upward stack weld. The idea is to do small my centimeter at a time. Move further up lay another short bead or stack, then come back after the first stack cooled and further it along.

    The metal theybused was cheap, but also properly etched with chemicals and oils. So it's naturally harder to weld. Most guys can't even bead in subframe reinforcements with any aesthetics.

  8. #8
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    The quality of your work depends directly on how well you degrease and clean the metal. Often you get bad seams because of okay debris, which leads to voids. Also, a significant factor that affects the quality of your work is the choice of a good welder. I was pretty bad at it when I first started welding, even though I stuck to specific techniques. My friend told me that my welder was not suitable for the kind of work I was doing, so I decided to look for a new one. I bought a new welder here https://ratemywelder.com/best-miller-welder-reviews/. The quality of work has increased several times over. So I advise you to pay attention to it as well.
    Last edited by maxauthor18; 11-26-2021 at 09:01 AM.

  9. #9
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    I do high heat and the pulse method. Slowing the tacks or time if you fell like its burning through.

    The higher heat helps burn out all the paint and crud between the metals. In the end acid dipping is about the only other way to prep it.

    Some times Ill torch an area that is just being super stubborn.

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  10. #10
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    Another point, clean both sides of the material. If you puddle into the other side, any paint or sealer will still enter the puddle, burn, and blow up the entire puddle.
    Also, the seam sealer from what I remember is oil based. There's a good chance the sealer penetrates the metal soakes and bonds that way to the surface layer. There are cleaners that can degrease sheet steel from penetrated oils. Which is a good prep step on any engine bay welding as paint is porous believe it or not. (Gence the seam sealers.

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