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weld-grind-weld-grind or weld-weld-weld-grind-grind-grind?

Discussion in 'The Hokey Ass Message Board' started by oldrelics, Nov 3, 2010.

?
  1. weld all then grind later

    56.1%
  2. grind your spots as you go

    18.0%
  3. clip your wire every spot, weld, grind

    13.7%
  4. clip your wire every spot, weld weld weld grind grind grind

    12.2%
  1. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,727

    oldrelics
    Member
    from Calgary

    What do you guys do? Do you weld in your sheet metal completely then grind all of it? OR grind your spots as you go. Seems you would get less pinholing if you grind your spots as you go and better penetration.

    PS-or how about: clip,spot,grind,clip spot grind?

    I'm trying to eliminate pinholing, explain your results!
     
  2. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,906

    need louvers ?
    Member

    Mig process - hot spot weld, partial grind (remove just the tops of the tacks), hammer and dolly to correct any shrink or warp, repeat with the next set of tacks. We are talking sheet metal, right?
     
  3. KrisKustomPaint
    Joined: Apr 20, 2007
    Posts: 1,107

    KrisKustomPaint
    Member

    pinholes? Did you run out of gas? Forget to clean the metal before welding? Pinholes are caused by contamination of the weld, not lack of grinding.
     
  4. I gas weld sheet metal. Far less grinding, no pinholes. Pinholes in MIG are most often caused by cold start. If you have pinholes you have poor penetration at the start of each new weld.
    You need to weld hotter, or better yet GAS WELD it!
     

  5. pimpin paint
    Joined: May 31, 2005
    Posts: 4,937

    pimpin paint
    Member
    from so cal

    X2! It's time to dump the "squirt-gun" welder and learn to handle a torch!
    No pinholes, and no silly grinding that leaves the metal hard & thin!

    '' Meanwhyle, back aboard The Tainted Pork"
     
  6. marshall
    Joined: Mar 19, 2001
    Posts: 754

    marshall
    Member
    from tacoma/wa.

    Two of the best post on the hamb this week
     
  7. I used to gas weld all sheet metal untill I bought a mig welder, now I'm back to gas welding. I can control the warping better, the grinding is not so much as it seems that the weld bead is not as hard.
     
  8. skottyknukkles
    Joined: Feb 19, 2008
    Posts: 314

    skottyknukkles
    Member

    i think he means pinholes from the welds not being close enough together?
     
  9. 19Fordy
    Joined: May 17, 2003
    Posts: 7,529

    19Fordy
    Member

    Old Relics. Please post a photo of your "pinhole" problem.
     
  10. mayerst
    Joined: Mar 3, 2008
    Posts: 23

    mayerst
    Member

    I'm not much of a welder but, I'm getting to be a hell of a grinder.
     
  11. skottyknukkles
    Joined: Feb 19, 2008
    Posts: 314

    skottyknukkles
    Member

    pics would def help.
     
  12. metal man
    Joined: Dec 4, 2005
    Posts: 2,949

    metal man
    Member

    I T.I.G weld sheet metal .I'll weld an inch at a time,moving around a lot.Then I hammer and dolly the welds before moving on,stretching it where it shrunk from the welding.Little warpage and no grinding. If you're stuck on M.I.G welding,sounds like you need to clean your tip or turn up your regulator.
     
  13. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,727

    oldrelics
    Member
    from Calgary

    I have clean metal and gas.

    I've tried and tried, got the smallest tip I can get for Smith torch, it welds but can snap apart a weld no problem, really brittle. I've played with the flame lots. I gave up.

    Yes, thats it, because if you spot right next to a spot you are either gonna weld partially on top of it(less penetration) or leave a tiny gap which only shows through when you backlight it.
     
  14. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,727

    oldrelics
    Member
    from Calgary


    They wouldn't show with a camera, and you have to backlight even to see them.
     
  15. skottyknukkles
    Joined: Feb 19, 2008
    Posts: 314

    skottyknukkles
    Member

    i have that happen too. some of the holes you cant even see unless you put a flash light to it at night. if i am in a hurry i dont worry about it. but if it has to be perfect i use a sanding disc to grind the welds down. then weld again. moving toward the previous weld. the sanding disc i use is the kind that looks like a turbine. keeps the metal cooler. im sure theres a proper name i just dont know what that is.
     
  16. skottyknukkles
    Joined: Feb 19, 2008
    Posts: 314

    skottyknukkles
    Member

    i know it looks f-ed up but imo i think it helps keep the filler set in better. almost like it has some thing to bite into. if that makes sense? or just call me crazy
     
  17. oldrelics
    Joined: Apr 7, 2008
    Posts: 1,727

    oldrelics
    Member
    from Calgary



    Maybe you should make a video tutorial for us squirtgunners....
     
  18. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,906

    need louvers ?
    Member

    Say what you will about mig welding, but I can gas weld as well - quite proficiently I might add, but gas hammer welding I find to be no faster than correctly doing sheet metal welding with a mig. I've been doing both for quite awhile though. I do understand that the weld from a gas weld is quite a bit softer, and that can be an advantage, but it just comes down to what is comfortable to the guy doing the work. Someday I will own a TIG, but that will be in the future when money is less of an issue.
     
  19. That could be my new signature:D
     
  20. Potential to be a great thread here.....
     
  21. thendrix
    Joined: Jul 19, 2009
    Posts: 157

    thendrix
    Member

    I have always heard those referred to as flapper wheels.
     
  22. grind more before you weld. raced my uncle with a torch and coat hanger, I had the mig we were filling holes in the firewall of a pickup cab . not only did he fill more holes but needed less grinding! that said although i'm good with the torch, i still use my mig. i've found 1/4" welds spaced 2" apart and cooling each weld with a blow gun. i cool it enough to touch in between welds eliminates warpage.
     
  23. skottyknukkles
    Joined: Feb 19, 2008
    Posts: 314

    skottyknukkles
    Member

    if i can i turn the heat up about 2/3 of the way even on sheet metal. rather than hold the weld for lets say 5 seconds. i zap it for 1 second. just to the point where it wants to burn through the metal. but in some cases where theres a gap i turn the heat down so i dont blow the edges off. its all trial and error which i am still doing even after 15 years of this shit. i have a tig welder and i have gas welding equiptment but always use my 110 mig for sheet metal. but there are people out there that gas weld and dont use any filler when they are done. i just havent met any of them yet.
     
  24. GARY?
    Joined: Aug 15, 2005
    Posts: 1,626

    GARY?
    Member

    Great question!
    I'm new to this and am doing it as a hobby so time is not a real concern.
    I've been happy with a doing few layers of MIG tacks, some grinding, more tacks, more grinding, on and on 'till it's done.
    I found with the TIG, things need to be really, really clean and you can't just sit down and weld a bead because of heat build up. That was without a pulser. My new welder does have a pulse option so I'll have to give that a shot.

    Questions for the MIG welders. Are you using flux core or gas? Using argon, a mixture of, or ??
     
  25. BCR
    Joined: Dec 11, 2005
    Posts: 1,262

    BCR
    Member

    To me it really matters what the part is and where it is.

    I can gas, tig, mig, they all have a place where they work best.

    If it is a part that I can get to the backside to hammer and dolly I will almost always tig it.

    If it is a part that it is cost prohibitive to get to the back side I will mig it with spot welds and keep it as cool as I can to minimize shrinkage.
     
  26. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,906

    need louvers ?
    Member

    I always use gas with my mig, especially on sheetmetal.
     
  27. Dougith
    Joined: Jan 3, 2008
    Posts: 13

    Dougith
    Member

    Always use gas when possible. Flux core never comes out as nice, at least that has been my observation. The cycle that you use of doing some welds then grinding always seems the best way to do it for me, plus it makes the task seem less repetitive.
     
  28. F&J
    Joined: Apr 5, 2007
    Posts: 13,221

    F&J
    Member


    I bought my Miller 35S mig used a little over 30 yrs ago and I am still practicing :)


    Back to topic; There are some jobs that can't be done with ox/acy and if you don't have a tig, then it needs to be done with mig...and yes, ending up with some pits in between welds.

    Here are a few pics of "wood to steel frame" conversion on a 2dr conv sedan.

    The first pic shows the top edge of the rear quarter. It is just a bent over 3/4" wide piece at the top to nail to the wood. I bent some 18 ga then used a stretcher/shrinker to curve it to fit on top of the flimsy flange.

    I now need to weld the inside 90 degree crotch of an upside down T shape. Impossible with gas due to warping, impossible to dolly. A tig would be best, but I used a mig.

    Some other edges on these pieces could be done easy with gas, but I prefer the mig for this.

    Last pic shows the other side of the car, and expand the pic to huge size to see the "pits" left by mig welding in short hits. Not a good thing, because those pits or craters are hard to clean without spot blasting, and could cause a paint bubble later. That's why I think tig would eliminate that possibility.

    Grinding these parts: Most rough work done with 4.5 angle with hard wheels, sometimes using worn ones to get into areas, some done with 4.5 cutoff wheel, or die grinder cutoff wheel, and then finish work with flapper on a 4.5.
     

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  29. BCR
    Joined: Dec 11, 2005
    Posts: 1,262

    BCR
    Member

    i use 80% argon 20% co2 in my small migs.
     
  30. need louvers ?
    Joined: Nov 20, 2008
    Posts: 12,906

    need louvers ?
    Member

    Nice work F&J! Nice to see someone else doing fine work with the equipment we have.
     

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