General welding questions that dont fit in TIG, MIG, Stick, or Certification etc.
TIG over MIG or MIG over MIG??
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GaryL
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    Wed May 27, 2015 9:24 am

I'm just a novice, so I've got a novice question.........

I bought a "project" that has a few 1/8' mild steel T joint welds that are "cold" and "globy". If I grind away as much of the existing MIG weld as I can: 1. Can I TIG weld over the MIG weld? or, 2. Should I re-MIG weld over the MIG?

What I need to understand regarding either approach would be much appreciated!!!
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dirtmidget33
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    Tue May 13, 2014 5:22 pm

1.Depends how clean can you get it? Was it painted, rusted, powder coated, etc. Do you feel like cleaning real good. TIG likes it clean
2. What are you more comfortable with? MIG or TIG
3. Which process is gonna be the easiest to get into location?
4. Would splatter effect area around it?

Either one works great when done right. Just depends I TIG stuff most people would rather MIG, but I like TIG so that's what I use.
why use standard nozzles after gas lens where invented. Kinda of like starting fires by rubbing sticks together.
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GaryL
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    Wed May 27, 2015 9:24 am

Thank you for the reply dirtmidget33. The surface was powder coated, but now has been sandblasted. Does that qualify as clean enough for TIG or, because of all the uncontrolled variables, is MIG the best choice?
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It comes down to what weld quality you need to have. What is a "project"?
Do you require structural integrity or is it just an appearance issue?

If you have a poor weld that need to take load, grind it down and re weld using the procews you do best.

Appearance, smooth it out with a grinder then wash the remains with tig.
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motox
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what kind of media did you use in the
blasting process. some area better suited
where welding will take place.
make sure its not impregnated in any
of the remaining weld metal.
craig
htp invertig 221
syncrowave 250
miller 140 mig
hypertherm plasma
morse 14 metal devil
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I just repaired some 14 year old aluminum ramps that were originally welded with mig.

I cleaned them up and tig welded them - no problems to speak of really.
Dave J.

Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

Syncro 350
Invertec v250-s
Thermal Arc 161 and 300
MM210
Dialarc
Tried being normal once, didn't take....I think it was a Tuesday.
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motox wrote:what kind of media did you use in the
blasting process. some area better suited
where welding will take place.
make sure its not impregnated in any
of the remaining weld metal.
craig
I've had this problem before - a little cleaning with a die grinder and I was back in business.

Good reminder :)
Dave J.

Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

Syncro 350
Invertec v250-s
Thermal Arc 161 and 300
MM210
Dialarc
Tried being normal once, didn't take....I think it was a Tuesday.
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