tig cover pass over mig base?

admin

Opinions needed...  Reason I ask is I have a chassis I have been working on for a while that was started by somone previous.  His mig welding was ok but not great, perfectly fine for the application but I have developed some tig weave skills recently and have thought about cleaning then going over the "not so apealing" joints to lay a nice weave.  Have any of you done this before?  I haven't tried it yet.  Wanted soem input first.  All of these areas are easily seen and have bothered me for a while, would love to get them up to par.thanks!
Reply:Originally Posted by ghaddonOpinions needed...  Reason I ask is I have a chassis I have been working on for a while that was started by somone previous.  His mig welding was ok but not great, perfectly fine for the application but I have developed some tig weave skills recently and have thought about cleaning then going over the "not so apealing" joints to lay a nice weave.  Have any of you done this before?  I haven't tried it yet.  Wanted soem input first.  All of these areas are easily seen and have bothered me for a while, would love to get them up to par.thanks!
Reply:That was my fear.  I may try it on a test piece of scrap to see what happens.
Reply:It's going to be hit or miss. I've heard of it being done by some, but I wouldn't, personally. If I was worried about the weld itself, I'd cut it and re-do it. Otherwise, don't risk compromising it by playing with it. A note on grinding, if it's for a race car, BE CAREFUL. A lot of sanctioning bodies prohibit the grinding of welds.
Reply:If the welds are inadequate then it may be a good idea, but if it's just for esthetics I'd leave well enough alone. Putting more heat into the already-welded joint may weaken it.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:If the welds were done with gasless flux core you're SOL... otherwise you can carefully grind only the weld and flow it back in with the torch with minimal issues. You'll need to remove all the glassy flux left behind from er70s-6 hard wire, and if there's any areas of obvious porosity expect it to be a pain.Welding/Fab Pics: www.UtahWeld.com
Reply:I have done it many times..I hate it.5 % of the time you get reasonable success.All the cleaning in the world don't help either.Tough situation my friend..If you can grind most of it away then the more the merrier but in most situations that is nearly impossible.Tough situation my friend.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by Silicon-basedIf the welds are inadequate then it may be a good idea, but if it's just for esthetics I'd leave well enough alone. Putting more heat into the already-welded joint may weaken it.
Reply:Any time you go over with  tig weld at least with the steel I generally use you get pulling or contracting issues.  I quote "to lay a nice weave" which sounds to me like things might move around a bit.  Mig is kind of a general term whether it is flux core self shield, flux core gas shield, solid wire gas shield and if the gas shielding got blown away for a bit will all most likely give different results.  I know tig welding into an oxy acetylene tack, at least one of mine makes for more activity than base metal.
Reply:If your going to do it you need to clean and grind the mig welds to get rid of all the silicon islands, paints and anything thing that isn't shiny metal.Vantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.
Reply:See?  Another example of someone asking a question I never thought of.  I learn so much here not just from the answers people post, but also the questions inspire thought too!Harbor Freight Inverter 130 amp DC stick/tig (sold, really!)Lincoln Square Wave Tig 175 AC/DC stick/Tig
Reply:THANKS for the input guys.  They are fine for their purpose just not as "pleasing to the eye" as I would like.  I am not worried one bit about the strength.  Just would like the appearance to match some of the other work I have done on the truck.  O well.  Its a prerunner by the way.  94 ford explorer.  Long travel beams.  full 1.75 chromolly 4130 cage.  3 link rear.  SBC th400.  Having a full interior done and tube wraps will hide what bothers me anyways.  My next project will be a race truck which will be fully tig welded with 4130 to meet SCORE specs.Last edited by ghaddon; 11-13-2012 at 08:34 PM.Reason: even after college I can't spell
Reply:Your most likely going to deal with porosity if you just use what the MIG put down....If your that unhappy with the cosmetic's  remove it all and start again.....I don't like the idea of putting that additional heat cycle on a joint that has to be strong especially if the tube is Chrome molly  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock