grind and rewelding mild steel?

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HelloI would like to know how many times you can grind out a weld and reweld it before it weakens the joint. It is on 1/8 inch steel tubing using a mig welder with gas mix. I have heard of people grinding out bad welds and re doing it, but do you only get one shot at it?Thanks.
Reply:I know of situations that were done 5-6-7 times over and they still can't get it right.Should not be a problem as long as you grind the WELD and not too much parent material..But if it's a rollcage NO GRINDING OF WELDS IS PERMITTED....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:You should be ok on mild steel.J.E.
Reply:I've seen guys do it over & over, right up until the boss hands them 2-checks for taking too long! Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Well, actually I guess there does come a time where you have welded too much:(pic posted by south paw) Attached Images
Reply:Thanks for the replies. I read where if I do it, that it will affect the HAZ and weaken the metal around the joint. It confused me because I also read where people make more then a couple passes filling a beveled joint.
Reply:It all depends on what you are working with, how fast you are working, and the intended purpose of the piece when it is finished.  In code welding, we use heat to reduce the chance of weld fracture from the rapid heating and cooling of the piece; but on thinner metals the heat is less necessary.  It sounds to me like you will not need to worry about pre-heating and, as long as you grind cleanly, you could re-weld until you're satisfied.Matthew MortonTexas A&M '06Logsdon Seminary '13"Who Dares Wins""AFTF""WH2PH"SA 200 (Code: 5337)TB 302CP 302 w/22A Wire FeederMillerMatic 200Miller Syncrowave 200MillerMatic 252BurnTables 4x4 CNC MachineHypertherm 65
Reply:thames1948Why is grinding out the weld multiple times the plan?ZapsterI interpret the rules as able to dress/grind the weld,while welding, ie. correcting a flaw.But all the final welds must be left raw.  The idea is to give inspectors reference to judge the caliber of the welds.Across a broad spectrum of metal work, if the weld is ground  -  It means something is wrong.OpusLast edited by OPUS FERRO; 02-14-2013 at 09:39 PM.Reason: punc.
Reply:All rework of welds, either partial removal of weld metal or complete removal of a weld,  causes a degradation of the base metals as well as induced stress. Depending on the design intent of the welded assembly, it can be a cause of weld or base metal failure.ChrisAuction Addict
Reply:Originally Posted by milomiloAll rework of welds, either partial removal of weld metal or complete removal of a weld,  causes a degradation of the base metals as well as induced stress. Depending on the design intent of the welded assembly, it can be a cause of weld or base metal failure.
Reply:Originally Posted by IGBTWell, actually I guess there does come a time where you have welded too much:(pic posted by south paw)
Reply:ZAIP said , ''I know of situations that were done 5-6-7 times over and they still can't get it right.''That reminds me of a teacher I went out with in my younger days ! I had to keep doing it until I got it right  !
Reply:Originally Posted by BD1That reminds me of a teacher I went out with in my younger days ! I had to keep doing it until I got it right  !
Reply:Originally Posted by SuperArcIGBT, I believe your pics come from the same booger welder in this video below.  To get to the good stuff, the cottage cheese with worms footage starts at 4:26.....
Reply:I'm puzzled...don't pipe welders sometimes fail an x-ray, gouge out the weld and re-do it?  Dave J.Last edited by MinnesotaDave; 02-15-2013 at 02:20 PM.Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:[ATTACH]CH]what am I doing wrong?  The weld doesn't look flat. Attached Images
Reply:Originally Posted by SuperArcIGBT, I believe your pics come from the same booger welder in this video below.  To get to the good stuff, the cottage cheese with worms footage starts at 4:26.....