TIG Process question...

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What kind of sin is it to go back over your weld with the torch, as in re-melt the filler material to 'fix' the layout of the material?As I am learning, I have found I can clean up my weld very nicely by 'visiting' it again.In any event, re-working the site is allowing me to spend more time on the torch - and I need as much of that as possible.I have found that using the foot control is a lot easier than trying to use the thumbwheel to control the in/out phase.Now if I could just stop ramming the electrode into the pool...Extra credit question: I notice that in my TIG practicing that clean metal does not seem to be nearly as important to the weld quality as in MIG which seems to be impossible without impeccably clean surfaces. Is that possibly correct or am I dreaming?Millermatic® 211 Auto-Set™ with MVP™Miller Diversion™ 180 AC/DC TIGEvery air tool made...if it can be driven by air, I want it.- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Neon Sign Fabricatorwww.casinoneon.com
Reply:Sin?Well it may not be a "sin" but going back over the weld is not good practice because it will reheat the weld HAZ and does change the grain structure. It would be better to leave it alone even if the appearance is not perfect.You have to think of the long term effects on the TIG weldment.If it is SMAW that is another discussion.Clean metal is always important in EVERY welding situation.Cleaner metal=a better weld.AWS certified welding inspectorAWS certified welder
Reply:Sounds just like me about 7 years ago. No, there is nothing wrong with making your welds look nicer, but only if the first weld was actually sound. Make sure that you are not covering up a bad weld with a pretty one. This only applies to non-critical, non-structural applications. If failure of the weldment has real consequences, seek expert help.  Foot control is easier, but if you have a chance to learn hand control take it. I learned foot control first, and switching to hand control was difficult, I think it would be much easier to switch the other way.Last edited by fortyonethirty; 06-24-2011 at 12:00 AM.Ian TannerKawasaki KX450 and many other fine tools
Reply:its done all the time!!!  its not like its gonna make you fail an xray .
Reply:More shrinkage and peaking as well as greater heat affected zone. "Washing" a weld for a better looking cap is common but it's better to just make a good initial weld and leave it alone.Two turn tables and a microphone.
Reply:Very good responses so far. Just about all shops do it. And you will find when you are welding that you may get a random gas pinhole at some point. We are not allowed to leave gas bubbles visible even though there is an allowance for them in the defect section of a specification. We will identify and wash out with a tad of filler before the part falls out of interpass temp. It still is a good idea to identify if there is contamination happening.You can also do washing to establish the profile if you want. If you are buttering up a worn section that will get machined back to size but you have a divot, wash it out. The customer will cuss you if you don't.As far as cleanliness, good luck on that.
Reply:If you do it correctly the first time there is no need to go over it again now is there.......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:Okay, sure I will just do it right the first time from now on...I had never heard of 'washing' so I have a new word to throw around at the people who know less than I do.I would swear this had to be done by others when you see these very complex jobs and they look 100% beautiful, an seemingly unimaginable feat for anyone but those with a lot of talent.I 'get' the fact that you can change underlying specs of a weld by playing around too much. A weld can look pretty junky but be 100% perfect in purpose.Millermatic® 211 Auto-Set™ with MVP™Miller Diversion™ 180 AC/DC TIGEvery air tool made...if it can be driven by air, I want it.- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Neon Sign Fabricatorwww.casinoneon.com
Reply:LiquidFire - If you aspire to weld well, and not just laying down "good looking" beads, take a Saturday or evening GTAW class at your local Comm. College. It will quickly build your skills and knowledge of the correct way to run the process. Especially when you get to aluminum.Not saying you can't teach yourself but it may be a long bumpy road trying it solo with some help from the web. The time invested in a class or two will really pay itself back in the long run.Eric
Reply:Also remember if you are only washing a certain parrt of a weld the heat will make the base material draw or warp. Like on pipe. We do this intentionally sometimes to strraighten pieces out mand make everything level. But if everything is already level and square then the heat will pull it out of level drawing to the side you put the heat on. Especially stainless. So make sure you are applying heat evenly
Reply:If you wash a root pass, you run the risk of knicking it or sucking it back. It is possible to re-consume a root but something tells me you are not at that level yet. If you are going for a better looking cap, you can use 1/16 wire over your cap and get good results.UA Local 598