HAZ zone: TIG'ing near captive parts

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Question.  Piece to be TIG'ed upon has captive moving parts (i.e. I can't remove them).Steel parts that rotate on a bushing.  Will be repairing some 1/16 inch sheet metalaround them. What's a safe distance from these parts to prevent them from fusingor warping? They're not hardened so I'm not too worried about losing temper.I'm guessing maybe 1/4 inch is a safe buffer zone?  This is probably a stupid questionfor the gurus out there.
Reply:Well I'm not a welding guru, so I can't answer your question, but I can add two problems you need to consider that you didn't mention.1) The 1/16" sheet metal being welded can easily warp and contact your moving parts.Preventing sheet metal from warping has been mentioned here time and again . . .2) Stray currents (not just heat) can weld things together.  I've personally seen this happen on a piece of chain.  Having a really good ground path can prevent this.  Distance really doesn't enter the equation too much on this one.Aside from that, what are the bushings made from?  Will they melt?
Reply:Pictures would help with specific questions. In general keeping the part cool, using damp rags, heat sinks, low amps tight arc short welds with cooling time between welds.
Reply:Originally Posted by rlitmanWell I'm not a welding guru, so I can't answer your question, but I can add two problems you need to consider that you didn't mention.1) The 1/16" sheet metal being welded can easily warp and contact your moving parts.Preventing sheet metal from warping has been mentioned here time and again . . .
Reply:Originally Posted by ericmLet's hope I can weld sheet metal without it warping.  If not, I need to practice a lotmore before moving on to this project. :-)I'd be worried the rags would ignite, even if they start out wet, but I will look intopossible heat sinks I could use.
Reply:Originally Posted by ericmOk, though it seems to be hard to believe that current would want to jump across thebushing just so it has to jump back to reach the electrode.  Usually it wants the pathof least resistance.  However, I will make sure to pin the rotating part in place so itdoesn't move around and create variable gaps.
Reply:I have had great success with heat sink putty/ clay for years doing HVAC work. It works pretty well to help stop heat from extending out past the area blocked, and it absorbs a considerable amount of heat, reducing warping. Places like Grainger, Johnstone supply will have it.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:I had a boat seat, broken at both rear verticals. It was about 1" tubing, less than 2" from upholstery. I used a wet shop rag. Just remember, it's only one tack weld after another. DO NOT be trying to run a bead.I didn't even have ONE char mark on the vinyl.Edit: I tried my TIG first, but it took too long to puddle. I had better luck with the 'stick welder' side of the welder.Last edited by Craig in Denver; 02-13-2009 at 11:10 PM.9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:i would think tig on  one inch tubing would puddle in a heartbeat.. was the wet rag taking the heat out? were you set at 5 amps?
Reply:It takes quite a bit to set a wet rag on fire. You can throw a wet shop rag on a red hot piece of axle tubing to chamber it with litte danger. Even a dry rag just kinda smolders instead of bursting into flames unless it's soaked in acetone or something.Tough as nails and damn near as smart