TIG weld 6mm steel?

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Hi guys,I can TIG-weld thin walled steel tubes quite well at the moment, but now I have a job where I need to weld some rather thick (6mm) steel bicycle dropout. What would "best practice" be in this case?Truls
Reply:Can you elaborate on what you are welding and what this thing is?  Are you welding the long bar to the slotted piece (dropout?)?  What is the function, this will determine weld requirements.  I'm picturing a 1/8" fillet around both sides of the dropout.
Reply:I wondered the same thing, but I think the half inch or so tube is just there for alignment purposes.   I'm assuming there was a crack in the rear of the dropout and the crack was cut out into a slot, to be welded up.  The crack should have been ground into a v-groove instead of an open slot, so it can be filled up with weld.  The slot can still be filled, but you will have to build up one side at a time until it closes enough to weld both sides together.  You'll want to clamp it on both sides to something thick and flat so it doesn't warp and cup during the welding.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Pics are hard to make out, but looks like you've got a Colnago with a semi-horizontal dropout and you are holding the derailleur tab?Looks like it has been ground out of original dimension with some material missing. If the gap is as big as you are demonstrating with the piece of square stock, I would fab the missing piece (instead of filling the gap with filler) and tig that to the lower portion of the drop. V grooves on both sides and secure flat as DesertRider stated. Then tig the complete lower portion to the frame in the same manner. Be methodical about the passes as to control the warping/pull from side-side and front-back.I'd practice on something dimensionally similar to judge the behavior and not roll the dice on a nice Colnago.Are the dropouts brazed to the cs and ss? An issue that comes to mind would be melting some of the braze if the heat is close enough. Again, can't really tell scale from the picture.Last edited by sporkedtospec; 09-21-2010 at 12:13 PM.
Reply:Ditto on checking if the drop outs are brazed.Either way I would start with building up the severed peice until its close enough to touch. Then v-groove the peices when you're ready to join them. Use low power and thin filler, and cool the dropout after each pass. I think i'd try to do it in about four passes.Ian TannerKawasaki KX450 and many other fine tools