Mig / Tig Tubing Setup

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I weld mostly 16 ga 1.5 inch square tubing and occasionally up to 11 gauge 2x2 with my mig.  I have always tried to cut and keep the distance between the pieces small or bevel if needed to make sure I get penetration.  I recently started learning tig and have a tough time with burn through when there is any gap at all or on square tubing that has the round edges instead of sharp ones.With tig, should I try and get the gaps close and tight as possible, or should I leave some space between the pieces?
Reply:A tight butt is the best butt Seriously though, I would recommend as tight a fit as possible with TIG on tube that size.
Reply:less heat more filler
Reply:I have tigged a lot of 16 gauge 2x2 tubing. It is frustrating at first with the round edge tubing because even if your fit is really tight, it is still easy to burn the lip on the cut edge because of the gap the beveled edge leaves. The way that works great for me is to start on the non-edge and get your pool going, then weave into the cut edge, letting up on the pedal a little, then on the pedal again and back to the non-cut edge. You are essentially weaving the weld, going back and forth between the two pieces, modulating the heat, and adding a lot of filler as you go. You still should use a small filler rod, 1/16 is what I use, as anything larger and it is hard to get it to melt into the pool at low amperages. I usually weld 16 gauge at 85 amps, but I am off the pedal a bit. I leave it at 85 for fillet welding the tube. Try to weave it between the two pieces. If you try to run a continuous bead with a gap on that thin of tubing, in my experience, the gap always wants to burn away. I guess it would happen on thicker stuff too, as your amperages are higher. Can someone with more experience help here? Is a weaving technique the best way to tig this tubing in this scenario? Works for me, but I am not qualified enough to tell you this is the 'right' way. I will try and post pics of the way I weave it if I get time.
Reply:Thanks for the info.. Any pic's would be great.. I have been running at 90 amps so I think I will turn down to 85 and try also. Other thing that is different is I have been using a 3/32 red tungsten and 3/32 filler which is probably too big now that I think about it..Is there a link or reference where I can find max amps for different tungsten's?
Reply:3/32 red tungsten is fine and what I use for everything. 3/32 filler is too thick. Get some 1/16 and you will be surprised how much easier it is to manipulate the pool. I have tried 3/32 filler and it just requires to much heat to melt into the pool, and you will end up burning the edge right off because it requires more heat. I stay at 85 amps, but once the pool is going, I am guessing I am running more around 65 or so. I will get some pics up this weekend. Try the thinner filler first. It makes a world of difference.
Reply:deere210,Here are some pics. 3/32 red tungsten 1/16 filler. You can see from the pics I left a pretty big gap intentionally. I weaved back and forth over the weld, again, starting the puddle on the non-cut and moving it into the edge, while letting up a bit on the pedal. While it is not the prettiest weld, filling a gap like that with such thin wall, it serves its purpose. I grinded it and cut it open to show the penetration. The penetration was full. Hope it gives you an idea by looking at the bead how it was weaved into the cut edge. Attached Images
Reply:More pics: Attached Images