I performed some repairs on an old "merry tiller" rotor-tiller today.
The main job was building up the outer tines which were worn down by many years of tilling. I layered on a bunch of 3/32" E70S6 rods using TIG with a good number of passes. The leading edges of the tines were worn into a tapered shape which was especially bad news on the outermost tines, because when they hit rocks on the side of the trench being tilled, the worn tines would thrust sideway on the rock and toss the tiller sideways. The "sharp" tine leading edge shape grabs and flips the rocks out much better. One thing that I figured out that was kind of fun, was using the filler rod and surface tension between it and the molten puddle, to "persuade" the puddle into a certain position (such as, holding it up against gravity) to control its position as it freezes and to control the shape of the solidified material.
I also repaired a frayed stainless steel clutch actuating cable. I welded on a solid "loop" of 309L stainless onto it.
I just used the torch switch to control heat for this, so I could do the repair easily with the tiller resting on the ground. I think it's pretty good evidence that you can control TIG heat with just a torch mounted on-off switch pretty darned well. I dial in a little bit of downslope (maybe about 2 seconds) which makes the heat react a little more slowly to the switch, then toggle the switch repeatedly on/off while welding to control the heat. It works quite well.
Since I was welding outside in light-moderate winds, I used my "big" #8 gas lens cup and didn't stick the tungsten out very much, and about 12 cfh. Worked well for not fighting the wind too badly. I sapped about 150 psi off Argon bottle doing this though.