I've seen regrousering done two times. Once was on a mine tour and that was impressive. In a mine, regrousering is routine business. They pulled the tractor (an 8L with a ripper) into the shop with the door open and surrounded all four corners with torches and welding cables - and 4 men. The operator stayed in his seat and the tractor idled.
He lifted the tractor from the ground with the blade and ripper, and the four guys went to work. Working at each idler, each would torch flat a pad, fit the grouser, weld it on in the flat position at close to 400 amps with 1/4" rod, and signal the operator to spin the tracks one more pad. As the pads from the front man reached the back fellow in sequence, all the rear guy had to do at the half-way point was weld the other flat side and the two ends, and they were done. I think they told us that a tractor was regrousered in one shift, no problem.
The other was at our forestry operation. The welder was working by himself in late November. The TD-20e was left idling to move the machine, and the welding truck was left idling to keep the welder and his smokes warm between passes. It was painful to watch after seeing the above method, mostly because of the cold. I'm sure that the two engines idled for a week solid for that job - there must have been some top-end deterioration in those engines from constantly idling.
My own JD450 has been redone, but that was before I acquired it. In any event, I wouldn't take the pads off the rails, just work off the sprocket and idler ends so you can weld with lots of amperage in the flat position whenever possible. The pads are easier to cut vertically too, rather than torching horizontally. Wear good leather - there will be a good wee bit of slag on this job.
John
