Re: Repairing Stainless Steel From Grinding
Don't think it's been brought up but probably the most important thing about doing this efficiently is to use the correct grit in the proper order.
Certainly one could 'polish' out scratches left from grinding welds off with a 36 grit flap disc using 1000 grit paper and jewelers rouge, but it's gonna take you a week and lots of paper and rouge...
In my experience, to do this effectively you roughly double the grit you started grinding with for every step. In other words, if you started with 36, the next step would be 72 (80), then 160 (150), 300 (320), 600 (600) and so on. Any step you skip doubles the amount of time required with the nest higher grade.
The quality of paper doesn't really matter, the better papers just last longer.
I like using a DA (random orbital) sander, the dual action seems to work better and faster than a straight rotary motion. I think it might have something to do with setting up patterns in the material being polished, but who knows? For small jobs a palm sander might work just as well.
And incidentally, once you get above 1000 or so you get a mirror finish without any 'polishing' at all. There is a recent post about it under 'DIY polishing new chainplates?'. By mirror finish, I mean you can clean Sharpie (don't know what they go by in your neck of the woods) marks off with a dry paper towel...