If you have a big enough compressor get a angle air grinder, not the sander but a regular air grinder. Mine is a Porter Cable 4" and cost about $80. No smoke, no cords, just plenty of grinding power, a little oil once in a while and your good to go. I was shop forman for a construction co. and my welder had arms the size of 5 gal buckets, so 4 1/2" grinders only lasted about a month, finally broke down and paid $175 for a Ingersoll Rand angle grinder and 4+ yrs later it still run's great.
