I just thought I'd share this for anyone else who has thought of doing the same thing.. Around 4 yrs ago I built a small walk behind grinder with a 13 hp motor. It works good on the smaller stuff and it definitely got my name around, but once ppl find out you grind stumps, stumps come at you in all sizes. I did a few 3 foot+ stumps with that just about killed my enthusiasm for grinding.. (and wrists & back) I just grind as a sideline so I couldn't really justify spending big bucks on a grinder that's not gonna get used every day. I rented a 1635 from the hardware store one time to do a bunch of big stumps I didn't feel like doing with my small one, but like most rental grinders, the teeth were horrendously dull and it was a pretty long day. I already owned a bobcat so I decided to build a grinder for it. I started on it over a yr ago then got busy with other things and it sat till about a 6 wks ago when I realized I just need to get this thing done. I have no idea how many pounds of welding rods I burned up, but it was a lot. Most of the metal came from auctions, the engine from Craigslist, and the teeth from Baileys. It's crude but I like being able to walk into the hardware store or deere dealer and get off the shelf bearings, belts, chains and sprockets, ect.. for it. I just ground out 3 stumps with it yesterday for the first time and it worked pretty well. Blew threw them like nobody's business ( at least compared to what I was used to) I know it's no 8018 or rg100 but given the amount I grind and I'm the only one running it I think it should do the job. Time will tell.