Well I wasn't going to post anything about this grinder untill I was sure if it was going to work but I decided to just incase someone was considering trying to make a belt grinder out of a treadmill. Hopefully this may help you decide if it is worth it or not. I know it has been done many times and there are youtube videos to prove it. I figured I would try it cause if it does end up working it will be a very inexpensive way to spin a 2 x 72 belt. So far i have: $30 for working treadmill (Kijiji) sometimes you can find them for free $45 for 4 skateboard wheels and set of bearings. Bearings were cheap ones incase it doesn't work. $5 Screws, nuts and washers. I could have found them here but you will see in the pic below why it was easier to buy them. $20 Couple pieces of square tubing and angle iron. Last night I gave up on it because the way I had the belt set up it would not spin fast enough to make a spark. I ended up using the pulley/Balancer? on the motor itself because it was a bigger diameter. I got it spinning a bit past half speed and I was able to actually remove some material off of a knife blank I saw cut using the skateboard wheel as a contact wheel. Here is what I got so far. The grinder is actually spinning fast enough in this pic to make sparks. As you can see there are more C-clamps holding it together than weld or screws. That's why I didn't want to go much faster. I am feeling pretty good about it so I will start welding it together making sure that I have everything as square, straight and parallel as possible. Tracking is a bit of a problem right now cause it is not square. I still want to build the grinder I have been designing but I just don't have the time and extra cash to do it right. If this works out I will be able to take my time with my design and get the proper motor, VFD and wheels. Who knows, I may even be able to keep it as a lighter duty back up grinder. I'll keep you posted on how it works out and feel free to comment or ask questions.