Great idea good job well made. The tracking is hard to get right for a diy project I've tried myself. The wheels being convex with the silicon or rubber does help and the blade doesn't hit the sharp parts on the wheel also.
Well done! you have great talent and made a nice machine using basic tools plus an old Sawbench. I would do the same myself but only for myself. I would become crazy if I had to make some for sale and give up in the end.