Hey, I am new to this forum hoping that I can get some help with a project. I also hope to be accepted as a new member, hopefully learning from everyone here. I am sorry to ask a simple question that may be easy. I am learning and experimenting as a hobby, I do not have access to super accurate milling machines, and I understand I will have to have some tolerance. I know I can order a whole new gear from ponoko.com, but I want to work with what I have. I am twenty years old, playing around in my garage with a welder, and a chop saw, etc... I also have a gear that looks like... (the gear does not have the holes on the edge or the same number of teeth, it also is not the same size. However, and unfortunately, the gear has the giant gaping hole in the center) The problem that I am having is that I am finding it pretty difficult to connect another (larger) gear with a chain, and have the two gears perfectly center. The two gears not being centered absolutely perfectly on their shafts causes, well, you know.... I have built a jig (before buying the chop saw), and I got the newly welded shaft to be about .02in off from center, as far as I could accurately measure. I was just wondering on some of the other methods to attach a shaft to the gear that is perfectly centered horizontally and vertically to the gear. I have searched around the internet and did not find really anything. Thank you for your time, Jordan EDIT: I can do all of the math on paper, drawing the circle with a compass, etc, but it does not come out into the real product.