Ive watched alot of videos but im still slightly unsure as to what im looking for. My lathe has a d1-3 spindle, Id like to purchase a decent 4 jaw chuck for alignment purposes. Shars makes a variety of chucks and backplates. Looking at the chuck I can see a few features that need to match up.... the chuck needs 3 cam locks of the correct size, the backing plate need to fit the chuck and the register on the spindle need to match the backing plate. Is this correct? I notice that some backing plates have different diameters. This measurement needs to be spot on correct? This isnt just a through hole.