Thanks to Allan for his post back in December on making his shop made 12" disk sander. Allan's post was very inspirational (and I badly needed a better disc sander). Here is my result.
The faceplate consists of a primary (attached to the pulley) and a secondary faceplate (attached to the primary). The pulley has a 2" x 1/2" recess on the face so I turned a tenon on the primary faceplate and recessed the pulley into the primary faceplate. This was epoxied and bolted together with 5mm countersink bolts. The secondary faceplate is also recessed mainly to keep it centered as it bolts on and off with 6mm countersink bolts.
Truing up the secondary faceplate was done with the whole thing together. I used a turning chisel and 12" long jointed stock to finish sand. The 12" jointed stock is used end-to-end on the faceplate keeping even pressure on it while you sand both sides (the disk going down and coming up) at the same time. This will true up a faceplate without possibility of convex or cancave dishing. I then varnished the secondary faceplate for a clean, smooth surface to take the disk.
It's a dandy little unit with a 1/2Hp. The motor cost me about 50.00 with the switch and I used 3/4" ply.
Once again thanks to Allan for his original post.