12" Disc Sander

This is a shop built 12" Disc Sander

Step 1: Motor Mount

As I wanted to use an old motor that I have had since the 70's, I needed a way to mount the motor to the 3/4" x 12" round disc. I found out that shopsmith used a motor mount to 1" thread for the lathe motor connection. With this and a 1" thread face plate I was in business.
I took a 3/4" birch plywood and marked the center with lines perpendicular to one another. I then marked a 12 1/4" circle and cut it on a bandsaw using a circle jig I also made. I left 1/4" on the diameter as I knew when I mounted it to the motor it would not be true.
I take care of this in the next step

Step 2: Trimming the 12" Disc to Size and True to the Motor

In this step I mounted the motor on my workbench near my vice. I used the 3/4" threaded rod that I purchased for the table mount to hold my lathe tool rest. With the 12 plate mounted to the motor I marked the disc at 12"
I then turned on the motor and cut the disc to size using my lathe tools.
Note that I made a box with base from 3/4" plywood assuring the Disc would be tall enough to clear the 3/4" threaded rod for the table.

Step 3: Balancing the Disc

Even though I cut the disc mounted on the motor I noticed I had excessive vibration when running the motor.
So I mounted the motor to the table, and spun the disc by hand, marking the top back of the disc once it stopped spinning. I did this 6 to 10 times and taped a washer on the back of the disc near the marks as these showed the disc section that was the lightest. I.e. The heavy part of the disc will stop at the bottom more than not..
I then turned on the motor and still had vibration, but less than the initial test. I repeated the above tests, adding one more washer. I then moved these washers toward the center of the disc and checked vibration. Once I was happy I epoxied the washers on and attached the sanding disc and checked vibration again. Zero vibration... I could run the motor with disc on my bench with no movement.

Step 4: Sander Table Mount and Back of Sanding Disc Shield

I had a Delta sander that I used the table off of. I put a 3/4" threaded rod through the middle of the box as seen in the first 2 photos.
I also cut a 12 1/2" disc and made a wood shield to cover the disc. I then painted the box and back shield.

Step 5: Adding Dust Collection

I used a 1 1/2" PVC Pipe and a wood adapter to make the dust collector and attached to the disc shield.

Step 6: Adding the Table to the 3/4" Shaft

I mounted the Delta Table to the 3/4" threaded rod.
I created a larger table to mount on top covering the entire 12" disc.

Step 7: Adding the Switch

I used an old Craftsman switch added to the sander to turn the motor on and off. I mounted the switch on the side of the sander behind the disc shield for safety.

Step 8: Finished Sander

This is the finished sander that is solid... I found a damaged Delta sander for $64 so I bought it and sold this sander for $120. The guy that purchased it stated he would buy it if he could not stop the motor sanding a 2x4... Sander did not stop..
I now have a Jet 12" that was damaged for $146... $600 sander and just minor repairs needed...