Motorized Sanding Dish

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Buffer This article will show how I accomplished a complicated but necessary sanding operation which improved the quality of my guitars. Any standard buffer allows for the removal of the buffing wheels and I replaced one with a purchased sanding dish. These dishes come with adhesive backed sandpaper and may be modified to mount as shown in the view below. In my case I had to drill a 1” hole in the exact center of the dish and sandpaper before mounting on the shaft.

Requiring a much slower speed than the buffer requires, the dish will contour sand the ribs for a perfect geometric fit with the guitar’s back. The corresponding domed back will have a flawlessly tight joint around the entire perimeter of the guitar. The sander should run at approximately 75-100 rpm for the smoothest operation. The use of either a gear reduction or motor speed control will should produce equal results. Be careful not to exceed 100 rpm because the dish will likely wobble and possibly become dangerous. Slow is good.
During sanding, use plenty of light and carefully check your progress so that all areas are sanded equally and uniformly
Sanding Disc Installed The sanding disc installed.
Demonstration of Sanding Disc Demonstrating the sanding procedure for the camera.
Sources:

Luthiers Supplies provides a variety of dish sanding disc radii from 15’ to 30’ and self adhesive sandpaper. I did find it necessary to re-enforce these dishes with a 3/4 inch plywood backing. They are a little thin in the center and tend to curl up, which decreases the radius.
Grizzly and Stewart MacDonald provide powered buffers or parts.