Come up against a small problem. I've cut a 150mm disc of pine by 19mm thick but I need to sand the outer edge accurately. I have a disc sander and was wondering if there is a simple-to-construct jig available ?
The simple answer if yes is to rotate the disc on a pin, moving the pin (on a pivoting arm) close to the sander. Be careful not to try to take a heavy cut, you need to only let the disc rotate slowly, for both safety and finish.
If your disc doesn't have a centre hole, make another disc out of scrap ply and make it perfectly round using the above sanding method. Then glue this on to your disc with hot melt glue and use it as a template using a bearing guided flush cutter to trim the disc to size.