Depends upon what you want to do with the disks. Facing off a disk merely
requires a chuck that will leave the disk proud of the jaws when the facing
is done. This is best doe with a collet type with a backing surface.
Edging is a bit more difficult and probably the best way is to use some
doublesided tape (not the foam stuff but rather the stuff that is using a
thin plastic center with adhesive on both sides) and a live center with
alarge pad rather than a point to hold the disk in place. The finished edge
needs to stand proud of the mountings.

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Why do penguins walk so far to get to their nesting grounds?