Although I recently constructed a micro-grinder
and -sander, I found that some hand-sanding device would be
desirable for very delicate operations. Sometimes just a few
strokes would be sufficient and the process would be difficult to
control with a motor-driven machine. A guided sanding block allows
to achieve flat and square edges. After some rummaging in my
collected stocks I found a piece of aluminium rail with a T-slot
at one end (I don't remember its original purpose), a piece of
thick aluminium sheet, some square aluminium stock, and a
well-seasoned piece of pinewood of just the right dimensions (5 cm
x 8 cm x 2 cm).
Holes were marked out, drilled and countersunk for the pieces to
be screwed down onto the wooden block. The four sides of the
wooden block were squared off in the milling machine with the
aluminium pieces in place. The wooden block then was carefully
levelled in the machine-vise and a slot milled into the aluminium
as a guide for the sanding block. Finally the surface was evened
with some light cuts with a fly-cutter.
A mitre-guide was fashioned from a piece of flat steel. It can be
mounted left or right and in different configurations.
The sanding block is fashioned from some 8 mm x 8 mm square
aluminium stock. It has shallow recesses milled into both sides to
allow for the thickness of the sanding paper. A knurled screw M3
serves as handle. to begin with a glued a strip of 600 grit
wet-'n'-dry paper onto one side and a strip of plastic coated with
abrasives as used by dentists for grinding and polishing teeth
onto the other side.