DIY Polishing Machine ~ Luthiery Laboratories

DIY Polishing Machine

This was my initial attempt at a polishing machine. Not pictured is the shroud I made for it to contain the spray.

This is for wet-polishing with sponges and automotive polishing compound. It is a very messy process - drops of "mud" fly everywhere. However, it does work. It takes great care to avoid going through the finish, which is a disaster. I have since moved to dry-buffing with cloth wheels.

The Harbor Freight polisher blew up a few days past the measly 90-day warranty. These Chinese tools often have almost no grease on the gears and bearings, and immediately start to tear themselves up inside. But I was expecting that, and had remedied it first thing, so I had to wait for some other part to fail. The trigger - easily replaceable, if you can get one, which you can't. That's today's lesson on cheap tools. I replaced it with a DeWalt that is still going like new.

Finishing

Black Polyurethane body. This is during the polishing process, you can see it is not even clean. The front came out like black glass. I smoothed the orange-peel with 1500 grit wet, then 2000 and 3000. Then I switched to the random orbital with a red sponge cutting pad and Turtle Wax rubbing compound that claims to remove 1200 scratches. Shouldn't be any 1200 scratches, since I started with 1500. That came out shiny, but with swirl marks in the light. Then I switched to another red cutting pad with Meguiar's Ultimate Compound, and finally a softer yellow pad with the same Meguiar's. At that point, it was pretty much a factory finish. I didn't work as hard on the back, it is nice, but will soon enough encounter a zipper or belt buckle, so the effort would be wasted.

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Fretboard Radius Jig

Front view of main frame, showing friction arm & setup supports inside.
The odd shape of the base was already that way, I just used it as-is.

The Radius Jig is capable of cutting constant radii from 6 to 16 inches, both concave and convex, as well as convex conical radii. That means it can cut sanding blocks, clamping cauls, and 'compound radius' fingerboards. Sanding blocks can be cut up to a finished length of 14", while fingerboards can be cut up to 28", enough for even an extra-long scale bass.

More: Fretboard Radius Jig ...