Thursday, August 20, 2009
Inlaying pearl is a challenge. The stuff is hard and brittle, and thus unforgiving. I'm not a huge fan of it for instrument work. I prefer more subtle materials like wood or ivory. Nevertheless, the shimmering iridescence of mother of pearl can be a nice touch when used sparingly, for my taste. So I chose this material to inlay into a Veritas Brass Insert Knob for a curly cherry side table I recently finished.
Working with the pearl requires some special considerations since the material cannot be cut using typical woodworking techniques.
I find it easiest to buy pearl in random sizes, but of a consistent thickness. The best place I know of to buy pearl is Depaule Supply. I pay around $10-$20 for an ounce of random pieces of white MOP.
Cutting the pearl is not difficult, but it does require a steady hand. I use a jeweler's saw with a 2/0 blade. I like Pike brand. A bird's mouth fixture is the best for cutting out small pieces.
This particular knob takes a 3/4" dia. inlay. I draw the circle on the blank, roughly cut it with the jeweler's saw, then take it close to my layout line on the belt sander. It's important not to breathe the pearl dust. I have a dust collector port next to my belt sander.
I sand up to the line.
I chuck a piece of scrap wood in the lathe and turn down the end to around 3/4" dia. This happens to be a piece of cocobolo. I don't typically use this as scrap wood, this is a reject knob from a Benchcrafted Tail Vise.
I glue the pearl disc to the end of the sacrificial piece with some CA glue, and take a measurement of the inside diameter of the knob. It's a tad smaller than 3/4". This is just for reference, I don't use the caliper to fit the inlay.
I turn down the pearl using a file...
...or sometimes a piece of course sandpaper wrapped around the file. Note my dust collection hood right behind the work.
I stop frequently and test the fit with the knob. I want it just snug, so there is no visible joint between the pearl and the brass.
Once it fits (ignore the shorter sacrificial blank, this is from another knob sequence) I apply some CA glue to the inside of the knob, press the knob onto the pearl inlay, then tap the knob with a small hammer to make sure it seats well.
I take the blank from the chuck and cut off the knob on the bandsaw.
I then mount the knob onto a special mandrel that Lee Valley also sells.
I place the mandrel in a drill chuck mounted to the headstock and begin to turn the remaining wood from the end of the pearl.
I don't use the tool to cut the pearl, but only to part off the wood.
Once the wood is gone I begin to work the pearl with sandpaper.
I slightly dome the end of the pearl and make sure is transitions smoothly into the brass knob. I work up through 1000 grit, using water once I get to 400 grit.
Finally I use a little Brasso polish to bring a nice sheen to the brass. The pearl takes on a nice translucent quality with depth and chatoyance.
The finished knob is lustrous and beautiful, like a piece of jewelery.
It adds a nice touch to this piece of furniture. The cool pearl contrasting nicely with the warmth of the curly cherry.