Turning Mother-of-Pearl Dots on a Drill Press

Many times mother of pearl dots are needed for a guitar fingerboard that are not available in the size required.  These may be produced in small quantities from small pearl or abalone squares or other odd shapes that are large enough to produce the dot.

First, and most important, WEAR A TOXIC DUST MASK rated for small particles.  I personally use a toxic vapors mask with charcoal filters and dust pre-filters.  Contrary to urban legends, pearl and abalone dust is NOT toxic, BUT it is very unhealthy to breathe.  The particles are sharp edged and the lungs find it difficult to expel them, resulting in silicosis, a nasty, debilitating lung disease.  However, if you wear a mask, and then wash all the dust off (a shower is preferable) then this method is totally safe.  It is also advisable to use a vacuum cleaner during the grinding to keep this dust out of your shop.

The method that I have used with success for small quantities employs small nails with a head slightly smaller than the dot you wish to make.  Using the exact brad point or forstner drill bit that you will use to drill the inlay cavities, drill a hole in a piece of flat hardwood big enough to clamp to the center of your drill press table.  This is used to measure the dot as you sand it down to the precise size you need.  Place the drill bit in the drill press, and lower it into the measuring hole you drilled previously.  Using the depth stop on the drill press, hold the drill bit in the hole while you clamp the wood to the drill press table.  This process centers the drill press quill on the hole.  Remove the drill bit leaving all drill press settings INCLUDING the height locked in place.

Take the number of pieces of pearl or abalone you want to make dots out of, and glue them lightly using cyanoacrylate (super glue) or five-minute epoxy to the requisite number nails, being sure the nails are completely straight.  Place the nail deep into the chuck, while still being able to lower the quill just into the measuring hole.  Take a stick of VERY hard wood (red oak is good) OR square aluminum, and glue a good quality strip of sandpaper to it.  I personally use 120 grit gold adhesive paper from Stewart-Macdonalds.  Any good sandpaper will do.  Start the drill press on medium speed.  Press the sandpaper LIGHTLY against the pearl / abalone, lifting away frequently so as to not overheat the pearl.  If you overheat it, the glue will release and you will never see that dot again!  Also, if you press too hard, you will bend the nail.  Test the size of the dot frequently.  While it is cooling is a good time.  When the dot easily enters the measuring hole, you are done with that one.

After all the dots are ground, either separate them carefully using a single edged razor blade or an exacto craft knife, OR if you used super glue put the nails and dots into a pan of boiling water, the dots will release within 30 seconds to one minute.

If a careful job was done, you now have PERFECT inlays dots that are EXACTLY matched to the actual drill bit you will use to make the inlay.  Be SURE to always test the dots in another freshly drilled hole before using them for inlay.  If they are too tight, the edges can be easily filed, but you DON'T want to find that out when you have glue in an inlay recess!  I have fingerboard-thick measuring boards of the three woods I currently use for fingerboards, ebony, rosewood and maple.  This is because these different woods have different compression factors, making the resulting holes SLIGHTLY different in size.

To do as close as possible to flush inlay, use super glue to attach FLAT toothpicks to the top of the dots.  Two toothpicks on the edges of the dot is preferred to one on the center.  Surround the inlay dot recess in the fingerboard with tape, either 'scotch' clear type or masking tape.  This protects the fingerboard from glue, which is VERY important if you are using a wood like wenge that has large open pores.  It is also important for fingerboards with a tight radius, such as a vintage Fender-style 7 1/2" radius.  It is also important for abalone, since abalone patterns change RADICALLY as you sand into the abalone to level it.  The tape compensates for the thickness of the glue between the toothpick and the pearl dot.

I hope you find the 'tech-note' useful.  Remember to ALWAYS work safe, and enjoy making guitars!