Mother of Pearl CNC Banjo Truss Rod Cover

A few weeks ago, I got a new-to-me 1995 Earl Scruggs Banjo from Turtle Hill Banjo Company. I highly recommend them. It played and sounded great but I wanted a bit lower action. I filed the nut slots a bit deeper and found that the strings were resting on the truss rod cover. This probably isn’t a huge issue in itself since it wasn’t buzzing but I didn’t like it. I then set out to make a slightly smaller truss rod cover on the CNC router out of Mother of Pearl to give some clearance and add some bling to it.

Here is a comparison of the original vs new size.

I used a Canon Flatbed Scanner to scan the original truss rod cover at high resolution and digital calipers to measure the hole spacing (1.925″). The image is then imported into Lightburn to vectorize it and save as a .dxf file. CamBam generated the toolpaths and g-code.

I chose a piece of 0.050″ thick gold/white mother of pearl from a lot that I bought on eBay and used the blue tape + CA glue method to attach it to a spoil board on my Shapeoko 5 CNC router. The cutters used are a 1mm downcut 2-flute carbide and a 1/8″ 60degree 2-flute V carbide both sourced from Amazon. These cut the mother-of-pearl surprisingly cleanly with no chipout. I used 24,000rpm at 10ipm cut / 5ipm plunge feedrate with 0.015″ passes. I used the V cutter both for the Earl Scruggs signature and to bevel the outside of the mother of pearl to give it a better look.

Lacquer Stik (fill-in paint stick) fills the Earl Scruggs signature. I applied it liberally then immediately wiped off the surface to leave only the lacquer in the engraving.