Block Inlay - Fretboard Cavity Radius?

Discussion in 'Luthier's Corner' started by turindev, Jun 10, 2019.

  1. turindev

    turindev Commercial User

    Jul 1, 2005
    Chattanooga, Tennessee USA
    For you inlay experts out there, I have a question regarding block inlay. I will have MOP block inlay in my current (first) build.

    I have done a little research and determined that the bottom of the inlay pocket in the fretboard (probably) needs to be radiused so that the ends of the MOP aren't paper thin. In my initial plan, I was going to just use the same radius my fretboard has, but that will mean the MOP will need to be slightly curved. Assuming I am approaching this the right way, do I just sort of "bend" the inlay and clamp it while it dries? On a similar note, should I purposefully cut the inlay cavity slightly shorter than the inlay so that the inlay will extend a bit high (which would then be sanded to match the fretboard). This is all probably simple, but I like to plan everything out first :) I will also be doing the whole exercise on a dummy neck a few times to get it right before I hit the birdseye.
  2. Frederiek


    Aug 8, 2016
    Real MOP is very fragile and I would not attempt to bend it. An acrylic can be used like that. I just did block inlays on a radiused fretboard and it is indeed rather thin at the edges. That should not be a problem though.

    I think it's easier to cut the inlays to the right size and slowly enlarge each cavity for a good fit.

    Attached Files:

  3. turindev

    turindev Commercial User

    Jul 1, 2005
    Chattanooga, Tennessee USA
    Thanks for your advice! I actually recently saw your thread on build 4&5, and your inlay is beautiful! Do you cut the bottom of the cavity flat and sand the top of the inlay to match the profile of the radius?
  4. Bruce Johnson

    Bruce Johnson Gold Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Yes, if you are working with real pearl or abalone, you can't bend it much at all. You should rout the cavities flat bottom, leaving just enough depth at the edges. Then make sure that your inlay is thick enough that it can be shaped to the radius.

    With the synthetics, you can bend them quite a bit without breaking. You can even heat them lightly and pre-curve them. The synthetic pearl is also available in thicker sheets and blocks. Very easy to shape and machine and glue.

    I use only synthetic pearl these days. So much easier to work with, more durable, no legal hassles, and in most cases I think it looks better too.
  5. turindev

    turindev Commercial User

    Jul 1, 2005
    Chattanooga, Tennessee USA
    Makes sense! Let me see which material I was planning on using, I have it saved in my build document here somewhere :)

    Looks like the material I was planning on using is a celluloid so it is probably flexible. My gameplan is to use some scrap to create a test fretboard with both flat and radiused cavities, and see which works the best. Thanks again for your help!
    Last edited: Jun 10, 2019