Fingerboard Crack and Divot Repair - Final Sanding

I let the ebony sawdust/CA fill dry overnight.  You'd think that superglue would dry quickly, but my experience with that much volume of the stuff is that it takes a few hours to really harden.

Next step is to get the mounds of filler down closer to the level of the fingerboard.  I just used some small files for this.

I'm really wary of changing the radius of the fingerboard, so I don't file the fills flat.

Once they're down to a manageable height, I can sand the whole fingerboard.

Stew-Mac will sell you sanding blocks that are cut to various radii (radiuses?).  I actually have a 7 1/4 inch one to use on Fender boards.  But I didn't want to spend the money on another one, and I figured I might be able to cook one up myself.

At first I thought I'd try to somehow just cut one out of a hunk of wood.

But then I had a brainstorm.

I have some of this InstaMorph moldable plastic.  I actually bought it to use as a caul on another part of the project, which is upcoming, but I wondered if I might make a fingerboard sanding caul out of it.

This stuff is pretty amazing.  It's little pellets of plastic.

Put them in some 140 degree F water.  I find that 160 actually works better.  Just toss the pellets in there.

They glob together, and turn from white to clear.  That's when they're ready for action!

Take the plastic blob (careful, it's hot), and mold it to whatever shape you want.

I stuck a piece of waxed paper on the fingerboard, and then molded the InstaMorph around it.

It took me a couple tries to get it right - the blob was too big and too tight on the sides of the board.  Whattya do?  Just toss it back into the water and mold it again!  Crazy!

Here's my 20 inch radius fingerboard sanding caul.

It fits the board very closely, and the radius is perfect.  Stick a piece of sandpaper on it, and go to town.

Need a 12 inch radius for a Gibby?  Mold one up!

I sanded the board starting at 220 grit and went up to 600.  You don't need to sand a lot - maybe 20 seconds on each grit.

Wasn't there a big ugly crack on the body end of this fingerboard?

And the filled divots.  They're a little 'shiny' looking, but with strings on, you will hardly notice them.  Much better than the big divots.

I thought about dying the board with a jet black dye - the ebony does have some streaks in it and some builders use dye to have a uniform color - but I kind of like the streaks.  From a distance, it's black.  You can only see the grain streaks up close.



The Complete Martin Guitar Restoration Saga
Restoration begins
Repairing heel break
DIY chisel for bridge plate removal
DIY bridge plate removal iron, Pt.1
DIY bridge plate removal iron, Pt.2
Steam removal of bridge plate
Bridge plate removed
Tongue brace removal
Crack repair and brace scallop
New bridge plate Pt. 1
New bridge plate Pt. 2
Patching hole in top
Final fitting of top patch
Installing carbon fiber rod
Fret removal
Fingerboard crack repair, Pt. 1
Fingerboard crack repair, Pt. 2 (This page)
DIY fret bender tool
Refretting Pt. 1
Refretting Pt. 2
Tuner shaft repair
Neck reset - dovetail fitting
Measuring neck set with DIY jig
Gluing the neck with hide glue
Tortoloid Pickguard
Fitting bridge pins
Brace reglue
Making bone saddle
Making a buffalo horn nut
Restoration completed