Friday, September 6, 2013

LeSpork Bass Prototype - Break On Through

You know the day destroys the night
Night divides the day

One of the project necks I picked up in a lot sale of three necks awhile back was for a bass guitar.

I probably can count on two hands the number of times I've held and played a bass guitar, including my repairs to a coworker's Washburn Lyon.  Still, I am intrigued by the instrument, and for the price I paid for the lot, it was like getting the bass neck for free.

By adding a bridge and saddle set, some tuners and a pre-wired pickguard, all it would take to make a prototype would be a body and few more bits and pieces.

Getting back to the neck, the front looked good and had no signs of damage or distress.  The truss rod seemed to be working fine, considering I could easily produce back bow in the neck with a few turns of an Allen wrench.  So far, it seemed to be the best one of the lot.

The back side revealed the reason this neck was on a repair bench.  A 1-1/2inch long crack at the lower frets with no other signs of damage was a bit mysterious.  Could that crack go all the way through to the truss rod cavity?  The only way to find out was by having a look at the other side, underneath the fret board.

A longer scale length doesn't make a difference in how I released the glue holding a fretboard to a neck.  Since the body-joint end of the fretboard was cut flush with the end of the neck, I started from the headstock end.  After applying some heat, I was able to get things started at the truss rod cavity with a 5-in-1 painters tool.

After about a half hour, I got my first look at the inside of this neck and her one-way truss rod.

Although the Martin-style truss rod is fine, it seems to have been involved in cracking the neck at the 1st fret.  You can see an impression in the truss rod cavity, where the smooth, round surface of the adjusting nut has been in contact with the wood.  The heat of the iron I used to release the glue must have resulted in the toasted look of the impression.  That must also have been where the nice aroma was coming from when I was working at the lower frets...

So, the good news is that crack in the neck is not all the way through to the truss rod cavity, and it is repairable with some glue and clamping, followed by some sanding and finish touch-up on the outside.  As for why the neck cracked at all, I'm guessing it was a combination of  things.  First, the neck has a very slender profile, and the location of the crack is at the weakest point of the neck.  Add to that the pressure of the end of a tightened truss rod, and it wouldn't take much to do some damage over time.  Finally, and this is just a guess, is that a misguided attempt to affect the neck set angle by over-tightening the truss rod resulted in damaging this neck.

I would like to do something to get a better distribution of the force into the neck to help avoid cracking at the back of this very slender neck.  This could be done by either using a longer truss rod, or filling in the first 1-1/4 inch of the truss rod cavity at the body-joint end.  Either way will put the adjustment nut so far into the headstock that it will not be possible to cover it.  Since this is going into a prototype build, I am opting to shorten the cavity at the body-joint end and use the existing truss rod.  Hopefully, the weather will cooperate so I can spend enough time in the shed to rebuild this bass neck over the weekend...


  1. I really enjoyed reading your post on how to transform the old guitar. I suggest that you also check the bass guitar for a better produced sound. Thanks!

  2. Thanks for the feedback, Danica. Stay tuned for more...