My customers bring the greatest stuff...
I have in a Shawn May 5-string bass made of many laminates of lovely woods. Issue: The customer decided to adjust attack the truss rod on his new, expensive bass, with no knowledge of dual-action rods. Result: He overdid it, and now the truss rod nut has been broken clean off, with the neck pushed into full back bow tension.
Do any of you have suggestions for safest ways to remove a tung-oiled maple fingerboard with as little discoloration/damage as possible?
The rod is a StewMac Hotrod, dual-action. Clearly the fingerboard has to come off. The rub - it's made of birdseye maple, which seems likely to suffer at minimum some discoloration, or possibly charring, in the course of the removal process.
I already attempted the unlikely fix of Dremeling a screwdriver slot into the nearly flush end of the broken truss rod, but the tension was simply too much to move this way. The truss channel is too deep/neck too thin to carve out at the headstock and attempt to yank it straight out, plus nothing to grab onto anyway.
The bass is neck-through, with numerous laminates, so I feel that attempting to inject steam into the truss cavity to loosen the board could cause laminate failure which could be catastrophic. I even worry about this with heating the board with irons, but hopefully it would be OK.
I may attempt to get a hot chisel into the fingerboard end seam, and hope to not get into the grain, but would still likely need heating first to have any success.
Id start by removing the nut , drill a few small holes along the fretboard for locating pins when you reglue it , I use a small floodlight to apply dry heat , so heat the area of nut to 1st fret , push a seam knife or bridge knife / spatula into the glue joint behind the nut , and work along the f/b , heating and prying . I don't think the heat will be enough to discolour the maple . I just did an Ibanez fretless with the same problem but not maple .
It might be a good idea to contact the builder to confirm what glue he used for the fingerboard. If it is hide glue, you may be able to walk a knife down the length with a hot knife and vinegar (or Adolph's meat tenderizer).
What happens if you straighten the neck with clamps? Might there be enough rod to cut new threads?
I'd see about getting a replacement fingerboard from the builder. Then you can just plane off the original board and be done with it. You'll save yourself a lot of time and frustration, and it shouldn't cost a lot anyway.
Len + 1: Fortunately the board is on with Titebond and presents little difficulty if done properly.
Heat the board with a luthier approved method - heat pad or lamps (I use a gun but you need a bit of experience to avoid torching the thing) applied over a long period of time and a spatula to wiggle (with the board grain direction) under the end to start the ball rolling. Don't be impatient - a good heat soak enables the final temperature step to proceed with a graduated approach once the board start to lift. Repeat: GO WITH THE GRAIN -but, if the neck is countergarined to the board go with the neck grain so any fork-up damages the board and not the neck. The board is replaceable - the neck isn't.
And, a lot of necks are put on with pins to locate the board - when you feel definite resistance to the spatula you have found one of the pins and will need to work around it. Work the spatula in a circular motion when you feel resistance to check out whats happening. If you are doing it right the board should come of with little drama. If you are forcing the spatula with both hands you are not on the money and need more heat (or have a chinese mystery glue neck which requires a demolition hammer to get off).
Titebond lets go at around 220 F but if you heat the spatula periodically (lift a bit of the board, get the heat back into the board and then remove and heat the spatula which then helps cut/shear the glue bond along with the leverage separation of the knife). The heat on the horizontal glue bond will not affect the vertical glue joint in the neck (if its a laminated neck). Don't use Chisel - if you apply the heat properly a spatula is fine - a chisel over- leverarges the board and will cause damage.
Before you start, strip out the existing tung oil with citric terpene and then a wash with acetone to neutralize any remaining extractives or tung which will possibly react to heat.
Dave, this is not a job for amateurs and if the instrument is valuable or loved you may not wish to assume the risk of a first time operation which is not without dangers (to the instrument and to your wallet). Plenty of cheap busted basses out there to practice on.