The Guitar Gallery Forums - The Guitar Legacy of Matsumoku

Seeking precautions and preparation tips regarding application of rotational torque to a truss rod for the first time in 55 years.

I want to reduce the existing amount of concave neck bow. I believe the truss rod is a single-action model. I intend to proceed by first reducing string tension, then tighten the truss rod by turning it CW so that the neck begins to straighten.

Access to the rod is at the headstock end of the neck. The instrument has always been stored in a relatively dry environment - exposed chromed metal surfaces (screwheads, pickup enclosures, vibrato) are rust-free. I assume that a daub of grease or light oil film was applied to the truss rod prior to assembly to provide lubrication for movement and act as a barrier coating against rust.

Small steps. VERY small steps and give it as much as several days each time to settle in.

I posted after being warned about the possibility that the truss rod's adjuster may have seized to the threaded rod. Your cautionary advice has turned my attention back onto the state of the neck itself !!

The instrument is kept at about 45% rH in its case through the use of commercial and DIY humidifying devices. Results are monitored using a verified Accu-Rite #01080M humidistat.

Do you recommend bringing the strings back up to pitch or leaving them detuned during the days in between tightening the truss rod incrementally to reduce concave neck relief?

Start with no tension on the strings until the neck is straight then tune to pitch to see what happens.

Will do. Thank you.

The pocket in the headstock is too short to facilitate inserting the short end of a conventional 5mm hex (Allen) key wrench into the socket head of the truss rod. (This guitar's string hold-down bar does not improve the situation.)

I do not feel comfortable using a ball-head, so I will find another 5mm to sacrifice. A few moments with a thin abrasive cut-off disk and I will have what I need to proceed.

I just love it when manufacturers do that. I have about 60 truss rod wrenches of about every type and size, SAE and metric, hex wrench and socket, only one hex with a short end and they'll have to pry that from my cold dead fingers.

I would just add one thing to the advice already given.

On a truss rod that has been inactive that long, or any guitar really, I would first turn it anti-clockwise (lefty-loosey) to ensure that is not seized up.

Backing it off this way ensures that it is functioning correctly without putting undue compression on the rod and accidentally breaking something.

If it moves freely it might be a good idea to remove the nut and add some lubrication while you have the opportunity. That will overcome any thread corrosion and ensure maximum efficiency.

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Great advice!

Been a long time since I've worked on a guitar this age.

If you would like to have a back-up for that treasured short-ended hex or you wish you had short-ended versions of OTHER sizes, here are links to a couple of US sources for 13 pc metric hex key sets made of Cr-V that sell for less than US$10.

• https://www.harborfreight.com/13-piece-metric-ball-end-hex-key-set-96416.html
• https://www.northerntool.com/products/grip-metric-hex-key-set-13-pcs-model-92250-27065
  .
• For those viewing from Canada, Princess Auto offers similar value.
  https://www.princessauto.com/en/13-pc-m ... 0008853681
  https://www.princessauto.com/en/9-pc-me ... 0009124777

Note that HF's Pittsburgh set and Princess's Grip set both feature ball ends on the long side.

I find Chrome vanadium is easy to work with. Shortening a hex key can be accomplished with a variety of tools fitted with an abrasive cut-off disk. Examples that can all get the job done include dedicated pneumatic/electrical cut-off tools, angle grinders equipped with a cut-off disk, rotary tools (Dremels and their clones).

Another tip is to use a torch to heat the middle of a hex key so that the hex at the end can be 'clocked' to a different position. This is for the situations where there isn't enough room to swing a hex key and it becomes necessary to switch back and forth between a regular and a 'clocked' hex key to get the fastener out/in. O/A, MAPP and propane torches will all do the job. I've never tried a butane torch, but expect that it would get this job done, too.

Thank you for the great advice, Barry.

I had hoped to be able to include a photo of the truss rod's head when I replied. Initial examination raised some questions, but photos and a more thorough examination have been held up.

More to come.