Kavanagh Customs

Project Guitar Help Centre: The KavanaghCustoms Heel Tennon Truss

We at Kavanagh Customs have for some time been trying to find a way to make heel-adjusted truss rods more useful.

The problem is that they rely on engineering from the first half of the twentieth century (getting on for a hundred years ago now!). We have our own design of dual-action truss rod that doesn't require that unsightly hole in the side of the bottom of the neck that other manufacturers are using, and we wanted to do something similar for heel-adjusting truss rods too.

The main problem with the original design of heel-adjusted truss rods is their length: they are shorter than you would get in a head-adjusted rod and equally less effective meaning that they are less stable: your guitar goes out of tune more often, you lose your pitch and your set-up every time the guitar gets cold and your neck starts to bow.

We have the answer! Our patented tennon truss is longer, more stable, and just as adjustable as any standard heel truss is, but with the additional length it needs to keep your neck stable for years to come.

Using your tennon truss

It's called the 'Tennon Truss' for pretty obvious reasons - there is an adjuster on the end of the neck that sticks out of the bottom of the neck. Don't let this put you off just yet. The section of truss which sticks out is there to allow you to adjust the relief of your neck.

OUR TENNON TRUSS NECKS ARE FULLY COMPATIBLE WITH STANDARD NECK POCKETS WITHOUT MODIFICATION!

As with all heel-adjusting truss rods, the neck must be removed from the body before you can make adjustments. All necks ship from Kavanagh Customs come with the adjustor piece - it is very important that you ensure you have found it before you throw the packaging away.

The adjustor is a small metallic tube, 24mm long and 8mm in diameter with a screw thread in one end, and an allen socket and four circular holes around the edge at the other:

All necks are ready-adjusted for gauge 10 strings before they leave the workshop, but should you find you do need to adjust it, insert the adjuster into the hole at the heel of your neck - threaded end first and turn clockwise to tighten.

When inserted and tightened, you will find that the adjustor protrudes from the bottom of the neck by about 8-10mm. To adjust the truss rod, you now need to use an allen key in the protruding end of the adjuster to tighten the truss rod:

Once you have made the desired adjustments, you simply need to remove the adjustor again:

The four holes around the edge are there deliberately to give you the extra leverage you need to release it. Use a small screw driver or other thin implement to push through two of these holes and then twist - it will unscrew again. If you find that the adjustor sticks too much and pulls your adjustments back out, you will need to apply a small amount of household grease (Vaseline or similar) to the inside thread. You can also use WD40 or similar agents to the same effect.

Once you have removed it, re-mount your neck, put the adjustor in your guitar case or somewhere else safe and that's just about it!

PLEASE NOTE: This truss system was developed and is intended for standard tuning conventions (E A D G B E), and behaves perfectly well with drop-D and the 'New Standard Tuning' (NST). However, you may encounter problems using the more exotic tuning systems due to the limitations in loosening the truss.

Loosening is still possible if you screw the adapter on tightly before making adjustments, but is more limited. If you require more adjustability in your neck truss rod we suggest you instead opt for our professional headstock-adjusted truss rod system - also available on request.