LMI Help Center

LMI Truss Rods

Often imitated, never duplicated, LMI’s popular line of truss rods retains a central position in the world of lutherie supply. Proudly made in the USA, these sturdy rods have been helping players dial in perfect action for over 25 years in thousands of high-end guitars.

Our double action rods are patented by our manufacturer and available nowhere else. The welded adjustment nut and opposing threads allow the neck to be firmly adjusted in either direction. Our single action rod shares the same slim profile of our double-action rod. Order the single-action rods if you want something a little less expensive or prefer to keep things traditional (most guitars on the market have a single action rod in them to counteract the pull of the strings). The low profile allows builders to keep more wood in the neck and to keep the weight low. Thin neck profiles are not a problem. The double-action rods require a slot 1/4″ wide x 3/8″ deep and the single action needs a 3/16″wide x 3/8″ deep slot.

Install the rod with the square stock against the fingerboard. Our rods can be positioned to adjust at either the headstock or through the body. Add a little bit of silicone caulking to the channel to help guard against vibration in the neck. As with any rod, you want to install it snugly, with no glue -and take precautions to prevent the glue from the fingerboard from getting on the rod (some tape or a thin wood spline will accomplish this). Our rods require a 9/64” hex wrench to adjust them and it is a good idea to get one from us (our SKU for the wrench is TRW) as a good fit will assure long life of the rod. Throw one in the case when you deliver the guitar to your customer! Avoid cheap wrenches as they can be made too small which may eventually strip the nut.

We sell our truss rods in several popular lengths, and you can special order any length you need at no extra charge (turnaround is about 3-6 weeks).

What’s the best length rod to get? It depends on where you anchor the adjustment end. Start with that and then imagine the center of the rod (do not include the nut, just the distance between the rod’s two end blocks) coinciding with the part of the neck that is most likely to flex under the string’s pull. Common knowledge points to the center point between the tuning machines and the body joint. Usually, this point will fall at the 7th fret on 14 fret neck to body joint. Needless to say, this calculation is not as precise as others in lutherie and it’s because the precise place where you will end up finding the most relief is not perfectly predictable. On guitars where the adjustment is at the soundhole, it is not always necessary for the end of the rod to land all the way at the nut, and in fact, it often ends up between the nut and the 1st fret. The adjustment end block should be solidly anchored in the tenon (or heel if using a butt joint). It is important that the rod is resting on the square stock and not on the threads.

Never modify your truss rod. Some luthiers advise that you should file down the bumps were the rod is welded. But in rare cases, this could compromise the temper of the weld or remove enough material to weaken the weld. It’s better to nibble a little neck material away (with a chisel) to accommodate the weld when you install the rod.

Every precaution is taken, by our manufacturer and by LMI, to test and inspect each rod prior to shipping. Still, given the great difficulty one would encounter in the unlikely event that a rod should fail, we invite each customer to clamp the rod in a vise and overextend it to test it before installing, and also check to see that the wrench fits nicely into the nut.