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Which truss rod to use?

Total Topics: 28
Total Posts: 67
Hi guys .. I am now looking to purchase the components to build my first guitar. An easy task I thought, then I looked on the web site for my chosen supplier, David Dyke , and I found that there are different types of truss rods to choose from.

10 x 10mm aluminium U-section type truss rods with an adjustable internal 5mm rod.

Threaded Rod Type 375 x 5mm as above, for 14-fret neck/body join Steel String Guitars

Am I right in saying that the only difference between these two are that the first one has a protective alluminium box around the thread? If so, does it matter which one I get?

If I choose the 5mm threaded rod my channel will be smaller and therefore stronger neck right? The 10mm minimum depth for the aluminium case will not leave very much clearance for rounding the neck and I am concerned that the neck would need to be thicker than I would like it to be. I do like a thinish neck so I am aiming for 20 - 21mm at the nut. Would this be strong enough if I choose the rod with the casing?

Sorry if this is a dense question but I don't want to destroy my first guitar before I even build it.

Your thoughts would be very much appreciated.


Jan 05, 10 | 3:01 am

Total Topics: 27
Total Posts: 668
Paul, it looks like he offers a traditional Martin style single acting rod (the U channel one) and a more modern double acting rod (the threaded one). As you probably know, Martin has switched to double acting rods. The StewMac catalog shows in more detail what they look like and how they work

I have built with both and they both work fine. The double acting rod has two characteristics that might take a little getting used to - (1) they both add and remove relief (single acting rods only counter the string tension), however I don't know why you would ever intentionally want to force the neck backwards, and (2) they move twice as much for a given turn of the adjuster (which means that you need to make very small adjustments).

If you build with the adjuster inside the body it will be way up inside the upper bout (right at the junction of the neck heel) if you use the double acting rod (you will need a long allen wrench to reach it). The single acting rod will be much closer to the soundhole.

If you are getting the neck blank pre slotted you should make sure that it is compatible with the TR you plan to use. I have never seen a neck that was so shallow that the depth of the slot was a problem. My last two builds, a very thin necked little parlor and a big hurkin' old 12 string both used LMI's double acting rod (like StewMac's) and I am very satisfied with them.

Jan 05, 10 | 6:25 am

Total Topics: 28
Total Posts: 65
Thanks Freeman ... that helps a lot. Sounds like the double acting (threaded type if I got it right) is the option I'll go for. Smaller channel and cheeper. At least at my supplier anyways.

Thanks very much for the info and advice I really do appreciate it. When I eventually get to building I'll no doubt being asking lots of questions and it's nice to know that there are ppl out there that is prepared to help.


Jan 05, 10 | 7:13 am

Total Topics: 27
Total Posts: 668
Paul, you might also ask Mr Dyke what he recommends for his necks. Both StewMac and LMI have instructions for installing their different rods.

Jan 05, 10 | 11:55 am

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