Official Luthiers Forum!

I have always bought my truss rods from either Martin, LMI or Stewmac. Standard Martin Style rods for neck with 14 frets at the body. Now when using one of these rods the rod would run from about 1 inch from the nut area to about 3" beyond the heel. Short enough that the rod doesnt actually go through the hole in the brace but works well.

Recently I bought a couple of rods from eBay which are 18 1/4" length and offered as Martin Style rods.

They seem much too long and I ended up shortning them and then routing the channel all the way into the headstock and still had to shorten by a couple inches.

When using these rods, I ran the rod so the one end went into the headstock and the adjusting nut went into the hole on the soundboard brace. This caused some problems because the space between the fingerboard and the rod is very small and had to thin the soundboard a little to make it work. Never had this problem with the Martin shorter rods as they fall short and slotted the soundboard to the extent there was never any conflict with the rod

Martin channels run shorter. Here is a picture from John Hall's eBay auction for necks to show a Martin neck, the channel and the rod. You can see by the picture the approx size of the truss rod in comparison to the channel.



So now the questions:

When you guys/gals install a truss rod, how long of a rod do you use and how long is the channel in the neck? Do you run your truss rods all the way through the hole in the soundboard brace or do you keep it shorter?

The rods on ebay are a good price ($18 for 2) but when you have to shorten them up it is not a great value for the small savings.

Rich,
If the adjustment is thru the soundhole, then you want the tip of the rod
about an inch from the nut and the "tenon" end of the rod to anchor at
the very end of your neck.

I would think that whether you need a hole in the upper brace would
depend upon your bracing layout and headblock design. For my design, I
have enough space such that I don't need to drill a hole in the upper
brace.

--
Simon

On a Martin 14 fret Neck, I believe the Truss Rod is approx 16" in length. 15" for the actual rod, plus 1" for the Allen nut (3/8" wide & 3/8" deep)). I have a Martin 14 fret Dread sized neck from Blues Creek and I set one end in the channel appox. 1" from where the nut is. The adjusting end extends out from the end of the dovetail heel about 2 1/4".



I was not sure where the end of it should fall, when you access it through the soundhole. I looked inside another Martin to get an idea. You have to bore a hole through the big brace in order to get your Allen wrench through it...to access the nut. The allen nut should be about a 1/4" behind that brace. I also had to notch the popsicle brace. You're right on your 18" truss rod, it might have been a bit too long.


RichB38941.6982060185

Cumpiano show the rod starting at fret 0 (the guitar nut) and the truss rod adjusting nut just out of the tenon, so it would be about flush with the neck block from inside. Most of the working of the rod will be at the center, so you want the center of the rod to be around middle of the neck (fret 7) if possible.

bump

Rich, I'm not that experienced with acoustics but I can tell you that I generally use an 18 inch truss rod on my solid body necks which have 25 to 25.7 inch scale length. It seems to me that it may be a bit long for an acoustic.