Neck thickness preference, how thin is too thin?

[NeilG495]

Wondering what neck thickness people aim for when carving a steel string guitar? I’ve built 4 guitars following the Compiano book, but find the necks a bit thick and hefty. He draws a pencil centre line down the back of the neck and then carves the profile leaving the line alone. On my last build I followed OBrian’s YouTube video where he rasps a groove at the first fret to a neck thickness of 21mm then another at the 10th fret to 24mm, he then carves the neck down to theses reference points. To my shock, when I did this, I broke into the bottom of the truss rod slot at the first fret and had to scrap the neck! How much wood should I safely leave from the bottom of the truss rod slot, without ending up with a chunky neck? Thanks in advance.

[John Parchem]

My necks are 20=21 mm at the 1st fret. So 14-15 mm of wood and 6 mm of fretboard. My truss rods are 9.5 mm. I install the truss rods flush, So even with 20 mm I still have 4.5 mm of neck wood. I have not had any problem with these truss rods.

If you sunk your truss rod too deep or had a thick fretboard you could get into trouble.

[NeilG495]

Thanks for the reply John, useful information and much appreciated. Could I ask, if the truss rod is installed flush without a spline to hold it down, do you use any glue or sealant in the slot to stop any potential rattling or movement?

[John Parchem]

I use a dab of silicon glue on each end. When I say flush I mean flush, so the fretboard holds it down. I use the LMI 2 way truss rods which are squarish. I slightly under route and work with a chisel until it is just flush. Proud is really bad as the fretboard will not glue on. I would use a spline if I routed too deep, but it may end up less than 1 mm.

I have found that just engaging the truss rod tightening until the rod is under tension but not bending the wood keeps the rod from rattling.

[NeilG495]

Thanks again John, I’m about to install a truss rod so I’ll give it a go.