Official Luthiers Forum!

Well it always seems with one step forward there are two steps back.
Long story short I am in the process of my first build. The neck and fretboard I got from Martins Guitar Makers Connection. This is a 14 fret OOO design. I opted for the "Hot ROD " truss rod from StewMAc. The nut end of the TR was taller than the slot on the Martin neck so I routed it out a bit to make it fit (this is the area down at the nut) When I got the TR in place and the fret board glued on I was checking the neck with a straight edge. There was a little relief so I adjusted the TR. i heard a "crack" and noticed that the nut end of the TR was coming through the back of the neck.

I can't see an easy way to fix this unless some has some suggestions?

I have another neck that I can start over with but I hate to waste all that time.

Thanks
Richard

New neck....your only realistic option!!!
Sorry

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Andy Z.
http://www.lazydogguitars.com

thanks, that's pretty much what I was thinking, oh well live and learn

Richard

Richard - Don't feel too bad, most of us have done that, some of us more than once.

You need to make yourself a drawing so that you understand how all the parts fit together. Once you do that you'll see that with a 1/4" thick fret board and a 3/8" truss rod gives you 5/8" (0.625") for break through if you slot isn't any deeper. Most of the time that slot is deeper as most put a thin piece over the truss rod, and most rout just a little deeper so that it fits. Let's say that on average the stack up for the rod and fret board is closer to .700". If you make a thin neck -say .750", if you don't sand through, you'll break through the first time you give that truss rod a good tweak.
Watch that thickness and slot depth.
Do you have calipers to measure the thickness ass you shape the neck?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

The StewMac HotRod truss rods require a .437" slot (7/16"), so the total thickness with a 1/4" fretboard needs to be at least .250 + .437 + .125 = .8125" or 13/16". I've seen 3/32" as the recommended minimum wood thickness behind the truss rod, but I try to make it 1/8" to be safe. But I don't use the HotRod truss rods because of the extra 1/16" of depth they require.

--Steve

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---Steve

I really like the StewMac HotRod truss rods but only use them with the adjustment exiting at the head stock for many of the reasons expressed here. With the adjustment at the head stock the 2 pressure point can be beefed up with the extract support.

Richard, you can splice a new piece of wood in your neck where the crack is and thereby adding additional thickness. However, if possible remove the fingerboard and make a new neck using a different TR if the adjustment is exiting into the body.

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Michael Lloyd

“I was born to ignorance, yes, and lesser poverties ...
I was born to privilege that I did not see ... I didn’t know it, but my way was paved” – John Gorka

I have a recommendation. Thin the back of the peghead by .060 or something relatively thick and fair this into the shaft and glue a matching back strap on the peghead and neck. Be sure to have the strap extend into the first fret area. Fair it all together so that the neck fattens some as it approaches the nut. It won't be what you'd hoped for, but it is a way of saving the build. You'll need to pre bend and fit it carefully, using shaped cauls, but you can do it. Open up the tuner holes with a smaller bit, drilling from the face side and open it up with reamers so you don't blow anything out.

Yup, that's what they do. I gave up counting a while back how many Hot Rod necks I've seen that happen on. Not a good design at all in my opinion, and I would never use one.

If you're selling this guitar, make new neck (without the Hot Rod). If it's a personal project there is a quick fix you can do. Work glue in to the crack, then loosen the rod to close the crack up. When that's dry, clamp the neck in to as much backbow as reasonable without cracking anything (leaving the truss rod loose). Then with a pipette, flow thin CA glue along each fret until it quits wicking it in. This is my proprietary "pseudo-compression fret" job , but does the same thing. The glue hardens in the expanded slots and has the same effect as a compression refret.

Assuming you can get enough glue to wick in, when you string it up now it should be in some decent backbow. Then you'll be left with a neck that should only need upward force from the reverse action of the rod, and it won't be pushing on the back to split it again. It's certainly a quick fix, and is a solution for a symptom but doesn't truly address the problem. If the neck is otherwise well made though, it should last indefinitely.

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Eschew obfuscation, espouse elucidation.

There's nothing wrong with the hot rod. I've built over fifty guitars with them without a problem. They certainly operate better than any other double acting rod on the market. Here's the math. Your average neck is between .825 and .850 at the nut depending upon the builder. Yes, there are other neck depths and that's a consideration, but that gives us:

.825 - .250 = .575"

.575 - .4375" = .1375"

That's more than enough meat to support the truss rod. .825" is a thin neck relative to most. Taylor's are .840"

This is affected by how thick your peghead veneer is as this will determine how much meat you have on the back of the peghead and thus the nature of the transition from peghead to shaft. Furthermore, you're not going to lose more than .044" (which would leave .093" under the block) going from the 1st to the nut. The only other consideration is how the rod is installed, either end will work.

I don't install these with a cover spline, they just go on flush with the neck surface.

The potential for a surprise like this could be avoided by using a u-channel type rod, such as the Martin-type sold by SM. With the u-channel glued along its length into the slot, the stresses put into the neck by the rod are spread along the length of the u-channel rather than at both ends of the rod and where the rod pushes against the back of the fretboard. Plus the u-channel type adds a considerable amount of stiffness.
Just my two cents.

Richard,

The suggestions here ought to get you through it. Good luck!

Pat

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formerly known around here as burbank
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http://www.patfosterguitars.com

Like I said this is my first guitar outside of a workshop so i am just trying to get to the end product. It is definitely not for sale. But here is what I did, we will see if it holds up. I took a piece of ebony cut it down to about and inch long and .200 wide and .100 high. i rounded the ends for aethetics. I made it a little oversized so it would cover the entire area of the defect. i traced it and routed it out with Dremel tool just like an inlay. I glued it in then filed it back down to the original curvature of the neck. So now it just looks like an ebony inlay on the back of the neck. i used ebony because I knew I could never match a mahogany patch and it look good and ebony being a harder wood would be less likely to crack against the pressure of the TR, the glue joint would probably break first.

Any way thanks for all the responses, we will see what happens
Richard