A few neck issues

[Bullet]

Hi all,

I recently ordered the Martin style truss rod from LMII but upon arrival it is longer than the neck of my neck. Is it acceptable to leave it hang out at the dovetail joint end? Its approx 20mm longer but would still stop before any bracing on the top. Strange that it is too long as it is a Martin dread style I am building.

Another dilemma I have is that I've taken the nut end of the neck blank down too far (1/2 "). Assuming I can get the neck angle correct (using the LMII neck angle jig) will this leave enough carving depth to carve the neck?

Don't know how I manage to get myself into these situations !!

Cheers Jason

[peter.coombe]

Solution to the truss rod probem is to put the LMI truss rod aside for another day and buy the Martin trussrod from Stew Mac. That is around 40mm shorter. Don't ask how I know. I think the LMI rod must be designed for headstock adjustment.

1/2" is really pushing it. You might get away with it if you are really careful and use a nice thick fingerboard. My neck template is 2mm thicker at the nut so I start out 2mm thicker than 1/2". Is far better to start too thick than too thin so if I was you I would toss it and start again. Neck wood is not all that expensive so why start out compromised.

You get into these situations becasue you stuffed up, just like the rest of us stuff up.

[slowlearner]

I really don't know this experience at all....

Meanwhile the other day...


I bought new trussrods. They're not that expensive and may as well do it right. I'll use these other ones for something else.

[Bullet]

Cheers Pete, you've confirmed what I suspected!

My shed has a lot examples of what not to do .... Guess that's called getting experience

[slowlearner]

Ah, that's a lot better...



Now for some routing.

[tippie53]

I have had too many of the stew mac rods fail. The martin truss rod design is not welded or silver soldered on the thread. A much more reliable design. They are usually in a shrink wrap blue or black. You don't remove the wrapper.

[slowlearner]

Can you just clarify which type of Stewmac rods you've had fail pls?

[peter.coombe]

Can you just clarify which type of Stewmac rods you've had fail pls?

Yep, do please clarify. We are referring to the Martin truss rod design as suppied by Stew Mac, so I suspect you might be barking up the wrong tree.

Peter

[tippie53]

The rod pictured is not a martin rod at all , the failure point on this one and others has to do with the design. In these cases the barrel nut is soldered or welded to the threaded rod. This creates a stress riser at the threads. The rods failed when they were tightened after neck assembly.

The martin design ( I am talking CF Martin ) not the fake martin designs out there is bullet proof.

Martin uses 2 suppliers and the rod will come in a black or blue shrink sleeve. This is not removed.
http://www.bluescreekguitars.com/shop/i ... cts_id=128

the design is simple and very reliable. The rod has a welded in the business end has a cylinder attached and inside this is the barrel nut. As you adjust the nut it will pull or push on the cylinder making it longer or shorter, This in turn makes the static rod bow in both directions. It is very reliable and I have not seen one fail.
The older Martin design was a single action rod that was inside an aluminum channel , and this only adjusted to create back bow. As a machinist and engineer I can say when you weld or braze a nut on to a threaded rod , you will change the rockwell hardness. This can make the weld point brittle , and that is where the failure occurs. This is not a new problem , it has been around for a while.

Nothing is more frustrating when a finished neck has a broken rod to be replaced.

[pat foster]

I've shortened the Martin rod. It was the one-way with the aluminum u-channel. Not difficult, though yours may be different.

Pat

[tippie53]

The Martin rod with the aluminum channel is a 1 way adjustable rod.
In the 2 upper pictures the red one is a stew mac hot rod. Mine snapped off at the barrel nut at the brazed end
the next one down is a 2 way design from lmi again it broke off behind the barrel nut at the weld

the blue on is a martin rod they will be in black or blue depending on the supplier they get them from The welds on the others are torqued and this doubles the force on the joint . On the martin rod the barrel nut is not welded , it is crimped . I tried to break it , and it took a lot more force than one would ever use .

If you set things up right , you don't need a 2 way rod . Wayne Henderson makes his own rods, they are a true tension rod. A long threaded rod with a barrel nut inside the guitar. He gets a tab welded on the end of it and it just lays in the channel. I have seen rods like that in Gibson that appeared to be long bolts like what are used on phone cable wire reels.