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I'm making a small batch of necks for 6-string acoustic guitars. I've made a couple of necks previously and they all ended up a bit chunkier than the pre-shaped items I've purchased from suppliers. (I suspect I've been overly cautious.) I'm wondering how much wood folks like to leave behind truss rod slots. Anyone care to share?

FWIW, Port Orford cedar and black walnut are the woods I'm using for this current batch.

Thanks in advance!

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George :-)

I aim for my necks to be 20-21mm including the fingerboard at the first, 24-25 at tenth.

Thanks for your reply, Ed. Do you have a standard dimension for the material you leave between the bottom of your truss rod slot and the back of the neck?

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George :-)

I like to leave approx. 3/16th inch of wood below the truss rod. I use home made Gibson style single acting rods, so it leaves about 3/8 ths to 5/8 ths above it including the fingerboard. The stiffness of the fingerboard wood in conjunction with the additional neck wood above the rod helps in it's performance.
Some leave less wood below the rod, but that can cause the wood to blow out when the rod is tightened.
Different types of rods may act differently, but I don't have experience with them.

I don't have a standard dimension per se, although it must be fairly consistent since I use the same truss rods and neck dimensions.

It's only the nut end to worry about as the rod is parallel to the fingerboard, so the meat behind it gets thicker as you go up.

Let's see

21
- 6.7 (fingerboard)

=14.3 for the actual neck. My rods are 9mm deep, so that still leaves 5.3 mm of wood behind the rod at the least.

George: Not sure what type of rod you use but I use the Stew-Mac aluminum channel Martin style. I epoxy these in and don't worry too much about the wood popping during adjustment. As to neck thickness's, mine are very much in the same ballpark as Ed.

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A person who has never made a mistake has never made anything!!!

Thanks for the replies! This is very helpful. I've used several different types of truss rods in the past and they all seem to work fine. This time I'm thinking of giving Stew-Mac's new low-profile, double action rod a try.

Thanks again,

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George :-)

Hi George,
I end up with about 17/32 at the 1st fret. That gives me around 8/32 of wood under my 1/4" truss rod. I think 3/16 would be fine

I taper to 27/32 at the 10th. These are all final measurements and are without fingerboard of course

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Joe Beaver
Maker of Sawdust

You just gotta love imperial measurements
Thanks though. I always seem to make my necks too thick. I'm saving these for next time once I've converted them to meaningful numbers!

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"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Peter,
I know what you mean. Not only are they hard to decipher, they are a real joy to add and subtract.

Allow me:

Hi George,
I end up with about 13-14mm at the 1st fret. That gives me around 6.3mm of wood under my 6.3mm truss rod. I think 5mm would be fine

I taper to 21mm at the 10th. These are all final measurements and are without fingerboard of course

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Joe Beaver
Maker of Sawdust

Thanks! I've definitely been making my necks way too thick.

_________________
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

Final is; .900 @ the first with .220 final fret board, .030 wood shim on top of a .350 allied/lmi truss. So about .300.

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Pat

Thanks, fellas. I knew I could thin my necks down a bit further, but was looking for some input on just how far I might go. Your replies are greatly appreciated.

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George :-)

No curve in the truss rod?
I cut the slots deeper further away from nut. It does make cutting the slot and filler more fun but assists in preventing rattles, but primarily because that's what I learned from books.

"No curve in the truss rod?"

A lot of the newer double acting rods don't use a curved bottom in the truss rod channel. Even a Gibson style rod doesn't absolutely require one, as the bowing of the neck will curve the channel (which you will then remove by tightening the rod and compressing the back of the neck). For the simple Gibson rod it is necessary to keep the rod low in the neck to make it effective.