# Help me understand truss rod channel routing

Discussion in 'Tele Home Depot' started by barbrainy, Aug 14, 2013.

1. ### barbrainyRIP

Mar 2, 2012
Northampton, UK
So, I am now working on my first scratch build, and reading lots of the build threads, but there is still one thing that I feel I haven't quite got the grasp of, so want to check something before I move on with making a neck. (And, God, have I spent many hours poring over threads on here, and many other place on the internet, but cannot find answers that really settle the matter in my mind)

I am going to make a two piece neck, RW fretboard. So I see no need for a skunk stripe, and am concerned that I would struggle to make a skunk stripe that was good enough anyway. I have visions of it not being a perfectly snug fit, and that always annoying me.... I like the look of skunk stripes, I just think for my first neck, why add that extra level of VISIBLE workmanship, when it can be hidden and less perfect.

So, that would necessitate me routing the channel from the front, and I want to use a single action truss rod.

Here's a little diagram I made myself to make the principles clearer in my mind:

So, in Fig 2, that shape is achieved by routing a curve, from the back, meaning the channel routed has made the curve by having the lowest points at either end, and the high point in the middle (convex, right?)

Here's where my mind is still going wonky:

Routing from the front, would one route a concave channel, with a corresponding insert to go over the truss rod once it's in the channel (so that insert would have a concave curve on the side facing down into the channel, and flat on top)? I'm assuming the channel needs to still be concave rather than being flat, as being flat with the curved insert would leave gaps in the channel when the rod is tightened?

How thick does the fretboard need to be to withstand the force of the truss rod & curved insert?

2. ### oigunTele-Afflicted

Apr 29, 2009
Haarlem, Holland.
Yes the channel has to be curved, the insert you can clamp into place so a curve is not necessary. The fretboard can be anywhere from 3 to 7mm thick. Beware not making the trussrodchannel too deep because you need some wood between the tr-rod and the back of the neck. You will not be the first digging up a trussrod while shaping the neck

3. ### barbrainyRIP

Mar 2, 2012
Northampton, UK
Thanks Oigun, but I am still confused....

If the insert is not curved, when the truss rod is tightened, what makes it convex - ie push up towards the fretboard to counteract the bow caused by string tension?

4. ### PictonFriend of Leo's

Age:
42
Feb 7, 2009
This used to hurt my brain, too. That's why I use two-way rods with straight channels; no fuss, no muss. It's more expensive, though.

5. ### LucretiaTele-Holic

Apr 18, 2009
Leeds, UK
Might be worth just doing a straight channel and a two way truss. Would be easier.

6. ### oigunTele-Afflicted

Apr 29, 2009
Haarlem, Holland.
Because you clamp the insert down and the insert will bend and is curved that way It follows the curve in the neckrout iow.

May 15, 2011
NJ

8. ### RogerCPoster ExtraordinaireVendor Member

Mar 30, 2011
Oklamerica
Yep. In my mind, the only reason to do a 1-way tr is so you can do a skunk stripe. If you're not doing the stripe, why not just use a 2-way rod?

9. ### motor_city_teleTele-Afflicted

Apr 25, 2005
motor city

If you picture your trussrod more geometricly as a two sides of a triangle connected with a hinge. The fretboard is the hypotenuse. Now if you shorten either of the two sides, it will try to push up in the center. If something is blocking the center from moving up, that same force will be apply to both ends but in the opposite direction.

10. ### barbrainyRIP

Mar 2, 2012
Northampton, UK
I don't really know why I want to go with single action, if I'm honest....making it vintage correct? Wanting the minimum amount of metal inside the neck? Because I am an idiot?

How does that differ from a dual action rod?

As above, I can't give a good answer to that! How much truth (I am fearful of a nitro v poly debate) is there in the claims that dual action changes the sound of a neck/guitar as it has that much more metal in the neck? (From wikipedia: A neck with a two way rod installed is often more stable and less influenced by climate changes. However, some players believe the dual action truss system has an adverse effect on the tone of the instrument, due to the weight of the second rod and the additional wood removal required for installation.)

Yeah, that makes sense. The bit I still can't get my head around, that Oigun was saying about, was how to make that top part of wood, just below the fretboard, block the centre as you say, without shaping it to be curved in the first place.....

11. ### PictonFriend of Leo's

Age:
42
Feb 7, 2009
No offense, but Wikipedia can say that "some players believe" whatever they want... it don't make it true.

JMO, but things like truss rod volume, wood thickness, wood species, etc matter A LOT if you're building an acoustic. Nobody will ever convince my ears that a dual-action rod makes a solidbody sound even remotely different than a one-way rod will.

Solidbody "tone" is about pickups, amps, and player technique much more than it is about how much metal is in the neck. I'm not trying to pick a fight or hijack the thread here, but if you're like me and don't feel that routing a curved channel is how you want to spend your time, a two-way rod with a straight channel gives excellent results IMO.

12. ### fabricatorTele-Meister

Jun 29, 2012
Texas
As someone who has built many different types of neck using different types of truss rods, I would recommend anyone building their first neck to use straight channel (and a 2-way rod is fine, as I doubt your ears would be able to discern the difference and they're easy).

The tone of any given guitar is in the sum of all its parts (some, such as pickups, adding more to the equation than others). I wouldn't obsess about the effect a truss rod has on the overall tone of your first build, just jump in there and build the thing! You'll probably find that it sounds a lot better than you expected once it's finished.

13. ### whodatpatFriend of Leo's

Jul 21, 2007
College Park MD
I can get Wikipedia to say Tone is the product of the moisture content of the fret markers and credit the statement to Leo Fender. Doesn't make it factual.

I am happy with a Straight rod (Martin Style) in all 2 piece necks because its just so easy.

Curved rod goes on all my 1 piece necks because it feels like I am "crafting" more of the guitar. But I would not hesitate loading a straight (Hot Rod Style) through a skunk stripe on the back of a One piece neck if I didn't already have a jig or want to make one.

It's importantly just make the thing.

14. ### oigunTele-Afflicted

Apr 29, 2009
Haarlem, Holland.
Just clamp it down and it will follow the curve automatically. When the glue has set you plane it flush with the neck...Its a thin piece of wood so it will bend pretty easy there is no need to make it curved.

15. ### dsutton24Poster ExtraordinaireAd Free Member

Dec 29, 2010
Illinois
The source of your problem may be that you've got the mechanics of the thing wrong. Your first drawing shows a force upward toward the fretboard. There is, indeed, force in that direction, but the truss rod works because the rod is in tension. Applying more tension shortens the rod, and it tries to straighten itself despite the hump of wood in the middle. The only way it can do that is by pulling the ends of the neck downward.

Picture it this way. Route your usual curved channel. Now make that channel as short as possible, and the only way to do that is to make it go straight, the ol' shortest distance / straight line thing. You could do this by putting a block under the midpoint of the neck, then cranking the ends down against the bench with a pair of clamps.

That's how the truss rod works.

16. ### Captain NutslotFriend of Leo's

May 3, 2012
Rochester, NY
"The simple mechanics of the truss rod. As the rod is tensioned it tries to straighten. In doing so it bends the neck in the opposite direction." - Melvyn Hiscock

17. ### dsutton24Poster ExtraordinaireAd Free Member

Dec 29, 2010
Illinois
Yep. Much more concise than my explanation.

18. ### Nick JDDoctor of TeleocityAd Free Member

May 12, 2007
Queensland, Australia
If you want to install a 1-way trussrod and don't want to make a jig to rout the curved channel, just rout a straight channel ... take your filler strip to the bandsaw once you get it fitted nicely ... and saw the curve into it.

Glue in the "curved channel" part ... then proceed as normal. Handy thing is you already have made your form-fitting skunk stripe.

19. ### Captain NutslotFriend of Leo's

May 3, 2012
Rochester, NY
Its all good, I hope it helps. I needed this same stuff and more explained a few different ways to grasp it. So far I've learned the most by just doing it and learning from the mistakes.

20. ### Jack WellsDoctor of TeleocityAd Free Member

Oct 19, 2003
Albuquerque, USA
Personally I think a one piece neck is the easiest once you have your truss rod channel jig made. I've made two piece necks by gluing the fretboard on a 3/4 in. neck blank then routing the channel from the back.

Fitting a skunk stripe isn't a big deal. Point is if you screw up and it doesn't fit, you make another one.

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