Martin Truss rod adjustment

TBman · #1 02-24-2007, 09:42 AM

I've got a slight bow. I know a small amount is normal, but its bugging me as my other guitars are straight as an arrow. The rod is located in the sound hole - I should turn it counter clockwise to loosen as a you would a screw. Has anyone else adjusted their Martin?

Randal_S · #2 02-24-2007, 09:48 AM

No, clockwise to tighten it (this will take bow out of the neck). Go slow, maybe an 1/8 turn at a time and give it some time (a few hours) to settle in before re-measuring and continuing adjustments.

TBman · #3 02-24-2007, 10:21 AM

If you tighten it, it wouldn't it make the rod "shorter", which would increase the bow? I want to lengthen the rod (decrease pressure) to straighten it.

For instance here a sideview of the truss rod with N = nut H = end by the soundhole.

N------------------H-- If you tighten, you are moving the H closer to the Nut which would make the rod bend wouldn't it?

Folkstrum · #4 02-24-2007, 10:48 AM

Quote:

Originally Posted by TBman

If you tighten it, it wouldn't it make the rod "shorter", which would increase the bow? I want to lengthen the rod (decrease pressure) to straighten it.

For instance here a sideview of the truss rod with N = nut H = end by the soundhole.

N------------------H-- If you tighten, you are moving the H closer to the Nut which would make the rod bend wouldn't it?

That seems right to me, therefore it must be incorrect. That's usually my luck. The MJ and my Epi beater both have the TR "nuts" in the sound-hole. I've wondered about that myself. Would it be like envisioning the sound hole as the headstock, so to speak?

guitarstrmr · #5 02-24-2007, 11:04 AM

TBman,
This might explain it better for you.
http://www.frets.com/FRETSPages/Luth...russrods1.html

But, clockwise to tighten (take out the bow or in other words, decrease the neck relief), counter clockwise to loosen (increase the amount of bow or in other words, increase the neck relief).

Joe F · #6 02-24-2007, 11:08 AM

Agreed.

Turn clockwise to tighten and straighten the neck. Think of it as a countermeasure to the strings. The more you tightened the strings, the more they would pull on the neck and increase curvature. Tightening the truss rod pulls it back in the other direction to straighten it back out. Think of it as one big steel string in a tug of war against those 6 little strings.

Tim McKnight · #7 02-24-2007, 11:10 AM

Guitarstrmr is correct. Be careful. Amatuers adjusting truss rods incorrectly is what keeps guitar techs in business

TBman · #8 02-24-2007, 11:22 AM

Quote:

Originally Posted by Folkstrum

That seems right to me, therefore it must be incorrect. That's usually my luck. The MJ and my Epi beater both have the TR "nuts" in the sound-hole. I've wondered about that myself. Would it be like envisioning the sound hole as the headstock, so to speak?

That's why I posted the question. Sometimes my interpretation of reality needs adjustment too.

TBman · #9 02-24-2007, 11:25 AM

Quote:

Originally Posted by guitarstrmr

TBman,
This might explain it better for you.
http://www.frets.com/FRETSPages/Luth...russrods1.html

But, clockwise to tighten (take out the bow or in other words, decrease the neck relief), counter clockwise to loosen (increase the amount of bow or in other words, increase the neck relief).

Quote:

Originally Posted by Randal_S

No, clockwise to tighten it (this will take bow out of the neck). Go slow, maybe an 1/8 turn at a time and give it some time (a few hours) to settle in before re-measuring and continuing adjustments.

Quote:

Originally Posted by Joe F

Agreed.

Turn clockwise to tighten and straighten the neck. Think of it as a countermeasure to the strings. The more you tightened the strings, the more they would pull on the neck and increase curvature. Tightening the truss rod pulls it back in the other direction to straighten it back out. Think of it as one big steel string in a tug of war against those 6 little strings.

Quote:

Originally Posted by Tim McKnight

Guitarstrmr is correct. Be careful. Amatuers adjusting truss rods incorrectly is what keeps guitar techs in business

Thanks guys. I will read the info carefully. I'll try the minor adjustment and see what happens. Should I loosen the strings first? - May not, I can use them as guides - if they sound lower than that would mean I went the wrong way, right? Because a bowed neck is shorter than a straight neck.

guitarstrmr · #10 02-24-2007, 11:38 AM

I don't think you should need to loosen the strings. However, another point I'll mention is depending on how your truss rod wrench lines up on the nut, be careful not to bang (technical term) the wrench into your strings, as you could damage them.

jeffnles1 · #11 02-24-2007, 11:57 AM

to the original question
rightie tightie
leftie loosie

To add relief (bow) loosen
To remove relief (straighten) tighten

As has been said, go about 1/4 turn at a time, let it sit overnight, check and tweak more.

Jeff

grantgsc · #12 02-24-2007, 12:10 PM

Take a few minutes and turn the adjustment both ways. Work in 1/4 turns Sight down the neck and see what happens each time you adjust it. Pretty soon you will understand how the truss rod works. If you have a beater, experiment on that. This is not a big mystery. It would be hard to mess up your guitar if you are working in 1/4 turns or less. If the rod is so tight you can hardly turn it then see your technician. Check the care and feeding section on the Taylor sight. I believe they have some good info.

By the way-the ideal adjustment is dependant upon the neck angle and the saddle height. Sometimes flat is the best, sometimes a slight relief is best. If you are scared to do this, use a beater to learn how. Guitars are like kids...they are all different and require slight adjustments to make them the best they can be.

Turp · #13 02-24-2007, 06:17 PM

Using TBman's image and adding strings:

S_________________S
N------------H---

The truss rod is counteracting the string tension so tightening the truss rod actually increases the amount of this compensation. Right?

TBman did you get the double top secret clearance from Martin to adjust you truss rod?

flyingace · #14 02-27-2007, 02:47 PM

The neck can bow forward or backward, so just saying 'bowing' isn't enough info. If the neck is bowing forward, tighten the truss rod. If bowing backward, loosen it.

I leave the string tension on and turn about 1/8 turn and recheck. Of course, the truss rod is just one of the adjustements than may be required - but IMO it's the first one.

Freeman · #15 02-27-2007, 03:29 PM

Before touching the t/r I always suggest that people go to Bryan Kimsey's site and read his three page analysis of the interaction between relief and action. Bryan has set up two of my guitar (both Martins) and I have tried to follow his lead when I do my others. A good straightedge and a set of feeler guages make it easy.

And to confirm what everyone has said, righty-tighty (cw) to take out relief. Also be very careful to not use one of those folding allen wrenches - a friend slipped and put a great big gouge in the sound hole of his D28 - I have a 5mm allen wrench in a small file handle that works really well.

edit to add, I believe a few of the new Martins now have double acting t/r's. They work the same - just push and pull.