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Okay, I got a guitar in that needs some backbow added to the neck...relief is too great at 6th fret...neck angle is good...truss rod is one of the LMI "Martin" styles...ie, it doesn't work...I can introduce more relief, but not backbow...my first thought is compression fretting the 3-9th frets or so...any wisdom or alternate ideas from you superheroes out there? TIA.

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http://www.presnallguitars.com

I used the LMI Martin double action rods for years and they always could
put backbow on a board with no problems.

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John Mayes
http://www.mayesluthier.com

Hi John! I don't know what the deal is with this one, it turns freely in both directions, not binding at all, but no backbow...only more relief!

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http://www.presnallguitars.com

I can't understand why it won't work other than it just can't put enough force on the neck by itself. You probably will have to introduce the back-bow by forcing the issue by bending it by hand, holding it bent, and then tighten the slack in the truss rod.

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

[QUOTE=Hesh1956] Larry is it already fretted?[/QUOTE]

Yep, it's a 2 yr. old guitar...

S, I think that's worth a try too...I had an awful experience with one of these truss rods in a guitar I built...a "pro" set up the guitar, or was going to, but broke the nut off the rod...I was able to fix it, but had to plane backbow into the neck and refret to get the right setup and the customer was left with essentially a "one-way" rod...now I only use the Allied rods...

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Refretting with wider frets might put enough force on it.

Don't make the slots wider, just press in wider frets.

Ronold man38871.4066898148

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OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

Larry, I had that same problem with one of the last ones I made. I did what Steve is suggesting and it worked out very well.

Hi Jimmie! I'm gonna try it this evening...I've had the guitar out in the shop acclimating this afternoon...I'll keep you posted!

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Yep, I've done it a couple of times. I also saw Dan Erlewine mention it on his DVD.

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

there is nothing "wrong" with the martin type truss rod design, i.e., the one housed in a square channel; i think if you check the lmi data you will find that it is a one way rod by design, and it should remove excess relief. have you removed the nut to see if it is stripped?

before you contemplate compresssion fretting you should establish why the truss rod is not working and if necessary and practical fix it.

the inexpensive way to remove some excess relief is to heat the heck to soften the fingerboard glue, apply force to induce the backbow, and allow it to cool.

compression fretting is used to straighten necks without an adjustable truss rod, such as martins built before the mid '80's. to use the technique correctly you need a stock of fret wire with the same bead but varying tang wtdths. such wire is still available from martin. after all there are a lot of them out there without adjustable. rods.

but i urge you to find out why the rod is not working as as it should as a first step!crazymanmichael38871.8153240741

no it is a two way, or double action rod. There is something wrong with it
if it is not going both ways. It does not make much sense why it would
work one way and not the other since it is a very simple mechinisim. If
your talking about this one that is: http://www.lmii.com/CartTwo/
thirdproducts.asp?
CategoryName=Truss+Rods%2FNeck+Parts&NameProdHeader=Truss+Ro
d+%2D+Martin%99+Style+Truss+Rod

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John Mayes
http://www.mayesluthier.com

from the LMI site:

Truss Rod - Martin™ Style Truss Rod

Our two-way adjustable rod, is the same type of rod that Martin™
Guitar is using. The rod, made for us by Gotoh™, consists of a U-channel
.360” deep by .400” wide and 15.15” long. Overall length of the rod,
including the nut is 15.94”, the nut is .79”. A rod .200” is flattened at one
end and welded at the boxed end. The nut (.356” OD), which extends out
from the rod .79” is captured by a collar welded into the channel. Three
plastic spacers keep the rod centered in the channel, while preventing rod
buzz.

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John Mayes
http://www.mayesluthier.com

you are correct, but regardless of whether it is a one or two way rod it should be able to reduce relief; this is what adjustable rods were initially designed and introduced to do.

before anything is done, the cause of the failure to function as designed should be addressed, determined and resolved.

Yep John, that's the one...steel square channel, not the aluminum one with the washer at the nut...heating the f/b on my blankee laid on a flat surface and clamped is one of my thoughts as well, but I'm afraid of messing up a good f/b and fret job...I did hold the neck in backbow and manipulate the rod...the rod goes in both directions, but really doesn't take the relief out...here's where I've ended up so far:

12th fret- low E is 3mm, hi E is 2.5mm
Relief at 6th with capo on 1st and held at 14th- 1mm
Strings are 10.5mm off the top at the bridge

Larry

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.John Mayes38871.8572800926

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John Mayes
http://www.mayesluthier.com

John, is that like, a mime post? I'm awaiting your wisdom!

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http://www.presnallguitars.com

nope nothing to add.... I was being a smart A$$ and decided the better of
it.

If your rod is broken, and will not adjust like it supposed to either pull the
board and put in a new one (I have lots of spares I can send you one) or
do your best to augment the board/carve relief in it.

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John Mayes
http://www.mayesluthier.com

Hi John, well, I think I'm gonna give it one more try as is, then see what the customer want's to pay for...either pull & replace, or heat the f/b and clamp, or comp. fret the middle of the neck....thanks for the offer!

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[QUOTE=crazymanmichael]


the inexpensive way to remove some excess relief is to heat the heck to soften the fingerboard glue, apply force to induce the backbow, and allow it to cool.



[/QUOTE]

So, what's the best way to keep the f/b from sliding sideways in a case like this?

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I would sure find out what is going on with the rod. If striped then it needs replaced or repaird as the guitar will need adjustment as it ages.