Guitar Truss rod adjustments

Subject: BS: Truss rod adjustments
From: Little Hawk
Date: 09 Jun 10 - 12:55 PM

My Martin HD-28 seems to have reacted to the change in the weather. It's buzzing on the 4rth string now, and perhaps a bit of buzz here and there on the 2nd string too. The action was nice and low before, but seems to be a bit too low now.

So...I am thinking of adjusting the truss rod.

Should I loosen off the strings before so doing? Or not?

I turn the truss rod counterclockwise to ease it off and to raise the action, right? How far? 1/4 turn? 1/2 turn?

Should I torque the neck a bit with hand pressure after adjusting the truss rod?

Have at it, resident experts. I await your collective wisdom, and thank you in advance...

Subject: RE: BS: Truss rod adjustments
From: Rapparee
Date: 09 Jun 10 - 12:57 PM

Rather than use a truss, why don't you get the hernia fixed?

Subject: RE: BS: Truss rod adjustments
From: Little Hawk
Date: 09 Jun 10 - 01:02 PM

Hmm. No, I have a better idea. Why not have some clone move this thread up to the music section where it F-ing BELONGS!!! Jeez...

------------Done. JoeClone----------------

Subject: RE: BS: Truss rod adjustments
From: GUEST,leeneia
Date: 09 Jun 10 - 01:07 PM

Why not call or e-mail the Martin Guitar customer service people for advice?

Subject: RE: BS: Truss rod adjustments
From: number 6
Date: 09 Jun 10 - 01:09 PM

Strings should be at the tuning you regularly use.

turn counter-clockwise to loosen

turn clockwise to tighten.

biLL

Subject: RE: Guitar Truss rod adjustments
From: Little Hawk
Date: 09 Jun 10 - 01:12 PM

leeneia - WHAT? And give up my Mudcat-chatting addiction for something straightforward, sensible, and practical???? Surely you jest! ;-)

Subject: RE: Guitar Truss rod adjustments
From: Will Fly
Date: 09 Jun 10 - 01:40 PM

LH - take a squint down the neck from the nut to the saddle. If the neck is straight and true, with no obviously raised frets sticking out, you might want to consider having a slight shim put under the saddle, or a slightly higher saddle. If you see irregularities in the line of the frets, a fret dress might be an option. Or it could indeed be the truss rod that needs tightening.

I mention all these merely to indicate that, unless you really know what's going on, leeneia's suggestion is a good one... :-)

Subject: RE: Guitar Truss rod adjustments
From: GUEST,kendall
Date: 09 Jun 10 - 01:47 PM

Unless you know exactly what you are doing, don't do it!

Subject: RE: Guitar Truss rod adjustments
From: Little Hawk
Date: 09 Jun 10 - 01:51 PM

That sounds like sage and sensible advice to me, Will and Kendall. Actually, I have 2 excellent guitar tech people I could take the instrument to, so that is what I'll probably do, I guess.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Whistle Stop
Date: 09 Jun 10 - 02:04 PM

Will's and Kendall's advice is good. The truss rod is there to straighten the neck; that generally has the effect of lowering the action, but if the neck is already straight enough (there should be a little bow, or "relief"; how much is a matter of personal preference), it's best to leave it alone, and focus your attentions elsewhere. That generally means looking at the bridge saddle to see if its height needs adjusting, before looking into more invasive procedures matters (fret work, neck reset, etc.). But it needs to be looked at by someone who knows to be diagnosed properly (in other words, advice on an internet forum will only take you so far). Good luck.

Subject: RE: Guitar Truss rod adjustments
From: number 6
Date: 09 Jun 10 - 02:38 PM

Those points I posted above are from the truss rod adjustments instructions that came with my Taylor. Over the 8 years I have owned it I have had to perform adjustments 3 times. It worked, no problem.

A truss rod adjustment is no big deal. If it doesn't work, then I would take it to a reliable guitar tech.

biLL

Subject: RE: Guitar Truss rod adjustments
From: GUEST,leeneia
Date: 09 Jun 10 - 02:49 PM

But what was that I saw on the Martin web site about the advantages of their double neck rod? Seems like that ought to be checked out before Little Hawk gets out the pipe wrenches.

By the way, it is okay to be straightforward, sensible, and practical, just so you keep it a secret from your fellow Mudcatters.

Subject: RE: Guitar Truss rod adjustments
From: number 6
Date: 09 Jun 10 - 03:12 PM

Martin's have a double neck rod?

biLL

Subject: RE: Guitar Truss rod adjustments
From: Bert
Date: 09 Jun 10 - 03:26 PM

What those other guys said. If the neck is straight don't touch the truss rod. A new saddle is really cheap and easy to fit and if you get it really wrong you can just get another one and start over.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Betsy
Date: 09 Jun 10 - 03:27 PM

As Kendall said "Don't do it".
Leave the problem to those who understand such things.
I'm sure in the correct hands it's not a big problem, however,
" tweaking it" yourself, in the wrong direction, could be the start of a nightmare.

Subject: RE: Guitar Truss rod adjustments
From: bigchuck
Date: 09 Jun 10 - 03:33 PM

Fret the low E string at the first and 13th frets. There should be a bit of play at the 6-7 fret, maybe enough to slip a business card under.If there's too much, tighten the truss rod a bit, if not enough loosen it. A quarter to a half turn at a time then recheck. There should be about 3/32" clearance between the bottom of the low E string and the top of the 12th fret.

Sandy

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Guest from Sanity
Date: 09 Jun 10 - 03:40 PM

Little Hawk, Yo-Ho!!...
Do this: First, Loosen the strings, and get them out of the way!..when that is done, lay the guitar flan, UPSIDE DOWN on a flat HARD surface, with the sound hole extending off the surface, so you can access it.(Just the neck, and fretboard on the surface).... Next, press firmly on the back of the neck, to push it flat against the surface, of the table. (I find that using a marble counter-top works well!), ...Next, go in through the sound hole with your Allen wrench and snug up the nut, from the rod....SNUG!!!!...DO NOT OVER TIGHTEN OR YOU WILL RISK SEPARATING THE HEEL OF THE NECK FROM THE BODY OF THE GUITAR!!!!!

While the strings are off, it is a good time to use a double sided whetstone to do your frets..especially 11-14th...but do all the frets! Oil the stone generously, coarse side first, and go ACROSS the frets, from side to side. You will see them get shiny. When that is all even, flip the stone over, to the 'fine' side. Once again oil the stone generously, and repeat the process, and polish the frets, till any and all micro scratch marks are gone. Wipe neck, change strings. If you still have any buzzes, which I doubt, it would then be in your saddle.

I've just done mine, since I got it back from the luthier. Blew the luthier, and other guitarists away by how smooth and fast it is! Have had several requests since then, to do,'whatever I did' to theirs! Also I use a polish to do the neck, and frets, at this time. I DON NOT use a water base polish, as some guitar manufacturer sell. But if I told you on here, what I used, some nutcase with start bantering that "You can't use that!!...Its going so mess up the guitar"...However, I've done it for years, with no problem..and my axe is incredible!!!....(Unless I'm playing keyboards!)

Hawk, What I just posted is gold..etch it in stone. I do it on my Martin D-21, my Larrivee, and my Brazilian Rosewood Strat, with Madagascan Ebony fret board. I have done it religiously for years!!...Nor would I steer you wrong, on something so sacred!!!!

Yo-Ho...and Highest Regards!!!

GfS

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Guest from Sanity
Date: 09 Jun 10 - 03:43 PM

Correction: First sentence: "..lay the guitar flan,..." Should read: 'Lay the guitar FLAT' Just a typo.....thought I'd get to it before 'Frogprince' corrected me.....AGAIN!

GfS

Subject: RE: Guitar Truss rod adjustments
From: GUEST,No to exclamation abuse...
Date: 09 Jun 10 - 04:09 PM

I'd say ignore GfS... there are more reasoned opinions out there than "Do what I say - it's gold."

FRETs.com article (Frank Ford)


Martin Forum truss rod threads

Truss rod adjustment is an aspect of a proper set up.

Subject: RE: Guitar Truss rod adjustments
From: buddhuu
Date: 09 Jun 10 - 05:45 PM

Where the feck do people get their ideas?

Frank Ford's site is very good. His advice is mostly excellent.

That said, if you are even a tiny bit uncertain then don't touch the truss rod. Just take it into the shop and let a pro do it.

On my £100 Chinese acoustic I tweak the rod with confidence as and when I need to (which is actually hardly ever). On a Martin I would be very careful and a little nervous.

Take it to a decent guitar tech. The adjustment, if it is just the rod, will be quick and cheap - and if done by a pro it will also be safe.

Subject: RE: Guitar Truss rod adjustments
From: Richard Bridge
Date: 09 Jun 10 - 05:49 PM

Truss rods are to adjust progression. That is all they are for. There is only one correct progression. It is that which as closely as possible results in the fretted string leaving the fret at the same angle whatever fret is chosen. It is usually much as Bigchuck describes but if you play unusually low saddle or unusually high saddle it may vary.

Subject: RE: Guitar Truss rod adjustments
From: kendall
Date: 09 Jun 10 - 07:17 PM

My Taylor 810 was built in 1983 and it has never been touched.Still plays like I want it.

Subject: RE: Guitar Truss rod adjustments
From: Little Hawk
Date: 09 Jun 10 - 07:50 PM

I have a Talor too, and it's marvelous. I like both it and the Martin just fine.

Subject: RE: Guitar Truss rod adjustments
From: Little Hawk
Date: 09 Jun 10 - 07:50 PM

Taylor, I mean.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,leeneia
Date: 09 Jun 10 - 11:53 PM

For sale on the Martin guitar web page - parts department:

TRUSS ROD WRENCH

Handle ball driver end and extended reach length. NEW ergonomic handle and rubber tubing to protect strings


Qty. Add Price Item Number
    $7.75
USD 13TZTRAW

---------------------------------------------------------------------




---------------------------------------------------------------------

Two Way Truss Rod Wrench

The two way truss rod wrench can be used on both the two way adjustable rod necks or single adjustable rod.

Qty. Add Price Item Number
    $3.65
USD 13WR0001

---------------------------------------------------------------------

So yes, some Martins have a 'two-way truss rod' whatever that may be.

They also have a list of a dozen approved Canadian luthiers. Hint, hint.

Subject: RE: Guitar Truss rod adjustments
From: Murray MacLeod
Date: 10 Jun 10 - 03:45 AM

Richard, I am intrigued by your "same angle" theory.

Assuming the distance between the top of the fret and the top of the saddle to the the hypotenuse , how is the adjacent side defined, which produces this "same angle " ???

Subject: RE: Guitar Truss rod adjustments
From: Murray MacLeod
Date: 10 Jun 10 - 03:47 AM

sorry, that sentence should read "Assuming the distance between the top of the fret and the top of the saddle to be the hypotenuse ..."

Subject: RE: Guitar Truss rod adjustments
From: buddhuu
Date: 10 Jun 10 - 04:10 AM

Still a lot of strange stuff emerging here.

I'm surprised so many Mudcatters still have playable guitars.

Really, rather than trying to understand the varied, conflicting and sometimes nonsensical contributions in this thread, anyone lacking confidence and/or experience really would be best advised to take any decent guitar to a pro for adjustments.

Truss rods are to counteract the string tension that naturally tries to pull the wood of the neck into a bow. The adjustable kinds are also used to set the amount of neck relief (bow). Different players like differing amounts of relief, so there is not just one right spec, although many manufacturers give guideline starting points from which individual players may vary to their taste.

Before messing with the truss rod it may be a good idea to check out other things that can be affected by the weather. As fretboards change a little with humidity frets sometimes raise a little out of their slots. Might just be worth checking that first.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Guest from Sanity
Date: 10 Jun 10 - 04:16 AM

I don't know who that clown was(probably some idiot from the 'B.S. Threads), but what I posted is how you adjust a truss rod. Truss rod adjustments are made, mostly, to take the 'bow' out of the neck, if that is the problem...not primarily to adjust the action!...That's why I spent time explaining whet stoning the frets!!..and concluded with, "If you still have any buzzes, which I doubt, it would then be in your saddle."

The reason you lay the guitar upside down, after the strings are removed, and press down on the back of the neck, is to alleviate the bow, and snug the rod to hold that position! That way you can get it right the first time! If you see someone tightening the rod, with the strings, either on, or doing it just by sight, I'd tell him to stop immediately! When tension is applied, by tuning the strings to pitch the strings, other that how I laid out, the person is only guessing how far 'straight' is!!

If you take your guitar, to a very knowledgeable luthier, you will see, that he does it, exactly as I described. Usually the amount of turning the nut, is just a tweak.... With the neck depressed, from the rear, against a hard flat surface, to the front, there is just a little slack, if any, that needs attention, till you feel the resistance firm up. This determines accurately, how much slack to take up than any other way!

As to the frets, use at least a 6" whetstone, laying it lengthwise on the neck----->         I I I I I*I I I*I III*IIIIII   covering as

many frets, as to assure..length---> [_______]
for uniformity in height

Direction of polishing motion----->    ^ ^ ^ ^
Whetstone-------->                   [--------]
Direction of polishing motion----->    v v v

As you draw the stone, and reverse direction, you will observe the shiniest parts of the fret wire, are the highest, and being buffed down. When the shine is uniform, across the whole neck, they will be the same height!

If you have ANY questions, print this, and take it to a knowledgeable luthier, and ask him. Chances are, he will tell you that unless you've done it before, he should do it, the same procedure...for a fee!

Little Hawk, or anyone else, YOU CAN DO THIS! Just pay attention to what you are doing, and follow the instruction explicitly...but before you start, look down the neck, and look to see if the WOOD is bowed. If its just the fret wire, do what applies to the frets, as per aforementioned!.....or both!

Truss rod adjustment can be done under five minutes. Fret wire takes longer.

Regards!
GfS

Subject: RE: Guitar Truss rod adjustments
From: Richard Bridge
Date: 10 Jun 10 - 04:36 AM

To a first approximation, Murray, the curve of the neck is a sector of a circle, so the angle is the angle between the tangent and the line from the contact point between the fret and the string to (as you say) the top of the saddle.

My theory will allow you the lowest possible rattle-free action.

The other possible desirable feature might be a constant pressure to fret the string at any point upon its length, but I think (I am not sure) that that is mathematically impossible to achieve.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Guest from Sanity
Date: 10 Jun 10 - 05:19 AM

Ohh! P.S. If you position the guitar, so you can access the sound hole, from the bottom(extending off your table, or counter), don't forget to allow room for the nut, at the other end of the table. This is easily achieved if you do not have the 'right' size table, by having the nut extend off the table, by positioning the guitar at approximately a 45 degree angle, near the corner of the table, so the body of the guitar, and the nut, are clear of the flat surface, of the table. The main thing you want, is for the neck to be pressed FLAT to the table top!!

The rest is laid out nicely!

GfS

Subject: RE: Guitar Truss rod adjustments
From: Murray MacLeod
Date: 10 Jun 10 - 05:29 AM

Your theory does seem eminently sensible, Richard.

Guest from Sanity, things have moved a long way from the 1960's when the oilstone fret dressing method was commonplace.

Nowadays, no luthier would dream of using an oilstone, they use a custom made fret levelling beam

What you say about pre-relieving the truss rod stress is essentially correct, although again, most professionals will do this by putting the guitar in a custom neck jig rather than laying it flat on a table and pushing the back of the neck.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,leeneia
Date: 10 Jun 10 - 06:41 AM

Little Hawk, did you make sure there's not a thumbpick hooked on the high E string, down near the bridge? That'll make a guitar buzz.

The last time my guitar buzzed, it was the downstream end of a string, resting on the spruce top. I had let too much of it stick out of the knot. I clipped it off, and that solved the problem.

On my dulcimer I can get a buzz when the butterfly stickers which mark the minor chords curl upward and touch a string. Do you have any stickers on your Martin?

Subject: RE: Guitar Truss rod adjustments
From: Murray MacLeod
Date: 10 Jun 10 - 08:26 AM

..."Do you have any stickers on your Martin"...

I think Guest leenia may have cracked it.

If it isn't one of the chord position markers on the fretboard curling up against the strings, then it could be that the big "I ♥ Bob Dylan" decal on the soundboard is flapping loose and causing a buzz ...

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Guest from Sanity
Date: 10 Jun 10 - 12:50 PM

Murray MacLeod: "If it isn't one of the chord position markers on the fretboard curling up against the strings, then it could be that the big "I ♥ Bob Dylan" decal on the soundboard is flapping loose and causing a buzz ..."

That was hilarious!!! Thank you!

....and whetstones, especially the 'fine' side to finish up, work just great! My guitars play like glass!!...but, I'm glad to see that there are new products out there.....thanks to government ingenuity!!!..wink!
I'm quite sure they work on the same principle..its just your choice of 'weapons'!

By the way, my Martin D-21 was made in the early 60's...when Martin's craftsmanship had a better reputation, than the newer ones. At that time, the fellow who made the guitar, at the factory even signed it, inside. When I talked to the person at Martin, in regards to this guitar, she told me that he was one of the older gentlemen, who had been with the company a long time, even back then! I feel fortunate to have one of his axes!

GfS

P.S. I hope you play your ass off..and good luck!..break a leg!

Subject: RE: Guitar Truss rod adjustments
From: Little Hawk
Date: 10 Jun 10 - 01:09 PM

LOL! This is getting damn funny. Look, I probably WILL take the guitar to an experienced guitar tech person, because that saves me the trouble of mucking around with a lot of arcane stuff that I may or may not fully understand and may or may not get right.

I started this thread for one main reason. I simply enjoy the yack-yack that ensues here whenever anyone raises any kind of question at all or talks about anything at all on Mudcat. I was curious to see what people would say. You have not disappointed me. ;-) In typical Mudcat fashion a host of eager people have rushed into the breach with their valuable information...and they are now squabbling with one another...resuming a few old vendettas here and there...casting aspersions on other people's advice....giving dire warnings NOT to heed so-and-so's advice...making jokes about my Bob Dylan worship...and here and there saying something that is genuinely interesting too.

Typical response, in other words! ;-)

Way to go, people. You have fully met my expectations. Leeneia, I do NOT put stickers on my guitars! Jeezus! Sacrilege!

Subject: RE: Guitar Truss rod adjustments
From: Will Fly
Date: 10 Jun 10 - 01:16 PM

Good one, eh, LH? If you haven't read lately about the Little Boy Who Cried "Wolf", you might get a reminder the next time you ask for tech info in a post. :-)

Subject: RE: Guitar Truss rod adjustments
From: JohnInKansas
Date: 10 Jun 10 - 01:39 PM

First you must firmly plant in your brain the notion that the strings are sinking because the bridge pad has lowered due to caving in of the belly of the guitar.

Once that idea is firmly in place, you can justify GETTING YOURSELF A NEW MARTIN.

You will have eliminated the present problem and the satisfaction of your GAS will give you immense pleasure that should last for ... ...

... ...

... ...

minutes at least.

You will need to consider carefully whether your explanation to the weasels for withholding their treats is due to "you're too fat" or "daddy really needed a new guitar," but should choose your course of action based on their (limited) ability to comprehend the necessities of life on the farm.

John

Subject: RE: Guitar Truss rod adjustments
From: Little Hawk
Date: 10 Jun 10 - 02:51 PM

Heh! You don't scare me, John. This Martin guitar is worth its weight in gold. Maybe more. I suspect it will outlive me by a considerable margin.

Anyway, I can't afford another case of GAS at this point. The last Taylor I bought damn near broke the bank.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Guest from Sanity
Date: 10 Jun 10 - 09:32 PM

John in Kansas: "Once that idea is firmly in place, you can justify GETTING YOURSELF A NEW MARTIN."

Shhh!....( looks around quickly, and stealthily to see if anyone is listening who would cause great bodily harm.....looks again, then crouches down, to avoid hurled projectiles...pops head up.. snaps a quick look around..and whispers)...."Older ones are better".....(runs, and ducks for cover.......peers carefully, recoils behind a corner...jumps out in the open, cups hands around mouth and shouts).... "Taylors are the most over-rated guitar on the plane-e-e-e-t!!!!!"....(turns, and quickly runs for cover!)

Last seen; a cloud of dust appearing several hills away, in the distance!!

Wink,
GfS

Subject: RE: Guitar Truss rod adjustments
From: Little Hawk
Date: 11 Jun 10 - 01:33 AM

Hey, Gfs...you're repeating the same old line I hear constantly among several middle-aged friends I have here who are "old Martin" fanatics. They all swear the "old" Martins are better, meaning the pre-war ones mostly. Well, I haven't played any prewar Martins, so who am I to say? But I think there are plenty of guitars being made now which equal anything from back then, and a lot more really good guitars being made now than back then.

One thing the really old Martins had going for them, they were a bit lighter built than modern guitars, and a lighter box has a bigger sound. The modern ones are built stronger for warranty reasons, I think.

Then there's Brazilian Rosewood. People are practically religious about the stuff. (shrugging shoulders) Yeah, I'm sure it's great, but there's a lot of other great wood for guitars too, so I don't get religious about an instrument just because it's made of Braz.

As for the Taylors, I have played so many terrific Taylors lately that I do not think they're overrated at all. Some other guitars I also don't think are overrated at all are: Collings, the better Larivees, Santa Cruz, the better Yamahas, and the better Martins.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Guest from Sanity
Date: 11 Jun 10 - 02:45 PM

Little Hawk, Yo-Ho!!

My D-21, in 1974 had the tone bars sculpted, and face micro-sanded way down,..so your rap on the lighter wood, is correct..this thing SINGS!!

I've played Taylors, that everyone thought was near sacred. I was underwhelmed. They just(at least the ones I played) didn't resonate was well as a GOOD Martin, a Larrivee, Thomsley, or Breedlove....but, yes the are still pretty good guitars. ( I personally wouldn't get one!...but then you never know where life leads you)

I thought I'd just bust your chops for fun. I'm sure you's receive it in the lightheartedness that it was intended....YOU MIGHT HAVE ACTUALLY GOT A GOOD ONE!!!!!!(Way lucky 'YOU'!)

Chuckling,

GFS

P.S. My Strat, was made for me at the factory. The body was made from one piece of Brazilian Rosewood! Weighs a lot, too. Great resonation, because of the denseness of the wood, however, it might not be everyone's cup of tea!...Hey, speaking of 'denseness of wood'..I think I'll mosey over to the B.S. threads! Great yakkin' at ya'!..By the way, my rap on truss rod adjustment and doing the frets is gold!..despite the leakage from the BS side!

Yo-Ho-ho-ho-ho-ho-ho-ho!

Subject: RE: Guitar Truss rod adjustments
From: buddhuu
Date: 11 Jun 10 - 03:18 PM

A two-minute Google returns the following:

From Taylor Guitars:

"A truss rod is an interior metal bar running the entire length of a guitar's neck. When tightened, it counteracts the tension created by the strings (the strings pull the neck forward; the truss rod pulls the neck backward). Proper use of the truss rod enables you to "balance" the tension on the neck and adjust the amount of bow to fit your playing style."

See also Frank Ford's Frets.com article on truss rod adjustment.

Subject: RE: Guitar Truss rod adjustments
From: HiHo_Silver
Date: 11 Jun 10 - 07:57 PM

I find this interesting. I have never seen a genuine Martin HD28 with an adjustable truss rod. In fact have never seen any of the older Martin Guitars with an adjustable truss rod. They have a T bar truss rod imbeded in the neck and are not adjustable.

Subject: RE: Guitar Truss rod adjustments
From: GUEST,Guest from Sanity
Date: 11 Jun 10 - 09:22 PM

High Ho, Hi ho, i don't know about HD28's, and my D-21 has no 'adjustable' truss rod....but many other guitars, than I've adjusted do. the process is the same. As so far as the fret job, that, I've done on all my guitars.....Sally forth!..Hi-Ho...and Awa-a-a-a-YYYY!

GfS

Subject: RE: Guitar Truss rod adjustments
From: Don Firth
Date: 11 Jun 10 - 09:27 PM

Same here, Silver. I've owned a couple of Martins, one of which was a steel-string (00-18). And I've known many people who own various models of steel-string Martins, but I've never encountered one with an adjustable truss rod. Or one that needed an adjustable truss rod. The set-up and action of every Martin I've ever seen was about as perfect as one could want. Of course, most of these were from the Fifties, Sixties, and Seventies.

Is this something new?

Don Firth

P. S. I currently own a Spanish-made flamenco guitar, and a top-of-the-line Japanese made classic. That Japanese make some extraordinarily good classics.

Subject: RE: Guitar Truss rod adjustments
From: Murray MacLeod
Date: 12 Jun 10 - 02:35 AM

Martin have been installing adjustable truss rods in all their guitars for years now.

Originally they used a T-bar, (as mentioned above) then they changed to a hollow steel 1/2" square box section, now they all have adjustable truss rods.

About time too, imo.

Subject: RE: Guitar Truss rod adjustments
From: JohnInKansas
Date: 12 Jun 10 - 03:22 AM

Richard Bridge - 10 Jun 10 - 04:36 AM suggests:

The other possible desirable feature might be a constant pressure to fret the string at any point upon its length, but I think (I am not sure) that that is mathematically impossible to achieve.

There have been numerous attempts to produce fingerboards with this – and a gajillion other – peculiarly desirable feature, and in this case it's quite easy to do the "thought experiment" that disproves the difficulty imagined.

A string supported at two points and under tension will be approximately a straight line. (Purists will say that the weight of the string will always make the "undeflected" string a catenary arc that's not quite straight, but the deviation from straight will be quite small.)

If you apply the same pressure against the string at each of many various points, it will deflect a certain distance at each point, depending on the location of each point along the length of the string. The difference in deflection from one fret to the next will be small, and if you include points "between the frets" you obviously will get a continuous curve "of deflection points." Consult M. Fourier for the writing of the equation, if desired, although fairly simple algebra can get you there if you have the patience and a basic understanding of stress/deflection fundamentals.

CONCLUSION:

If you apply the same pressure at each of the fret positions, and measure how far the string is pushed sideways to achieve the same "pressure" for each fret, the deflections away from the straight string position will form a curve.

To have your "constant finger pressure at all the frets" all you have to do is bend the neck (or at least the fingerboard) so the tops of the frets are on that curve.

A few luthiers have published mathematical(??) analyses purporting to "prove" that the "ideal neck" is slightly concave, and have claimed to deliberately build their products that way. The usual implementation relies on making a straight neck that is then bent concave by the string tensions, and then pulled back "to the ideal curve" by some or another (sometimes quite exotic) "truss rod" device.

Since an "end-loaded" uniform beam can only be bent to a parabolic curve by linear forces applied at the ends, some claim to build in a "tapered stiffness" so that a slightly different curve can be achieved.

(I'm a bit doubtful that any of these "analysts" actually achieve what their theories proclaim, although some of them – I'm told – have made some very nice instruments. If it really made all that much difference, it would likely be a "trade secret" that they wouldn't tell us about.)

John

Subject: RE: Guitar Truss rod adjustments
From: Murray MacLeod
Date: 12 Jun 10 - 06:54 AM

A practical, and easily accomplished, experiment to ascertain the curve would be to set up a dial gauge in a holder with a given weight attached to the plunger, lay a guitar on a surface plate so that the strings are perfectly parallel to the surface plate, (with adequate support and restraint ), and move the dial gauge along taking a reading at each fret (and intermediate points if required).

Not as accurate as a Fourier analysis, but accurate enough for all practical purposes (accurate to half a thou is good enough for me ).