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Hi folks,

I just got one of the triple bend truss rod wrenches from SM. I’m wondering how popular these things are with the repair community or just in general? This would eliminate needing to split the popsicle brace and putting the hole in the upper transverse brace.

However, I bet nothing would piss off a repair person more than having to buy a $20 tool to do a setup.

Curious what you guys think.

Brad


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Nothing bugs me like getting a Larrivee with the homemade truss rod wrench. I really don't like all this fussing for adjusting a truss rod, sorry.


Pierre
Guitares Torvisse

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Pierre Castonguay

The winner is Santa Cruz with that homemade truss rod system... the whittled-out recess is a distinctive touch of woodbutchery.

As to trussrod wrenches, we had at least 2 dozen we used on a common-enough basis to warrant having them out and available (see picture). Most of the repair people I have talked with have no issues with a hole in the UTB, assuming it is correctly placed. We had a fair number of triple-bend wrenches, both vendor and shopmade. $20 to save a few minutes is a good investment... we had at least four 5 mm variants just for the Martin single and double-action rods.

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For the times they are a changin'

- Bob Dylan

Once you get used to that type of wrench it’s just as easy as anything else. I still use them even though it put a hole in my UTB.

As Woodie said, putting a hole in the UTB reduces its strength and utility not one whit.

FWIW, Larrivee has started putting holes in their UTB…

I don’t know many repair shops that don’t have the full set of SM wrenches and in many cases the gripper variants too, or the equivalents from some other brand like Music Nomad. You’d be out of business in a month if you had to stop work to fabricate or order and wait for a wrench for every unusual guitar through the door. $20 for a truss wrench is nothing - it’s a device that makes money for you.


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Many of ours we made too and you kind of have to sadly.

But we have a position on this that a truss rod AND it's access need to be serviceable easily with half the world's guitars living in climates that may necessary seasonal truss rod tweaks.

The brands that make the truss rod less than accessible get downgraded on their "SQ" my term for "serviceability quotient" and there are a number of them that qualify for the infamy here. Even Ov*tions got the truss rod wrong.... with a port on the back and a level of complexity that's, well...... b*llcrap.

One last dig from me... The first thing I do when triaging an instrument is tip the neck and sight the neck. The next thing I do is make sure the truss rod(s) works... Peg head access is appreciated greatly....

I don't drill through the upper transverse brace, nor do I use a popsicle brace. The trapezoidal brace I do use can easily be gapped in the center to allow for Allen adjustments.
My guitars are adjusted by reaching inside the hole and inserting the short end of a standard Allen wrench, either 5mm or 3/16", depending on the rod used.
I have one triple bend 5/32" (4mm) wrench that fits a few different brands. It was given to me.
I am not a fan of headstock adjustments, especially those that feature a hex nut. The large channel required to clear a socket or a box end wrench contributes to broken headstocks.

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John

[quote="Hesh"]

"But we have a position on this that a truss rod AND it's access need to be serviceable easily with half the world's guitars living in climates that may necessary seasonal truss rod tweaks.

The brands that make the truss rod less than accessible get downgraded on their "SQ" my term for "serviceability quotient" (…)"

Yeah, I'm with you, Hesh. I'm up North, so truss rod tweaks are necessary at least twice a year, so…

Pierre
Guitares Torvisse

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Pierre Castonguay

I used to think that a hole in the UTB would reduce strength too but an engineer friend of mine and a discussion I believe on this forum once changed my mind. I drill a 3/16th hole aimed directly at the truss rod so all a user has to do is insert into the hole and it's guided right in.

Me too except I go 1/4”. Once you get used to through the sound hole access its faster than having to take of a truss rod cover…

I've cut off several long Allen wrenches and glued them into corresponding 1/4" sockets. With a 1/4" ratchet handle, I've found it's easy to adjust the truss rod through the soundhole without loosening the strings.

We used a 1/4" socket handle with extensions for the afore-cursed Santa Cruz bolt head rod, but for all those serpentine, multibend rods, we used the longer version of the ball-end T-handled hex wrenches as a base tool for mods. The Bonhaus wrenches have a generous handle and good tip geometry, and that's what I primarily used to duplicate much of the truss rod wrench selection on the way out the door. Not evident in the photo above, but most of the wrench shanks are shrink-wrapped to minimize 'wrench rash' and any string or tuner post dings when used with strings at tension.

As a repair person, I want to prefer headstock-adjustable trussrods, but there are those little screws and that often beat-up piece of plastic or wood to remove and then reinstall, so even with the need to drill that 1/4" hole in the UTB for a 5mm wrench or fish around with that serpentine wrench, the body-end truss rod adjustment is my personal preference. And with the Martin 2-way rod (not Martin style...the genuine item), clearance from the UTG is assured. We used an oval-shaped UTG in new, non-vintage construction as the best solution to eliminate stress risers, but that trench down the middle required by other truss rod designs has no real impact on doing the job that UTG's do.

The boys had some fun one day when one of the octave mandolins they built long before I started arrived in the shop for the usual tuneup work. I had forgotten that the access to the rod was made via a hidden channel in the extension block, so spent a little more time than usual before grabbing the nearest adult male idiot to vent re: building instruments with non-adjustable trussrods. Even then, that shrink wrapped shank on the trussrod is, while not essential, certainly nice to have to avoid marring the top finish, so I tend towards peghead adjustment for F-hole instruments despite the creation of a huge stress riser and inherently weak construction.

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For the times they are a changin'

- Bob Dylan

This thread joggled the memory dispenser such that the following dropped into the tray and could be extracted:

What red spruce is left after making a 1/4" diameter hole one-sixteenth of an inch below the top plate on a 1/2" x 5/16" UTB with fully radiused bottom (free) edge will still carry well over 700 pounds of tensile load. Increasing the depth of the UTB by just 10% (0.55" x 5/16") increases the tensile load capability to about 880 lbs. Loss of stiffness through the access hole area is somewhat compensated for by the top and fretboard extension's contribution.

_________________
For the times they are a changin'

- Bob Dylan

Seasonal truss rod tweaks are the wrong methodology, since most of the action variation is due to movement of the top, not neck relief.

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John

Not sure about the various North American climates but in these parts seasonal truss adjustment is absolutely part of the methodology. I document before and after relief measurements on every instrument through the shop and relief change of two to four thousandths from wet to dry season is normal. This is along with the changes to the body you mention. My seasonal service for regulars is truss tweak, restring, swap from summer to winter saddle or vice versa.


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Josh, where do you live? As far as seasonal relief changes, I would also factor in the neck/fretboard wood, cut, how long it's been in service as culprits.

Pat

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Pat

Wood does not change length with moisture changes.
Even if it did, the result would be that a shrinking fingerboard from lower humidity would increase relief. That is opposite the normal situation, where action gets lower in the dry season.

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John

Yes it doesn’t change length (very much) but it does change in its other dimensions and where a neck is composed of two different pieces (and usually species) of wood these changes can and do change neck relief. I think temperature plays a part too, possibly a big one. I have always assumed it is the result of some differential movement of the fretboard and neck wood. I’m far from the only person to observe the phenomenon.

I’m located in the subtropical climate zone of the eastern coast of Australia. Seasonal humidity variation is from 90% to 30%. Ironically, temperature is more of factor here than in temperate climates because although there is overall less swing in temperature annually, there is also much, much less use of central heating in our mild, warm winters. In fact it is practically unheard of. So guitars do have to live through wide temperature swings of roasting hot summers to overnight minimums close to freezing during winter, year in, year out.

The seasonal relief changes I describe do take place and I see them almost universally where there is a rosewood/ebony board on a maple or mahogany (or khaya or whatever) neck. Ebony performs worse than the rosewoods and I will not use it on my own builds.

Yes, I would suspect ebony especially if it's flat sawn, to have more of an effect than others.

I can't say that I have clients that come with the same guitar regularly twice a year, however it's pretty rare that I see a guitar that doesn't need a truss rod adjustment. I am in a mild temperate climate, but still get RH lower than 35% in the winter.

Central heating unheard of, fascinating. Do people there just use electric space heaters?

Pat

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Pat

Beg to differ John: We have to do season truss rod tweaks because the necks not only often go into back bow on a dried out guitar they almost always need neck adjustments if the instrument gets dry.

Action is adjusted at the saddle(s) but only after nut slots addressed, relief set (truss rod adjust) and then it may need and usually does attention to to saddle too. This is the sequence that I work to and it works great for me and our clients. My approach has always been sequential and what it get me is I never have to back track and set something I already set such as nut slots or relief as we isolate the variables.

Builders like Mario who was the first on this forum that I recall advocating shipping with two saddles one for the dry season and one for summer were/are addressing the top. But this was never intended to address what the necks do when an instrument dries out.

Right that's our experience and if it gets even more dry the neck can and commonly does go into back bow. We see it much more on say Gibsons than Martins.

This is often fret sprout city too if they go into back bow which is illustrative of the cross grain shrinkage but not the along the grain shrinkage as you said.

That's our experience too Pat and pretty rare here too that we are not adjusting a truss rod. In fact we will not take an instrument in even if it's for something unrelated without working the truss rod while the client is still present. If it's going to be a can of worms with a broken truss rod we want in real time the option to 1) have the client fully understand that they brought it to us this way, we didn't do it.... and 2) we may decline for bandwidth reasons if it's going to be a can of worms with a truss rod replacement possibility and we are booked to the max.

This is our experience too and if I might suggest that Josh you and I work on electrics as much if not more so than acoustics or at least that's the case for me. Electrics have lower action typically, narrower necks in many cases (Gibson early 60's SGs....) and as such are even more of a weather vane if you will.

Our friend Dan Earlywine when he comes to visit and we talk fretting he speaks of "rubber necks" with instruments like Riks, P bases, J basses in mind so neck shape, construction, even function say a bass and string tension, tunings etc are all variables here too.


Bottom line: IT SURE IS NICE TO BE ABLE TO CONTROL RELIEF WITH A TRUSS ROD SO PLEASE USE THEM

Another bottom like: It's even nicer to be able to save the day with a double action rod so please consider using one of these too.

It's February here in Michigan so we are seeing lots to back bow, cracks, fret sprout etc.

I’m just happy that my clients keep my guitars between 40-50%RH constantly so I never have to worry about this stuff.

Edit: Their guitars…