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Thread: Truss rod preferences

  1. #1

    Default Truss rod preferences

    I'll be gluing up a neck blank today. I need to start thinking about the truss rod.

    What sort of truss rods are the builders on this site using these days?

    I've made the old style (sort of like a horizontal '7') out of 4140 but I need to make special jigs for each scale length as well as filler strips.

    I'm tempted to use a 'u' style but am concerned about the additional few ounces of steel in such a short neck.

    Fabrication of the truss rod is not an issue, even if welding is involved.

    I recall reading in an old Frets Magazine that the original Gibson design didn't work well and a design change was implemented early on. The Loar plan I have shows a slightly arched (upward) rod with nuts on both ends. I'm assuming the nut buried in the heel was welded or staked to keep the rod from rotating. Correct?

    Any help or advice would be appreciated.

  2. #2
    gary nava; luthier GarY Nava's Avatar
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    Default Re: Truss rod preferences

    No doubt you'll get as many different responses as there are luthiers! My preference is to stiffen the neck with two strips of carbon fibre (from StewMac).

    You might find my blog post of interest... http://guitar-maker.blogspot.com/201...1_archive.html

    Cheers Gary

  3. #3

    Default Re: Truss rod preferences

    I like Gary's idea, stiffen the neck with carbon fiber will keep the neck straight.
    You won't have the truss rod to worry as to how to adjust it.
    My Ovation has carbon fiber enforcement and I never have to worry about a warped neck.
    My Kentucky does have the truss rod, if it get warped someday, I will wonder which way to turn the screw !!! turning it the wrong way could damage the neck.

  4. #4

    Default Re: Truss rod preferences

    I use carbon fiber, but I would recommend getting it from dragonplate, as the prices are a lot more sensible.

    /Magnus

  5. #5
    Registered User sunburst's Avatar
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    Default Re: Truss rod preferences

    I like for necks to be adjustable so I use adjustable rods rather than CF stiffeners. I make my own steel truss rods (with help from a machinist friend) by welding an "L" on the heel end and threading the business end of a length of 3/16" gas welding rod. It doesn't harden like drill rod and some other steel. They weigh about 23 grams with nut and washer because I have material machined off of most of the length. I set them about 1/8" from the back of the neck, with the slot following the back of the neck rather than the fingerboard surface. In other words, the slot is deeper at the heel because of the neck taper.

    The Gibson curved rods did not have welded nuts on the heel end. They were not staked either, but the end of the rod may have been peened slightly. At any rate, it is no problem to remove the nut from the heel end of an old Gibson truss rod with the neck off of the mandolin. The curve of the rod generally prevents the rod from turning in it's little tunnel, so if all is working well the nut at the heel end stays put.

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    Default Re: Truss rod preferences

    John,
    I tried to enter your site but was unable to. Are you updating it?

  7. #7
    Registered User sunburst's Avatar
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    Default Re: Truss rod preferences

    No, my web site is so out of date and in need of work that I'm basically ignoring it hoping it will go away . I haven't been there is a while myself, maybe I better check it out...

    EDIT:
    The link worked for me, even if the site didn't work very well.

  8. #8
    Registered User barry k's Avatar
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    Default Re: Truss rod preferences

    Here is my only question with carbon fiber re-enforcement..No doubt that it stops the neck from warping, but what do you do if a customer wants more or less relief in the neck. just say live with what you have? What amount of relief is preloaded into the neck to deal with no flex? I personally prefer and use 2 way truss rods and havent noticed any drastic noticable weight disadvantage. I even extend my rods into the fingerboard extension . This has vitually eliminated all those 12th -15th fretboard humps that a lot of mandolins develope over time, if it does show up , it can be adjusted out. I plane my necks dead flat before I install the fingerboard, when the strings go on and everything stabilizes I can adjust the neck to where it needs to be. I make the rods myself, as I have the standard Givson type.

  9. #9
    gary nava; luthier GarY Nava's Avatar
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    Default Re: Truss rod preferences

    As far as relief goes, Iíve never had anyone ask for adjustment on one of my mandolins, so Iím perfectly happy with CF.
    As I join my neck to the body with a large mortise, I can run the carbon-fibre to about the 15th fret, so there is no distortion at the neck joint.
    Cheers Gary
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  10. #10
    Mandolin Botherer Shelagh Moore's Avatar
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    Default Re: Truss rod preferences

    I'm with Gary on this (but then I'm the proud owner of one of his fine mandolins!). My National RM-1 has an adjustable trussrod, and I did need to tweak it to my preferences, but Gary's was perfectly set up regarding neck relief and will never move.

  11. #11
    Registered User Rob Grant's Avatar
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    Default Re: Truss rod preferences

    A bit of 5mm stainless steel rod threaded to take a small Fender(?) bullet-headed truss rod nut. I put a sharp 90 degree bend in one end that I bury in the heel. Lay the whole works as close as I can get it to the back of the neck. I rarely need to touch the adjustment on short scale mandolins with the three piece laminated necks I build. It did come in very handy with the long scale octave mandolin (23") I just completed. Basically a straight compression rod. I've tried commercial double action rods, but I wasn't overly enthusiastic about the quality of the workmanship, the complexity of the operation and the bulk and weight.
    Rob Grant
    FarOutNorthQueensland,Oz
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    Default Re: Truss rod preferences

    Does anybody have any experience with the dual action truss rod from Steve Cumberland? It looks to be lighter than the Luthier's Merc one and can be custom cut shorter than 7.25" when in need replacing a non functioning single action rod where the end is buried in the heel and hard to extract totally.

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    it comes in either hex nut or allen wrench ended

    Is the allen wrench end more low profile/easier in general than the hex nut??

  13. #13
    Registered User Bill Snyder's Avatar
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    Default Re: Truss rod preferences

    Do you mean from Steve Smith of Cumberland Acoustics?
    Bill Snyder

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    Registered User Doug Edwards's Avatar
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    Default Re: Truss rod preferences

    I've pretty much decided to go with Steve Smith's or Bill James' dual Truss Rod for my next builds.

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    Default Re: Truss rod preferences

    "Do you mean from Steve Smith of Cumberland Acoustics?"

    no, i mean Steve Cumberland from Smith Acoustics

    ....DUHHHHR - I apologize.. (Trying to give this really nice guy a plug - and I totally botched it)

  16. #16

    Default Re: Truss rod preferences

    "Steve Cumberland" checking in here. All seems well, carry on . . .

    Oh, before I go, here's a link to the page with our dual action truss rods on it. And, as mentioned above, we can do custom lengths, if our standard lengths don't work for your particular application.

    (Scroll down a bit to get to the truss rods)

    http://cumberlandacoustic.com/id2.html
    Last edited by Steevarino; Dec-18-2011 at 7:12pm. Reason: speling errir

  17. #17
    Registered User Wes Brandt's Avatar
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    Default Re: Truss rod preferences

    My preference is for a tightly fitted, single straight 3/16 solid rod imbedded parallel about 3/16 in from the BACK of the neck. The filler piece must fit tightly and be carefully glued in to avoid getting too much glue on the rod in the rod channel. I wax (paraffin), the top and bottom of the rod but not the sides, (you don't want wax on the sides which would contaminate channel sides when you lay the rod in), and clamp the filler piece firmly to squeeze the rod, not too tight but to make it "become one" with the neck. When the glue is dry enough I tighten the rod to be sure it will move slightly in the channel, in case any glue did get in, and also seat the anchor end firmly. It will move.

    I use the same system on guitars and mandolins... I don't mention anchors or nuts because that varies (make very sure the rod can't rotate though) but the important things are-

    1. I absolutely want an adjustable neck... you cannot satisfy a range of playing styles/setups without being able to adjust the relief in a neck... especially with guitars

    2. I do not like these two piece truss rods that do not "become one with the neck" and which I have seen, on well known makers instruments, cause weird relief (pull up) shapes or even slight bumps on the fingerboard.... they lay in a channel under the fingerboard and "push up" to counteract the bowing where ever they happen to touch first. The rod I describe precisely compresses the wood along the back of the neck to counteract the string pull. Completely different system. I also like the fact that there is no rubber in the neck and that the rod is very much "one" with the neck not just flopping around in there dissipating energy(I exaggerate but still...). No extra weight either. I did not invent this... it has been used for decades by Gibson, Guild and others.

    It's the human tendency to try to make everything easier and that's how I see these rods. The drop in rod makes it easy to install a rod.... 1/5 of the work above. The double acting rod makes it easier to not pay attention to the quality/seasoning of the neck wood, assembly and fretting ...end up with a back bow, just "adjust it out", though it will need more adjusting as the string tension does it's thing.

    With the above system, you must build some relief into the neck and you must be careful not to bend the neck backwards with too tight of frets. You end up with precision, adjustable neck with the best possible acoustic properties... not a small thing. I have considered adding carbon fiber into this system though.
    WesBrandtLuthier.com
    BrandtViols.com

  18. #18

    Default Re: Truss rod preferences

    I'm resurrecting an old thread with a question about truss rod choices and neck relief for the beginner.

    I'm building my first mandolin, and looking at what sort of truss rod to install: non-adjustable, single-action adjustable, or dual-action. I've read many threads on the subject here--enough to know that there are lots of opinions. I get that a non-adjustable truss rod may help stabilize the neck, and that an adjustable one can be helpful for dialing in neck relief.

    This being my first build I'm inclined to go with adjustable--I have little faith that I'll get the neck relief exactly right on my first try--but I'm willing to listen to arguments in favor of a carbon fiber rod. I'd love the simplicity of a CF rod--plane the fingerboard to flat and allow the string tension to put some relief in the neck--but it seems like a gamble to me.

    If I go with adjustable, then I need education on single-action vs. dual-action. I actually have a single-action truss rod from LMI, and I’ve looked at Robbie O’Brien’s installation video, but I have no problem spending $20 for a Cumberland Acoustics double-action rod. Single-action, when properly installed, appears to give the user the ability to put back-bow or hump into the neck--that is, to bring the middle of the fretboard closer to the strings. I don't see any way that a single action can actively put the neck into relief (relaxing existing hump-creating stress would move the fretboard back toward being straight, but not into relief). Do I have this wrong?

    Based on the variety of respected opinions I've read I'm sure there's no one right way to do things. That said, I'd love opinions on how a careful beginner who doesn’t realize how much he doesn’t know can arrive at the most forgiving result.

    Thanks for your help.

  19. #19

    Default Re: Truss rod preferences

    You are so correct, Derek. There are many different styles of truss rods available for mandolins. In fact, we regularly carry three different styles for mandolin alone, and that is not counting different wrench-end options or custom lengths.

    Concerning the price of a two-way truss rod, I invite you to make one yourself. When you add up your material and labor costs, and maybe a bit of value for the skill you have to machine parts, cut threads, heat shrink, assemble, braze, silver solder, etc., I think you will see that it is really a pretty good value.

  20. #20
    Registered User Steve Sorensen's Avatar
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    Default Re: Truss rod preferences

    All the options discussed here work just fine.

    A couple of notes that I didn't see -

    CF strips are actually lighter than maple . . . so the neck is substantially lighter than either solid wood or a steel truss rod. I have had a couple of players say they believe that the added mass of a steel truss rod impacted tone -- not sure about that, but I did notice a "Zingey" feedback sound if the nut is physically touching the carbon fiber, so I always scrape out a small space in the top of the rods under the location of the nut so that the nut is seated on wood only.

    If you use CF strips, this is the one place where Gorilla glue makes sense -- it will bond to both lightly scuffed carbon fiber and to wood.

    Steve

  21. #21
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    Default Re: Truss rod preferences

    Here's my experience.
    I used a Stewmac straight rod on my earliest(modern era) mandolins because it was easy to install. But later I felt an LMI one way rod would be a good option. The type that has a flat steel blank with welded end pieces with a 1/4" rod underneath threaded into the rear extension. This is a one way, not a 2 way. It is in fact just a shortened guitar rod and I felt it was so stout that it would easily adjust the neck.

    But with one of the first I sold I heard that a luthier said it was not working at all. It was later taken to TJ Thompson who said this was true but got it to a playable state. But it nearly got returned to me.

    The size of that rod seemed too much and I had a family member- toolmaker make some 3/16" stainless units that worked the same but fit a mandolin better. Someone with one of those went to cranking on it to the point of separating the fingerboard at the nut, indicating it was trying to do what it should. I think he was trying to correct more than relief but I had to remove the board and ended up filling the slot with CF.

    These experiences told me that this type of rod is not as effective on the short mandolin neck as a compression rod. I think they work better on long guitar necks where you have better leverage.
    That's when I decided to set up to install a traditional Gibson style curved rod and also tried to understand how it worked better. There's been a narrative that says it is curved the wrong way and will only make things worse. But I just remember Charlie Derrington saying how well A Loar responds to adjustment. I think folks don't realize that the rod is only supposed to raise or lower the first few frets to both counteract string tension and control relief, not deal with any level problems over the entire board.

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  23. #22
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    Default Re: Truss rod preferences

    This is the LMI rod I am trying to describe.
    I'm just catching on this was a revived thread. I question why a 2way would be needed on a mandolin. I know Hans B. used them and would fret the board once glued on and correct any back ow with it but I just try to keep a level board to start with. But I don't think you would expect much back bow one strung up.
    When I get home tomorrow I'll post a shot of the stainless rod I used for a while.
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  24. #23

    Default Re: Truss rod preferences

    Quote Originally Posted by Steevarino View Post
    Concerning the price of a two-way truss rod, I invite you to make one yourself. When you add up your material and labor costs, and maybe a bit of value for the skill you have to machine parts, cut threads, heat shrink, assemble, braze, silver solder, etc., I think you will see that it is really a pretty good value.
    Oh, I definitely think your truss rod is a good value. I think maybe you misread my comment; I said I have NO problem with paying $20 for your truss rod. I'm spending enough money on tools and building jigs; I don't need to get into metalworking as well.

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  26. #24
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    Default Re: Truss rod preferences

    [QUOTE=barry k;997712]Here is my only question with carbon fiber re-enforcement..No doubt that it stops the neck from warping, but what do you do if a customer wants more or less relief in the neck. just say live with what you have?

    Let's say I am, or could be, one of those customers. I want a neck with adjustable relief, period, because I cannot trust your assurances, or those of other builders that make these claims.
    "No doubt that it stops the neck from warping"? Really? What does that even really mean? How and for how long has that been tested? And, warping up/down? Side to side? Pulling forward? Dipping or crowning? In the first place, what we're really talking is the fretted fingerboard, not the "neck". One doesn't play the neck, one plays the fingerboard, and for whatever combinations of forces, time, or errors, the fingerboard doesn't have to obey the command being given to the "neck", and often does not.

    I read over and over both owners and builders stating to the effect that non-adjustable neck stiffeners will "keep the neck from warping", or "no way the neck can bow with CF stiffeners", "a mandolin neck is too short to need stiffening", or "give just the right amount of relief under string tension", etc. Well, how many years will you guarantee it? All that is great if *your* own mandolin's FB stays flat without adjustment. Mine don't, none of them, so these assurances don't help me.

    I don't have a single mandolin, vintage, recent, or in between, that hasn't needed the relief adjusted. And, every one with non-adjustable rods or stiffening systems has developed too much relief. Every one. So, my dysfunctional collection at least hasn't heard of these guarantees, and isn't willing to obey. Not one has become back-bowed, by the way - they all develop too much forward relief. That is, it is not random; it is an axiom, which I will take bets on: "Mandolins Without Adjustable Truss Rods Will Develop Too Much Relief" - Just give them time; you can almost bet the ranch on it. This includes some very nice, high end instruments that I wish I could be regularly playing, but cannot because they are (for me) unplayable until they receive expensive work, at the least replaning/refretting. That is very disappointing.


    So I will answer the question of what I think the customer ends up doing:
    1) selling the mandolin (usually not acknowledging they are not happy with the fingerboard or relief or playability), or
    2) replaning/refretting, and hoping once is enough for 5-10 yrs, though as I now know from experience, it may not be.

    Even WITH an adjustable truss rod, there can be difficulties and compromises enough in setting up and adjusting for your own version of good playability and relief, especially as things age under stress. Isn't the better design approach one that takes this into account?? To opt, from step 1, to use a non-adjustable neck system is not a good decision, in my view, and I really can't see myself ever considering buying a contemporary instrument that does not allow relief adjustment.
    Last edited by acousticphd; Nov-02-2015 at 1:13pm. Reason: typo
    Jeff Rohrbough
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