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Thread: Neck reinforcement vs a truss rod

  1. #1
    Registered User John Bertotti's Avatar
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    Default Neck reinforcement vs a truss rod

    My OldWave A has a neck reinforcement but not a truss rod. Tension has not been released on this neck since I bought it other than to change strings. No neck issues. That begs a question in my mind. Do F style instruments have enough added string pressure to need a truss rod? Is the difference that great or is it a peace of mind thing? In my head, no knowledge to prove this preconception, a solid neck with say a carbon fiber rod would be tonally better than a neck with a truss rod in a groove. How wet is my line of thinking?

    I have never really played or handled an f style but one cheap import at a local mom and pop for about two minutes. It seemed to be a bit longer scale but not much really and the tone was a bit to tinny to my ear.
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    Registered User Glassweb's Avatar
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    Default Re: Neck reinforcement vs a truss rod

    I won't buy a mandolin without a truss rod anymore... and then only if it's a functioning truss rod... which takes some inspecting to ascertain.

    In my mind a well-functioning truss rod is essential for a proper set-up... getting your mandolin to sound and play its best.

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  4. #3
    Registered User John Bertotti's Avatar
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    Default Re: Neck reinforcement vs a truss rod

    Well I don’t buy that my A has a fine setup even without a truss rod. Now should it ever need adjusting, and it hasn’t since I got it in ‘07, then a truss rod could come in handy. But Oval A’s built after the Gibson variety seem to function fine with out them as does my Vega Bowl back. So that still makes me wonder about F style and why they seem to all be built with them.
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    Registered User sunburst's Avatar
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    Default Re: Neck reinforcement vs a truss rod

    One is adjustable, one is not.

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    Default Re: Neck reinforcement vs a truss rod

    I see necks with solid reinforcements that are straight as an arrow and solid as a rock.
    And necks with solid reinforcements that are bowed and need service.

    And necks with adjustable rods that are working well.
    And necks with adjustable rods that are not working but are straight and solid.
    And necks with adjustable rods that are not working and need service.

    And instruments with necks that are not stiff enough with adjustable rods that need to be re-necked.
    And necks with adjustable rods that have been ruined by folks messing with them who don't know what they are doing.

    When I see an older instrument with a bowed neck, I always look to see how stiff the wood is that was used, and wonder how well the instrument was cared for.

    This is a fight I'm not going to.
    Last edited by rcc56; Jul-16-2021 at 12:26am.

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  9. #6

    Default Re: Neck reinforcement vs a truss rod

    There are lot of 100 year old Gibsons out there without a truss rod and perfectly straight necks.

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  11. #7
    Registered User John Bertotti's Avatar
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    Default Re: Neck reinforcement vs a truss rod

    Guess I got my answer. I was curious it seemed more of an fstyle thing and wondered if there was some reason they would be more prone to bowing than an old a oval or modern take on it. Thanks all no need to to keep going. Thanks again.

    Does any one here measure the stiffness of their neck wood? Other than by feel.
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    Default Re: Neck reinforcement vs a truss rod

    Whenever I see a badly bowed neck, I flex it carefully to see how stiff it is. This gives me some guidance on how to proceed with the repair.

    F-5's do have necks that are longer and usually slimmer than 1910's Gibson oval holes. Does that mean that F-5's need adjustable rods or is a solid reinforcement sufficient? See my last comment in my previous post [#5].

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    Default Re: Neck reinforcement vs a truss rod

    There are two separate things going on here - neck stability, and neck adjustment.

    When a neck is first built, the builder wants it to sit in exactly the right place once the strings are on. And not to move around over time - perhaps string tension gradually pulls up the neck, perhaps the wood itself decides to move (because wood has a mind of its own sometimes). Neck reinforcement for stability is designed to deal with this issue. Essentially, some stiffer element (ebony rod, carbon rod, metal rod) is incorporated. Neck reinforcement is less needed on short scale instruments - I build ukuleles and never reinforce their necks. Mandolins are short scale but have a lot of tension, so most builders now reinforce (but in the past they didn't always).

    Neck adjustment is for when either (a) the stability system didn't work as planned (e.g. the neck still bowed, even though reinforced), or (b) the player wants the neck a different shape from the shape it naturally adopts under string tension. Again, players of short scale instruments are less likely to need such adjustment. On longer scale instruments like guitars, the amount of forward bow in the neck (its 'relief') is ideally different for different playing styles. So guitar players like easy adjustment (well, some do, others just randomly adjust it themselves to try to fix other issues). An adjustable truss rod provides both stability reinforcement and also adjustability. If the reinforcement is not adjustable there are other ways of adjusting the neck - compression fretting, sanding relief into the frets - but these require a high skill level to get right.

    In theory an adjustable truss rod is a good thing because it does both jobs, but there are trade-offs (added weight, risk of malfunction, problems of building access to adjust, etc). On a ukulele the truss rod would never be used, so it just adds weight and complexity. If I build a guitar I always include a truss rod (but some guitar builders don't, because they are very good at stable necks which don't need adjustment).

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    Registered User John Bertotti's Avatar
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    Default Re: Neck reinforcement vs a truss rod

    Was there a need for a thinner neck on an F5?

    - - - Updated - - -

    That I understand which rove my question of why F5 seem to all have them.
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    Default Re: Neck reinforcement vs a truss rod

    I think (but could be wrong...) that the Gibson truss rod might predate the F5 model by a little bit. It came along at about the same time as the slimmer necks of the snake heads and F5s as well as the longer necks of F5s. It was a development across the Gibson line including guitars; necks became thinner and adjustable truss rods were added. Did the slimmer necks have problems and lead to the addition of adjustable rods or did the addition of adjustable rods lead to confidence that slimmer necks could be used? Chicken or egg? I don't really know.
    As an aside, CF Martin resisted adjustable rods for many years before finally adding them to their guitars. After they finally made their necks adjustable (a development applauded my many repair people) they began to offer slimmer necks as an option. The slimmer necks later became the standard.

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    Default Re: Neck reinforcement vs a truss rod

    Truss rods first appear in 1921, before the introduction of the F-5. Like many of the other changes made by Gibson during the early years, it took a while before truss rods became standard on all instruments. The earliest instruments with truss rods have the larger necks characteristic of the 1910's.

    The decision to reduce the size of the necks may very well have been a decision by someone in the front office or the marketing department, and may just been the personal preference of some executive. I do not necessarily believe that the decision was made because of the introduction of truss rods, although we could surmise that the presence of a truss rod made them feel more comfortable with the idea of a smaller neck.

    Trends in neck shapes, profiles, and fingerboard widths have come and gone over the years. Martin guitars started with an average nut width of 1 7/8", were reduced to 1 3/4" in the early 1930's, were reduced again to 1 11/16" in 1939, and stayed there for decades. More recently, their standard nut width was changed back to 1 3/4". Their neck shapes and profiles have also changed several times. Gibson necks have also changed a number of times over the years. I have played many modern era Gibson mandolins with necks that were very narrow indeed, with steep sides. Such necks do not fit my hands, and I cannot play those mandolins well or for very long. I do not know how they are building them now.

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  21. #13
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    Default Re: Neck reinforcement vs a truss rod

    Back in the day, I built a few electric mandolins. The first few had reinforced necks ala Martin guitars. The rest had truss-rods. It's a very small sampling, but I never had to do neck work on the truss-rod equipped mandos. I did have to do repairs on one of the reinforced necks -- I put a truss-rod in it.
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    Default Re: Neck reinforcement vs a truss rod

    In the 132 mandolins that I've built, I've only had one with a neck issue. It had a Siminoff style truss rod with the right angle bend that broke at the bend- just like 99% of bicycle spokes brake at the bend. Of the probably 400+ old Gibsons that I've worked on, the only ones that had neck issues were truss rod models that hand been improperly messed with by their owners.

    The purpose of a truss rod is to adjust the relief in the neck, not to adjust the action height. The action height does move during the adjustment, but this is not the primary purpose. It is surprising how much damage a well intentioned, uniformed person can do to a truss rod.

    You can also have the best truss rod on the planet with a poor neck design or a neck made from poor materials and it will not help.
    Go read some of the bass forums if you want to see some amazing overly complicated neck failures with not just one but multiple truss rods!

    On my personal mandolins, I always prefer a solid carbon fiber beam. I can hear a tonal difference and I've taken them to an engineering lab and measured everything with lasers and all the fancy tech. There is a tremendous difference in the way a rigid rod neck moves vs a tensioned truss rod- almost shocking when you see it.

    On a customer's mandolin, the person that writes the check is the one who gets to decide...

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    Default Re: Neck reinforcement vs a truss rod

    Quote Originally Posted by j. condino View Post



    On a customer's mandolin, the person that writes the check is the one who gets to decide...
    And that seems to be the bottom line, no matter what our personal opinions are.

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  26. #16
    Registered User John Bertotti's Avatar
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    Default Re: Neck reinforcement vs a truss rod

    I need to double-check but I think Bill used a cf rod in my OldWave. I am inclined to do an oval f scaled mandolin with a neck I like, I like a nice v, and a cf rod. Obviously, all my guitars have truss rods. Even the 000-18GE.
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    Default Re: Neck reinforcement vs a truss rod

    I did have an early teens plain style A come my way with a badly warped neck. I've known the owner for decades, and he had kept the mandolin strung up to pitch with 11 - 16 - 26 - 41 strings for years without taking it out of the case. Here in southeast Tennessee, the average humidity during the summer will cause an old Gibson to rise a full step in tone and stay there all summer. I suspect that's what happened to this mandolin.

    Anyway, I bought the mandolin, which was otherwise in good condition, as-is for a few hundred. I pulled the board, applied as much heat as I dared to the glueing surface, clamped it into a very slight back-bow [perhaps 0.015" or so] and let it sit for a few days or a week. Then I re-installed the fingerboard [using hot hide glue] with the same slightly back-bowed clamping rig, and gave it a good compression fret job. When I strung her up, she was straight as an arrow and stayed that way.

    The pickguard was missing, also the original removeable bridge saddles. I made replicas, and put the mandolin up for sale in the classifieds at a reasonably friendly price. Nobody bit, so after a couple of months I consigned it at a Nashville shop, and they sold it within a couple of weeks for more than I listed it for here. The neck was still straight. I asked the store owner to notify me if the neck developed any problems later-- I warranty my work. That was 2 or 3 years ago, and no problems have come to my attention.

    I've also had a few of the old Gibsons come through here that needed some modest levelling and a fret job, but nothing severe. Those old necks generally stay reasonably straight if the mandolins are well cared for and haven't been over strung. I've rarely seen any others that were badly warped, and in just about all of those cases, the mandolins showed obvious signs of neglect, heat damage, and/or plain old fashioned abuse.

    I don't build from scratch, although I'm thinking about building a 12 string guitar somewhere down the line. About 80% of my work has been on Gibson and Martin instruments made before 1945. I've seen a lot of old Gibson guitars with rods that were barely functioning at all. Knowing the history of some of those instruments and their owners, it seems like the ones that have been adjusted often are the ones that have quit operating. For some reason, 60's Martins seem to be more prone to warpage than earlier models. I believe that it's a consequence of Martin's switch from hide glue to white PVA glue.

    I've only installed a carbon fiber rod once. It was in a Gibson Roy Smeck Hawaiian guitar with an un-reinforced neck that I converted to standard play. I kept the guitar for at least 3 years after I converted it, and the neck stayed straight for the duration.

    I found that levelling a carbon rod after installing it is difficult. The stuff is hard as a rock and doesn't sand or tool easily. If I do another one, I'm going to recess it 1/16" or so beneath the neck surface and cover it with a thin maple strip so that it will be easy to level.

    As an aside, I'll mention that the Martins and the one Larson that I've seen that were built with ebony neck reinforcements have held up quite well.

    I'm a firm believer in using only hot hide glue to glue a fingerboard to a neck. It doesn't creep, and all of the yellow and white glues do. I know of one banjo maker who is using epoxy, and I have heard that some of the current guitar makers are using it also. They believe that if the board ever needs to come off for any reason, it will let go with a reasonable amount of heat. I wish them luck if they ever have to pull one of their own boards. My experience has been that epoxied joints are difficult or impossible to open with heat, at least without damage.

    If a modern instrument that has an epoxied-on fingerboard ever comes my way needing neck service, I'm going to decline the repair and have the owner send it back to the builder. The only way I'll take such a repair is if the builder is no longer in business, and then I'll have to inform the customer that the board may very well have to be ground off and replaced.
    Last edited by rcc56; Jul-16-2021 at 8:00pm.

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    Default Re: Neck reinforcement vs a truss rod

    Quote Originally Posted by John Bertotti View Post
    I need to double-check but I think Bill used a cf rod in my OldWave. I am inclined to do an oval f scaled mandolin with a neck I like, I like a nice v, and a cf rod. Obviously, all my guitars have truss rods. Even the 000-18GE.
    So far, the instruments that have been built with CF reinforcements seem to be holding up very well. You will have an easier time building it if you recess the rod slightly and cover it with a wooden strip, as I mentioned above.

  30. #19

    Default Re: Neck reinforcement vs a truss rod

    If you build with a carbon fiber reinforcement, how much relief do you shoot for? My problem with mandos without adjustable truss rods is that almost every builder seems to think a mandolin neck needs more relief than it does. The only builder I've found who gets the relief (and the entire setup) exactly right for me is Michael Heiden--I've never touched the truss rod on any Heiden I've owned. Almost every other mando I've owned (many more than I'll admit to) has needed relief taken out of the neck.
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    Default Re: Neck reinforcement vs a truss rod

    That's another fight I won't go to, except to say very little at all. That is, if the frets are accurate, and there is no rise in the fingerboard after the body joint.
    If a mandolin is rattling with the action set at 4/64" between the bottom of the string and the top of the fret at the 12th fret, see above.

    Truss rods are for straightening a neck, not for adjusting action. Basic set up for all fretted instruments are the following steps in order:

    1] If a neck is adjustable, set it for minimal relief.
    2] Insure the frets are level.
    3] Adjust the nut slots so the strings barely clear the first fret when fretted between the 2nd and 3rd fret.
    4] Set the action by adjusting the bridge saddle height so that the action is 4/64" between the string and the top of the 12th fret on a mandolin. For a flat top guitar, 5/64" between the 1st string and the 12th fret and 6/64" between the 6th string and the 12th fret should be sufficient for a light player. Add 1/64" for a medium handed player. For a slammer, it can be raised to a maximum of 7/64" for the 1st string and 8/64" for the 6th.

    If the instrument won't play, either the set up man has mis-adjusted something, or the frets are not level, and/or there is a rise in the fingerboard.

    Excellent tutorials on fret work, written by experts, are available at www.frets.com, under "Items For Luthiers."
    Last edited by rcc56; Jul-17-2021 at 12:39am.

  33. #21
    Registered User John Bertotti's Avatar
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    Default Re: Neck reinforcement vs a truss rod

    I don't understand why it's a fight. Like everything, there will be those who swear by it, those who don't care, and those who don't like it. My guitars have them and I like them. I replaced a neck on one Strat because the truss rod would not keep it straight and I didn't have the knowledge to fix it. Nice big 1/4" bow to it and it didn't take years to happen. In less than a year it bowed badly and nothing I did from humidifying to, a neck press, string changes, and truss rod adjustments had no effect on it. The new neck with Thomastik Jazz BeBop 12 stays perfectly set up. Sometimes wood just doesn't want to do what you want. It was a skunk stripe maple neck on an anniversary Strat so I didn't cut it apart to get the rod. I just set it aside to keep in case I ever decided to sell it. But the point is people just need to respect a person's decision on how they prefer to build a neck. I'm going to try as you stated above but I think it will be an F style length, V and I.m debating making it a bit taller than the neck on my Oval A just a tiny bit taller in the V the full length of the neck, and a CF bar down the middle.

    As Glassweb above won't buy without a truss rod I can't bring myself to play a Gretsch with a tension bar Bigsby. When you know what you like run with it. Right or wrong. If someone has a compelling explanation why I should reconsider state it. I understand the POV of future adjustability but on the small neck I am will to chance no truss rod, that's on me and apparently I'm not the only one.

    I appreciate everyone's replies they were all very helpful thank you!
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    Default Re: Neck reinforcement vs a truss rod

    Quote Originally Posted by sunburst View Post
    One is adjustable, one is not.
    Bingo.
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    Default Re: Neck reinforcement vs a truss rod

    As Dave Hanson says, the old Gibson mandolin doesn't damage the neck without the truss. It may be the result of not being tensioned for many years. As an example, my Gibson F-4 was manufactured in 1916 and has no truss rods. I own it and play it with almost tension for 46 years, but there is no bow warp of the neck that interferes with the performance.

  37. #24
    Registered User John Bertotti's Avatar
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    Default Re: Neck reinforcement vs a truss rod

    What profile did the older larger necks have on Gibsons Mandolins? Rounder, or V? etc.
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    Default Re: Neck reinforcement vs a truss rod

    Quote Originally Posted by John Bertotti View Post
    What profile did the older larger necks have on Gibsons Mandolins? Rounder, or V? etc.
    V, slightly rounded.
    The old Gibson necks were short and stout, made of mahogany and most had a triangular maple stiffener inset into the length of the neck. The black line on the back of the necks was sometimes a laminated piece of dyed-black mystery wood and sometimes just an inlaid piece of dyed-black mystery wood to give the appearance of a center laminate. Fingerboards were about 1/4" thick ebony.
    The maple insert and the rather thick ebony 'board were contributors to the stiffness and stability of the old Gibson mandolin necks, but for the most part the short length and full profile were probably the main reasons so many of them are still straight enough to be playable.

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