Essex SX truss rod?

Discussion in 'Hardware, Setup & Repair [BG]' started by Mustang Surly, Feb 7, 2014.


  1. Mustang Surly

    Mustang Surly

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    I have an Essex short scale whose truss rod appears to be bottomed out. By that, I mean the truss rod is functional, but will not flatten out the neck as much as I would like when completely tightened. From what I understand, this can happen when the threaded nut or plate on the body end of the truss rod (inside the neck) crushes the wood against which it bears, thereby reducing the rod's potential, over-all, effective travel.

    The bass in question is currently strung with light-gauge, round wounds: .036"-.054"-.062"-.088" (according to my calipers). Certainly nothing excessive which one would expect to overwhelm the truss rod. Of course, I don't know whether the previous owner used heavier strings in the past. When I got the bass, it had already been adjusted to the point where there was not more that 1/8 of a turn left in the "tighten" direction. When I lower the action to taste, I get fret buzz when playing in the upper registers (above 10th or 12th fret) unless I play with an EXTREMELY light touch.

    With a truss rod that has a nut on the headstock end (under the truss rod cover, like a Gibson) the solution is supposedly to remove said nut and add spacer washers under it. But I'm not sure how something equivalent could be done with the SX truss rod, which is a rod with a (female) hex on the headstock end, rather than a solid rod with a nut on it.

    If I have a correct understanding of how these truss rods are constructed, I assume that the round collar (visible inside the truss rod hole, headstock end) of the Essex, through which the rod itself seem to pass, could also be shimmed. But that would require completely unscrewing and removing the entire truss rod, leaving the plate on the body end of the truss rod route still loose inside the neck.

    My concern is that I worry that once the truss rod is shimmed and re-inerted in its hole from the headstock end, that it might get cross-threaded in the plate at the body end (since there is no way to hold that square to the rod as it is re-threaded.

    If I am misunderstanding how the components of this Essex truss rod are constructed and how they fit together/function, or if I am over-looking some easy solution, please school me, as I am obviously no luthier (though I have managed to perform serviceable set-ups on my other basses, none of which suffer from the malady outlined above).

    Thanks in advance.
     
  2. bassbenj

    bassbenj

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    I am not familiar with short scale SX basses so following could be wrong. But the question is: Is your truss rod "double acting"?

    If it is, it's not a rod at all! In generaly all my 34" SX basses use one or more double acting truss "rods". They are not "rods" at all. They are sort of a sandwich of three pieces of rctangular metal that are fitted together in a stack. At one end there is a "female" hex screw that operates it. When you tighten the screw one way the rod flexes in that direction and if you tighten the screw the other way you bend the metal stack the other direction. It fits in a groove under the fingerboard.

    If this is what you have the bad news is it's going to be tough to fix. The mechanism is sort of glued in place in its slot and may have come loose. usually the neck is absolutely flat with no tension on strings or rod. But if the wood is compressed or glue loose you may not be getting enough force backward against the strings. There is no simple way to fix this save, take the fretboard off and reshim and glue the truss "rod".

    If this is indeed the case, I'd save the bass for when I wanted to make it fretless then I'd get a new fretless fingerboard for it, steam the old one off and fix the truss rod problem while it's apart.

    Sorry.
     
  3. Mustang Surly

    Mustang Surly

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    Ugh...

    I don't think I'm getting a clear picture in my head of how what you have described works, but it sounds like kind of a Mickey Mouse arrangement. Does the other end of the female hex bolt at the peghead push on the end of the "stacked rods", causing them to flex? What does the female hex bolt thread into? The "glued in" part has me scratching my head. You don't happen to have disassembled one of these necks and have any PICs of one of them with the fretboard off, do you? If I could see what this "trussrod" looks like in place, I think I would better understand how it works.

    Guess it's not really reasonable to expect sophisticated engineering at this price point, which is a shame, since it is otherwise a pretty nice little instrument.

    Crap...
     
  4. lowfreq33

    lowfreq33

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    In your case I would just shim the neck.
     
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  6. T-Bird

    T-Bird

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    Hi.

    https://www.google.fi/search?q=trus...tGciY4wSH0YHADA&ved=0CCkQsAQ&biw=1024&bih=605

    From those pics You can get a pretty good idea how the dozens of different adjustable TR designs work.

    I have never seen a three rod double acting TR, and as an engineer, can't quite understand why it would be better than the normal 2 rod one.

    Got a pic, bassbenji?

    Also, in a case of a compressing single acting TR, IME if Your neck is dead straight as opposed to slightly convex with strings off and the TR loose, you're in trouble sooner or later.

    AFAIK only certain Rickenbacker traditional TR's are removable without major surgery, so there should not be need to concern Yourself with the possibility of the anchor end coming loose unless there's steel nut and it seizes.

    There's also quite a few modern TR designs that allow to replace the TR without taking the FB off, Warwick has probably the most common one.

    Regards
    Sam
     
  7. Mustang Surly

    Mustang Surly

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    I may try the clamping technique mentioned here:



    He says that the neck may "take a set" if allowed to sit improperly adjusted over a long period of time, and that in such a case, the truss rod will have a hard time overcoming this "set". The idea behind the clamping is to loosen the truss rod and then use the clamp to unbow the neck, then re-tighten the truss rod with the clamp in place. This way the rod only has to hold the neck flat rather than un-bending it. Sounds logical to me, and Erlewine certainly has a good reputation.

    I guess it's worth a shot, and what do I have to loose? I'll cut some clamping blocks on my band saw to match the FB radius and pad the clamp to (hopefully) prevent any denting of the back of the neck.

    I'd really like to save this neck since it has the old style headstock and I don't care for the newer, "canoe paddle" look. I also want to use slightly heavier flats (.045"-.100") so the bow has got t'go.
     
  8. Mustang Surly

    Mustang Surly

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    So, I removed the neck and found a small sandpaper shim at the wrong end of the neck pocket plus some wood chips that look like they came from the bit flutes when the holes for the neck attachment screws were drilled at the factory (I seem to recall others complaining about the latter lack of neck-pocket house-keeping by Rondo factory personnel). Really no excuse this, even in a low-priced instrument, given how trivial it is to avoid it. So it appears that part of my problem involved the shim and chips buggering proper neck angle.

    Anyway, I brushed out the chips and made a new shim for the OTHER end of the neck pocket and reassembled (Thanks for the suggestion, T-Bird). The upper-register fret buzzes are now gone with these light-gauge, round-wound strings (with the action at a playable height, intonation set and string arc matching the the fretboard radius) but I think I will still have to clamp/flatten the neck if I want to lower the action and use slightly heavier flats. They will doubtless pull a little harder on they neck, which already has the absolute maximum relief I can live with with the truss rod completely maxed out. I've started making some padded clamping cauls so as to avoid marring the neck during the process.

    If that doesn't flatten the neck a bit, I guess I'll have to find some lighter flats, like maybe La Bella Deep Talkin' extra lights (.039"-.096") for this bass and learn to live with the slightly higher-than-optimal action.
     
  9. Ric5

    Ric5 Supporting Member

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    I usually ended up replacing the necks on all of my SX basses ... problem solved.
     
  10. Mustang Surly

    Mustang Surly

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    "I usually ended up replacing the necks on all of my SX basses ... problem solved."

    That would do it all right. Problem is:

    -I'm pretty dead set on having the "old style" headstock, which is no longer in production (so far as I know) and hence not readily available as a replacement part from Rondo.

    -There are at least 2 distinctly different, old-style headstock, short-scale, SX neck widths (at the pocket) made that I've seen. I'm talking about 1/4" difference here (2" vs. 2-1/4"): not inter-changeable with just a bit of "fine-tuning" of the fit.

    Of course, at this price point, I suppose there's an argument to be made for buying up a stack of complete basses and re-assembling the best parts from the lot into two or three really nice ones. But, depending on how many would be required, that starts to erode the "deal" you're supposedly getting by owning an SX in the first place.

    In any case, I have other basses to play while I try to salvage this neck, so down time isn't a major concern. I'm curious to see whether or not I can make the procedure work. I guess that, even for an experienced luthier (which I certainly am not) it's kind of a crap shoot.
     
  11. Bobster

    Bobster

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    Mustang Surly,

    You should be able to remove the truss rod's barrel nut, put washer's on the rod, and reinstall the nut.

    In theory, that's how it's done.

    Not sure if, or why your bass would be different.

    All the best,

    Bob
     
  12. Mustang Surly

    Mustang Surly

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    Completely loosened the truss rod and clamped the neck into a back bow. Cauls on the FB side are radius-matched and padded with leather. Back caul matches neck profile and is also padded with leather. The clamp "button" fits into a flat-bottomed hole which I cut into the back caul with a 3/4" Forstner bit and the clamp bar fits into a slot in the side of the back caul. These latter two features help hold everything in place while you tighten the clamp.

    [​IMG]

    Re-tightened the truss rod after about an hour. Re-installed the neck and put on some 45-100 flats, brought the action down as far as possible (w/o buzzing) set the intonation and matched bridge saddle curve to FB radius.

    Much better, but still not where I'd like it (still a bit too much relief). I hesitated to remove the truss rod nut completely because it seemed to "stick" when I got it all the way loose, which suggests to me that the threads may be buggered on the very end. This could have made threading it back on problematic, so I wanted to see if it would hold the neck flat flat after clamping without added spacers.

    Since it seems to need spacers, I quess I'll have to pull the nut all the way off and hope that it dresses the threads on the end of the rod as it comes off and doesn't cross-thread when I put it back on after adding a spacer or two.

    Wish me luck!
     
  13. bassbenj

    bassbenj

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    It's my fault but I don't have a pic. When I had the SX apart converting it to fretless i didn't think of taking a pic of the truss "rod" until I had the new fingerboard glued on! <sigh>

    However, the thing is very much like those stacked dual rod double acting arrangements where when you get a differential presusre beween the two rods it bows them up or down in the center. You can see that kind in the Stew-Mac catalog to sort of get an idea.

    But the SX mechanism is a stack of like three metal sheets that fit vertically in a long slot in the neck under the fingerboard. Thus the "rod" has no rods at all and is sort of long and rectangular in cross-section. The Allen female screw on the end somehow creates a differential force that bends the stack up or down at the center. It actually works rather well even though it does look a bit hokey! One thing that bothered me about it was that it seemed to have no lube at all and that made it seem to operate rather "bindy". So when I had mine apart I gave them a spray with some teflon lube before I put it all back together and that made the truss rod adjustments seem MUCH smoother.

    That's about what I know and sorry I didn't think of pictures until it was too late.
     
  14. Mustang Surly

    Mustang Surly

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    bassbenji,

    "The Allen female screw on the end somehow creates a differential force that bends the stack up or down at the center."

    Can you describe what the "Allen female screw" threads onto/into, allowing it to exert force on the "stack"? I'm trying to figure odds of getting it re-threaded are if I remove it completely. I'd rather switch to lighter-gauge strings (that this truss rod, un-shimmed), might handle better) than to wind up with a truss rod rendered completely non-functional by my not being able to re-thread the nut. Also, were there enough extra threads on yours to accommodate shims/spacers?
    ________________________________________

    "...sorry I didn't think of pictures until it was too late."

    That is a shame: I'd really like a clear visual of exactly what I'm dealing with, here. If anybody else who has had one of these necks apart has PICs of "the innards", I sure appreciate your posting them.

    Has anyone else here completely removed and then re-threaded an SX truss rod nut with the fretboard still on the neck? I'm speaking specifically about these oddball SX rods, here: I already know that the nuts on Fender and Gibson truss rods come off and on as long as the threads are un-damaged.

    Thanks again, everyone, for your input.
     
  15. Mustang Surly

    Mustang Surly

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    Here is a video that gives you a brief glimpse of the SX truss rod (@ about 1:14):



    Note that the guy says that it is the double-acting type and implies in passing that nut does NOT come off. I have verified this with Kurt at Rondo (who, as always responded within a day), so shimming the nut is out. I was afraid of this, both because of what bassbenji stated in his original response and also because my nut loosened only so far and then stopped, just as it does when you reach the limit of its range in the clockwise direction. In other, non-guitar applications, I have sometimes encountered "non-removable" bolts/nuts (end of bolt swedged or last couple of threads otherwise intentionally buggered by the factory).

    So I guess my only two options left for this neck are:

    (a)-loosen the truss rod, clamp the neck into a back bow for maybe a week, re-tighten the nut to the max and hope that this give me a better result.

    and/or

    (b)-go to lighter gauge strings (than 45-100s) and hope that the reduced tension will result in less relief.

    Too bad, this bass is dead mint: not a mark on it. But the action is simply too high. Guess it may wind up as nothing more than interior decoration if neither (a) nor (b) does the trick.

    Oh well, beats a portrait of Emmet Kelly painted on velvet...
     
  16. bassbenj

    bassbenj

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    Yeah, that's the double-acting truss rod. As you can see it's not a rod at all but rectangular. And if you get a close look at it you'll see it's actually a stack of flat pieces. Somehow (and I haven't a clue how the mechanism works) creates differential force on the flat pieces causing the "rod" to bend either one way or the other.

    If the bass is down to being a decorator item and you can't find a new neck for it, I'd try the rule: If it sticks, force it. If it breaks it was probably bad anyway! But before I tried that I'd see if I could get some oil (or maybe better would be teflon spray) dripped down that screw and worked around by tightening and lossening it a number of times to work the lube into the treads. And then see if I could get the rod to work. If its double acting it should work two ways. One way should give you even MORE relief and the other way take relief away.

    I know these rods can sometimes be stiff to turn and I'm wondering if you just got too paranoid to give it enough pressure. But as I said they work MUCH better if you can somehow get some lube into the screw end of the mechanism. Between the two directions of tighten or loosen the screw is very loose and rattly. But it gets tight pretty quick either way.
     
  17. Jazz Ad

    Jazz Ad Mi la ré sol Gold Supporting Member

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    Neck short scale neck at Rondo's = us$ 49.95.
    Is it worth the effort ?
     
  18. T-Bird

    T-Bird

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    Hi.

    Thanks for the video.

    That's a normal 2 bar TR he's holding.

    Flat bar on top, round on bottom.
    Enveloped in shrink tubing.

    Judging by the size of the allen key (and the shrink tubing), it's the one with just RH threads and the the nut anchored with a collar.

    If the allen key is smaller, then it's usually the barrell type.

    Regards
    Sam
     
  19. bassbenj

    bassbenj

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    On a closer look, you are right that one is round on the bottom.

    The ones in the bass were not round on the bottom and some of the shrink tube was damaged and you could see the interior.

    And like I said, I really don't know what they use on short scale basses.
     
  20. Mustang Surly

    Mustang Surly

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    I sincerely appreciate your input, guys, and really don't mean to play the "glass half empty" guy, but...

    Bassbenji,

    "Between the two directions of tighten or loosen the screw is very loose and rattly. But it gets tight pretty quick either way."

    That's how mine is: not a huge amount of range/travel, but not stiff or bindy at all until you reach the two extremes.
    ____________________________________

    Jazz Ad,

    "Neck short scale neck at Rondo's = us$ 49.95. Is it worth the effort ?"

    Good point, and one which I already considered awhile ago. If the measurements in those listings are accurate (and I have no reason to doubt that), I think that both those necks are too narrow for my neck pocket. The RWFB one is listed as 2-1/8" at the 20th fret and the MFB one, 2-3/8" (and in any case, if you try to put the maple one in your cart, it shows up as "out of stock"). My neck measures 2-1/2" at the 20th.
    ___________________________________

    T-Bird,

    "If the allen key is smaller, then it's usually the barrell type."

    Mine takes a 4mm Allen key. Kurt seemed pretty emphatic that the truss rod nuts are NOT removable on ANY of the guitars/basses that Rondo sells. I'm proceeding based on that assumption unless somebody with an older SX SS bass posts here that they have successfully removed and re-installed their nut and wound up with a fully functional truss rod.
     
  21. Mustang Surly

    Mustang Surly

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    Gremlins!

    So I pull the bass in question out this morning and the action doesn't seem quite as bad. Only thing I can figure is that the neck had, indeed "taken a set" (as mentioned by Mr. Erlewine in the previously-linked-to video) and that my clamping knocked some of the starch out of it and allowed it to respond better to the re-tightened truss rod. They do say that it can take a couple days for a neck to respond to an adjustment.

    Then I was comparing the problem bass to another (that is set up JUST how I want it) and noticed that the E and G nut slots seemed a bit higher than on the "good" bass. Plugged into the tuner and sure enough: with the E and G dead on open, they were a shade sharp fretted on the first fret (hey, I never claimed to have perfect pitch!) So I cut those two slots a few thousandths lower and damned if that make a noticeable difference in playability!

    This little journey is sure giving me a greater appreciation of how minute tweaks can yield surprising benefits. Still don't have this thing right where I want it, but at least it's heading in the right direction.
     

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