BacK bow in new Ovangkol necks with completely loose truss rod

Discussion in 'Luthier's Corner' started by akori, Jan 4, 2014.

  1. akori


    Oct 18, 2007
    Hey, it's a long read, but help me if you can...Ugh. This sucks. I've ordered four ovangkol neck blanks from Gilmer over the last six months. Had them built into 1 piece Jazz bass necks by USA custom.
    Three fretless, one fretted.
    The Fretless with Ebony is fine... It's been on for three months, and is straight and stable. Sound is stellar.Though it's rod may have only a little tension on it, it set up great and plays great.
    A blackwood fretless board with the same ovangkol neck (appears) to be turning out OK, because I can induce forward bow with adjustment-even though it's not strung up...I'm still applying finish.I am encouraged that it will bow forward without strings on it. I have the highest hopes for the sound of this combo...
    The two problematic ones are a bit scary. A *gorgeous* sounding Pau Ferro fretless board on ovangkol has a totally slack rod, and bowed back pretty bad...after a third leveling, it is ALMOST ok. With Super light TI jazz rounds ( .89 -.43 gauge ,like rubber bands), it actually sounds great with only a few buzzy spots. Immense bottom end and midrange growl, clarity... It may turn out fine, but if it backbows more...disaster.
    One might say -"Just use regular 45-105 strings to induce forward bow...but i'm a TOTAL Thomastik fan, and have grown completely attached to both the the TI Jazz flats-very slack, and the TI jazz rounds- almost like no tension at all. They're both loud and incredibly musical. To me, after getting used to TIs, they simply ruin you for other strings, as they are so easy to play and incredibly nuanced. They make regular strings and gauges seem like clumsy cables with lots of wasted effort to produce clunky sound. I really mean that. And i've loved & played so many brands over the decades. The freedom of expressiveness on such light, yet lively strings as these is incredible, once one gets used to them. No lack of power. Just a tiny flick and the kick and growl.

    Lastly, and WORST, there's that FRETTED ovangkol neck with a wenge board.
    It's really back -bowed, when testing with a true straight edge and a fret rocker, all over the lower to mid-positions, and I wonder/doubt whether any amount of fret leveling can correct the backbow on the top side...again, the rod is TOTALLY slack. No more adjustment to be made. I told my tech I wanted to try leveling down to the super-low Jeff Berlin-type of fret height, but he says my 6150s will be too square at the base and will just feel awful...I have to question this...seems I've seen very fat frets leveled almost flat that felt great in the past. But all would be rendered moot if said leveling didn't correct this freaking backbow...geez, can you tell I'm mad?
    Being from USA CUSTOM, they are single -acting truss rods, and they won't to double-acting (I dislike the extra 4 oz weight and effect on tone/ wood vibration anyway). I understand why some manufacturers/ techs like double-action rods, but am firmly in the camp of many who just feel the metal dominates the sound, and really changes the wood's resonance. Plus the arch enemy. All moot regarding any solutions on these necks, anyway.

    I am at a loss as to whom to approach; USA may say the wood does what it does; it's not their supply. Although I'd WISH they had some useable insights! As to Gilmer; I imagine they'd refund me the truly minor cost of the blanks...but I still lose the extra 600.00 -plus bucks invested in each neck.
    I can hardly imagine heat treatments *really permanently* correct the bending of such a stiff wood as ovangkol, and so many people DIY crazy things, and I KNOW they don't operate with extremely close tolerances as the setups I use...30 -45 thousandths clearance at the 12th position. If they just want vague "playability," well, maybe. The whole purpose of my last six builds is ultimate sound, playability and STABILITY. So-so is just firewood to me.

    I will be consulting the very best luthiers I can find here in Colorado: but as always, the real qestion is Does Anybody Here KNOW (not guess) about wht can or can't be done to relevel the fingerboard to correct backbow, or heat treat & clamp a neck, *IF* a permanent reshaping is even possible? LIke, have you seen it, done it?
    This is a seriously cosytly and heartbreaking problem, affecting at least two, maybe three of these otherwise superb
    necks. I sure would appreciate any informed opinions, as I go to other luthiers.
    I Understand that taking off fingerboard material on a fretless can obviously correct the effect of the backbow, leaving a perfect playing surface, and that if the back bow does not continue, it would be fine. IF, THAT IS...
    I understand a single-acting vintage style rod won't correct back bow. (And that there's no chance of changing the rod type ) I did NOT like double acting rods anyway, and many others concur. Great adjustability, different vibratory properties.

    I know wood, especially super strong wood like Ovangkol, can do whatever the hell it wants to do. I have however, NEVER encountered this backbow before...I son't know what a manufacturer like USA Custom does with a neck blank (like quartersawn one piece ovangkol); whether they should somehow cut it differently than, say maple, to counteract the possibility of backbow, or if the trussrod should have been laid in differently...It's REAL hard to get detailed, cogent answers, just quick ones.
    I am surprised if GILMER, respected as they are, sent me two to four ovangkol blanks that are so nicely quartersawn, yet are warping like personal contact at Gilmer assured me this is very well aged and tended- to wood. Again, I doubt they'd fuss too much about a refund. but each neck now represents about a 600.00 investment, after plainboard design with totally custom top lines ...oh crap, the effort that went into these otherwise perfect necks. None of them even weigh that much & the sound of each pairing is stellar.

    I am a little surprised that USA would build any backbow into the neck, as if it were maple, because Ovangkol is SO much stronger...unless their fingerboard fallaway is just that...such a thing is easily correctable by re-levelling.
    Lastly, I am peeved and bewildered that own my tech(after constructing SO many builds, first told me that removing fingerboard material at the apex of the backbow would be a VERY simple fix, then reversed his statement after the third relevel, saying "All I can do is level the board...taking material off to compensate for backbow doesn't work)...really? It's a TOTAL reversal of what he originally assured me was a piece of cake.

    I would assume with enough fingerboard, planing off the board would correct and perfect a stable piece of ovangkol beneath, again, ughh, so long as it does not continue pulling backward.

    If you've read this far,, any helpful suggestions, or is there a viable fix? I especially worry for the fretted neck. although I do in fact want the Jeff Berlin "Fretless Wonder" super low frets on this one, with a hump at about fret 6-12, this may be impossible. It may be a write-off unless there's a way to reshape the neck itself, or pull the frets and shave the board, then refret. Oh joy. That would really be a waste and a gamble.
    I guess I can't believe that three respected parties in this process have to be addressed seperately, and each may just shrug it off. I 'd like some other input from people with REAL WORLD experience her before I call them.

    Can you help with ideas? MUCH APPRECIATED!
  2. Meatrus


    Apr 5, 2009
    Clamp them flat and leave for a couple of weeks. Don't try removing any material from anything till you know you have to....and you don't have to right now. No heat will be necessary, the above will get them flat, then you can see what they will do next!
  3. akori


    Oct 18, 2007
    Thank you MEATRUS:
    Is there proof that this works on a permanent basis, especially with very rigid woods like ovangkol, pau ferro & wenge? It is easy to imagine bending wood temporarily, and we all know it is done permanently in hundreds of time-tested fileds like ship building, constructing guitar sides, etc, BUT: These methods utilize permanent reinforcement in the form of powerful trusses, bracing, glues and rivets, screws, etc. Obviously, there's NO way to do this with a neck.
    Have you yourself ever seen a back-bow become permanently repaired through simple clamping? How long would you mean by "permanent," if so? This is the vital question. Evidence, not speculation. This is NOT meant to be a snub in any way, but what a clamped neck does next, as you put it...that's the catch isn't it...just a temporary fix... isn't a fix.
    I would be VERY appreciative if you'd reply your experience in detail.
  4. JayGunn

    JayGunn Supporting Member

    It's significant I think that the fretted neck is the worst. Significant because the fret tangs themselves cause some backbow, because they are wider than the fret slots, of course, and the hard fretboard wood doesn't dent easily to accommodate the extra width. That's why I think clamping/weighting the neck may help. You're not just temporarily or permanently warping or unwarping the wood, you're mostly forcing the fret tangs into dents in the fretboard slots to relieve the backbow pressure they are applying now. And when the dents are mature, removing the clamps/weight should not cause a rebound.

    Anyway I'd try it and if the theory is correct, you may be pleasantly surprised. Good luck!
  5. akori


    Oct 18, 2007
    Here's a pic of two of these builds. They sound incredible & are lightweight.
    It is like impossible to post a pic or a link here...this was a URL I posted according to instructions in advanced editing. Meh.

    Thanks JAY GUNN:
    Any opinions on the fretless set: Holy crap, these are amazing necks...Do you predict better or worse outcomes on shaping fretless necks?

    One reason I'm getting as much info -in detail I can is, I'm talking to several luthiers this week...all the input I can get will help me understand their point of view. I know this problem is likely to be looked at as a lost cause by MANY repairmen. And I obviously have no hard proof clamping, heat, etc, work at all, anyway...not permanently.

    Can I just bitch again, what a M.F. this situation is? I got my dream necks, and now I wonder if they won't be trash! Hopefully not! Granted, if these necks turn out absolutely flawless, the builds will be incredible...they sound great, and are all unique. But just for the money of the four necks, I could have bought a freaking Pedulla Pentabuzz used, or a new 4 string buzz. Ugh!
    My WISH is that somehow, forward bow could be introduced, so the trussrod could actually have some traction in the case they don't give in to string tension with some break in. Because even if it sits dead straight (the way I run all my necks), a tiny shift in humidity might necessetate the same thing all over.
    Like it would be so cool if I gould get the reverse of what I saw Dan Erlewine do in a video...he took a FORWARD bowed instrument, clamped it, re-tightened the trussrod, then "claimed" it would be OK...because it no longer had to move the neck, just hold it. Of course it was a vintage instrument. These are brand new builds , with the *tightest tolerances* for effortless playing. I set them up such that most players can't believe it. But it's a treat. That's why I ONLY keep the most stable instruments. I have no problem tweaking setups...Obviously I just need useable trussrods or necks that NEVER move. Along those lines: Next project: I'm calling STATUS tomorrow and ordering a graphite fretless J neck, and will (ASK) if he could possibly make it a bit lighter than normal. I'm also sending an indian rosewood J neck from USA Custom to Michael Pedulla, to coat with his poly...that will cost me about 500 in the end, but Indian just feels soft and kind of lifeless to me after using Brazilian, pau ferro, ebony and African Blackwood.
    Please let me know, again, if you think fretless necks are more problematic to clamp/ reshape. (BTW, the back bow is not insane, merely obvious.
  6. Meatrus is onto a solution. Timber is unique to most materials in that suffers a phenomena called "creep". Basically under load timber gradually sags. It won't break, but it does give and bend. That's why trussrods are required.

    I'd even go a little further that Meatrus...

    I've had a couple of issues with necks developing backbows after fretting despite a. the board being flat and b. the saw being the right width for the fret tangs. I always use double actions trussrods, but I aided the issue this time by "pre-stressing' the neck for a few days with this 16lb weight.

    I'd advise a similar thing. You might even like to lightly clamp it in the middle to bring a forward bow into the neck over a period of a few weeks. It's my feeling it will help a lot.

    Your other alternative is to play the bass with high tension flatwounds (Fender or GHS) for a month or two. THis has also worked for me in the past. It's not as comfy to play, but it will be a more natural settling process and give you a stack of cool 70s tones! :D

    Anyhow, as you say, at this stage give anything a go. But like others I'd say heat is not a good idea.
  7. akori


    Oct 18, 2007
    Thanks, REVERENDRALLY. Interesting pic; looks like that weight is from the early 1900s. Nice fanned frets there, too.
    But...the $64,000 question is? Do you, by experience, know, that bending, clamping, etc., by any means, can reshape the structure so as to make it permanent? (I know the question can lead to complex answers, like, maybe a year, or a week). It's not as though I don't appreciate your assertion that your feeling is it may help a lot...I'm just looking for a definitive, experienced-based answer. Like, "Yes, I did this four years ago, and the neck kept it's appropriate ability to be in relief, to put the trussrod into play if needed, and I didn't need to re do this process." Or the opposite: "Look, I've tried it, seen it tried many times, and it is really just temporary, only a matter of days to (maybe) a few Colorado seasons, then you're back again."
    It's really a critical thing, before I ask Gilmer to refund or replace, and ask USA to maybe give me a break on recutting.
    I'd LOVE to hear an empirical yea or Nay from you. Based on experience.[/B] This is a really un-fun process. For me, trying to figure out who effed a cost of 3k...or if I can fix it, for real, or have to just face stop gap measures. I get no joy out of that...I have to play and instruct for a living, with axes on my shoulder all week long, every day. These are special basses I've been waiting to have all my life. I need them light, of stellar tone, super playable. My collection of tonal needs is almost complete have this hitch at this juncture is maddening. That's why I keep re-inserting the request for empirical knowledge...
    Thanks so much, I appreciate your time.[/I]
    UPDATE, REVERENDRALLY: A really long-time, superb luthier basically agreed with your asessment, adding that the hot iron treatment would do the trick with good reliability if done right. Thank you. So I believe at least the fretless neck will fare well. The fretted..have to see, as i don't know how much the tangs will impede bending.
    Thanks again
  8. FBB Custom

    FBB Custom TalkBass Pro Commercial User

    Jan 26, 2002
    Owner: FBB Bass Works
    I doubt clamping is the solution to your problem. If you apply heat during clamping, correctly, then maybe. You have seen acoustic guitar sides heat bent so you know it is possible to effect wood with heat and/or steam, but will it work on a 5/8" neck shaft with a 1/4" fingerboard laminated to it? My sense is that when people attempt to heat bend a neck you get some shift in the fingerboard/neck joint and that can help remove relief, especially with yellow glue, which does creep.

    It sucks that you are having trouble after you invested so much money, but you are requesting a level of empirical knowledge and guarantees that most here are not qualified to give. And who would want to guarantee their advice? Those who have worked a lot of wood know that it can be unpredictable and there is no one-size-fits-all solution to the problems wood can present. It moves, for a number of reasons, including moisture content and internal stresses released during milling. Did you let the wood acclimate after receiving it from Gilmer?

    I think you are expecting a lot to get your money back from anyone.
  9. Meatrus


    Apr 5, 2009
    Well I can't give you the perfect answer you require as I haven't done it with a neck I must admit, but I have done it countless times with other guitar based pieces of wood and yes it was permanent. The fact that it's a neck could actually make it work even better, as you have string pull working for you. If you can get it flat with the clamps the string pull would keep it there. Even ti flats should have enough pull to stop it happening again. But as rev says, you could string up with some heavier gauge strings for a while to help it a long.

    Give it a go, you've got nothing to lose except time.
  10. akori


    Oct 18, 2007
    agreed, and thanks. My basic desperation is in the huge investment in the best materials, well respected suppliers and manufacturers, a very good tech, and some custom additions (If only I could post pics, you'd like the design tweaks). I always look for cause/effect and evidence. So I get very direct on hunting down solutions. But, everybody here has basicaly said "maybe." No sleight intended there. It's what their experience suggests...maybe.
    Today I spent an hour with one of the really great acoustic luthiers around...a guy who was with Guild for fifteen years, and worked with some of the really influential designers that came out of Martin, into Taylor, etc. He looked at the Ovangkol neck/ pau ferro board bass and agreed; no truss rod in play would be a disaster in Colorado. Any moisture can have a huge effect after 3% humidity for weeks. BUT: he said;
    Put your TI flats on it. They at least have SOME string tension, instead of TI rounds (incredibly light). Wait up to TWO WEEKS.( After that, if it hasn't coaxed enough forward bow to allow the trussrod to actually be useful, it won't do it.)

    At that point, (and keep in mind this guy is literally in the annals of acoustic luthiery in the USA during the important period of late 60s-70s), he said, heat treating the neck to induce some forward bow is the way to go. He also was very skepctical that the cellular structure of the bulk of the neck would change much. He believes it is the glue joint between the fingerboard and neck...which will move and create the requisite shape change. Being careful not to delaminate, of course. He said it's no problem to use heat (in the correct method (and he pulled out the old iron specifically used for doing this with necks) to create the little bit of relief needed. Then, he said, the trussrod would be in position to actually force the neck from backbow to straight, if and when it crept back again. As to permanence? He said it is likely to be long -lasting, perhaps permanent, perhaps not. So, As I know Andy personally, and have seen his work, I can trust his experience. It jibes with what roughly half of posters here -and elsewhere's the way to go, can be really long term, might not. Not hard to do, if you truly know what the hell you're doing. disastrous if you are winging it.
    He also said (though he made no assumptions, or do I claim I know what the manufacturer did with the trussrod channel), that the trussrod should be laid in -I believe I remember him saying- with a bit of a trough beneath the center of the rod? forgive me, I'd have to ask him to repeat it. Basically he said simply laying it in a flat channel could invite this situation in a single acting rod on wood that could it might be totally preventable if I communicate this to the builder for new builds. I will definitely pursue that concept, getting him to re-clarify his assertion so I get it right to the manufacturer. He did allude to the fact this was's not simply the wood.
    So! I put on TI flats, which probably have 10 lbs more pull, and will simply wait two weeks. Meanwhile, I'll contact the manufacturer, and run it all by them.
    (BTW, my fretted ovangkol/wenge neck has not gotten ANY relief in 24 hours of being strung up with DR Highbeams 105-45. This signals to me that THAT neck may really be a problem. That trussrod is just hanging loose, and the neck won't flex. But heat would be applied there as well if need be. I will still most certainly try to see if manufacturer will at least throw me a bone for being a very loyal repeat customer, and maybe discount two rebuilds...again, this backbowing *might* really have been avoidable. We'll see. It's going to take a month or so to begin to know. That sucks.

    In the meantime, partly disgusted with everything, I called STATUS GRAPHITE at 4AM...they were MOST professional, courteous and detail oriented...answered my questions (the freaking phone secretary!) with knowledge and authority, and passed on all requests for custom options for a Jazz fretless neck. Totally open to suggestions, in command of the process. I am going to most likely order one and give it a serious go. They did say they coulf play with the weight of the neck (main concern), and agreed with me that it'a all about the weight vs stability issue, and not to go too light, so they seem uncommonly sensitive to the important realities of the full-time pro who needs a comfortable, nearly perfect workhorse. Very good impressions so far.

    I'll keep you all posted about the process of trying to correct the backbow/ trussrod issues of these two necks. Hopefully, Andy, with his very high pedigree of experience, will have the vbest fixes available, and I'll let you know, for the sake of improving the knowledge base. Again, I wouldn't just take someone else's word on how good he is...I know his work, and he's in the history of modern acoustic luthiery. So I shall report what I find.
    And I'll also report how USA responds-if indeed there's anything they could have, or can do...I love their work, and have ordered so much from them. I go Warmoth too, and have good things to say about them. The main reason I go to USA for necks is, they offer improved but still traditional truss rods...I avoid that nasty 1/4 lb of extra steel in double-action rods. Especially since I sometimes have an 8 oz Delano double J HE series PuP in the bridge...things get heavy fast. I shoot for necks at 1,5 to about 1,85 lbs. I have a real comfort range that extends up to a max of 8.75 lbs, preferably more like 8,25. After that, all the teaching and playing sets up problems. It isn't fun, then it hurts.
    Thanks to all...I will keep you posted, and thanks for your input. It is most welcomed.
  11. akori


    Oct 18, 2007
    MEATRUS:, Thank you. Your basic opinion was very well supported by a proven lifetime pro luthier of the highest caliber, whom I'm lucky enough to know.
    He just said give it two weeks with heavier strings. If that doesn't do it, we can use the proper, conservative heat method with the iron, and coax the fingerboard/neck glue joint to move, inducing enough forward bow to make the trussrod useable, actually bearing some weight.
    He said it's a good, likely long-term fix, though shrugged about ultimate permanence. He did not express much doubt that it was none the less cheap, easy (for someone with the experience) and quick.
    So as I research this with the manufacturer to discuss trussrod placement, I may well be on my way to ironing some boards. Well, Andy might, anyway. I'll watch and report.
    Thanks, and again, thanks to ALL..if anybody else wants to chime in, or comment more, please do, the variables in this should be continually pushed toward scientific certitude (haha, as much as possible). This is why I always use the word "empirical," so we don't chase our tails).
  12. Bummer. Sounds like the fingerboards on the problem necks were extremely dry when glued up to the neck blanks. I believe you're on the right track regarding heat induced glue joint creep. Worth a try. Worst case is you get USACG to remove and reapply the fingerboards. Not the end of the world.
  13. Short answer...


    It's just a matter of how long it takes.

    Let me give you an example. I've got a mexican tele with a maple neck/board. I've owned it 8 years now. About a month back I noticed the neck had a little too much relief. When I went to adjust the rod, I found it was completely slack. Ie. it had never been tensioned up in the previous 8 years. The tension of the light guitar strings (0.010-48") had very gradually pulled the neck into relief. I've seen the same effect on this bass using the double action truss rod and flatwound strings.;-fundabirds-go-pew-wood-962492/index5.html#post14667971

    Let me put it this way...

    If bending/clamping didn't work, we wouldn't need trussrods to keep necks straight. ;)
  14. akori


    Oct 18, 2007
    DMUSIC148 :
    Thanks. But, HEY! I hear people (some talk of removing boards, like it's not too bad). Others , including some manufacturers act like it's not nearly worth the effort. Like it's a real waste of man hours...I KNOW it gets done when it's it really that easy / nondestructive to do?
    I will read up on it, but would appreciate your experience...
  15. Yes, unless you've got a glossy clear or painted finish, it's really not a big deal.
    I would suggest you give USACG a call and discuss the situation with them.
  16. akori


    Oct 18, 2007
    Thanks, dmusic148
  17. akori


    Oct 18, 2007
    Thanking you again, REVERENDRALY: My friend, a longtime luthier who has immense experience, said if the neck doesn't forward bow in two weeks with heavier strings, he'd have a relatively easy time applying an iron to loosen the glue joint between neck/ board, and reposition it. Said it's likely to work very well, and cheap.
  18. pilotjones

    pilotjones Supporting Member

    Nov 8, 2001
    If you're trying to induce a forward bow using tight strings, it will help if you raise the action high. Greater bending moment on the neck beam.