2008 620 backbow/twist

Setup, repair and restoration of Rickenbacker Instruments

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Blomp
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2008 620 backbow/twist

Post by Blomp »

Hi

I have recently purchased a used and pretty much unplayed 620 that a previous owner had left on a stand with apparently 'wet noodle' gauge strings on and seemingly not adjusted the truss rods at all, so it had developed a backbow I thought I could easily correct...

Upon putting 10 gauge strings on it (as this seems to be the standard, recommended gauge - I have every intention of using my preferred 11-52 gauge set on this guitar!), the buzzing in the lower fret area improved a little after a couple of days, but was still unacceptable. I tried loosening the truss rods incrementally, using 1/6th turns on each (hex nuts giving me the visual cues as to how far I had turned them) and then checking - but all that happened there was that the neck bowed in the middle but stayed bowing back around the 5th fret to the nut area and I was still getting an unacceptable amount of buzz on the bass side - so a kind of "S-shaped" neck problem

so following a recommendation I read on here, I've taken off all the string tension, loosened off the truss rods all the way, and let the guitar sit with no tension for 48 hours. What I have now, with no tension in either direction on the neck, checking with a notched straight-edge is a perfectly straight treble side and a very slight backbow on the bass side, indicating that there's a slight twist in the neck. It's very small but it's there.

So, what would you guys recommend I do? Where should I go from here? Just string it up and set it up as normal with the heavier strings and hope for the best? :lol: I'm optimistic that I'll be able to get this sorted without having to resort to heat treatment, re-leveling the board, etc...
"Say what you wish in abuse of me, for my silence towards the idiot is indeed an answer. I am not at a loss for a response but rather, it does not befit the lion to answer the dogs." - Imam al-Shafi'i

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Re: 2008 620 backbow/twist

Post by maxwell »

"Where should I go from here? Just string it up and set it up as normal with the heavier strings and hope for the best?"

My two cents: Absolutely. Certainly, this is the least expensive and most conservative (cautious) approach.

Yes, put your favored strings on, tune up, check & re-tune daily for as long as it takes for the neck to settle into whatever position it is destined to assume. I'd make sure that the truss rod nuts were loose so to not have any limiting influence from the truss rods; you can adjust those later. I'd give it at least a week, checking and retuning once a day. (A little of that settling in de-tuning will be due to residual new string stretch.) Guys who are impatient and try to speed/muscle things along seem to be the ones with the most unresolved and/or new problems. You seem to have a good handle on this; seems like it will work out OK.

PS - If you find, for example, that your high e side has reached a pretty good relief/good action, then you might lock it in by snugging up the truss rod nut for that side only. Continue to check and re-tune, allowing the low E side to hopefully continue to favorably change. If it stops changing, then loosen that first nut, which will hopefully allow the entire neck to change. (In my experience I think that the rods are too close together and centered in the neck to allow for controlled lateral independent change. Also, if you truly have a slightly twisted neck, just ignore it.)
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Re: 2008 620 backbow/twist

Post by Blomp »

thanks - i'll try that. I did see a step by step guide someone made where they said to gradually introduce string tension and counter-balance it with just a little tension on the truss rods, but I think that was mainly aimed at guitars with the older style truss rods.

I'm not expecting to have to do any major corrective surgery here but if it comes to it i'm fine with it - but as the only issue is that the strings start to get progressively more 'choked' as I go below the 5th or 6th fret and then are pretty much unacceptably rattly/buzzy at the 1st and 2nd fret (more so on the bass side), it probably shouldn't take much to put it right.

I can certainly understand why some people would be impatient though, it's difficult not to play these guitars! :lol:
"Say what you wish in abuse of me, for my silence towards the idiot is indeed an answer. I am not at a loss for a response but rather, it does not befit the lion to answer the dogs." - Imam al-Shafi'i

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Re: 2008 620 backbow/twist

Post by maxwell »

"... but as the only issue is that the strings start to get progressively more 'choked' as I go below the 5th or 6th fret and then are pretty much unacceptably rattly/buzzy at the 1st and 2nd fret (more so on the bass side)..."

This sounds like a problem with the nut/nut slot depths, i.e., cut too deeply and allowing/positioning the string(s) too close to the (first) fret. I say first fret, as this is where nut slot-string clearance is typically measured.

What would be cool is if the nut were loose and you could lay in 2 or 3 thin strips of something (e.g., index card) under the nut to raise it upward just as an experiment to see what happens. You could probably do something similar at/on the nut slot(s) themselves (tiny pieces of paper in the slot), again, just to see what happens to the string-fret relationship and playability (no, it's not going to sound great; we're just experimenting/diagnosing). If you think you'd like to fix/adjust this sort of thing yourself, then you'll have to buy a set of nut files (if you don't already own them). There's a company called Nomad that make neat little setup items that I like, e.g., gauges with recommended adjustment ranges.

One thing that I bought years ago was an 18-inch aluminum ruler (at Hobby Lobby) to assess neck relief/curvature. On one side/edge I marked off fret positions and carved out half circles to allow the ruler to sit on the neck, bypassing the frets. (The metal is relatively soft and cuts with a bur, which is easier and faster than using an abrasive stone; messy, of course; wear a mask, use a vacuum to clean up or sit in your back yard when doing this.) This, like the fret files, is something you don't use much and so you question the value of buying these things. But it sure is useful. If you didn't want to cut out areas for fret clearance, you could use the edge on the frets; not quite as accurate for assessing, but probably OK, especially if the fret aren't worn and they all seem to be seated well. I used this (the notched edge) to adjust the neck on my 325 the last time I worked on it (it's easier with the strings off). I hold the notched edge so that it contacts the neck proper and peek along the length of the ruler to see where it's touching and not touching the neck. In my case, I had that typical bow, too much relief (too much clearance at the middle of the neck) that I wanted to eliminate. So, adjust a little, see what you get, adjust again (aiming for a perfectly flat neck for now). When I got close and it became tricky to assess/eyeball the degree of clearance, I used a quarter inch strip of paper to use as a shim; lay the shim midway on the neck between frets, reposition the ruler (don't press downward), and see if there is any drag on the shim as it is pulled out, a sign that you're there. If you're really particular, you'll adjust until there is an equal degree of drag at all three check points (near the nut, middle of neck, near the body). That's probably over-kill, as the neck will assume some relief once the strings are in place and things settle in. You could repeat the check & adjust with the strings on if you wanted a really flat neck.

Well, anyway, I read your reply and it just seemed to me that there could be a problem at the nut....
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Re: 2008 620 backbow/twist

Post by Blomp »

So far the neck seems to be responding well to the tension of the 11-52 gauge strings with no counteracting tension from the truss rods :D I do know someone who has a 1953 gibson les paul, who has it set up with the truss rod bolt loosened off all the way with 11-54 gauge and it plays great. I guess some guitars are just like that. But obviously I'm gonna let the guitar sit for a few more days, checking periodically.

Good point about the nut, I haven't actually paid much attention to it yet - I'm actually gonna have to widen the nut slots to fit the strings properly, as they are currently riding on top of the slots (i'm gonna leave that alone for now, though), so naturally the height of the nut slots is gonna be checked in the process. But there was some measurable backward curvature in the neck that was also consistently observable with the fret rocker (rocked very slightly on almost every fret), although actually I think the perceived "twist" was being exaggerated by a slightly raised 3rd fret inlay throwing off my measurements :lol:
"Say what you wish in abuse of me, for my silence towards the idiot is indeed an answer. I am not at a loss for a response but rather, it does not befit the lion to answer the dogs." - Imam al-Shafi'i

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Re: 2008 620 backbow/twist

Post by maxwell »

Good deal!
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Re: 2008 620 backbow/twist

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Several weeks later and - well, it's certainly playable, but it's only improved enough to make the first fret notes sound relatively clean but get choked much more easily when playing harder, and this isn't something that gets fully corrected by raising the action super high, the 'theshold' of attack where the first fret notes sound kinda dead/choked is much lower than all other frets. The neck still appears to ramp backwards toward the nut (reverse ski-slope), a little more on the bass side than the treble side - even with the truss rods disengaged and the string tension pulling it forward, it kinda bows normally in the middle and still has a hint of backward pitch around the 2nd and 3rd frets. it's better than it was and it might fully correct itself over time under the tension of my preferred 11-52 gauge strings, but if not, I guess I have the following options:

1) I could try removing/refitting the truss rods, i've seen people saying that sometimes the modern style truss rods can get turned over inside the channel causing them to exert pressure in weird places. From a mechanical standpoint, it's easy to visualize how this could be a potential source of the neck seeming to be mis-shapen! so it might be worth checking. I might have a bit of difficulty getting the rods out though - the finish has been applied after the rods were fitted (this, apparently, was standard practice, according to that rickenbacker factory tour video from around 2010, though it seems they changed this process more recently?), and there's a lot of lacquer buildup inside the slots for the truss rods at the heel - the bass side rod is practically glued in place!

2) Failing that, it likely needs either heat treatment to straighten it out (it's only minor, and I've seen old posts from John Hall saying that Rickenbackers generally respond very well to this) or even just some fret leveling. I don't think it's gonna need anything as drastic as having the board re-leveled at this point. but that's something I'm willing to have done if it needs it! I have a regular tech that I use for most setup work that can't be done by turning a few screws, though he'll probably point me in the direction of his recommended luthier if he thinks the neck is too out of whack to level the frets. Also I'm not that far from Jonny Kinkade if he's still doing that kind of work (If you know, you know :wink: he's probably the industry's best kept secret for guitar repairs in the UK... and he's only about an hour away from me - i only know him because he used to be one of my neighbours in Bristol!)
"Say what you wish in abuse of me, for my silence towards the idiot is indeed an answer. I am not at a loss for a response but rather, it does not befit the lion to answer the dogs." - Imam al-Shafi'i

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Re: 2008 620 backbow/twist

Post by maxwell »

I had a thought about enhancing the (forward) bow action of the strings, and that would be to place a small block of wood (maybe a half inch high, wide enough to straddle a couple of frets to avoid marring the fretboard finish) and having the tightened strings go over that block. Place the block where the greatest errant curvature of the neck is. It would look sort of like a suspension bridge. The strings will necessarily leave their nut slots.... Well, it was just a thought.

I've fooled around with truss rods an awful lot. I understand what you're saying about curved truss rods and their relative/rotational positions within the neck truss rod concavity. Typically the rods are pre-bent and placed into the neck with the concave side facing "up" towards the fretboard and the convexity that will serve sort of like a fulcrum for the activated (tightened) truss rods. Like this, it's easier to slide/tap the rods into the neck (at the headstock), and this orientation minimizes potential damage at the body; they do have to protrude an inch or two in order to place or remove the nut and washer assembly. For my Rose Morris model 1996 (import 325), I thought that if I could rotate the rods so that the bent concavity of the rods faced away from the fretboard that this would enhance the neck straightening (reduce relief) that I wanted. I did do this by using a box wrench ("spanner"), turning the acorn nuts at the lower end of the neck beyond simple tightening, so that this nut turning actually turned the truss rods themselves. I had to mark the circumference of the nut to ensure I turned it/the rod a full 180 degrees (only). It was not easy and was sort of scarry, as it's easy to scratch up the body down there; not much room; have to lay down some protective material.

But, fooling around with the rods with this goal is only potentially helpful when the rods (truss rod nuts) are not activated (tightened). Once you tighten the nuts and shorten the rod lengths, the shape of the rods change (straighten) and engage (touch) the convexity at the underside of the neck, tending to actively produce a backbow force. This negates pretty much any potential influence of the curved, non-activated rods. So, there's not much sense in even trying something like this in mind. I've concluded that all this Rick truss rod manipulation to correct everything is over-rated; any attempted correction via truss rod adjustments beyond establishing the action is misplaced expectation. Oh, I've read a couple anecdotes of successful un-twisting of Rick necks, but I'm dubious; doubtful of a correct diagnosis in the first place.

(A pure twisting of the neck in and of itself is not really cause for much concern; well, I'll say, a full-neck-length twist. Over 10 years ago now (wow, how time flies) I had a lengthy thread on the RIC forum, entitled "Rats! Twisted Neck!" and it documented my attempts to straighten that. One guy posted a photo of a bass guitar that had the twist purposely incorporated into the neck design, meant to reduce wrist/hand strain while fretting. Anyway, if you take two pencils and hold them parallel between straightened and outstretched fingers and then rotate your hands slightly in opposite directions, the pencils move but do not bend, and they still remain basically parallel to each other. In the end, I ignored the twist. I was able to compensate for slightly differing string heights at the bridge via saddle height adjustments. Both the "e" and "E" strings parallel the neck nicely.) Your twist seems to be something partial and focused, limited to that troublesome area you mentioned.

I (personally) would take the guitar to KInkade after letting your final adjustment settle in (so he can perform an accurate/non-dynamic assessment of the situation). (Regular/general luthiers/techs without good Rick experience will disappoint.)

I am hoping for some other participant input here. Anyway, this is interesting. Good luck on your quest.
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Re: 2008 620 backbow/twist

Post by doctorwho »

Blomp wrote: Sat Feb 24, 2024 7:15 pm ...

2) Failing that, it likely needs either heat treatment to straighten it out (it's only minor, and I've seen old posts from John Hall saying that Rickenbackers generally respond very well to this) or even just some fret leveling. I don't think it's gonna need anything as drastic as having the board re-leveled at this point. but that's something I'm willing to have done if it needs it! I have a regular tech that I use for most setup work that can't be done by turning a few screws, though he'll probably point me in the direction of his recommended luthier if he thinks the neck is too out of whack to level the frets. Also I'm not that far from Jonny Kinkade if he's still doing that kind of work (If you know, you know :wink: he's probably the industry's best kept secret for guitar repairs in the UK... and he's only about an hour away from me - i only know him because he used to be one of my neighbours in Bristol!)
FWIW, I had a local-to-me luthier heat-treat the neck on my 1970 331LS which had neck issues (it had sat in the back of a closet unstrung for some years), and that worked out great.
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Re: 2008 620 backbow/twist

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maxwell wrote: Sun Feb 25, 2024 2:17 pm I had a thought about enhancing the (forward) bow action of the strings, and that would be to place a small block of wood (maybe a half inch high, wide enough to straddle a couple of frets to avoid marring the fretboard finish) and having the tightened strings go over that block. Place the block where the greatest errant curvature of the neck is. It would look sort of like a suspension bridge. The strings will necessarily leave their nut slots.... Well, it was just a thought.

I've fooled around with truss rods an awful lot. I understand what you're saying about curved truss rods and their relative/rotational positions within the neck truss rod concavity. Typically the rods are pre-bent and placed into the neck with the concave side facing "up" towards the fretboard and the convexity that will serve sort of like a fulcrum for the activated (tightened) truss rods. Like this, it's easier to slide/tap the rods into the neck (at the headstock), and this orientation minimizes potential damage at the body; they do have to protrude an inch or two in order to place or remove the nut and washer assembly. For my Rose Morris model 1996 (import 325), I thought that if I could rotate the rods so that the bent concavity of the rods faced away from the fretboard that this would enhance the neck straightening (reduce relief) that I wanted. I did do this by using a box wrench ("spanner"), turning the acorn nuts at the lower end of the neck beyond simple tightening, so that this nut turning actually turned the truss rods themselves. I had to mark the circumference of the nut to ensure I turned it/the rod a full 180 degrees (only). It was not easy and was sort of scarry, as it's easy to scratch up the body down there; not much room; have to lay down some protective material.

But, fooling around with the rods with this goal is only potentially helpful when the rods (truss rod nuts) are not activated (tightened). Once you tighten the nuts and shorten the rod lengths, the shape of the rods change (straighten) and engage (touch) the convexity at the underside of the neck, tending to actively produce a backbow force. This negates pretty much any potential influence of the curved, non-activated rods. So, there's not much sense in even trying something like this in mind. I've concluded that all this Rick truss rod manipulation to correct everything is over-rated; any attempted correction via truss rod adjustments beyond establishing the action is misplaced expectation. Oh, I've read a couple anecdotes of successful un-twisting of Rick necks, but I'm dubious; doubtful of a correct diagnosis in the first place.

(A pure twisting of the neck in and of itself is not really cause for much concern; well, I'll say, a full-neck-length twist. Over 10 years ago now (wow, how time flies) I had a lengthy thread on the RIC forum, entitled "Rats! Twisted Neck!" and it documented my attempts to straighten that. One guy posted a photo of a bass guitar that had the twist purposely incorporated into the neck design, meant to reduce wrist/hand strain while fretting. Anyway, if you take two pencils and hold them parallel between straightened and outstretched fingers and then rotate your hands slightly in opposite directions, the pencils move but do not bend, and they still remain basically parallel to each other. In the end, I ignored the twist. I was able to compensate for slightly differing string heights at the bridge via saddle height adjustments. Both the "e" and "E" strings parallel the neck nicely.) Your twist seems to be something partial and focused, limited to that troublesome area you mentioned.

I (personally) would take the guitar to KInkade after letting your final adjustment settle in (so he can perform an accurate/non-dynamic assessment of the situation). (Regular/general luthiers/techs without good Rick experience will disappoint.)

I am hoping for some other participant input here. Anyway, this is interesting. Good luck on your quest.
Thank you for the very in detailed and thorough advice - I really appreciate it :D So in your experience, it's not really worth removing and re-seating the truss rods? That certainly would save me a bit of hassle :lol:
doctorwho wrote: Sun Feb 25, 2024 4:46 pm FWIW, I had a local-to-me luthier heat-treat the neck on my 1970 331LS which had neck issues (it had sat in the back of a closet unstrung for some years), and that worked out great.
That's good to know - I think this may be what has happened to this guitar, possibly next to a heat source too - the glue under the nut seems to have run out a little - I would be very surprised if the guitar was like this from the factory!
"Say what you wish in abuse of me, for my silence towards the idiot is indeed an answer. I am not at a loss for a response but rather, it does not befit the lion to answer the dogs." - Imam al-Shafi'i

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Re: 2008 620 backbow/twist

Post by maxwell »

"So in your experience, it's not really worth removing and re-seating the truss rods? That certainly would save me a bit of hassle "

Beyond simple, straight-forward neck relief adjustment, I (personally) don't think rod adjustments really do much. (Historically, was the addition of a second truss rod a marketing ploy?) Over-zealous adjustments can lead to problems that will require taking the rods out. Of course, you (anyone) must be able to recognize if a problem with the rods per se truly exists or not. One good thing about having two adjacent rods is that you can compare them for functional/positional symmetry. If one is longer than the other, or bent compared to the other, then there is cause for concern (referring to the readily visible rod ends where the adjustment nuts are located). If you just want the experience, go ahead and pull them out (just work slowly, being careful and deliberate in your moves; have proper tools and good hands). If you want something of a vicarious experience, you can read my thread -- while this guitar has only one truss rod, you can still glean a lot. (My dual-rod Rose Morris Model 1996 neck & truss rod adventure was detailed on the old RIC forum.)

viewtopic.php?t=417714

Your description of your neck suggests a problem beyond anything a truss rod adjustment will correct. If Kinkade has the Rick repair experience you suggest, just let him comprehensively evaluate the guitar. He will probably be able nail down your problems(s), their required repairs, and your cost within minutes.
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Re: 2008 620 backbow/twist

Post by Blomp »

Thanks for the link - if anything that's proof that I should leave that sort of thing to a profesional :lol: I imagined that you would pull the rods all the way out from the body end.

It just occurred to me - my 620 has this style of inlay (this is a stock photo from a retailer, not my guitar!):

Image

I mentioned earlier, that the 3rd fret inlay seems to bulge upward slightly, pulling the binding upward in that area too. The 'problem area' seems to be behind this inlay, and the problem is more noticeable on the side of the neck where the inlay is thicker. Could it be that this inlay has been cut slightly too large, and therefore is preventing the fingerboard from "compressing" to the desired shape to allow the neck to have proper relief below the 3rd fret?

I've heard of necks refusing to bow forward due to the frets being fitted too tightly into the board. Can this also be caused by inlays?
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Re: 2008 620 backbow/twist

Post by maxwell »

You have an interesting theory. I'm afraid I cannot offer any suggestion or comment --- totally unfamiliar with this type of inlay/neck.
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Re: 2008 620 backbow/twist

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I've still not got around to taking the guitar to Mr Kinkade but I'll be giving him a call ASAP. I'm kinda expecting that it's gonna need to have the fretboard planed, which also means a refret/refinish of the fretboard is unavoidable - but I'm willing to go that far to get this guitar playing the best it can.

In the mean time, a couple of days ago I tried removing the truss rods just to be absolutely sure there was no problem there, and there isn't. It achieved nothing other than showing me that the truss rods are fine, but at least I know I can safely remove/reinstall truss rods, for future reference (I'm intending to acquire few more Rickenbackers in future, already got my eye on an early 90s 330! :lol: ).
"Say what you wish in abuse of me, for my silence towards the idiot is indeed an answer. I am not at a loss for a response but rather, it does not befit the lion to answer the dogs." - Imam al-Shafi'i

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Re: 2008 620 backbow/twist

Post by Blomp »

Right: I've spoken to Kinkade today and based on my description he told me that planing the board flat to counteract the warp is about the only thing that can be done, it's expensive, and he's also got a 3 year waiting list, and obviously priority is given to customers who are bringing in guitars that he built for them! So I have to think about whether I can wait that long to get it done or if I should find some alternatives :lol:

It didn't occur to me when I was on the phone, to ask if I could put myself on the waiting list anyway and just contact him to take myself off the list if I get the work done by someone else in the meantime.
"Say what you wish in abuse of me, for my silence towards the idiot is indeed an answer. I am not at a loss for a response but rather, it does not befit the lion to answer the dogs." - Imam al-Shafi'i

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