Neck relief for minimum action

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Neck relief for minimum action

Postby Beate Ritzert » Thu Mar 15, 2018 8:55 pm

... a new thread as this does concern 4 existing basses. My goal is be able to achieve a very narrow string spacing without rattle.

Four measurements, all: number, scale, action of G string at 12th fret, type, remarks

1) 30,0" -- 1.3 mm -- Framus J375 -- DIY SG bass
2) 30,0" -- 1.7 mm -- Framus J375 -- DIY RD bass, ski ramp even with light strings
3) 30,5" -- 1.5 mm -- Epiphone EB3
4) 30,5" -- 1.8 mm -- Gibson EB11, PLEKed, still buzzing

1) and 4) use the same strings. 1 has a pretty straight neck, bow under tension around 0.1-0.15 mm. 2) needs 0.25 mm to compensate for the ski ramp, 3 needs also around 0.2-0.25 mm. The neck is just straight without tension, and i had leveled the frets a bit so the fret surfaces line up straight as well.
Under heavy load that neck also develops some ski ramp, but actually all 4 basses will do that (i can easily live with that using not too heavy strings ...)

I would like to improve 2) and especially 4).

2) - the RD would mean working against the ski bump. How? I did not find anything. (Despite of that it plays comfortably)


4) is the most frustrating. Not only because it has been my most expensive bass. But mostly a can more or less play with truss rod tension / bridge adjustment. As soon as the front bow comes below 0.25 mm there is string buzz on nearly all frets. The feel is a lot worse than the measurements indicate.

So what would You do /check for in order to get that Gibson bass at least somewhat closer to my DIY SG?
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Re: Neck relief for minimum action

Postby David King » Fri Mar 16, 2018 2:41 pm

I thought the PleK machine would give you a print-out showing exactly what the fingerboard is doing and where the fret tops are located.
The only sure way of eliminating the ski jump would be to pull frets 12-and up, rout 2 slots, one on either side of the fingerboard as deep as you can go, inlay massive CF and cover with matching fingerboard strips before putting the frets back in.
If you have enough fret height to work with you can sand the upper frets to achieve a flat fret plane from fret 12 to end of FB while under string tension but this still allows the neck to keep bending further over time as the wood fatigues/creeps.
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Re: Neck relief for minimum action

Postby Bob Gramann » Fri Mar 16, 2018 5:09 pm

What I have found in my history of building and working on guitars: Two guitars set up to exactly the same specs can perform differently. The necks and bodies can vibrate differently allowing the strings on one to buzz while the other plays buzz free. Pleking doesn’t guarantee a perfect fret job.

Assume a perfect fret job—in other words, start with that. With an adjustable bridge, you can put a capo on the twelfth fret and set the bridge height as low as possible without buzzing. That will be the best it can be for the frets above 12 and the neck angle. With the capo removed, you can set the relief as small as possible without the frets buzzing when you play on the lower frets. Now that you have established the relief, you can adjust the depth of the nut slots as appropriate. What you get depends on the instrument. Sometimes, you end up with very low action but more relief that you would have expected and the guitar plays silky. Other times, you realize that you have to change the neck angle to be able to dial in perfect action.
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Re: Neck relief for minimum action

Postby Beate Ritzert » Fri Mar 16, 2018 7:47 pm

Bob Gramann wrote:Assume a perfect fret job—in other words, start with that.


Which means, especially for the Gibson (all the others are actually acceptable for my present needs): release the strings, release the truss rod, check the actual state of the fretting, and then decide what to do, doesn't it?

EDIT: after loosening the strings and the truss rod it looks as if the neck is slightly warped (i actually noticed that i needed to give a lot of force to the truss rod to take the neck back).
I know it is too early for a final statement, especially because that specific neck usually takes its time to react on adjustments, so I'll give it another day.

And no, i am not afraid to correct that...
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Re: Neck relief for minimum action

Postby Mark Wybierala » Sat Mar 17, 2018 10:09 am

Bob G... described my point of view on this quite well. I'll add that every stringed instrument fretted and unfretted will have its own individual sweet spot for the relief adjustment yielding optimum playability. It comes down to how the energy of the vibrating strings travels through the guitar. Assuming that the fretwork and geometry is perfect, every guitar has its own unique setup requirements. Specifications and measurements are only guidelines provided by some manufacturers to get a guitar to play and really have no place of value except for rough adjustments. I have seen a few manufactured guitars that have a slightly better consistency with how they react and its my feeling that this must be the result of the overall recipe used to build them -- materials, components, mass, and design. But its never a sure thing but rather a generalization.

You can get a little visual insight into this by watching an electronic tuner. On some guitars, a single note, as visualized on the tuner, will be relatively solid maintaining a steady pitch while another guitar will drift up, down, back and forth and then finally settle at a consistent pitch. Its just the nature of the instrument. If you pay attention, you'll notice that the drifting is not random. There is a consistency to the drifting pattern on any given note that you monitor.
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Re: Neck relief for minimum action

Postby Barry Daniels » Sat Mar 17, 2018 12:11 pm

Beate Ritzert wrote:Which means, especially for the Gibson (all the others are actually acceptable for my present needs): release the strings, release the truss rod, check the actual state of the fretting, and then decide what to do, doesn't it?


NO!!!!!! I never would do that. What is important is the shape of the playing surface with the strings to pitch and the truss rod engaged.

What the neck does without string and truss rod tension is not relevant, except for what you might have to do to get the frets leveled. If the neck goes squirrly when you release the tension you might need a string tension gauge to level the frets, but that is a whole 'nother issue.

If your neck is a bit warped without string tension, that is not something to correct. If you do correct it, then when stringed to pitch the neck will warp in the opposite direction. Not good.
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Re: Neck relief for minimum action

Postby Mark Wybierala » Sun Mar 18, 2018 9:48 am

Basses are a bit more difficult for me when I try to squeeze mojo from them during a setup. They just are.

Something that I've found when I run into a problem where using the conventional setup process results in less than anticipated results...

Check for an elevated 1st fret.
Its not easy to do and even more difficult when its a set neck instrument and worse if its a bass. I have a tensioning jig for bolt-on necks.

Probably wouldn't do it exactly this way if it wasn't a set neck bass. Tune to pitch and adjust the trussrod for zero relief. Use a machinists rule and see if you can slip a .001 feeler gauge between the rule and the 2nd fret while the rule sits on top of frets #1 #2 # #3rd...

If the first fret is elevated above the flat plain of frets, it will cause all relief indications to be corrupted. I've run into this quite often yet it still takes me a while to think about checking for it.

You need to check for this at multiple locations across the 2nd fret.

An elevated 1st fret throws the entire setup routine off. including the adjustment of nut slots.
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Re: Neck relief for minimum action

Postby David King » Sun Mar 18, 2018 5:11 pm

I used to believe in the troublesome neck syndrome where some necks can't have the action go as low but I'm coming around to the view that it's possible to get the action equally low on just about every neck. I might have to dress the fingerboard 2-3 times over a period of a month to have that low action "stick". My only explanation is that I'm unable to get all the way there in one leveling and polish for whatever reason. The second and third dressings are usually very minor and often dealing with the same areas as the first major dressing but taking it just a little further until perfection is achieved. There is usually a little tweaking of the truss rod which probably explains the need for further dressing. It may also be that some customers just like to complain about a set up out of habit regardless of the results that were achieved the first time. I tent to accumulate this type of customer when all the other shops in town have put their foot down and told them to go see me.

Reminds me of the story of the piano tuner at Carnegie Hall who would get called in at the last minute before a performance and have the soloist claim in front of the whole orchestra and conductor that the piano was flat or sharp because they had perfect pitch and were infallible. Inevitably the conductor and concert master would agree, saying that it did sound "a little flat (or sharp)".
The piano tuner would dutifully go through all the motions of tuning but knowing that the piano was perfectly in tune to start with wouldn't actually touch a single note. Upon the return to the stage of the assembled musicians, a few notes and chords would be struck and the impresario would invariably declare that it was "much better" and all the attendants would immediately concur. The performance would proceed on schedule.
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Re: Neck relief for minimum action

Postby Beate Ritzert » Sun Mar 18, 2018 6:26 pm

Thanks for all the tips and hints so far.

In order to understand if there is something wrong with that neck (the Gibson) i try to look closer to it as i would normally do. First of all: if i release both the strings

Maybe i start form Mark's comments:

1st fret height: variable. 1.06 mm at G string, 1.3 mm at D, a bit smaller on the deeper strings.
2nd fret height: variable. 1.1 at G, 1.06 at D, 1.3 at A.

some of the frets seem to show tiny gaps against the wood. (really tiny...)

"Tune to pitch and adjust the trussrod for zero relief. "
impossible when stringed.
I can try that on the plain neck without strings, i.e. compensate for the forward bow. Even then it feels as if i needed to adjust the trussrod fairly close to its limits. And of course the fret relief is a bit uneven - see above.
Tuning the bass to the neck will bow more or less into the relief it has had without load. Apparently not quite, because the strings are light, but very close. And with the saddles adjusted to "almost but not quite" buzz free i end up with the action i am used from this bass. This is a normal and typical action for a short scale bass (~1.9-2 mm at 12th fret) but nothing more, and as already mentioned this is more or less the best value i can achieve. Not quite buzz free.

Straightening the neck a bit further is actually possible, but it will need "violence" on the truss rod.

Mhmm. Looks to me that the neck is slightly warped (or even cut this way during the PLEK process), but not so much that is absolutely *necessary* to correct. But maybe in order to improve playability further.
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Re: Neck relief for minimum action

Postby Mark Wybierala » Tue Mar 20, 2018 11:46 am

There are some who will only adjust the trussrod with the strings loose and then tune up to see what the result is w/ relief. This is a cautious practice and I won't fault them. Most certainly on an old Rickenbacker doing this is necessary when they have that evil split-rod trussrod. Each guitar is different so you take take each on its own ability to react to changes of trussrod adjustment. Gibsons generally respond very well to putting some high quality grease on the trussrod nut and threads. I've seen it make a night and day difference in the amount of twisting force required to achieve an proper adjustment. I have been scared into giving up when the trussrod gets really tight on a number of occasions. But I've also had many successes taking off the tension, removing the trussrod nut, applying grease, and physically forcing a backbow while tightening the nut. I believe you can always back off the string tension while the strings are up to pitch. Also consider, that if indeed there is an elevated first fret, the relief measurement you see is false. Consider that you can always check the relief using the second fret as the reference which might add to the understanding of what is actually going on.

You can add one or two #10 steel washers under the trussrod nut if you are actually running out of threads. On a Gibson this is easy but you might need to reduce or modify the outer diameter of the washer.
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Re: Neck relief for minimum action

Postby David King » Tue Mar 20, 2018 1:00 pm

As Mark mentions above a washer or two under the truss rod nut may be in order here. Take the nut off and apply some moly grease to the threads while you are addressing the washer. Brass washers will work a little easier with a file while steel washers can be easily ground to shape on a grinder.
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Re: Neck relief for minimum action

Postby Beate Ritzert » Tue Mar 20, 2018 9:24 pm

Success!

In lack of a fitting washer i just greased the nut a bit and filed the frets a bit (very carefully and very little because my file is actually too coarse). Although i'll probably need to repeat this more thoroughly with a finer file the improvement is really noticeable.
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Re: Neck relief for minimum action

Postby Barry Daniels » Tue Mar 20, 2018 10:08 pm

A big step up from files for flattening is the long flat surface provided by a 2 foot long carpenters level. Find one with flat sides. Glue strips of sandpaper to it. Your frets will be much more level with this kind of tool.
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Re: Neck relief for minimum action

Postby David King » Wed Mar 21, 2018 2:18 pm

Files simply aren't very flat but you can use that to your advantage in certain circumstances. I mark my mill files as to which side is bowed up and which is down. You can also get a sanding beam from the model shop which is used for sanding model airplane wings. Midwest industries makes them in several lengths and they are both very light and stiff. A very popular sanding beam now is an angle iron made from thin aluminum, 1.5mm or .060" that's 3/4" or 1" wide as it can be slipped in over the frets and under the strings so you can file frets while the neck is under string tension. An angle iron that's 1" x 1/2" would be ideal for bass work. (Thanks to New York Guitar Repair's Evan Gluck for this tip.)
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