'71 P Neck - Relief in "wrong" spot???

[Nate74]

I won a '71 p-bass neck off ebay a while back that had the frets removed. I got it for a song and figured I'd refret it and be ahead. It's in a good shape but when I got it, I discovered a pretty serious back-bow. I refretted it and have been using a clamp fixture and iron to gradually remove the back-bow. Now, with no string tension the neck is straight. When I use my trusty fret rocker gage, I find no high/low spots anywhere.

However, under tension, the action is highest around the 5th-8th fret and I get some serious fret buzz in that area as well.

I checked the relief with a capo at the first fret and sure enough, it appears that the relief has "settled" around the 7th or 8th fret, rather than around the 14th where I'm used to seeing it (hope that makes sense).

Is there a way to "move" the relief on a neck? I can't get my head wrapped around the physics of the problem I guess.

Since the fingerboard is the very thin veneer type, I don't believe removing the frets and planing the board is an option so I'm guessing any fixe will involve more clamping and heating?

Any and all thoughts would be most appreciated!

thanks in advance.

[ubnomnar]

Bump for an interesting question... could fall under "Hardware, Setup & Repair," too.

I wonder if higher or lower tension strings would change where the relief "settles?"

[Sardine]

Capo fist fret, fret E and G strings at the 15-16th fret, and you should see about .005" or less relief at the 7-8th fret (you can check it with a feeler gauge). Add a dash of salt and adjust truss rod to taste.

[Nate74]

Originally Posted by Sardine

Capo fist fret, fret E and G strings at the 15-16th fret, and you should see about .005" or less relief at the 7-8th fret (you can check it with a feeler gauge). Add a dash of salt and adjust truss rod to taste.

Not sure where you came up with .005"? For a 7 1/4" radius board (which this is) Fender says .014 at the 7-8th fret.

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The problem I'm having is that if I set the relief so that it's .014 at the 8th fret, it quickly is touching the fret at about the 12th/13th frets. I.E. the relief is not semetrical between the first and last frets. I may try to do a quick CAD 2D tomorrow at work to post to show this in more detail.

[JLS]

IMO, the backbow should've been dealt with before the neck was refretted. I would have done a heat treatment to the unfretted neck, then level the fingerboard, then refret.

[Nate74]

Originally Posted by JLS

IMO, the backbow should've been dealt with before the neck was refretted. I would have done a heat treatment to the unfretted neck, then level the fingerboard, then refret.

An informed comment to say the least. I went back and forth on how to proceed. Ultimately, I opted to get it straight with the frets on... but I'm certainly not beyond considering removing the frets and trying this again.

[walterw]

so when you tighten, you get back-bow in the middle of the neck while you still have up-bow around the lower frets?

yeah, more involved repairs are in order. you might be able to de-fret and plane the wood somewhat more true, then install tall frets and level them down enough to get things playable.

if these warps are not showing up when de-strung, you'll need to use some sort of tensioning jig when leveling both the wood and the frets so you can actually knock off the "hills" while leaving the "valleys" alone.

you might also be able to "compression re-fret", using skinnier tangs or larger slots in the middle where it's back-bowing and fatter tangs down low where it's up-bowing, in an attempt to push the neck to where you need it.

finally, you might try the heat-pressing method in the zones where you need it.

[walterw]

also, relief around the 14th fret usually means a rising tongue, and is a bad thing.

you want the curve to come or go evenly with rod adjustments between say 14 or 15 and zero, and 14 on up to be flat or even drop off a little ("fallaway", it's called).

[Nate74]

Originally Posted by walterw

also, relief around the 14th fret usually means a rising tongue, and is a bad thing.

you want the curve to come or go evenly with rod adjustments between say 14 or 15 and zero, and 14 on up to be flat or even drop off a little ("fallaway", it's called).

Excellent point. I'm going to put the neck back on and get some detailed measurments so i can get a better picture (and share it) of what's going on.

My concern with any sort of planing is the veneer on this board is so freakin' thin. If I took more than .010 off, I could be flirting with too much...

[Nate74]

UPDATE: I put the neck back on the bass and have it tuned up. With a capo at the first fret, no truss rod tension at all and holding the low E string at the 15th fret here's what I found:

15th - 9th fret: the string contacts each fret
8th - 2nd fret: the the string does not touch the frets, even at the second.

Interestingly, there was more relief in the neck the last time I had it installed, making me say "hmmmm..."

I don't think I have the back bow issue taken care of as well as I thought. Do I pull the frets and then try doing the clamps & heat?

[Slowgypsy]

Sure sounds like a "ski-jump" situation to me.

[mongo2]

Originally Posted by Nate74

UPDATE: I put the neck back on the bass and have it tuned up. With a capo at the first fret, no truss rod tension at all and holding the low E string at the 15th fret here's what I found:

15th - 9th fret: the string contacts each fret
8th - 2nd fret: the the string does not touch the frets, even at the second.

Interestingly, there was more relief in the neck the last time I had it installed, making me say "hmmmm..."

I don't think I have the back bow issue taken care of as well as I thought. Do I pull the frets and then try doing the clamps & heat?

Personally, I'd look for a neck without those issues.

[Nate74]

Originally Posted by mongo2

Personally, I'd look for a neck without those issues.

What would be the fun in that? Seriously, I have a lot of basses. Some are my gigging basses, some I've guilt from scratch and I get 'em out and admire them, and some are investments. I also enjoy the challenge of a project like this. Hopefully getting to learn a new skill is worth the $300 I paid and the time I've invested thus far.

[Nate74]

Originally Posted by Slowgypsy

Sure sounds like a "ski-jump" situation to me.

It could be. With this "ski jump" thing, would I only get fret buzz between the 5th and 8/9th frets? Then it's playable the rest of the way up?

Is there an industry standard fix for a ski jump neck?

3 hours later... well, after doing much reading, thanks to ubnomnar, I'm now confident this is NOT the ski-jump thing. Rather than the action being noticably higher from the 12th fret up, it's actually lower from the 12th on up. I'm not 99% sure that the back-bow is not gone and that I need to remove the frets, return to the heat & clamps, plane the neck and refret it. Hopefully there will be enough fingerboard material to do this...

[john grey]

Originally Posted by JLS

IMO, the backbow should've been dealt with before the neck was refretted. I would have done a heat treatment to the unfretted neck, then level the fingerboard, then refret.

Frankly, the above was the correct procedure IMO.
But it's done and you need to move on and see what can be done. There ARE guys who work on guitars who have a machine (I think they are custom items from production facilities) that "bow" a neck safely front or back and are used to apply warmth from a heat gun or whatever. At a certain point there are Lutherier's "custom" rods that carry more tension at one point or another. I don't know the cost of them but I did have a web site (there's a few) where they sell them.
But it doesn't do any good without the know-how and the rig. A good guy COULD get it right. Your cost may be about $200+ for the labor and the rod....Realistically.
You could find out all the idiosyncrasies by contacting a serious repair guy in your town and see if he knows neck straightening on a more complex level than "righty tighty, lefty loosey".

[mongo2]

Originally Posted by Nate74

What would be the fun in that? Seriously, I have a lot of basses. Some are my gigging basses, some I've guilt from scratch and I get 'em out and admire them, and some are investments. I also enjoy the challenge of a project like this. Hopefully getting to learn a new skill is worth the $300 I paid and the time I've invested thus far.

Good luck.

[202dy]

Originally Posted by Nate74

I won a '71 p-bass neck off ebay a while back that had the frets removed. I got it for a song and figured I'd refret it and be ahead. It's in a good shape but when I got it, I discovered a pretty serious back-bow. I refretted it and have been using a clamp fixture and iron to gradually remove the back-bow. Now, with no string tension the neck is straight. When I use my trusty fret rocker gage, I find no high/low spots anywhere.

However, under tension, the action is highest around the 5th-8th fret and I get some serious fret buzz in that area as well.

I checked the relief with a capo at the first fret and sure enough, it appears that the relief has "settled" around the 7th or 8th fret, rather than around the 14th where I'm used to seeing it (hope that makes sense).

Is there a way to "move" the relief on a neck? I can't get my head wrapped around the physics of the problem I guess.

Since the fingerboard is the very thin veneer type, I don't believe removing the frets and planing the board is an option so I'm guessing any fixe will involve more clamping and heating?

Any and all thoughts would be most appreciated!

thanks in advance.

Maximum deflection in relief should be found around fret seven or eight. That is dependent on the length of the truss rod and the anchor points. Moving that point can be done two ways: Either by changing the length and anchor point of the rod or by planing the fingerboard.

What material was used for fret markers? If the material was too thick for the slots it would create a back bow. This is actually a technique used for straightening necks that do not have a truss rod. Frets with a larger tang than normal are installed into the regularly sized fingerboard kerfs. This wedges the fingerboard into a back bow. The technique is called compression fretting. Conversely, frets with a narrow tang can be used to allow the neck to pull into more relief. This might be a solution to the problem.

[Nate74]

Originally Posted by 202dy

What material was used for fret markers? If the material was too thick for the slots it would create a back bow. This is actually a technique used for straightening necks that do not have a truss rod. Frets with a larger tang than normal are installed into the regularly sized fingerboard kerfs. This wedges the fingerboard into a back bow. The technique is called compression fretting. Conversely, frets with a narrow tang can be used to allow the neck to pull into more relief. This might be a solution to the problem.

When I received it, there was nothing in the fret slots, though i can't attest to the fact that nothing had ever been in there. What I suspect happened was that somebody encountered the same problem I have, gave up, pulled the frets and put it on ebay for the next guy (me) to deal with.

Being in LA, I'm sure I can find some incredible guitar techs that would make short work of it. So if/when I get to that point, I'll have some options... and that day seems to be getting closer and closer.

[walterw]

if this thing is backbowed just in the middle while strung and with no tension on the rod, maybe try the heat-clamping thing again just on the middle section to get it to up-bow somewhat.

if you're lucky, that new up-bow would converge with the up-bow you already have on the lower frets to give you one even curve, which you could then use the truss rod to straighten out properly.

(might as well leave the frets in and try it.)

[Nate74]

Originally Posted by walterw

if this thing is backbowed just in the middle while strung and with no tension on the rod, maybe try the heat-clamping thing again just on the middle section to get it to up-bow somewhat.

if you're lucky, that new up-bow would converge with the up-bow you already have on the lower frets to give you one even curve, which you could then use the truss rod to straighten out properly.

(might as well leave the frets in and try it.)

I had a similar thought, but I'm wondering how much bow I can induce in that area. Roughly the 7/8th to 14th frets... Worth a try for sure.