There's another storm brewing!

[pilotjones]

Last night

Nothing like an old pants leg as a fretboard-protecting prophylactic.

Tonight

Put strings on. Nominally in order to confirm bridge positions, but not really necessary since I have the measurements from the first bass. (Positions were confirmed though.) Actually, because I wanted to string it up!

- the feel on the neck, and of the instrument in general, is nice
- the EVO gold vs. the strings is subtle, at least now while the EVO is bright (the fretwire was definitely darker as received than after sanding, so I assume it will oxidize back to darker after a while).

And now the problem that I was hoping would go away, but didn't: the slight backbow that had developed in the neck. The string tension when tuned up is not quite enough to bring the neck into enough relief. (With the trussrod fully loosened.) Actually there's enough relief on the treble side of the neck, but not enough on the bass side. The B string, which needs the most relief, has only .002-.004, eyeballing it.

I do have the option of removing and reversing the truss rod, to allow it induce forward bow. I'm not thrilled with the prospect of this because 1) I'd have a fair amount of difficult close-quarters work to get rid of excess glue-up epoxy that is blocking the rod's exit, and 2) I really don't want to put more relief at the G string side of the neck.

So, I am considering removing some wood at the bass side of the back of the neck, to essentially let it twist forward more on that side.

Thoughts?

 

[Manton Customs]

Ouch that's a long build to find out you've got a twisted neck at the end of it! You've got a few options:

1, pull the frets and level the board
2, if it's not too severe clamp it flat for a long period, making sure you remove the twist as you clamp (you may need shims)
3, heavier gauge strings
4, heat and clamps, like no 2 except with heat.

No 1 is my preferred as it's letting the wood do what it wants to do naturally and a refret isn't a huge job. With the other options it's possible for the twist to return.

I wouldn't remove wood from the back as it may not be enough to work and then you've got a neck profile you might not actually want.

 

[Jonny5bass]

Not sure if it would help it or exacerbate the problem but maybe make it an E-C 5 string.

 

[MarkA]

Last night

Nothing like an old pants leg as a fretboard-protecting prophylactic.

Tonight

Put strings on. Nominally in order to confirm bridge positions, but not really necessary since I have the measurements from the first bass. (Positions were confirmed though.) Actually, because I wanted to string it up!

- the feel on the neck, and of the instrument in general, is nice
- the EVO gold vs. the strings is subtle, at least now while the EVO is bright (the fretwire was definitely darker as received than after sanding, so I assume it will oxidize back to darker after a while).

And now the problem that I was hoping would go away, but didn't: the slight backbow that had developed in the neck. The string tension when tuned up is not quite enough to bring the neck into enough relief. (With the trussrod fully loosened.) Actually there's enough relief on the treble side of the neck, but not enough on the bass side. The B string, which needs the most relief, has only .002-.004, eyeballing it.

I do have the option of removing and reversing the truss rod, to allow it induce forward bow. I'm not thrilled with the prospect of this because 1) I'd have a fair amount of difficult close-quarters work to get rid of excess glue-up epoxy that is blocking the rod's exit, and 2) I really don't want to put more relief at the G string side of the neck.

So, I am considering removing some wood at the bass side of the back of the neck, to essentially let it twist forward more on that side.

Thoughts?

Ouch that's a long build to find out you've got a twisted neck at the end of it! You've got a few options:

1, pull the frets and level the board
2, if it's not too severe clamp it flat for a long period, making sure you remove the twist as you clamp (you may need shims)
3, heavier gauge strings
4, heat and clamps, like no 2 except with heat.

No 1 is my preferred as it's letting the wood do what it wants to do naturally and a refret isn't a huge job. With the other options it's possible for the twist to return.

I wouldn't remove wood from the back as it may not be enough to work and then you've got a neck profile you might not actually want.

I'm a player, not a builder, so take my advice for what it's worth, but removing wood from the back of the neck to effect a change in relief on one side sends up a red flag for me. It seems like it would be difficult to localize the change (I could be wrong, though) and I worry that any removal substantial enough to effect the change you want would be easily felt by your left hand when playing (again, I could be wrong).

LeFay instruments offers an option for their necks called "B-bow" (does not stand for "back bow"), wherein there is more relief on the B-string side than the G-string side. I believe that they use a single truss-rod (and are philosophically opposed to using dual rods) as you do. I think, but do not know, that this gradation of relief is accomplished simply by planing the fingerboard accordingly, as on a doublebass. (Perhaps none of this is new for electric bass, but LeFay are the first I recall making explicit mention of it -- that it's a 500 Euro option on their site makes me think it's not a standard construction technique!)

Here is a short video where they talk about it:


I thought I saw, somewhere on their site, measurements for the amount of "B-bow" relief on each string, but can't seem to find that now.

Anyway... if you can defret, address the twist/relief at the fingerboard level, and refret, that seems the best option to me. Whether this involves trying something like the B-bow (no idea how hard or time consuming it would be to do that properly) or simply getting the board "straight", it seems to me preferable to taking wood off the back of the neck. You might find that there is still some compensation to be done at the fret level, but it should be much less, I'd think, than if the fingerboard is not addressed.

Some other thoughts from a non-builder:

• I'm not sure what kind of strings you're using, but I am a fan of balanced-tension sets. Relatively speaking, these will have more tension on the bass-side than traditionally-gauged sets. That might go a small way toward addressing your problem. Kalium Strings is a nice resource for this and they deal with fanned fret instruments a lot.
  
• If the amount of back-bow is small, going up one string gauge overall might be enough to compensate for it.
• If you remove wood from the neck to correct the back-bow, I'd do so conservatively, and I'd be careful of altering the profile of the neck too much. Easier to take it off than put it back, as my college barber once told me.

I know that heat and pressure have been used to good effect on old Fender necks that have developed twists and ski-jumps, but I don't know much beyond that. Also, just because something seems risky to me, doesn't mean that you can't pull it off, or that others haven't done it to good effect --the procedure might be more predictable and the amount of wood involved less than I'm thinking -- but those are my thoughts on the matter.

Still enjoying following your build, and I wish you best of luck.
-Mark

 

[Beej]

Because it's alright on the G side and really close on the B side, I'd probably first try @Manton Customs 3rd suggestion, which was try some heavier gauge strings. If it works and you can get by with it, you may find it settles over time. You can always pull the frets and level the board a little later in the build if you find you need that as well. Occam's razor dontchaknow...

 

[gsnad2000]

What if you tighten the truss rod (strings removed) to introduce a slight back bow. Then level the frets just on the B side. Sounds like you only need a couple thousandths more clearance. Shouldn't take a drastic fix.

 

[pilotjones]

Neck straightening, part 1


I decided to try heat straightening the neck. For this go at it, I have used a method of clamping a beam (aluminum level) to the centerline of the fretboard, to bring the backbow up to dead straight.

To apply the heat, I set up two 500W halogen lights to hang above the neck, hanging from another long level which is suspended from the ceiling. This allows shifting the lights up and down along the neck. Here's what it looked like.

And this is the neck under the nuclear glare.

After one run, the neck had pulled up some, but not enough. For a second run, I added shims under the beam, graduated from 0 at the ends to .010" at the center.

That resulted in
- still has a little backbow with strings off
- with strings on and tuned, and no truss rod force, .020 relief at the B and .028 at the G

That still has a bit too much extra relief on the wrong edge of the neck for my tastes. And the backbow would continue to make fret leveling difficult. So, there will be another straightening session, with different fixturing. Details to follow.

 

[Fat Freddy]

Neck straightening, part 1


I decided to try heat straightening the neck. For this go at it, I have used a method of clamping a beam (aluminum level) to the centerline of the fretboard, to bring the backbow up to dead straight.

To apply the heat, I set up two 500W halogen lights to hang above the neck, hanging from another long level which is suspended from the ceiling. This allows shifting the lights up and down along the neck. Here's what it looked like.

And this is the neck under the nuclear glare.

After one run, the neck had pulled up some, but not enough. For a second run, I added shims under the beam, graduated from 0 at the ends to .010" at the center.

That resulted in
- still has a little backbow with strings off
- with strings on and tuned, and no truss rod force, .020 relief at the B and .028 at the G

That still has a bit too much extra relief on the wrong edge of the neck for my tastes. And the backbow would continue to make fret leveling difficult. So, there will be another straightening session, with different fixturing. Details to follow.

Fascinating....Good luck!

 

[MarkA]

Fascinating....Good luck!

Ditt and o.

 

[Vincent Stroup]

Any luck straitening the neck?

 

[tbrannon]

always wondered what happened with this.

 

[ctmullins]

Yep, would love to see this beauty finished!

 

[pilotjones]

Back From The Dead (!!!)

So, what happened three years ago can quickly be summarized as

• I did another neck straightening session.
• I pushed it a little too far in the wrong way, probably with too much heat. It started to delaminate badly. As fast as I could I clamped it as best I could while it was still hot.
• The next day when I took it out of the clamps and checked it out, there were visible gaps between layers, from about the first fret to the twelfth fret. I was disheartened, disgusted, sickened, you name it.

Then, roughly three years of life throwing crap passed, and me occasionally glancing at this sunken-dream-and-most-likely-waste-of-1000-hours in the basement and walking away again.

——————————————————

A few months ago, I decided to put strings on it and tune it up slowly, and if it explodes — it explodes. It took the tension, so I let it sit that way for about two weeks. Still together, I banged on the neck quite a bit, and played it. Action was pretty good. No apparent odd warps. Adjusted the truss rod, and it still didn't blow apart. So I let it stay under tension for a few more weeks, playing it one in a while, and there were no problems.

So, I figured that the quick clamping had sufficiently united it at the middle of the neck, but not as well at the edges. This could be something I could work with.

I have been working on it now for the past couple of weeks. More updates to come.

 

[Grapevine921]

Back From The Dead (!!!)

So, what happened three years ago can quickly be summarized as

• I did another neck straightening session.
• I pushed it a little too far in the wrong way, probably with too much heat. It started to delaminate badly. As fast as I could I clamped it as best I could while it was still hot.
• The next day when I took it out of the clamps and checked it out, there were visible gaps between layers, from about the first fret to the twelfth fret. I was disheartened, disgusted, sickened, you name it.

Then, roughly three years of life throwing crap passed, and me occasionally glancing at this sunken-dream-and-most-likely-waste-of-1000-hours in the basement and walking away again.

——————————————————

A few months ago, I decided to put strings on it and tune it up slowly, and if it explodes — it explodes. It took the tension, so I let it sit that way for about two weeks. Still together, I banged on the neck quite a bit, and played it. Action was pretty good. No apparent odd warps. Adjusted the truss rod, and it still didn't blow apart. So I let it stay under tension for a few more weeks, playing it one in a while, and there were no problems.

So, I figured that the quick clamping had sufficiently united it at the middle of the neck, but not as well at the edges. This could be something I could work with.

I have been working on it now for the past couple of weeks. More updates to come.

This is my favorite thread on Talkbass. Glad it's coming back!

 

[ctmullins]

Sometimes things don’t go as planned. It can take a while to come to grips with that. Good for you!

 

[Delusionati]

Brewing indeed - in 8 years you could have made a decent Scotch!

I have checked on this thread a few times since 2017. I agree with Grapevine, this is also my favorite thread ever.

BTW your last post neglected to include beer. Let me fix that for you.

 

[BioWeapon]

Talk about a revival! I hardly remember where we left off so I guess I'll go read the whole thing again

 

[pilotjones]

This is my favorite thread on Talkbass. Glad it's coming back!

Glad to be back.

Sometimes things don’t go as planned. It can take a while to come to grips with that. Good for you!

Thanks.

Brewing indeed - in 8 years you could have made a decent Scotch!

I have checked on this thread a few times since 2017. I agree with Grapevine, this is also my favorite thread ever.

BTW your last post neglected to include beer. Let me fix that for you.
View attachment 4087887

Or an 8-year-old imperial stout

Talk about a revival! I hardly remember where we left off so I guess I'll go read the whole thing again

Or if you really want some extended bathroom reading, look up the thread for my first bass. It'll take you a month

 

[pilotjones]

First step — the fixing.

I needed a way to apply pressure to the edges of the fretboard without bottoming out on the peak of the radius at the center, and without damaging the frets that are already installed. And not mar the already-shaped back of the neck.

For the fretboard side I got some 1/8" sheet rubber, and some 1/4" think rubber strip with adhesive on one side.

This is the assembly of the rubber upper caul - first, cutting the thick strip into blocks to fit between the frets

Then after pre-cutting the thin sheet, I peeled off the adhesive backing piece by piece and let down the sheet. This is it, assembled and flipped over

The caul in position on the neck

I also made a caul or clamping board for the back of the neck. A sheet of masonite, with two tapered rails made from some moulding glued to it.

Between the back board and the back of the neck I put a tapered piece cut from a very large fiber-reinforced flexible pipe.

This is a side view, showing back of the neck taped with yellow tape, and the front and back cauls roughly in place. This is the worst gap to be fixed, measuring about .005-.006" wide.

For clamping, I got a bunch of square U-bolts with flat plates.

Glue up consisted of fitting a few clamps loosely, applying epoxy to the glue line while coaxing it to flow into the narrow gap, and tightening up the first clamp. Then more epoxy further up, tighten another clamp a few inches back, etc. until I worked all the way up the neck.

The neck glued up and clamped

It mostly worked well. When I did the second side of the neck there was some combination of a few pieces of the thick rubber strip hanging over the edge, and/or too much clamping pressure, which caused a few blocks to squeeze out of the clamps. But I think it worked well enough. After letting it set for a few days to fully cure (cold basement), I unclamped it and worked to clean up the extra epoxy. The end result looks near perfect. I strung it up again and played it, with no problems.

 

[MarkA]

Sometimes things don’t go as planned. It can take a while to come to grips with that...

I might have to put this on a wall and read it daily for awhile.

@pilotjones, glad to see you back and at it. I wish you the best with this pursuit and others but, whether it pans out or not (I think and hope it will), I think that you gain something by facing it again, even three years later.

Skol!