So now Happy Jack has a Mike Lull 5-string neck...

[Andyjr1515]

And so, the fretboard removal.  Pretty straightforward.

 

After masking the paint on the headstock (I don't want to have to do that again  ) I made a small jig so that I could apply pressure from the heel end without having to clamp, and thus possibly damage, the neck:

 

To remove a fretboard, the good news is that almost all manufacturers and builders use Titebond or similar...and it softens with extreme heat.  The really good news is that I made this neck...and so I know it's used Titebond.

 

So first tool is an electric iron.  I use a cheap travel iron:

 

It takes a LOT of heat.  Max temperature and sitting on the wood here for at least 15 minutes before I even start (and this is a thin fretboard!).  After 15-20 minutes, I test the joint with a single-edged razor:

 

Then I 'borrow' one of MrsAndyjr1515's pottery tools to start ease the thin steel end between the fretboard and neck:

 

And that allows me to start sliding my perfect-for-the-job piece of sheet steel (it's actually a proper tool designed to help hand bend acoustic guitar sides) into the gap.  Then, mm by mm, you can inch (there's a contradiction) the iron and sheet steel forwards.  This is after about 45 minutes after the initial success with the razor blade:

 

Patience is the name of the game.  Any attempt to rush risks snapping the fretboard.

 

And around 1.5hrs in total - it's off, with neck undamaged and fretboard in one piece   :

 

Note the amount of forward bow that trussrod was trying to apply to counteract the 2mm back bow of the neck.

 

So - that maple must be SEVERELY back bowed to resist that truss rod and still bend the wrong way, right?

 

So I put my levelling beam along it, expecting it to be sitting on a substantial hump in the middle of the neck:

 

Flat as a pancake!

 

And that has led me to the position of having never, ever seen something like this and not believing, if it hadn't been right in front of me, that what has happened could happen.

 

But explaining to those interested what has happened will take me a little while.

 

The good news is that all it needs is a new truss rod (because this one is now comprehensively f****d ) and then the fretboard gluing back on

 

[SamIAm]

Your skill is amazing @Andyjr1515!!!

 

S'manth x

[JGTay]

38 minutes ago, Andyjr1515 said:

But explaining to those interested what has happened will take me a little while.

Colour me intrigued. 🤔

[Andyjr1515]

19 minutes ago, Smanth said:

Your skill is amazing @Andyjr1515!!!

 

S'manth x

Well...maybe not.  Remember who made the neck in the first place 

[Happy Jack]

13 minutes ago, JGTay said:

Colour me intrigued. 🤔

 

You're not the only one ...

 

[PaulThePlug]

Mmmm...

If the neck is flat... it must be the fretboards fault! Naughty Fretbord...

[Hellzero]

Or the trussrod. 😉

[JGTay]

Or the maker! 😝

[Richard R]

Or all three...

[Andyjr1515]

OK - let's start with the basics.  With acknowledgement to theelectricluther.com who's website has this picture:

 

 

For clarity, I'll use this terminology above in the explanation of what I think is going on.  Oh - and bear in mind that this is an Andyjr1515 interpretation of the physics of a bass guitar

 

But first of all, some basics and where it was that this neck didn't respond to the basics

 

So - what we are aiming for is pretty much the Flat-Neutral neck when the strings are tightened to pitch

 

But if you didn't have a truss rod or stiffening rods in the neck, the string tension will pull the neck into a bow - Up-Bow in the above diagram.

 

And so what the primary aim of the truss rod is to apply an opposite force - a Back-Bow

 

So if the Up-Bow of the string tension = the Back-Bow of the tightened truss rod, you should end up with a Flat-Neutral Neck.

 

"What about neck relief?" you ask.  That's simple.  Pretty much ANY Back-Bow will cause the strings to buzz in the middle of the fretboard.  So, the way of making sure that, regardless of 'normal' temperature changes and minor tuning differences, you never end up with Back-Bow, is to add a little Up-Bow.

 

 

And so, if you take the strings off a bass and the neck off, but don't loosen the truss rod, it will have a back-bow, created by the truss rod:

 

And when if you then loosen the truss rod, it should return to how it was when it was made, Flat-Neutral:

 

Our problem was that when I loosened the neck, it still had the Back-Bow.  And a big one - at the centre of fretboard it was 2mm higher than the nut and heel

 

That in itself is not that unusual - often a neck will end up with a 'set' bow...and, depending on the circumstances, this can be in either direction.  But it is usually small.  And with a two way trussrod - capable of bending in either direction - easily correctable.  And usually, if it is a back bow, then simply fitting the neck and strings and bringing them up to pitch will straighten it.

 

But in my case, with the strings fitted, there was still a back-bow...and a big one

 

So I turned the trussrod in the opposite direction as much as I dared to create an Up-Bow force so that the trussrod was adding to the tension of the strings to try to counteract the back bow.

 

It reduced the back bow, but only a small amount - from 2mm to 1.5mm. 

 

So I put a clamp on at the middle of the neck to try to force it straight and hope that the wood would 'remember' the new position:

 

 

And after two days of this extreme force...

 

...as soon as I took the clamp off, it sprang back to exactly where it had been to start with, with a severe back bow with or without the truss rod acting to counter it.

 

And so:

- the fretboard just bends to what the neck is doing

- and so it must be the neck underneath the fretboard that is bent

- and when I take the fretboard off, I would find that the maple neck has a 2mm or more set back-bow in it that I would need to plane flat

 

Hmmm...no.  As in the previous post, the neck beneath was flat.  Completely flat.

 

Conclusion in the next post  

  

 

 

 

[Happy Jack]

Aaaaaaargh!

[Hellzero]

That said the terminology used is against the common sense.

 

I think that using correct and non subject to interpretation words like concave and convex will make explanations way easier to understand. 😉

 

It's just like the front and rear pickups... 🤦‍♂️

[Andyjr1515]

It's easier if you think of a bow and arrow bow. 

  

 

[PaulThePlug]

Flat Neautral Neck Pic...

I would of expected the truss rod to of been bending tother way, to counter the strings in being flat...

 

Back Bow... Straight truss tod (loose/centered) but even with string tension, back bowed?

 

Confused...

 

Truss Rod Channel?

Edited October 1, 2022 by PaulThePlug

[Hellzero]

Woods moving at different speed like ebony and maple. If one wasn't as dry as the other, this may result in this scenario.

[JGTay]

43 minutes ago, PaulThePlug said:

Confused...

The pics are based on Fender style necks where the truss rod goes in from the back. 

[Daz39]

I’ve solved it: It was the Truss Rod Channel, in the basement, with the Levelling Board!

*turns cards over*
D’oh!

 

I dunno: can we get to the design leap of neckless guitars; coz that seems to be where all the problems are!!

[Andyjr1515]

46 minutes ago, PaulThePlug said:

Flat Neautral Neck Pic...

I would of expected the truss rod to of been bending tother way, to counter the strings in being flat...

 

Back Bow... Straight truss tod (loose/centered) but even with string tension, back bowed?

 

Confused...

 

Truss Rod Channel?

That's my fault.  I should have said - ignore the truss rod itself on those pictures (which is a single action one).  I was using the pictures more to describe which way the neck bends with string tension or truss rod.

[Si600]

1 hour ago, Andyjr1515 said:

It's easier if you think of a bow and arrow bow. 

  

 

The neck becomes the stave and you can use the truss rod as an arrow?

[Andyjr1515]

19 minutes ago, Hellzero said:

Woods moving at different speed like ebony and maple. If one wasn't as dry as the other, this may result in this scenario.

Yes - I don't think it is quite that, but it almost certainly to do with what those two woods have been doing in the unusually hot weather of this summer...and maybe the glue too...

 

I'll post shortly.

[Andyjr1515]

3 minutes ago, Si600 said:

The neck becomes the stave and you can use the truss rod as an arrow?

No

 

So no

 

[Hellzero]

Don't take it bad @Andyjr1515 but ebony is not as stable as maple when it comes to drying and taking (and releasing) humidity, so you better glue two ebony reinforcements in the neck otherwise this scenario will reproduce itself during the winter.

 

During this very hot summer all instruments I know have been moving a lot including my Le Fay with a stainless steel fingerboard!?!

 

All instruments? No, my Leduc's didn't need any single truss rod tweaking. Strange? No, the explanation lies in the way he's making the necks and the woods used.

 

My main bass is a Leduc MP 628 SF with a slim one piece hard rock Canadian maple through neck, a Brazilian rosewood fingerboard and a single action truss rod and this bass never moves. This is a strong alliance of woods.

 

I have another sixer Leduc (HMP 624) with a Macassar ebony fretboard and to prevent it to move, Christophe makes the neck in 5 parts of the very same Macassar ebony and hard rock Canadian maple all glued together, this way the neck is as stable as possible.

 

Check this:

 

His woods are also stocked at permanent same hygrometry for years or even decades and this helps too.

 

In fact, if you ask for an ebony fingerboard, the 5 pieces neck becomes ... mandatory.

 

So, one will ask why don't classical instruments move even without truss rod? The ebony fingerboard is way thicker and ... rounded stiffening the whole neck a lot more than conventional modern electric luthiery approach.

 

It's all about mass or even masses and mastered rigidity. 😉

[Andyjr1515]

OK

 

I can't be certain which - and both are equally improbable - but there are two possibilities or a combination of those.

 

A significant factor is that Jack shipped me the neck in early July.  And July in the middle of the UK was the hottest month on record with temperatures up to 40 degrees and days above 38 degrees.  The neck was kept in a spare room wrapped in bubble wrap and away from direct sunlight.  It is likely that the trussrod was still tensioned to give back-bow as I hadn't asked Jack to relieve the tension and didn't start working on the neck itself for some months after receiving it.

 

@Happy Jack had been using the bass and had not experienced any buzz or trussrod issues - which he certainly would have if it had already gained such a degree of Back-Bow (remembering that I was unable to make any tangible difference to that back-bow when I strung it up to full tension this month)

 

So one possibility is what @Hellzero suggests:

 

- that the maple neck wood shrank in length over that period.  If it did that, and the ebony stayed the same length, then it would act a bit like a bimetal strip used in thermostats.  The maple would try to shrink at the back, the ebony, though, would stop it shrinking at the top (the glue join) and so it would bend.

 

But if that was the case, you would expect that there would be at least a hint of that back-bow remaining once the ebony was removed, as that maple at the top will have been held at its original length through the hot weather and now back to largely normal temperatures.  Also, this is fully seasoned rock maple.  And shrinkage, even when it is freshly cut, tends to be tangential and radial as the sap hardens and shrinks.  There is pretty much nothing in the wood structure that would make it shrink lengthwise.  It's why sharp fret ends can often be a problem over the years - the fretboard is shrinking in width - but I've never come across, say, an acoustic with fixed bridge go out of intonation because the neck's getting shorter! 

 

The other possibility is:

- that the high temperatures allowed a miniscule softening of the glue.  Yes, 40 degrees is far short of the 180 degrees that I've just used with my iron to get it off.  But remember that it is probable (my bad) that the truss rod was still tensioned throughout that period and the neck would have had a back-bow on it...and normally with a bass or guitar, the neck is straight because the strings are also on so even if softening did happen, nothing would go anywhere.

So if there was even the smallest amount of softening, over weeks of very high temperatures it is at least feasible that the fretboard and neck would slide relative to each other, in the same way that laminated sides of acoustic guitars are made.  Once the temperatures cooled, the glue would revert to rock-solid and the curve would be permanently set - until the laminate (fretboard) was removed.

 

But there lots of 'ifs and buts' with this possibility too!

 

 

Both possibilities are in the zone of things I've never ever come across before.  It's a bit of an enigma

 

 

 

But the good news is that, whatever the cause, the neck IS straight, the fretboard IS undamaged and so all it needs is a clean off of the glue from the mating surfaces and a new truss rod and we will end up with a straight serviceable neck closely followed by a fully playable shell pink bass  

[Andyjr1515]

13 minutes ago, Hellzero said:

Don't take it bad @Andyjr1515 but ebony is not as stable as maple when it comes to drying and taking (and releasing) humidity, so you better glue two ebony reinforcements in the neck otherwise this scenario will reproduce itself during the winter.

 

During this very hot summer all instruments I know have been moving a lot including my Le Fay with a stainless steel fingerboard!?!

 

All instruments? No, my Leduc's didn't need any single truss rod tweaking. Strange? No, the explanation lies in the way he's making the necks and the woods used.

 

My main bass is a Leduc MP 628 SF with a slim one piece hard rock Canadian maple through neck, a Brazilian rosewood fingerboard and a single action truss rod and this bass never moves. This is a strong alliance of woods.

 

I have another sixer Leduc (HMP 624) with a Macassar ebony fretboard and to prevent it to move, Christophe makes the neck in 5 parts of the very same Macassar ebony and hard rock Canadian maple all glued together, this way the neck is as stable as possible.

 

Check this:

 

His woods are also stocked at permanent same hygrometry for years or even decades and this helps too.

 

In fact, if you ask for an ebony fingerboard, the 5 pieces neck becomes ... mandatory.

 

So, one will ask why don't classical instruments move even without truss rod? The ebony fingerboard is way thicker and ... rounded stiffening the whole neck a lot more than conventional modern electric luthiery approach.

 

It's all about mass or even masses and mastered rigidity. 😉

 

Fascinating stuff @Hellzero (and NICE bass  )

 

Only issue is that I don't think ebony expands...certainly ebony fretboards shrink...but that would bend it the other way...    But certainly the answer is somewhere in this kind of area and most definitely linked to the weather.

 

Like you, I've come across loads of folks who have had all sorts of things go on this summer.  A pro-player I know asked me about his mandolin - honestly, the neck was like a banana!  I suggested, especially as they don't have truss rods, that he waits until the weather cools down and then check again.  Within three weeks it was completely back to normal!

[MacDaddy]

5 hours ago, PaulThePlug said:

Mmmm...

If the neck is flat... it must be the fretboards fault! Naughty Fretbord...

 

4 hours ago, Hellzero said:

Or the trussrod. 😉

 

4 hours ago, JGTay said:

Or the maker! 😝

 

4 hours ago, Richard R said:

Or all three...

 

I blame the Government!