Straightening a bowed neck pt.2

[Jono Bolton]

I posted on here a while ago about a bass neck that had too much relief and couldn't be straightened with the truss rod. I had it clamped a few months ago without heat and it's still got a bit too much relief. I've applied some heat to it today and currently have it clamped into a forward bow; the idea being that the heat makes the neck more pliable,  and as the neck cools, it should help to set in the forward bow until string tension is applied. 

 

I slackened off the truss rod nut before heating it; should I be screwing the nut right in while it's clamped? Also, how far in should the nut go? If I screw it as far as I can get it, it's about 5 or 6mm in from the end of the neck.

 

Thanks in advance.

[Doctor J]

I'm unsure what you're trying here. Relief is the amount of forward bow, as in, the direction the headstock is pulled with string tension applied, relative to the straight line of the string. If you have too much relief, surely you need to apply back-bow?
 

Either way, as you're trying to manipulate the wood into a shape here, make sure you do it with the truss rod fully slack. The truss rod is (usually) a tool to counteract the pull of the strings. If there's no string tension, there shouldn't be any truss rod tension either. The nut shouldn't be putting any tension into the rod so it shouldn't be making contact with anything.

[Stub Mandrel]

On 02/10/2021 at 19:29, Jono Bolton said:

how far in should the nut go? If I screw it as far as I can get it, it's about 5 or 6mm in from the end of the neck.

 

On all the truss rods I have seen, the nut doesn't move in and out, it's the rod that gets pulled by it (or pushed and pulled if double acting).

[Jono Bolton]

38 minutes ago, Doctor J said:

I'm unsure what you're trying here. Relief is the amount of forward bow, as in, the direction the headstock is pulled with string tension applied, relative to the straight line of the string. If you have too much relief, surely you need to apply back-bow?
 

Either way, as you're trying to manipulate the wood into a shape here, make sure you do it with the truss rod fully slack. The truss rod is (usually) a tool to counteract the pull of the strings. If there's no string tension, there shouldn't be any truss rod tension either. The nut shouldn't be putting any tension into the rod so it shouldn't be making contact with anything.

 

Yes, I meant back bow. This is what I was doing:

 

 

I'd slackened the truss rod right off and taken the adjuster out before heating and clamping, I just wasn't sure how far in I should be screwing the adjuster before taking it out of the clamp. I've sorted it now though.

[Jono Bolton]

35 minutes ago, Stub Mandrel said:

 

On all the truss rods I have seen, the nut doesn't move in and out, it's the rod that gets pulled by it (or pushed and pulled if double acting).

 

On a heel end-adjustable truss rod, if you turn the cross-head adjuster to the left and keep going, it comes right out. Similarly if you tighten it, it goes further into the neck. Not my neck but you get the idea:

 

 

Maybe 'nut' isn't the right word, but as I said in the post above, I figured it out for myself and have it working correctly. 

[NancyJohnson]

Just to clarify on the terminology for neck issues; let's just use the terms back-bow (headstock arching away from you, strings bottoming out somewhere along the fretboard) and front-bow (headstock pulling towards you and high action mid-fretboard).

 

Assuming the truss rod is fully operational and the end nut/bolt/whatever isn't maxxed out, the expression righty-tighty and lefty-loosey comes into play; if the neck has a back-bow, the truss rod is doing too much work and needs to be loosened (lefty/anti-clockwise), if the neck has a front-bow the truss rod isn't doing it's job and needs to be tightened (righty/clockwise).  As my late father would say, 'You don't need to schrawnch it,' so quarter turns, allow the neck to settle, tune up and repeat if necessary. Overriding factors here can apply to string gauges/non-standard tunings and even amount of wood in the neck (I owned a Thunderbird with a very skinny neck that moved at will).

 

I bought a 45 year old '70s Mustang neck a few years ago from a guy in the US - unbeknownst to me the truss rod was toast (or possibly made of toast) and the previous owner had put washers down the trussrod adjustment hole to try and give the nut something to bit against, but it was a lost cause; I sold it here as seen and I often wonder whether the buyer had any luck fixing it. 

 

 

 

 

 

[Jono Bolton]

19 minutes ago, NancyJohnson said:

Just to clarify on the terminology for neck issues; let's just use the terms back-bow (headstock arching away from you, strings bottoming out somewhere along the fretboard) and front-bow (headstock pulling towards you and high action mid-fretboard).

 

Assuming the truss rod is fully operational and the end nut/bolt/whatever isn't maxxed out, the expression righty-tighty and lefty-loosey comes into play; if the neck has a back-bow, the truss rod is doing too much work and needs to be loosened (lefty/anti-clockwise), if the neck has a front-bow the truss rod isn't doing it's job and needs to be tightened (righty/clockwise).  As my late father would say, 'You don't need to schrawnch it,' so quarter turns, allow the neck to settle, tune up and repeat if necessary. Overriding factors here can apply to string gauges/non-standard tunings and even amount of wood in the neck (I owned a Thunderbird with a very skinny neck that moved at will).

 

I bought a 45 year old '70s Mustang neck a few years ago from a guy in the US - unbeknownst to me the truss rod was toast (or possibly made of toast) and the previous owner had put washers down the trussrod adjustment hole to try and give the nut something to bit against, but it was a lost cause; I sold it here as seen and I often wonder whether the buyer had any luck fixing it. 

 

 

 

 

 

I've had the neck clamped twice previously but without applying any heat to it. Previously the truss rod was maxxed and I couldn't take the forward bow out. 

 

This time, I applied heat to it before clamping it into a back bow and leaving it to take the new position. Before putting the X-head adjuster back in, I chucked in a couple of washers that a mate had machined for me.

 

When I strung it up again, the strings were bottomed-out all the way up the neck; it still had too much back-bow, which was something I'd not encountered after previous attempts. I slackened off the truss rod a touch and have managed to get it to the Fender-recommended amount of relief, which I've not been able to achieve before. I'm going to keep an eye on it over the next few days and see how it holds up, but this was a last-ditch attempt to save it before it was scrapped. I'm not getting carried away, but hopefully this time it works.

[NancyJohnson]

1 hour ago, Jono Bolton said:

I've had the neck clamped twice previously but without applying any heat to it. Previously the truss rod was maxxed and I couldn't take the forward bow out. 

 

This time, I applied heat to it before clamping it into a back bow and leaving it to take the new position. Before putting the X-head adjuster back in, I chucked in a couple of washers that a mate had machined for me.

 

When I strung it up again, the strings were bottomed-out all the way up the neck; it still had too much back-bow, which was something I'd not encountered after previous attempts. I slackened off the truss rod a touch and have managed to get it to the Fender-recommended amount of relief, which I've not been able to achieve before. I'm going to keep an eye on it over the next few days and see how it holds up, but this was a last-ditch attempt to save it before it was scrapped. I'm not getting carried away, but hopefully this time it works.

 

There's a lot of good advice on Basschat; it just takes a bit of time to find the right answers.

 

Report back on how thing pan out; every nugget us going to be useful to somebody.

 

[Jono Bolton]

2 minutes ago, NancyJohnson said:

 

There's a lot of good advice on Basschat; it just takes a bit of time to find the right answers.

 

Report back on how thing pan out; every nugget us going to be useful to somebody.

 

 

Most of the information I gleaned before trying it, I got from on here! A few people I'd spoken to had recommended heating the neck. My methods were far from professional; I stuck it in a low-temp oven for a couple of hours to heat it, but it seems to have done the trick. That particular tip came from Talkbass I think.

[NancyJohnson]

Just now, Jono Bolton said:

 

Most of the information I gleaned before trying it, I got from on here! A few people I'd spoken to had recommended heating the neck. My methods were far from professional; I stuck it in a low-temp oven for a couple of hours to heat it, but it seems to have done the trick. That particular tip came from Talkbass I think.

 

I have a mate who owned a Jackson USA guitar that had a slight twist in the neck between the nut and about the 5th fret, heat/steam was useful there, combined with rapid cooling.  (If you trawl You Tube, you'll find plenty of video of carpenters bending wood using steam.)

 

I worked for a medical company that did these machines called 'Hot Ice'; it was a medical unit that could be used to resolve muscular issues by repeated hot/cold cycles in quite specific areas.  Borrowed one for the weekend, we just clamped the guitar up, sprayed with a little water on the neck, applied the pads, heated it up, twisted a little, cooled it down and repeated.  It always seemed to move back a little on cooling, so the final trick was to over twist it a little so it kind of settled back to what passed as normal.

 

[Stub Mandrel]

5 hours ago, Jono Bolton said:

On a heel end-adjustable truss rod, if you turn the cross-head adjuster to the left and keep going, it comes right out. Similarly if you tighten it, it goes further into the neck. Not my neck but you get the idea:

 

That could be part of the problem...  I've got a Fender Jazz with a heel-end adjuster and it doesn't move in and out. It stays level with the end of the neck. Ditto for a guitar I have with one.

[Jono Bolton]

42 minutes ago, Stub Mandrel said:

 

That could be part of the problem...  I've got a Fender Jazz with a heel-end adjuster and it doesn't move in and out. It stays level with the end of the neck. Ditto for a guitar I have with one.

That doesn't sound right, every neck I've had that adjusts at the heel has allowed me to take it out. Skip to about 1 min on this video to see what I mean, maybe I'm not explaining it very well.

 

 

[Stub Mandrel]

1 hour ago, Jono Bolton said:

That doesn't sound right, every neck I've had that adjusts at the heel has allowed me to take it out. Skip to about 1 min on this video to see what I mean, maybe I'm not explaining it very well.

 

 

 

Yes you can screw it right out, but when it is actually doing anything it only has one position.