Can You Straighten A Classical Guitar Neck?

[RobKay]

I picked up a nice classical vintage guitar at a boot sale yesterday, its probably 50 years of age and nice condition but the action is quite high and the saddle is sanded down really low........can classical necks be straightened?

[Howard Emerson]

Originally Posted by RobKay

I picked up a nice classical vintage guitar at a boot sale yesterday, its probably 50 years of age and nice condition but the action is quite high and the saddle is sanded down really low........can classical necks be straightened?

Rob,
Absolutely, but the cost may outweigh the benefits.

HE

[rmp]

There is tool that heats the neck while it puts it back in line.

I had a classical with no truss rod that was fixed with this kind of tool

[Gitfiddlemann]

Howard's right Rob.
It's doable, but getting that fixed correctly will require the right person to not only fix the neck but get it back into playing shape. That's crucial for you to enjoy the guitar.
You really need a luthier, or an uber-experienced Frank Ford type of tech. to do this kind of work correctly.
But it might be worth it depending on the value of the guitar. What's the make?

[YamaYairi]

Does the neck have too much bow in it, or does it need a neck reset? Neck resets are impossible on a classical guitar. I once looked at a Yairi that some idiot had put steel strings on and it needed a neck reset. What a waste.

[Aspiring]

For.a budget fix this might do it:

https://www.stewmac.com/luthier-tool...bridge-doctor/

Depends of course on the exact problem

[RobKay]

Thanks, its not an expensive guitar its actually made by Suzuki violin company around 1973 under another brand name, it sounds really nice and plays really well at the lower end of the neck and the condition is like new. I think it was purchased and someone gave up and just left it in its case and over the years the tension of the string has slowly bent the neck.

[offkey]

Elderly Instruments once heat pressed a classical neck on a guitar I consigned with them. I never saw the results but assume it worked. You could call and speak with the shop about your idea.

[FrankHS]

Originally Posted by YamaYairi

...Neck resets are impossible on a classical guitar....

Not impossible, just expensive assuming traditional Spanish heel construction. Bolt-on necks exist on some (even luthier-made) nylon string, and relatively inexpensive to adjust. A 70s Suzuki would be traditional neck.

[kirkham13]

you could pop out the fret and plane the fretboard flat... might be a fun experiment.

[Itzkinguitars]

Is the neck bowed causing excess relief or has the soundbox distorted changing the neck geometry? If the former one can use a heat press to straighten the neck, this isn't necessarily a permanent solution and is best paired with a carbon fiber rod inlayed under the fretboard (probably not worth it for a mass produced guitar).

If the latter the frets can be pulled and fingerboard planed to a new taper to correct the geometry. If necessary the frets slots can be filled, an ebony shim glued atop the fretboard, the correct neck geometry planed, and frets slots recut. Again, this repair might exceed the cost of the instrument.

[Taylor814]

Originally Posted by FrankHS

Not impossible, just expensive assuming traditional Spanish heel construction. Bolt-on necks exist on some (even luthier-made) nylon string, and relatively inexpensive to adjust. A 70s Suzuki would be traditional neck.

In a Spanish heel guitar the top, back and sides are literally glued to the heel. You'd have to deconstruct the entire box without breaking anything, and then reset the neck before reassembly. Sounds pretty impossible to me.

[nikpearson]

First you need to find out what the problem is.

Acoustic guitars tend to fold up around the waist/sound hole area, leading to non-optimal geometry and high action.

Classical actions are typically 4 mm on the low E, 3 mm on the high. Measure these first as the action may just look or feel high compared to other guitars you’ve played. The lower tension of nylon strings requires a higher action to a lid buzzing,

Is the neck bowed excessively inward, that is it has too much relief? You can measure relief by fretting at the first fret (a capo helps here) and the 12th fret. The gap between the top of the fret and the bottom of the string is the relief, usually greatest around the 6th fret. A good relief on classical instrument is 0.1 to 0.2 mm; you can measure this small gap with inexpensive feeler gauges.

If the neck is excessively bowed, it is possible to straighten by applying heat and clamping the neck with a straight and stiff brace.

To check geometry, rest a straight edge along the top of the frets. Classical guitars are usually built with a slight forward geometry. Ideally the straightedge should clear the soundboard above the bridge by around 10 mm. If the straightedge is much closer to the soundboard than this then the only remedy is to adjust the neck geometry.

Classical guitars with a traditional Spanish heel can have their necks reset but this is a particularly complicated job because the neck joint is integrated into the body. The back can be ‘slipped’ in relation to the heel block, shortening its length and bringing the neck angle back to where it should be. This is a job for a skilled luthier with experience of classical guitars. It will also be expensive.

Good alternatives include replacing the fingerboard with a (tapered) thicker one, or adding a tapered piece of neck wood under the fingerboard. Both of these require the fingerboard to be removed, still a substantial piece of work.

All the best,

[Rudy4]

Originally Posted by kirkham13

you could pop out the fret and plane the fretboard flat... might be a fun experiment.

It's not uncommon to see this done for classical guitars:

[nikpearson]

This is added to obtain an even saddle height and therefore optimum string height above the fingerboard. There is considerable variation in what that ideal height should be. Many builders cite half an inch (12 to 13 mm), although I believe Trevor Gore aims for 10 - 11 mm.

The reason I raise this: planing the fingerboard to taper it from the nut end will change the neck/fingerboard geometry but only by so much. You will also have less fingerboard depth at the nut end. The alternative of replacing the fingerboard certainly involved more work and will give more neck depth. Swings and roundabouts.