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A person brought me a guitar that has a cracked neck to repair. you can't tell it is cracked unless you pry the neck back. With the crack so small would it be best to pry it open and add thin CA glue or would another method be better?

that isn't a crack , that is officialy a break .
There are some things here that concerns me as a repair guy. #1 a cross grain break. This will take some planning. Epoxy can be a good choice if you use the right one. CA may work but you still will need to use a spline or the break may reopen . Without a hands on inspection , but from what I can see you actually have 2 breaks and wood missing.

First I would likely use a thin CA or Hextal epoxy. Then once this cures I would use 2 splines glued in. Then lay a filler into the area of lost wood. The splines I would make about 3/8 thick and rout just short of the fretboard.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I'd use slightly watered down Titebond, really flexing the break to let glue soak into the crack.
Then I'd route two slots and splint it, followed by touching up the finish.

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"Act your age, not your shoe size" - Prince

I have done a few of these repairs , The big issue is the cross grain break and how bad it really is. Tite bond won't flow as well as thin CA or the Hextal. . I have yet to see any glue do very well long term on a cross grain failure that is this bad. The splines will aid in structure. The hextal epoxy is used in high end repair. It takes a about a week to set but it can wick into the wood very well and is often used for high end restoration.
the structure compromise with the double break has me concerned.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I agree that is much more than a crack. Depending on the guitar (and client) I might even suggest replacing it rather than repair. You run a really good chance of a repair failing and in turn reflecting on your reputation.

I would agree with John about not using Titebond on a crack like this. Think of it as if you are gluing 2 pieces of wood together end grain to end grain, it just doesn't hold very well.

If repairing it I would consider using 4 splines. 2 on a side with the lowest ones close to the truss rod channel and the others in the sides near the fretboard. You need to be sure you don't run into the truss rod channel but it should be reinforced there since that is the weakest spot. I would probably make the splines about 3" or 4" long and a minimum of 1/4" wide. I would also use slow setting epoxy.

If this were my guitar I would probably repair it but if it were a clients I would suggest a replacement at least going by the pictures you posted. Again pictures can be deceiving and having it "in hand" could tell a different story.

Good luck with it

Bob

I make guitars but have a lot more experience making furniture and restoring antiques.

I see most cross grain breaks in rear chair legs. I've tried everything over the years and have found that a good quality epoxy
(West System, for example) to be the only thing that MIGHT hold it, but that's along with adding a dowel or pin of some kind to the joint. The problem with any water based glue is that it will swell the wood fibers making it very difficult to get a good joint that comes back together properly.

No harm in trying but it may not hold, - no matter how many splines you can crowd around the truss rod.

The problem with using splines in this situation is that unless you taper the ends to nothing, you end up with a weak end grain to end grain joint at the ends of the splines.
I just repaired a Gibson the other day which had been splined previously and broke at the end of the spline, Looking at the orientation of the break, It would probably have done fine just glued up.
I would probably do a backstrap repair here, feathered in at the ends, if the value of the guitar warranted the work
Or just glue it up with CA, with no expectations of a long life

I agree with Bob. A repair would be a patch job at best. Like him I also would repair it if it were my guitar. But only to see if I could in fact repair it.


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A neck replacement is not a bad idea. That is a sever break and it may be best in the long run to replace it. What you have to look at and understand is the stresses on the neck. In theory the neck is under a tensional load not a shear . You need to make the back of the neck to be most structural to carry that stress. It would be fine once that part is repaired but you also have to consider a shock as being dropped.

This is your call but there is an educational opportunity to do what may be a skill for other repairs.
In my years of work I have tossed out most epoxies and opt for the Hextal. While this is expensive , it takes days for this to set but also wicks as into the wood a great deal. Frank Fork Turned me on to this and I have added it to my arsenal of glues. Most epoxies set fast and don't wick in very deep. CA can wick well and is not a bad glue.
For the splines I would epoxy.

the only reason I am suggest to attempt this type of repair is that you can learn something , even if it is not to do something. We all posted our opinion and in reality , that is what these are opinions , you have the part there and now you can experiment.

When you start to work on guitars you soon discover there are decisions to be made based on
1 value of instrument
2 structural integrity
3 cost

A repair on a low end guitar may not be the same for a high end.
If this is a lower quality instrument , it may cost more to reneck than the guitar is worth so that has to play into the equation

the choice or repair technique must be able to stand the structural stresses

The time and material needed will add to the cost or repair.

now lets look at this scenario
cheap guitar you just want to make it structural

mid range
you want structural and visual

High end
You want Structural visual and reversible.

so now you have a base line to work with. Choose what is best for your customer and you.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

My concern with any type of wicked in repair adhesives is the truss rod. That break surely looks to go at least as deep as the truss rod pocket. If it is a two way rod you stand the chance of locking up the rod.

While I have not used the epoxy John mentions I have yet to see any adhesive work on endgrain long term. And by all appearances that break goes clean through with the only thing really holding it together being the FB. So even with splints or a backstrap you still at best will only have 50% of the long grain strength after any repair.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

If it is a good guitar I would make a new neck. If it is a cheap guitar after gluing it up, I would consider using a biscuit cutter (lamello) to cut some slots and fit a few custom made splines. Making it look like anything more than a "hack job" might not be cost effective, and might be a good reason to reject the work.

John,
Are you refering to HXTAL NYL-1. epoxy?

Never heard of it but that is what came up on a search for it. Not many distributors for it but I am interested in trying it.

I have always used 24 hour set epoxy if I want it to penetrate more or I have actually brushed on a little lacquer retarder on the parts just before applying the epoxy. That seems to get it to go deeper into the wood but end grain joints are usually a pain unless you dowel them.

Cheers,
Bob

yes
As per the worry that you will lock up the rod .
I never seen that happen. Most 2 way rods are encased in plastic unless it is a stew mac .

The Hextal is used in high end restoration. It can take a week to set so allow plenty of time but this wicks in wonderfully. Thanks Frank Ford.

_________________
John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

That has got to be some weak wood in that neck to break like that. It looks a bit like philippean mahogany which would be unsuitable for that purpose. I assume this is a cheap import guitar.

While I think epoxy might be the only chance for a cross-grain repair like that to hold(and I really doubt it could ever give long-term satifaction), I would be interested in seeing an even closer picture with the finish-off in the break area. I am wondering if this is not already a failed repair. I think that straighness of the crack across looks like a crack in something other than wood- heavy finish/glue/covered former life sins. My 2 cents. Not worth much anymore.

Of the hundreds of neck crack repairs I've ever done I have never seen one like that. That is a particularly nasty break as others have mentioned. I would go the epoxy and splint method myself but replacing the neck would be the best option. All comes down to the value of the instrument.

First I would like to thank everyone for their suggestions. With this guitar not being an expensive model, I think I will either turn down the repair or have a good understanding with the owner that CA glue is probably just a temporary fix. I don't really know how or have the correct tools to do a splint.

The picture that I showed was with clamps prying the crack(break) open in order to be able to see what the problem is. Without it being pried apart, you are unable to see the break, even with the strings tuned to pitch. Thank you again for your suggestions.