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I just reset the neck on #1 built from a Martian kit in 05. I was way too liberal with the glue on the dovetail and fretboard (tightbond original I think it’s been awhile) it was a pain. I have a dozen or so resets under my belt counting a few Taylor’s that don’t really count, mine was the most difficult to remove by far mostly due to a rookie mistake. Now I am about to pore fill #15 and am quite happy about the neck geometry and fit, I’ll attach the neck after finishing. Now the question Why not secure the dovetail with a bolt either though the tail block or perhaps through the back with bolt covered with something decorative using no glue on the dovetail . Convince me it’s a bad idea.

I've thought the same thing Chris. Since a well made dovetail really only needs a small amount of glue, why not use a bolt and make a reset easier? You'd really only need a screw from the neck block to stop the joint from sliding apart.

My reason not to do it rests with -- Why go through the hassle of making a perfect dovetail if you aren't going to use glue to hold the joint?

So, a nicely fit M&T with a couple bolts is easier and works just as well.

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Brian R, Wood Mechanic
N8ZED

I agree. if you are going to bolt it why complicate the join with a dovetail, it doesn't add anything.

Ta da!

Chris there is also the option to use minimal glue now that you know what that gets you when you use too much... The dovetail, a beautiful thing and a skill worthy of letting people know you can do a dovetail only needs a little glue as insurance. Be judicious and under the extension use Mario's method of a small puddle in the middle of the extension the size of a quarter or so.

As a repair person if I see a bolt I am going to assume it's a bolt on neck. It will be a big surprise if it's not. Additionally when I install strap buttons I look at the block and if I see a bolt I get the magnets out to be sure I am not drilling into a bolt. You may not be who services this guitar someday so I would be keen to have it be able to be understood as to its construction by who services it in the future.

If it were me I would avoid the bolt and just use less glue on a proper dovetail.

You might get a surprise then with a Gore type neck joint...
Brass or aluminium in the heel.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Yeah I might be thankfully we have never seen one before. If it was their brand we would know.

We do not take a lot of small builder instruments in unless they work in the trade. A hobbyist built guitar we only take in under special circumstances when we are doing a favor for the builder. That has not worked out for us and we avoid them now they can be a real can of worms and we don't want to get any on us.

We also don't see a lot of classical guitars and when we do it's the student models since we have 50,000 students within 5 miles of our shop. Your classicals don't need new pick-ups very often... and even the neck angles seem to last longer with the lower tension. We do see some bridge reglues though particularly on cedar tops even with the lower tension of classical strings.

Part of building serviceable instruments is to not have any hidden surprises in the construction that can mislead the approach to serviceability. Some here have made it clear that they don't care about the lowly repair person.... but everyone here had better care about the customer, always because that's who will be financially hurt if something lacks serviceability.

Chris--

I hope all is well, and I hope you are coping OK with all of the snow we have been seeing in WV for the last two months!

I wrote the below-quoted post on the OLF a few months ago when someone brought up a similar idea, so I'm just copying and pasting it here:

"You might want to look into how Grit Laskin does dovetail neck joints. A number of guitar makers do it this way, having learned it from him. After fitting the dovetail in a traditional manner, he drives a screw through the body’s headblock into the face of the dovetail tenon. Threads are created in both pieces of wood, not just the tenon, so the two pieces of wood do not pull together. The point of the screw is not to act as a screw, but rather to act as a pin that is easy to put in and take out, due to being threaded. The pin keeps the tenon from sliding out of the mortise in the only direction of movement available to it. This replaces the glue otherwise used in the dovetail joint. Glue is only used under the fingerboard extension. It is a proven method of using a traditional dovetail neck joint, but avoiding the use of glue in the joint, thereby making future neck resets less traumatic for the guitar. I don’t speak from personal experience with this method; I’ve used glue in the dovetails I have made. But I’ve read a lot about it, and Grit Laskin is a pretty big name, so if he uses it, it probably works."

This is different from the bolted dovetail idea you bought up. I'm skeptical of bolts being useful in a dovetail joint, because of how and which direction they pull versus what really holds a dovetail joint together. But I'm not skeptical regarding the Grit Laskin screw idea, because Grit Laskin uses it with success, and his use of it makes sense in terms of what the screw is actually doing (described above).

My first guitar was a dovetail kit and I did not understand exactly how it worked. After fighting it for a long time I added a couple of inserts and made it a bolt on. As Don says, it really defeats the whole idea.

I understand dovetails now having built a few and reset a bunch more. I prefer bolted M&T joints but there are a few cases where they are impossible (guitars without sound holes) and I have to break out my dovetail bits.

A locking bolt through the neck block and into the neck would loosen the joint and create a thicker, weaker glue line. It takes a self-aligning joint and reduces it to no better than a mortise and tenon joint. Likewise, a locking bolt through the back and vertically into the dovetail produces a downward pull on the dovetail which will compromise the neck/fretboard joint at the body given any serious mechanical advantage. Either approach simply recreates a bolt-on mortise and tenon neck with the additional complications inherent to fit-up. Likewise, using transverse pins similar to Mr. Somogyi's neck joint simply recreates a pinned mortise and tenon with the additional complication of a single axis of withdrawal and a more complicated fitup. Why add complications to avoid what is a pretty straightforward process done perhaps twice in an owner's lifetime if he or she is statistically fortunate and able to collect social security through their 10th or 11th decade.

Dovetails are relatively straight-forward joints. For the sliding, tapered dovetail we use, it's a case of getting the cheeks trimmed and fitted for back-angle and side angle, figure out the thickness of the shims to fit to the tail, then get the fretboard extension fitted to within 0.020", of the top. Goop with hot hide glue and clamp to fit. Between a sharp chisel and some care in fitting, we seldom saw any need for touch-ups on the neck or body lacquer. A mortise and tenon is simpler in terms of geometry, but wants some hardware to hold things in place. Removal of a standard dovetail these days is just two of the Hot Stick units from Stewart MacDonald and a bit of patience. I've grown to prefer fitting them over mortise and tenon due to less in the way of possible slop and fussing on resets with bolt alignment.

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A constellation only takes shape when one maps the whole.
- Beth Brower

Great post from Woodie as always.

The longer I am a luthier the more I acquired a healthy respect for tradition and mostly for one reason only - it works and has worked in some cases for hundreds of years.

A traditional dovetail joint is very hard to beat for performance, serviceability and value. In the Martin world there is still a very strong contingent of traditionalists who claim a sonic benefit too. No comment on that from me it's subjective.

So here is a bit more and something different from Furch. Lots of folks who come to lutherie think that a better mouse trap can be had and they go for it. They often are not aware of other attempts to address similar issues. Adjustable neck angles are not new the Hauser that I posted pics of on the OLF some years ago had an adjustable neck angle. There are other modern efforts too ask Ken Parker.

This is self adjusting or billed as such. I don't see it reactive enough to save the gig but maybe in a day or two it can help you feel better when your Furch dries out. But it won't repair the crack on the top from drying out and as such it seems to me that simply not letting your guitar dry out in the first place might be a better option.... But that's just me.

So for those of you who appreciate a hardware store inside your guitar neck and think that everyone who came before us were dotards who lacked innovation check this out. A self adjusting neck angle that moves with the RH swings but likely some time later.

I don't have objection per se to hardware-dependent joints, but I would prefer they be designed to purpose, rather than adapted without deep understanding of how the original joint functioned. I can think of at least one use case for the clockwork or adjustable joints such as the Furch rendering that Mr. Breakstone was kind enough to post, with that being the ability to have both a good fingerstyle blues setup and acoustic bottleneck slide work on the same instrument without the usual compromise setup.

For what it's worth, the relieved UTB shown in the image sounds like a clever idea, but after repairing what was in excess of 60" of cracks in top and back plates on a single instrument with ubiquitous use of that design feature, I found the practice to be a lovely way to generate stress concentrations (albeit primarily on the stump-wood Brazilian rosewood back. Mr. Breakstone will likely be able to declare a date range for that guitar sight unseen, and I for one will not miss that penny-wise, pound-foolish approach to sourcing BRW.

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A constellation only takes shape when one maps the whole.
- Beth Brower

It’s not a bad idea, but you still have to fix the extension down is some fashion.

After many variants of neck joints I’ve settled on a bolt on butt joint. Super simple with a glued extension. You can reset the neck without having to untether the extension, requires no fancy routing jigs, and if for some reason the neck does have to come off, releasing the extension is the easy part of a traditional reset.

After a few iterations of a bolted on extension, I have found value in the sheer strength of the glue to keep the geometry in place.

Ed, just curious, are you flossing in the butt joint (omg) or do you sand the footprint of the body where it meets the heel flat or…?

In our uke building classes it’s a nightmare to floss in the butt joint.


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I relieve the butt joint so that only about 3/16” of the edges are touching, in the same manner that you do a dovetail or other M&T joint. It’s not a full contact joint. I’ve got a box of dumpers out the shed I’ll post a photo later.

Oh sure, makes total sense. It’s still a bolt on after all so glue surface is irrelevant. Thanks for confirming.


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The inserts are buried about 1/8” into the face or the neck, in order that you can take a router to remove all but the edges of the joint. Flossing the entire joint would drive me mad. This is done after the angles are set and the inserts inserted, but before the fingerboard is glued on.

Awesome. Thanks for sharing that!

In the uke class we converted the neck in the kits to bolt on and so I’m going to look closely into adding relief like you’ve shown. I do this for M/T on my guitar builds but not sure why it never clicked to just do it on the converted bolt on.



Brad


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I do know of one builder who uses a screw-pinned dovetail https://www.threetguitars.com/genfeatures.html but it seems somewhat superfluous to me since the glued extension prevents it from sliding upward anyway.

I am curious how a glued dovetail performs compared to unglued in high and low humidity. The neck and headblock have different grain orientation, so it's possible gaps could open up inside the joint. But with how forcefully wood moves, glue may not make any difference anyway. If I were going to build a dovetail, I'd be very tempted to match the grain orientation.

I agree this is the best style of bolt-on (or with M&T if you want a lower profile external heel). The extension still performs its structural role, preventing the heel cheeks from indenting the ribs and shifting the neck angle, and strengthening the area between headblock and upper transverse brace. And being able to reset without ungluing anything is a major advantage over dovetail.

The extension may prevent the neck from moving upwards, but it will not prevent a dovetail from loosening at the heel if for some reason play is introduced…

OMG, I am so embarrassed. Shear.