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I am thinking about trying something, and I wanted to see what current fellow OLF folks think about the idea. There have been some discussions here over the years on related techniques, and I have read through those threads. However, it felt to me like those discussions devolved into some heated disputes (heated for the OLF, anyway), and it also felt to me as if there was at least a little misunderstanding of what was being proposed. So, I am hoping to cleanse the palate and ask this in a different way.

Context: So far, I have only built guitars with bolt on necks of various types. I would like to try building a few with a traditional dovetail neck joint. I am fine with gluing down the fingerboard extension. However, I am not crazy about the notion of putting glue into the dovetail joint itself, because I have watched videos of a dovetail neck reset, and I really don't think my guitars would react well to all of that steam if they ever were to need a neck reset. I build with hot hide glue, and I use a stacked heel. There are times when I use a glued/stacked neck block inside the guitar. I want to stay away from the possibility of those parts just letting go, due to the steam.

As I understand it, the glue that most folks put into the dovetail is a safety net. It might or might not be needed to hold the neck on, because the dovetail joint itself is sturdy without glue (in the short term, anyway), and the fingerboard extension is glued down. I also understand that a dovetail neck only ever loosens by having the neck tenon rise up out of the body mortise. So, the glue in the dovetail is only there to work, along with the pinching nature of a dovetail itself, at keeping the tenon down in the mortise.

My question is whether that job, the job of keeping the tenon down in the mortise, can be accomplished by using a locking pin instead of the glue in the dovetail. My thought is that, after the dovetail is properly fitted, I could reach inside the guitar and drill a hole through the neck block and into the tenon of the neck for a tight fitting grub screw (I hate calling it a screw in this context) that will thread into both the neck block and the tenon and lock the tenon in its proper vertical location without glue.

Given how the prior discussions went, let me make it clear that I am NOT talking about having a wood screw go through a larger, unthreaded hole in the neck block and then thread into the tenon. I understand that this is something that could work at cross purposes with the pinching action of the dovetail. It could pull the tenon toward the body of the guitar. That is probably bad.

I am also NOT talking about having the grub screw only thread through the neck block and then mash up against the end grain of the tenon. This also could work at cross purposes with the pinching action of the dovetail by pushing the tenon toward the neck.

My thought is that, if the hole (tight enough to allow the wood to thread around the grub screw) is drilled through both the neck block and the tenon, then there won't be any pulling or pushing. It will just rigidly lock the tenon vertically. That's the job the glue does, and it seems to me that the grub screw could do that job, instead of the glue.

I understand that a smattering of Canadian builders (serious builders like Judy Threet, Grit Laskin and others) refrain from gluing the dovetail, and instead drive a wood screw through the neck block and into the tenon. In reading the prior OLF discussions about this, it occurs to me that, perhaps those builders do something similar to what I am talking about with the grub screw, in that they have the screw thread through both the neck block and the tenon. I think the OLF folks who spoke out against this method in the prior discussions probably assumed that the hole in the neck block would be larger and unthreaded, such as to let the screw move freely through the neck block, but thread into the tenon. That would definitely cause the tenon to pull toward the body, and that is probably bad for the dovetail joint. But if that screw instead threads through both the neck block and the tenon, then maybe (like my grub screw idea) it neither pulls nor pushes the tenon; maybe it just locks it in place vertically.

In any event, I look forward to hearing your thoughts about this. If I might be so bold as to put some guardrails up, though: I doubt we need to get drawn into disagreements about which neck attachment methods are better than this one. Everybody has their favorites, for good reasons. I am hoping to focus this discussion on this particular idea, if we can.

Thanks for your input.

Hey Don,
I really don't know how a dry dovetail joint would fare over time but I'm not optimistic.
Wouldn't a pin be adding a belt to suspenders? How would the neck loosen from rising up if the fingerboard is glued down?
I also think the glue line is important to spread the load across the relatively week short grain of the tail. The tail glued to the neck block would seem to add strength to the block as well, much as a strip of apposing grain in a tail block helps to prevent splitting.
Another concern would be all the cycling that's taking place. Swings in humidity and from full string tension to none over and over. A small glue line prevents even microscopic motion trying to compress the tail and socket wood. Any play that develops can't be taken out by pushing the joint further together if it's already all the way down and the fingerboard glued.
It seems like a question so complicated, theorizing on what might fail and how might not be as useful or quick as making some prototypes and seeing what gives.

One thing I can say for certain, a great deal of dovetail dis-assembly struggle could be avoided if anything remotely like an appropriate amount of glue is used during initial assembly. Just a thin layer on the surfaces that slide against one-another. Humans apparently just can't overcome the urge to empty a bottle of glue into a neck joint.

David--

I appreciate your thoughts. If a thinner layer of hot hide glue were to be used in a traditional dovetail, do you think the removal would just go quicker via the steam method, or could the steam be completely avoided? I'm trying to completely avoid the steam. It would be awesome if, after the loosening of the glue under the fingerboard extension, a person could just give the back end of the neck heel a whack and the glue in the dovetail would let go, sort of like removing a nut that has only been glued down by two small glue dots.

Maybe a different question could add some clarity: for folks who focus on repair, have you ever worked on the neck joint of a guitar made by one of the Canadian luthiers I mentioned who use no glue in the dovetail and replace it with a wood screw? If you have worked on a guitar like that, was the lack of glue and/or the use of the wood screw a cause of or contributing factor in the problem you were hired to fix? We have a few decades of those guitars being out there in the world. If problems flow from doing what they do, we should see those problems show up in your shops, right?

A screw going through the back plate, neck block into the tenon (covered with a cap) would pull the joint together in the proper direction and allow adjustment for the stinkage that will occur over time

_________________
Ken Cierp

http://www.kennethmichaelguitars.com/

Thanks, Ken. Let's assume I don't want to go down the road of putting a screw through the back of the guitar. Any thoughts on the pinning idea? Any experience repairing a dovetail that uses a wood screw through the neck block instead of glue to help the tenon not climb out of the mortise?

Epoxy or another waterproof glue could be a solution for the stacked heel side of things.

_________________
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.

Thanks, Colin. I'm pretty committed to using hot hide glue exclusively. I also don't want to bandsaw the neck out of a solid billet. So, yeah, I have some other considerations going on that create the defined parameters for this question. I want to use a dovetail that can be disassembled without the use of steam. Any thoughts on what the referenced Canadian luthiers are doing? Any repair stories to tell regarding the "wood screw instead of glue" approach?

I gave a quick look at a photo on Judy Threets site and saw the screw. Doesn't make sense to me but she's been in the game a long time.
You could try sending her a message and asking about it.

I've never had a dry dovetail joint on my bench but stringing up martin types dry during a re-set with a small clamp holding it down works fine. I just don't think I'd want it getting bumped round like that.

I am of the opinion that downward pressure pushing the tenon into the mortise is key to joint integrity. Perhaps installing a threaded insert in the mortise at an angle -- the screw would be pinching and pushing the tenon downward. A horizontal pin or screw will only keep things in place if nothing shrinks over time.

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Ken Cierp

http://www.kennethmichaelguitars.com/

So this sounds pretty similar to the Cumpiano/Gurian/Somogyi pinned mortise and tenon except its a pinned dovetail...

So all the fiddly and trouble of fitting a dovetail and then stuff a pin into it so it doesnt slip.

A couple questions to think about..

How are you going to get in there and drill the holes?
How are you going to get the pin in
How are you going to get it back out when future work needs to be done?
Is there any reason that a bolted or pinned M&T isnt good enough?

And last... Its worth thinking about why the vast majority of users of this joint style have jettisoned it for either the traditional glued dovetail or the bolt on...

Focusing on the particular idea, as you asked: I would want the fastener to pull the neck into the body and somehow it should be reasonably easy for a future repair person to be able to tell that it is a dovetail with hardware, not something very many folks would expect to see.

However, I am wondering, if you're going to put hardware in the joint then why take all the extra time to fit a dovetail? In my mind the two advantages of a dovetail joint are 1) tradition, and 2) no hardware. Just my opinion, obviously.

If you follow through with the idea please keep us informed. I would like to know how it turns out.

_________________
Steve Smith
"Music is what feelings sound like"

John--

I actually built my first guitar using a Cumpiano pinned neck joint. No, what I describe above is not as much like that as you are thinking. That method used a pair of wooden tapered pins, which entered from the side of the neck block. I am talking about using a single threaded grub screw, entering from the soundhole face of the neck block. Or just a wood screw, same location. The important factor is that it would thread through both the neck block and the end of the tenon. But yes, you are correct that it would involve building a traditional dovetail (with all the good and bad associated with that) and then, instead of using glue to keep the tenon from climbing out of the mortise, it would use a pin. That pin would be threaded, so it can be either a grub screw or a wood screw.

Answering your specific questions:

I would drill the hole (one hole, through both the neck block and the end of the tenon) by drilling a pilot hole in the neck block before putting it in the guitar, and then using a drill bit of the appropriate size, but with a hex base, in a flex shaft hooked up to a hand drill. The drilling would happen as the final step of the neck attachment process, after gluing down the FB extension. With the pilot hole already in the neck block, I think it will be easy to just extend the pilot hole into the tenon.

I would get the grub screw in by threading it in with an Allen wrench. If I used a wood screw, then just a screwdriver.

Getting either one back out is just unscrewing, thanks to the threads.

The question of whether there is any reason why a bolted or pinned straight mortise and tenon is not good enough assumes that I see some deficiency in either one. I don't. I have built both. I want to now try a dovetail, but I want to build it so that, in a few decades when it needs a neck reset, the guitar won't have to go through being steamed.

That last question you asked is something I will challenge as being based on an incorrect assumption. You are equating the Cumpiano pinned mortise and tenon with a pinned (screwed) dovetail, but I don't think they are the same. I agree that Cumpiano doesn't pin his mortise and tenons any longer, but the people who have been driving a wood screw into their dovetail joints, and skipping the glue, have not backed away from that, as far as I can tell. Grit Laskin and Judy Threet still do it this way, I think.

Anyway, it would be great to hear about anyone's experience with the "wood screw, no glue" dovetail approach used by the builders I have mentioned. Thanks again.

Forgive me Don, I still don't understand. How can the tenon climb out of the mortise with the fingerboard glued down?

David--

I don't know that it would, but from what I understand, that possibility is the only reason people glue the dovetail in place. The joint is touted as being strong enough to work without glue, but without something in addition to friction and pinching (the inherent traits of the dovetail), I guess folks have thought through the years that it might come loose. So, it gets glued. Or, for some builders, it gets screwed.

I just want to build a traditional dovetail a few times; I'm learning how to build guitars by building guitars. But I'm hung up on the steam thing. If I can save the guitar from having to go through that someday, while still building a traditional dovetail, but the only compromise is the addition of one grub screw or wood screw, that doesn't feel like a huge compromise to me.

I cut quite a few dovetails by hand long before I thought about building a guitar. The beauty of guitar-type tapered dovetail is that you can cut too tight and then trim to fit perfectly. Now, I am the sort who believes in a belt with suspenders, so I always will insist on a mechanical connection and a glue connection. But I do think it may be possible to cut this sort dovetail precisely enough that you can get by for quite some time with only the fingerboard glued. If/when inevitable seasonal changes/string forces loosen it up, then I could pull it back apart and try only glueing the bottom lamination near the heel. You might drill an access hole to direct the steam later to this exact area.
But in any event, it does all assume you will be the one later to disassemble. A pin near the bottom might be nice(since I am belt/suspender guy), but I am not sure the next person will notice before beginning to try and disassemble. So for this reason maybe you might really reconsider the hide glue stack-if you are thinking about the next guy-when you are maybe gone. Perhaps we would all like our work to outlive us.

I build with the traditional dovetail joint and glue both joint and fingerboard extension. I think you could add a crew or pin but as others have said I don't believe it would add anything to the structure. However, it could, if hidden, add grief if a neck reset is needed.

I have also removed several dovetail joints with the steam and I can assure you done right there's not a lot of water that goes anywhere but to the joint being released. The steam applied is not under a great deal of pressure and basically just heats the joint to soften the glue. It quite localized so I wouldn't worry about the stacked heel, bindings etc.

_________________
Michael Lloyd

“I was born to ignorance, yes, and lesser poverties ...
I was born to privilege that I did not see ... I didn’t know it, but my way was paved” – John Gorka

If you used a block heel instead of a stacked heel I doubt you would ever have any problems from steaming the neck off. A reasonable amount of hide glue should make things fairly painless.

I think considering the expectations of future repairpersons is an excellent point, and it is a warning I should definitely heed.

If I do something unusual, I should make it obvious. Maybe that's why the builders I keep referencing have used a wood screw instead of the "stealth option" of a grub screw. I would hate for somebody to be steaming the guitar to death and not getting anywhere because of the pin!

Or, maybe I just need to bite the bullet, use glue, and be mindful of the fact that a little is all that is needed. I'm encouraged by the comments that the steam probably won't cause me problems with the stacked parts. My fear of that problem is my primary reason for exploring the pin idea. I will probably just build a few guitars with a traditional glued dovetail, but keep the glue on the sparse side, and hope that a future repairperson has an easy time taking the guitar apart.

Thanks for the input, all.

Don

Is there a problem with the bolt-on necks you have done that you are trying to solve?

Also, there are a couple of major builders using bolt-on M+T joints who only use one bolt and it is down low near the back of the instrument. I have done 2 this way - the oldest one is now almost a year - and have seen no problems. The strain is at the bottom of the joint and the top of the joint seems to be in compression. So the only tight fitting area of the dovetail needs to be at the bottom - it is easy enough to make the whole thing tight, but if you are struggling with the top area I think it would be OK to leave it a little ill-fitted. Following this, just a touch of glue at the bottom of a great fitting dovetail should do it.

Does anyone have experience with this?

Ed

Ed--

No problems with my bolt-ons. I'm just trying to teach myself how to build by building. I've not done a dovetail yet, and I feel like I ought to learn. Plus, I am gravitating toward more traditional aesthetics, as well as using some old school building methods (100% hot hide glue during construction, traditional French polish finish). It feels like I should at least try combining those things with a real dovetail and see how I like it.

My most recent bolt-ons have been completely glue free, by the way. I even built an adjustable neck angle guitar for my daughter. It works pretty well, but I learned some things that will help me do a better job next time I try an adjustable neck angle. I want to also try Trevor Gore's bolt-on, bolt-off design. It looks pretty good to me.

I am thinking of doing a dovetail with screw also. Part of the reason is also because I have not done a dovetail joint yet and I would like to be comfortable with any joint. So why the screw instead of glue? I am making the neck out of spruce and I am wondering if come reset time the steam will not play nice with the spruce. In reading this thread I was wondering if it would be advantageous if the glued dovetail joint also include a small hole in the neck block to introduce the steam and an escape hole.

Steam port might be a pretty good idea -- you'd need to have an output tube to direct the steam out through the sound hole. Exhausting into the body could result in a real mess

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Ken Cierp

http://www.kennethmichaelguitars.com/

It sounds like you are designing with "probable failure" in mind.
If your body is built strong, and the neck-to-body joint is built right, it won't fail, ever. And if by some way-outside chance it does, either you can repair it, or some other wiz-bang repairman will.

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David--

Trying to fit your observations into the context of the question, let me ask: are you saying that, if I build the body strong, and I build the neck joint right, and I forego the gluing of the inside cheeks of the dovetail itself (gluing only the fingerboard to the top), the joint will never ever come apart? Because not having the glue inside the dovetail is the only reason I was asking about the pin idea.

Or, are you saying that the steam needed to loosen the glue inside a dovetail is never going to make a stacked heel (or neck block) come apart?

If you are saying something else, maybe you could help me better understand your point.

I'm just trying to make sure I don't set a guitar up for problems later in its life.

"I just want to build a traditional dovetail a few times; I'm learning how to build guitars by building guitars. But I'm hung up on the steam thing"

Hi Don,
If you want to build with the traditional dovetail neck joint, I say "Go for It!". Traditionally it is glued, and even if it is perfectly fitted the glue makes the joint stronger and more shock resistant. Don't let yourself get hung up on the steam thing - if the guitars well built, that's the next guys problem (and probably not a problem anyway.)

P.S. I do think your idea would work, just that glue is better.