Official Luthiers Forum!

Curiously, i think that even though i'm still fresh at building guitars and that my craftmanship SUCKS, a fellow who visited my shop one day made this kind remark when holding my unfinished guitar and after looking at it from inside out said " You're a natural". Didn't really know at the time what he meant by that, i even thought he was laughing at my poor skills cuz i thought of my bolted and glued dovetail joint.

But after reading your last post Don, i understand he was refering to my resourcefulness. Getting better at building sometimes means to be innovative and get out of the ranks and you sure are one innovative guy for thinking of new ways to do this!

So from A Canadian Bear point of view, you are Canadian my brother Don!

Todd, how about one inward and one downward like your sketch, wouldn't it secure the joint on both axis?

Ummm....I don't get it? Why would you need downward force? A tight dovetail can pretty much hold itself. You don't use downward force with a M&T, why would you need it with a dovetail? If anything, it's far less prone to slipping than a M&T, especially when it fits snuggly as it should. I'm having a hard time wrapping my brain around that...

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

I think he means that the bolt will pull the tenon tightly into the mortise and secure it by wedging it tight. This would require a V-shaped (and not straight) dovetail, as in a Martin one; a dovetail that is wider towards the fingerboard than towards the heel cap. Todd, am I close?

I do a barrel bolt / straight tenon joint and have zero experience with dovetails by the way...

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Rian Gitar og Mandolin

The traditional dovetail had two angled surfaces. These surfaces work together to secure the neck into the head block and pull the neck flush. As you push down on the neck, the tenon needs some place to go. There is more room at the back of the headblock because of the dovetail. The neck is compressed against the side of the guitar and sits nice and tight.

One way to visualize these sorts of things is to imagine how it would work if there was only one of the angles. Suppose that it was just a V shaped tenon. As you pushed the tenon down it would align the neck virtically and horizontally but there would be nothing to draw the neck into the body and you could pull the neck straight out.

No suppose that you have a simple dovetail that has parallel sides. This joint would keep you from pulling the neck out and provide alignment but would be as tight or as loose as you cut the slot. It would be very easy to go from too tight a joint to too loose a joint with just a few strokes of sandpaper.

With the compound joint, that last little bit of downward pressure that you get when you clam the neck to the body is also the part that pulls the neck tight against the body.

If you add a bolt to pull the neck the neck into the body, you are actually releasing the pressure on the mating surfaces of the dovetail. Consider an extreem case where the dovetail was set too loose. The bolt pulls the neck into the body and the sides of the dove tail pull apart and may not even touch each other. In that case you have, structurally, the same thing as a pure bolt on and even lose the alignment that a straight tenon would give you.

Don, You say that you can't get your mind around the simple butt joint with screw inserts. What exactly do you mean? That you don't understand how it is supposed to work, or that is it offends your sense of aesthetics (a valid point of view that, by definition, is impossible to debate).

I've done the butt joint with inserts and cap screws, and aesthetically it looks like a dovetail unless you look in the sound hole...which is to say that you basically can't see how the neck is put on from the outside.   I built what is my main personal guitar like that a good seven years ago, and the neck has never come loose...the bolts have never needed tightening, the neck hasn't skewed, yawed, or budged.   I think worries about that may just be a non-issue that people get all worried about, but isn't really an issue. And if the neck does move a little?   Just tighten the ****** thing up.   It would be the easiest job in lutherie and take all of about one minute. Big deal.

I've learned not to get all up in my head worrying about obscure things that might happen to my guitars and so I concentrate on making them easy to adjust, easy to work on, and reliable enough to survive Antarctica at 40 degrees below zero.   Why make guitar making any more difficult than it already is?   

I'm telling you, a simple non-tennoned, non-dovetailed bolted butt joint works just fine. Use inserts, Allen head cap screws, Belleville washers (which are like single layer compression springs) along with regular washers.   Make your neck and butt blocks out of Baltic birch plywood. Tighten up the cap screws nicely.   End of problems.   You'll have a tough guitar that's easy to tweak.LanceK38849.3133912037

When Don first pondered this, I had been considering it as well. In fact, the sketch Todd shared is pretty much exactly like one of my concepts! An alternate to that would involve a foot on the neck block and a leverlike clamp that would fit into a notch in the male of the dovetail to apply downward pressure. In any case the downward pressure would be key to allow the dovetail to work it's natural holding power. The bolt just replaces the hold that the glue would otherwise provide, right?

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DES - Shepherd, MI

What Rick said.

My guitars look like any other's from the outside, and since I now stick a label over the bolts on the enck bloack, they look "normal from within, too <g>

Simple butted joint. Been doing them for ten years now. No failures. No loose necks.

How many Taylors have been built to this date? Every one, a simple butted neck joint. Even their "new' joint is still a butt joint.

From a structural standpoint, bolting a dovetail doesn't make sense, because you are, as a few have [pointed out, pulling it apart with the bolts. Yes, it works, but it works as a bolted neck, not as a dovetailed one. The only advantage to this style is that you can tell you customer that they are still getting a dovetailed neck. Since few understand the geometry involved in a dovetail, few will question whether it is a good thing or not.

The only way bolting a dovetail would make any sense, structurally, is to do it like Todd drew up, pulling it tighter. problem is, where do you access the bolt, such that you don't have it showing?

But again, why bother? Want to do doevtails? Do dovetails, and gleu the ****** things. Want to use bolts? Do a simple butt, or a M&T if that will help you sleep better at night...LanceK38849.3113425926

I have to diagree with the concept that bolting a dovetail will release the pressure on the mating surfaces. That's impossible with a tight joint, because the sides and heal cheeks are pressed up against each other tightly as well. There's nowhere for it to move to. The only way the pressure can be released is if you over-tighten and compress the wood fibers. Think about it in respect to the whole structure, and not just the inner dovetail.

Rick, I understand what you and Mario do, I just have a hard time mentally figuring out how it can be as strong as the other types of joints, or how to eliminate alignment issues. That's because I'm just not at all experienced with it, nor can I figure out how to machine it all with any degree of accuracy. It's a fine joint I know, but ME making it work is what I can't get my brain wrapped around, considering my partiality to tenons/dovetails.

[quote=Often Grumpy Guy]But again, why bother? Want to do doevtails? Do dovetails, and gleu the d___ed things. Want to use bolts? Do a simple butt, or a M&T if that will help you sleep better at night...[/quote]

I hear ya Mario, but I still think it would have some advantages in the setup process, and the neck setting as well. You can't adjust your neckset without removing those bolts, can you?
Not sure why the rigid viewpoint against the idea when apparently so many are using it for what they feel are very good reasons. Judy Threet sure makes a heck of a great guitar, and that's exactly what she does..

BTW, It has nothing to do with sleep... I don't get enough of it no matter what neck joint I use.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Hi Don,
Todd and Mike beat me to it. If I was to add any hardware to a tapered
dovetail joint I'd like to see the bolt pulling the dovetail down, as in
Todd's illustration, thus locking the neck and body together without the
need of any glue (your initial requirement). I have a fixture/template I
built for cutting a tapered dovetail which should work for most any guitar,
I think. I can bring it with me to Sunday's meeting, if you like. Even if you
don't use it, it might provide a point of departure for building something
of your own.
Craig

Don, you're not mentally grasping the dovetail and all the angles involved. Sure, a tight fit joint won't be pulled apart in the literal sense, but the mating surfaces will indeed have their pressure released by the bolts, thus, negating any real benefit of the dovetail... The bolts will pull the male half of the dovetail away from the female. If I could draw on the computer, I would, and it expain it clearly, but I can't.... As I said, the joint works, but not because of the dovetail, but because of the bolts.

And no, no need to remove the bolts to adjust the neck angle. Just loosen them a turn, and slip some paper in there. The bolts hold the alignment. In fact, I don't actually use bolts anymore, but studs. I can set the neck entirely without every slipping a nut on there at all. The studs hole the neck in place while I work.

As for how strong it is, well, it is proven to be strong enough. As strong as a M&T or dovetail? No, because there's much less "meat" there, but strong -enough-? Millions of solid guitars prove that it is. A steel neck would be stronger than a mahogany neck, but that doesn't mean we need to stop making necks of wood, right? Stainless steel bracing would surely be more solid than the spruce we use under our tops, but it's not needed, correct? The floor in my house would be much more solid if it were 12" thick, steel reinforced concrete. But the wood framed floor is strong enough.

Sometime ago I was involved in taking apart and rebuilding an Early 17th Century Giovanni Heiber 8-course lute, that had seen better days, If you'd been around nearly 400 years you'd need a bit of TLC! When the top was taken off we found that the neck was held on with two dowels and a 2" hand made wood-screw. The neck body join is a simple 60deg butt joint and the screw had been put in to allow easy removal of the neck while adjusting the angle of the body/neck join. When this is correct the dowel holes are drilled and the neck glued up and the dowels glued in place. Normally the screw would then be removed and another dowel fitted. But obviously it was just left in place. In the two Heiber style lutes that I have made I too have left the screw in the joint in honour of the builder 400 years ago.

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.

Mario, so let me see if I have this right...
If I can paraphrase, you're saying the action of the bolts causes the joint to slip apart away from itself upward due to the shape of the joint? Do I have that right?
I guess I'm just gonna have to try a dovetail to see for myself what you're saying. Maybe I'm having a hard time understanding how it could possibly move when it's already forced against the body, but perhaps I'm not understanding that properly.
I should say I have done one butt joint...on my ukelele, and it does seem plenty strong. I like the idea of the studs better than threaded inserts...unless they are at all prone to loosening.
That makes more sense to me. I can wrap my brain around that.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

If you're afraid of anything coming loose, use nylock nuts. But in ten years, I';ve not seen any of mine come loose, and I've only ehard of one Collings with a loose nut that was causing a buzz(the second one held the neck tight).

In the end, there are countless ways of attaching a neck to a body. Some are simple, some are complexe. I'm a K.I.S.S person, through and through, and can't for the life of me wrap my head around using a method or technique that is more complicated than necessary. I just can't <g> So take my arguments with a grain of salt, and always keep the above fact in mind. Some folk take the Rube Goldberg route to everything, some take the easy route.

I was refering to the studs themselves, which I assume are epoxied or something into the heel?

Are the holes in the neckblock significantly larger than the bolt diameters to allow some adjustment?
Darn it Mario, you got me thinking about trying that now.
GRRRrrrrrr....

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Don, believe me, Mr Grumpy here is right on this one too!

Great illustration,Todd.

Okay, this had been my concept a while back in order to "conceal" the bolt as Mario mentioned earlier. Sort of a COMPLICATED version of an interference fit like in timber framing. The washer as it may seem in the drawing has flat sides so it's more like a wedge or cam. However, I have always felt that the method illustrate earlier by Todd with the bolt at the bottom the simplest. Just conceal with an extended variation of a heel cap.

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DES - Shepherd, MI

You guys beat me to the punch -- I made up my diagram so I'll post anyway

I know I mentioned that I use a dovetail joint – having said that – what Mario says makes a lot of sense.   If you look at the diagram below, the natural string tension will try to rotate the neck around the point where the inside of the heel meets the underside of the fretboard extension. The string tension will try and pull the heel away out of the body, while at the same time the fretboard extension is pushed downward on the top.

I think I get what Mario is saying – you don’t need a neck tenon and it doesn’t make a whole lot of sense to try and bolt a dovetail joint either.


If you want to bolt your tenon to couteract the forces trying to pull the tenon out of the body -- no point in using a dovetail joint.Anthony Z38806.5590046296

The thick black line is the heelcap. Todd, please pardon the use of your drawing, but I believe this would best serve Don's objective. You got us all a flutter, Don! Good luck!

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DES - Shepherd, MI

Ok guys, going back to how a dovetail works...
..or how I perceive it to work :

1. As the dovetail joint is slid together, not only does it tighten against itself, but if done correctly,
it also tightens up the cheeks against the sides of the guitar does it not?

2. If therefore when it is fully engaged and locked into itself,
and both the angled surfaces of the joint are in contact, and the cheeks of the neck heel are in tight contact with the sides,
how the heck can it be drawn into into the body farther as Todd's drawing suggests????
That is a physical impossibility, unless as I said, the fibers on the heel and body are compressed in the process.
You guys are thinking that since there's a gap behind the dovetail, that it can move in that direction,
which it can't because the cheeks of the heel prevent it from moving in that direction, unless it moves upward also.
It can't move backward any more than it can move forward.
You can't negate the front part of the joint from your argument and say that it will move. AS I said, you have to look at the whole unit and not just a part of it.
If there are no heel cheeks, of course it can move.

A perfectly fitted dovetail does several things:
It aligns itself.
It aligns the top of the neck perfectly to the top.
It draws itself inward and draws the heel up against the sides.
Right?

Maybe I'm just dense...but my logic seems correct.
Don Williams38806.6064351852

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

Why make it all so difficult? What is the advantage of the dovetail?   Is this an intellectual excercise or a tour de force in craftsmanship, or is it way to make a better guitar that is easily repaired in the future? I get the sense that the love for dovetailed neck joints is more of an emotional bond to a romantic past than good modern engineering.

If you tighten the bolts you will get some compression of the wood fibers. The joint probably won't pull apart but the pressure on the face of the dovetail will drop. You probably won't lose alignment either which is why other builders have used it successfully.

Suppose that you didn't get any compression of the wood fibers. Then, what function is the bolt doing? The only degree of freedom that is not locked in in a dove tail is the lifting of the neck. The pressure supplied by the bolt is at 90 degress to the direction of motion.

I suppose that a well fit dovetail joint doesn't need to be glued at all once the fretboard extension is glued down. That will prevent the neck from lifting.

It draws itself inward and draws the heel up against the sides.

Correct, but once you introduce a bolt, you'll pull the heel tighter into the side, and the dovetail away from itself, even if it can't be measured. But the fact remains, you've now put the neck's torque onto the bolts and the heel/body fit, and away from the dovetail to neck block fit, so why bother with that part of the equation?

I love the idea of the tapered washer thingie. I've long thought that if I were to go back to dovetailed necks(I used them for a year's worth of guitars in '99-'00) I'd come up with a cam system or something. There it is.... The elongated heel cap would work, but it would be a bugger to fit nicely(the cap), and iot would not look "traditional" for those of us in a market that asks for that look.

But my customer base is happy with my neck present neck joint, and I have no need to fix what ain't broke. I guys, this joint ain't my idea for a long shot; I took it, part for part, from the early Taylor guitars. If the joint was weak, Bob would have used something else. They're not big fans of warranty work, I'm sure.

Don one last practical consideration (sorry to pile on here), but dovetails often don't perfectly aligned even with accurate jigs. It's a whole lot easier to perfectly align a square tenon than a dovetail tenon with the old sandpaper between the rib and heel trick. Try doing that with a snug dovetail joint -- it ain't fun. Also its easier to trim the cheeks of a square tenon than a dovetail tenon. [Now that I think about what Mario said earlier -- I am wondering why even bother with a bolt-on/tenon combination].

So at the end of the day -- what have you gained by bolting/screwing in a dovetail? (Nada)

Tony Karol has been telling me for years "why bother introducing all those additional operations."   

The only reason I use a dovetail joint is because I build archtops and don't have the luxury of a 4" soundhole. Someday I'll get a welder to make me up a 25-inch long allen key wrench so I can bolt'em on from the end pin hole    Revelation -- loose the tenon and it'll be a whole lot easier to fit the neck extension!

Don I would have never thought of this if it wasn't for your _____ dovetail idea Anthony Z38806.6963888889