Bolt-on Dove Tail?

[Ben-Had]

I would love to to spend a day with John learning to set a dovetail neck! Maybe I can work that out on a future build.

I don't think of a dovetail as having a higher failure rate or inferior in any way......just takes more time to deal with (at least it would for me). This joint has stood the test of time. Just the way people are, but you may or may not have success convincing a customer to use a different option. Push back too much and they may just look elsewhere (might assume you don't want to use this style neck join so may not do the best job).

Personally, I want to know how to fit a dovetail. It's considered the traditional option which appeals to a lot of folks. I want to build bluegrass guitars......and these folks tend to be traditionalists. If you don't believe this, build a banjo killer with an artsy-fartsy style headstock and take it to a few festivals and try selling it.......

Bluegrassers do like traditional but I think it is more of "how the guitar looks" as opposed to "what type neck joint" it is.

I will grant you though, the DT is expected among many of them until they have seen/heard otherwise. My Dread I built is a Martin D-18 in every way except it has a M&T joint. I do repair work for a number of Bluegrass bands locally and have raised quite a few eyebrows when they play it and subsequently learn it has a M&T neck joint. While my guitar building skills are no where near complete (or as refined as my repair techniques) I do have 6 commissions to build this year even though they know it will be 4-6 months before they get them. Most are to be M&T joints.

[dgarrett]

Wow! What a bunch of input. I guess I did strike a nerve. Thanks much for all the data.

I read in a different forum, about using the bolt-on to get the joint just about right, then
use glue to finish the joint using the bolt as a clamp to hold the joint together. I like that
idea and have moved in that direction. The bolt holds the joint for eval, then I remove it
to fine tune the wings and work the angles, then rebolt to test the fit and shape.

When all is right and I like it, and the neck is complete, I'll apply glue and bolt and hope for the best.

After I get a little more experience I'll try a better join. I got a process much like the Taylor joint
from a website and that appears to me to be the way to go. Here it is if your interested.

http://liutaiomottola.com/construction/Bolton.htm

Thanks again for all the input...Dennis

[Darryl Young]

I read in a different forum, about using the bolt-on to get the joint just about right, then
use glue to finish the joint using the bolt as a clamp to hold the joint together. I like that
idea and have moved in that direction. The bolt holds the joint for eval, then I remove it
to fine tune the wings and work the angles, then rebolt to test the fit and shape.

When all is right and I like it, and the neck is complete, I'll apply glue and bolt and hope for the best.

Are you describing a dovetail joint here? A bolt pulls a dovetail joint apart (not together) and a primary benefit of using a bolt is for easy disassembly.......so why add glue to a joint that will be pulled apart with a bolt? Sounds like you expected the bolt to add to the strength of the dovetail joint..........and that won't happen as John previously stated. You either get the strength of the bolt or the dovetail but not both. I would either nix the bolt and use glue.......or add the bolt(s) with no glue..........but would not use glue and a bolt together. BTW, you don't need a bolt to hold a dovetail joint together, the beauty of a dovetail joint is it wedges and clamps itself. Watch John's video on setting a dovetail joint and give some thought to how the joint works. Your post makes me think you aren't completely understanding it.

[tippie53]

A dovetail is a compression joint and works by itself. A bolt pulling on a good dovetail can weaken the joint by pulling the mating surfaces from each other . That is a fact of design in a Martin style dovetail.
The working surfaces are the heel on the outside and the angled tenon on the inside. as the dovetail tightens they pull themselves together. That is the design of a dovetail joint. A mechanical fastener is not needed
If you are not experienced and you destroy the mating integrity you can use a bolt as that will compress the outside heel but now you do longer have a true Dovetail but a modified Bolt on.

One fact that has been totally overlooked is that of the integrity of the joint . If your joint is sloppy , no matter bolt on Dovetail what ever , this is not the best for the guitar . I agree that the neck is not the main tonal part of the guitar it is the top . I never said a Dovetail will sound better or worse but a bad neck joint will not make for the guitar to be the best that it can be.
Not all bolt on designs are the same . Some are true bolt on joints as the taylor some are hybrid as what Martin uses. I also use a bolt on with my kits that uses 2 bolts for the neck .
Learning to set a neck is not easy but is a skill that takes time and practice . When in the market place you have the law of supply and demand . There are plenty of customers for contemporary designs and those that want traditional and that don't care one way or the other .
Find your niche and be happy that you found it . There is no one perfect answer but to say that the more precise your joinery the better the fit and finish and appearance will be . I am and will be a dovetailer that is my niche and what my clientele want . I am happy with that and I am lucky that I have enough work to keep me busy.

[Ben-Had]

A dovetail is a compression joint and works by itself. A bolt pulling on a good dovetail can weaken the joint by pulling the mating surfaces from each other . That is a fact of design in a Martin style dovetail.
The working surfaces are the heel on the outside and the angled tenon on the inside. as the dovetail tightens they pull themselves together. That is the design of a dovetail joint. A mechanical fastener is not needed
If you are not experienced and you destroy the mating integrity you can use a bolt as that will compress the outside heel but now you do longer have a true Dovetail but a modified Bolt on.

John, where/what is the problem with a dovetail when pressed into the joint it pulls slightly forward at the bottom of the heel when the extension is clamped down?

[tippie53]

Can be any number of things. I find that you need to spoon out a bit , if there is anything that can hold off this area it can show as a slight gap or worse pop the heel off.
You can get a nice mate if you use a 320 grit paper about 5/8 wide and gently scribe sand the mating surfaces.
One thing when mating a dovetail or any neck for that matter can be mating the heel to the body. If you use a Martin neck block there is a slight radius on the Dovetail blocks , and thus you may be tight at the center and the arch of the radius falls away giving an open appearance on the joints edge.
I like to flatten this area before setting a neck as it is easier to mate flat surfaces .

I see this on martin necks also. Sometimes there is a bit of warp in the heel and it may open and close as the seasons come and go.

[dgarrett]

Wow..so much stuff. Many thanks for all the info.
My aim was to learn the differences of the two joints. And I think it's has now been well covered.
My thinking about going ahead with the bolt was to get a snug and aligned neck join so I could get
a better fit in the end. I have to undo it about a dozen times to do the adjustments, but I was having
trouble with the neck, coming off while sizing it up. Once the fit is how I like it, I will then make sure it
is still tight without the bolt, using John's method (video), then I can glue it into place like it should be.

Hope all had a nice holiday and again thanks for all that input...Happy guitar making...Dennis

[Kevin Waldron]

In regards to tenon joints....... It is possible to take a Martin style dovetail and re-route it to make a tenon joint with out adding extra material to the neck and with the proper jigs/templates, it is also possible to fill the head block with wood material and re-route it for a tenon joint.......

Another scenario is to add material back to a neck where the dovetail is where the material has been cut away more than required ( you've got a big problem ). If you do this you will need to make a U-shaped piece of material with a taper on the inside that will fit the dovetail ( usually a 7-9 degree angle for the dovetail bit and a 20 degree total angle or 10 degree either side) and re-route the joint with proper jig/fixtures. If you do this, we have found it best to add a wood like ebony for the new spacer/repair wood or something with little grain pattern that will not easily split. If done correctly this will look like an intentional highlight if you use a contrasting wood. ( you can even use acrylic/Corian or anything else that has little contraction/expansion )

Another hybrid joint is the floating tenon which can or can not use bolts. To use this style joint you would need to cut a mortise in both the neck and the head block then use a spline or floating tenon. ( this joint works much like a biscuit joint does ) if you use this style joint we personally prefer a large tenon but small can be used. Along with this style you can also use wooden/plastic round dowels for making the connection. ( Problem with dowels is that it usually is a one time joint and has to be broken to release )

There is always another way ........., lemons where made to make lemonade!!!

God Bless.

Kevin

[Ben-Had]

Very true Kevin, I had to do just that as you mentioned in the second scenario and it worked very well. Actually, for me, the hardest part was getting the "fill" piece to fit in correctly. After I re-routed it I was amazed to find how little of it was left (the fill piece) and how close the original joint actually was, Amazing that such a small piece of wood could make the joint seem so far off. For anyone thinking why not use shims it was because it was in the bottom portion of the DT and had to be dovetailed with the bit.

PS EDIT: Thanks for those other solutions, I am sure they will be useful to me in the future.