Neck Tenon vs No Neck Tenon (for Bolt-On Necks)

[Darryl Young]

FYI, here is a description of the new style Taylor joint if anyone wants to read it. I'm going to dinner so will post more later.

http://www.frets.com/FretsPages/Luthier ... joint.html

[Kevin Waldron]

We build necks both with tenon and dovetail for sale and for in-house use. We glue both styles on the instruments that we build and both joints have little if any play in the joints.

If you think about it most of the componets on a guitar rely strickly on glue joint and very little mechanical connections. ( top to sides, bottom to sides, bridge to top, kerfing/lining to sides, braces to top and back, fret board to neck etc. )The dovetail is both wooden mechanical and glued but does it make it any better than mechanical steel and glue.... (as for Martin going to dovetail totally now... could be there tooling setup which I saw some where was now being done with a dedicated cnc style machine) From an engineering standpoint I think you'd have a hard time proving your case that one joint would out last another using glue and bolts or wooden mechanical joint and glue.

When we build instruments in-house we do build and cut the head block after the box is finished and we do cut the neck joint to match whether it be tenon or dovetail. We personally use the Neck Angle jig made by Luthiertools...

http://luthiertool.com/neck%20angle.html

there are other jigs that allow for this as well like the Simpson Jig http://youtu.be/v-uILpnd9kw

When its time to fit a neck either at the beginning or the box closure, it comes down to a personal preference, we all have an opinion why do you think Crayola makes 256 colors in the crayon box......

Blessings,

Kevin

[Darryl Young]

I respect the opinions given here as each of you have more experience than I. I am missing something in your points that I would like to understand.

The bolt-on necks I have worked with came from Hannalei (sp?) Moon and the style seems to be similar to the previous version of Taylor bolt-on necks which were used for years. I can only speculate about the original design as it's not my own......but I have read an article where Bob Taylor gave the history of the bolt-on neck and told how it evolved.

So here is what I don't understand:
The mortise and tenon on Taylor necks aren't glued in place (fretboard extension is glued down on the previous version) and Taylor explains that this allows for a quick neck angle adjustment by sanding the heel then bolting the neck back in place (no glue). Now if you have a tight fitting tenon, you can't adjust the neck angle by sanding the heel only......you would have to also adjust the tenon fit; else, the neck angle would NOT change as the tenon would hold the neck angle right where it was previously. You would have to get into the complicated task of adjusting and fitting the tenon and at the same time adjusting the heel to maintain a nice fit with the sides. This is similar to the complicated task of fitting a dovetail and the heel at the same time.

But the beauty of the Taylor design (as I understand it.....and this is where you may need to correct my thought process) is that the tenon is NOT a tight fit and only the heel is adjusted to change the neck angle which makes it simple, quick, and easy. You can't glue the tenon because it doesn't have a tight fit with the mortise (the slop allows for small angle adjustments of the neck without the tenon interfering).

I realize there are some bolt-on designs that utilize a glued in tenon. I'm not sure I see a lot of benefit to those designs over a traditional dovetail joint. Please don't misunderstand, I have nothing against a dovetail joint......they function great but have the drawback of being complex and time consuming to set properly. I think this is verified when you see that Martin doesn't even make small changes to neck angle as it's very difficult to make small, accurate adjustments. Instead, my understanding is that they get a good fit that is acceptably close to the ideal neck angle.......then swap out bridges until they find one at a height that matches with the current neck set. That's not what I would call high precision......and it's not what I would call the ideal way to get the best tone out of the instrument since the string height at the bridge changes depending on which bridge is used.

So is the only drawback to using a bolt-on like Taylor has used for years (the previous version to the current one) that the bolts may loosen or that the threads might cut into the bolt holes?

It's very easy and simple to check the tightness of the bolts when changing strings (if they are not hidden under a label). Also, you could use Lock-Tite if one is really worried.

As for bolt threads cutting slightly into the wooden neck block, seems that is a good thing if that's what is needed to match the right neck angle. Now it would be bad if this allowed the neck to somehow move to an undesired position/angle. So is this the case?? Do Taylor necks just go off and become unplayable or the action height go high/low mysteriously? I know I've never seen this.....but again, I don't have a repair history behind me so there could be a lot of things I've not seen. Now I have seen a Martin D-35 action go wacky and go crazy high (dovetail joint) and it had to be sent back to factory for repair (which took about 6 months).

My understanding is that the Taylor neck, specifically, the previous version of the Taylor neck, redefined action height, playability, and repeatability. I've only heard good things about their necks and haven't heard complaints about how they hold up over time. The redesign of this joint to the current pocket system was done so the fretboard extension could be kept at the perfect angle after a neck reset (per Bob Taylor in the article I linked to in a previous post above). This neck extension issue is not unique to bolt-on joints.

[tippie53]

To answer Rick's question
at one point Martin did have a few different sizes of bridges , Now there are 3 and we are talking about 5/16 11/32 3/8 do you can see they are not that far apart.
The Martin Bolt on was a glued joint as stated and the new neck design is from a engineer from a flooring company. The new procedure for setting the bridge is a nightmare . The tops are having finish cracks because of it. The rout out a pocket that the bridge sets into , this causes a stress riser and the corners crack the finish.
The new sliding dovetail is actually setting the body to the neck . The joint is cut after the guitar is finished so the joint is pristine.
Thanks for your participation Rick

[B. Howard]

Darryl, I think the point you are struggling with is you are viewing the mortise and tenon from a traditional woodworking/cabinetmaking standpoint. in those applications the tenon is a tight fit all 4 sides with the cheeks controlling depth. On a guitar neck only 3 sides can be tight and in actuality only two usually are ( the sides, not the bottom). The sides will keep the neck positioned on the center-line and provide indexing. Even if the bottom of the tenon is tight to the bottom of the mortise when built, when a re-set is done the angle always changes so that the bottom of the tenon is pitching up off the floor of the mortise. I have never done a neck reset that involved changing the neck angle in the direction of string tension which is the only instance there could be interference there.

Here is a link to Frank Fords page where he describes the Taylor joint in fair detail
http://www.frets.com/FretsPages/Luthier ... joint.html
If you look at those mortises closely you will see that the fret board extension is a snug fit in the top portion of the stepped mortise. IME the other pieces are a snug fit as well. But this system only works if you have the CNC to make wooden parts accurately at these tolerances.

[B. Howard]

The new procedure for setting the bridge is a nightmare . The tops are having finish cracks because of it. The rout out a pocket that the bridge sets into , this causes a stress riser and the corners crack the finish.

Yes, i saw that the last time I was up there and have been dreading the day I need to pull one of those set in bridges.

[tippie53]

the best way is rout it off.