Martin Applied Dovetail

jcwukes

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My question isn't about how or why it is done. I believe that is explained in the video. I am not intending to criticize the method either.

My question is about the actual strength of the joint. When it's all said and done, it doesn't seem like it would be any stronger than a simple butt joint.

Am I correct, or is there something that I'm overlooking? The explanation of the Applied Dovetail begins at about the 11:35 mark in the video.

 
Imagine the applied dovetail piece of wood glued into the female dovetail in the neck block first...then the neck glued on afterwards without the screw then it would be a standard butt joint, which could be weak...So the screw makes it a little stronger, but the screw isn't very long and screws into the end grain of the neck (as the man said "to act as clamp" for the glue)..again not very good :( ...so my thoughts are if you are not going to make the traditional one piece compound dovetail (which is proven over the years to be a strong joint) Then you might as well do a "bolt on cross dowell" neck joint. :2cents::eek:ld:
 
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What Chris glosses over is that in the 70s they sold all of the jigs, tools and part finished ukulele in exchange for some koa... So when he talks about amoratising the tooling costs they had to start production from scratch using their museum models as starting points.
 
I looked at the video, and I'm not particularly impressed with how they're doing that joint (especially given what they charge for their instruments). That said, I would say it's a bit better than just a butt joint because the locating pins and screw will help prevent twisting forces from stressing the glue joint. The other half of the joint, dovetail into the body of the uke, should be quite strong because of the mechanical fit and sidegrain-to-sidegrain gluing area.

It would be much better if the dovetail was actually part of the neck rather than a glue-on piece. In the video, they say that prevents them from having to undercut the "cheeks" (they say the correct radius is presently cut by the neck cnc operation) but I image there must be a way to do that efficiently with modern tooling.

There is also the possibility of using a "loose tenon" type joint, which would also be better.
 
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Martin probably carves the "applied" piece on a CNC machine. As such the neck and neck block are probably done on a CNC as well. Thus the curve of the body and the curve of the mating part of the "applied" dovetail can be machined to match the body curvature with very high accuracy while the female dovetail on the neck block and the male portion of the "applied" dovetail piece can likewise be produced with great accuracy.

Fitting neck to body has the potential to remove a lot of the "fitting" time compared to traditional methods and could save Martin lots in production costs. Plus fewer men can control several CNC machines, thereby reducing labor costs more while upping production.

Since string tension on a uke is low, even on a tenor ( approx 44 #) the strength of the joint shouldn't be an issue.

Finally, it remains to have a head to head showdown; applied dovetail Martin against a Timms soprano to answer the Man vs. Machine
Argument.
 
He's the "Left-Brain Lutherie" author, if I'm not mistaken.

EDIT: Googled it. Yup! That's him.
 
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