Ellis Neck Joint

**mdlorenz** · Jul-09-2009, 11:42am

Saw this & though it was interesting...http://ellismandolins.com/SHOPPAGES/shop_pg_11.htm

Looks like there's an arch to the dovetail... Is this common? Just curious...

**sunburst** · Jul-09-2009, 12:18pm

It's a curved mortise and tenon rather than a dovetail, it is not common, it would be difficult with hand tools or with shop jigs, it is really only feasible with CNC equipment.

**blawson** · Jul-09-2009, 12:20pm

Hey John -- What about strength vs. a typical dovetail?

**sunburst** · Jul-09-2009, 12:27pm

A "typical" dovetail is a self-locking joint, a mortise and tenon relies more on the glue joint than the physical joint.
It would be possible to string up a well fit dovetail dry, no glue, but not a mortise and tenon. In real life, however, with bumps and knocks, with heat and cold, with humidity changes, both joints require glue for their long term integrity. Both are plenty strong under normal use, but both can succumb to improper treatment.

**Rick Turner** · Jul-09-2009, 12:51pm

Around here, folks string up dovetailed guitars without glue all the time when doing a reset to test the neck angle.

**mdlorenz** · Jul-09-2009, 1:04pm

Oh yeah I didn't even really notice that there wasn't any "Dovetail" to it...

Is there a benefit of curving the sides like that?

**thistle3585** · Jul-09-2009, 1:05pm

Originally Posted by sunburst

It's a curved mortise and tenon rather than a dovetail, it is not common, it would be difficult with hand tools or with shop jigs, it is really only feasible with CNC equipment.

One of the photos on his shop page shows cutting it with a router and a jig. I wouldn't see why that wouldn't work. Isn't that jig system fairly common in guitars? I'd be interested in seeing the setup for it. I don't know that I'd do it that way but I really enjoy seeing the creativeness that goes into alternative approaches.

I am guessing that the curved sides of the joint match the curve of the heel which allows for a very minute amount of stock leftover to fit to the rim at the headblock.

**sunburst** · Jul-09-2009, 1:49pm

The old Gibson mandolin had a curved heel profile, like many other instruments with dovetail neck joints. A straight-sided mortise and tenon joint, like the one in the Siminoff book, requires straight sides on the neck heel. By curving the sides of the mortise and tenon, the neck heel can be made curved to look like the old Gibson neck heels (as well as like many modern mandolins with dovetail or hardware joints) while using the simpler-to-execute mortise and tenon joint.
I always assumed that Tom chose the curved mortise and tenon because he had the ability to tool up for it while maintaining the aesthetic of a curved neck heel.

Perhaps Tom will stop by soon and give us "the real story".

Perhaps one could make a precise enough router jig to make the joint fit, but comparing it to jigs that guitar makers use for dovetails is not a very good comparison. Guitar dovetails generally have straight sides, and the final fitting is done by hand. Fitting the curved joint could be done by hand, but not easily, not as easily as fitting a dovetail with chisels and files.
It just seems to me that the precision of CNC and the curved mortise and tenon would be such a good match that that would be the way to do it in a shop so equipped.

**Bill Auld** · Jul-09-2009, 2:16pm

Thanks, mdlorenz, for bringing this up - saw it the other day and was curious about it as well.

John - thanks for your comments. When I first saw it, I was struggling to figure out how this could be done so cleanly by hand (unless perhaps as Andrew suggests). CNC makes sense.

Anyway, it's a very interesting approach.

**ellisppi** · Jul-12-2009, 10:39am

I've been down with a bad back all week. Here are some more pics of the router jig. John described it correctly. There is a pic of Nate using it on the website. the templates are cnc but they could just as easily be handmade. Sound tricky and time consuming? You bet, about as fussy as it gets no matter how you do it. I just bought (hopefully my last purchase of anything ever) a right angle head for Blue. Here's a pic of Nate setting up the fret slotting saw. Out the back of the RA head is another arbor, so we now can set up to really do them on the cnc. We are having custom tapered tools made so the new method will have the same angle as the fingerboard taper and therefore a slight dovetail.