Mortise and Tenon problem

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edbanas
Posts: 17
Joined: Thu Apr 17, 2014 10:06 am

Mortise and Tenon problem

Post by edbanas »

I am building a deed kit from LMI. Now it's time to install the bolt-on neck and there seems to be a problem....maybe. The neck angle is not bad - a little adjustment will make it fit quite well. But the tenon is about 1/4 in. short of settling tightly against the neck block. The cheeks of the tenon fit tightly against the guitar body and when I crank down the bolts the joint seems to be perfectly fine. It just looks odd with the space. Once the FB is installed, it will never be seen. I could conceivably cut the cheeks of the tenon to set the tenon tight in the mortise and at the cheeks, but that would move the 14th fret 1/4 in. well over the body and closer to the sound hole. Should I make an adjustment or, since the joint seems stable, should I leave well enough alone?
JLT
Posts: 209
Joined: Wed Nov 02, 2011 9:13 pm

Re: Mortise and Tenon problem

Post by JLT »

Leave well enough alone.

That 1/4" gap between the end of the tenon and the end of the mortise is perfectly normal. It ensures that, when you tighten the bolts, all the pressure is on the flanges of the neck and the top of the mortise, which is what you want.
Ben-Had
Posts: 1405
Joined: Fri Sep 03, 2010 2:14 pm
Location: Creedmoor, NC

Re: Mortise and Tenon problem

Post by Ben-Had »

Correct, that is exactly how it is suppose to be. Some glue the tenon into the mortise, when performing a neck reset (should it ever need one), the 15th fret is pulled and 2 small holes are drilled thru the fret slot into that gap and steam is injected into the gap to soften the glue to remove the neck. You find the same gap on dovetail neck.
Tim Benware
edbanas
Posts: 17
Joined: Thu Apr 17, 2014 10:06 am

Re: Mortise and Tenon problem

Post by edbanas »

Thanks. The only reason I questioned leaving it alone is that in all the pictures I've seen of projects in this state of progress, that tenon looks like it fills the gap. Again, thanks.
tippie53
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Location: Hegins, Pa
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Re: Mortise and Tenon problem

Post by tippie53 »

there is something you need to know
the mating part of the neck joint is not the bottom of the tenon but the cheeks of the heel. The controlling part of the joint is the point of where the heel meets the sides of the guitar. That controls the neck angle and the neck center line.
If you thought the bottom of the tenon to the neck mated to the bottom of the neck mortise that is not how the joints work.
We are all here to help you get this right.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
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