Tenon quandary --- where to start?

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Danl8
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Tenon quandary --- where to start?

Post by Danl8 »

This is my second project also a rescue. The body (000-17SM-like) and neck were never joined, but should be the right type together. This joint is a bolt-on dovetail straight tenon (seems to be a contradiction...). The problem is I can't figure how they should altered to get a good fit. The mortise seems normal and the tenon seems okay, too. But the fit not even close. Problem is that I'm not sure of how to proceed. I can add wood to the dovetail tenon and get a fit that way, but I'm sure that I'm overlooking an easier or more robust solution. Please offer suggestions. Thanks, Dan.
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johnnparchem
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Re: Tenon quandary --- where to start?

Post by johnnparchem »

It is not a bolt on but a standard dovetail. The bolt you see if for a manufacturing process. You should just ignore it. If the tenon is loose in the mortise adding shims to the tenon is the right thing to do.

If you have not set a dovetail before I would go over to the Blues Creek guitar site and find John Halls video on setting a dove tail neck joint.
tippie53
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Re: Tenon quandary --- where to start?

Post by tippie53 »

Actually the bolt was used and I assume they will use them again. Too many loosening up.. I would flatten the dovetail and make it a tenon and add the 2nd bolt. I have done a few of these from GMC.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Danl8
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Location: Chadds Ford, PA

Re: Tenon quandary --- where to start?

Post by Danl8 »

Thanks to both of you. The dovetail is like a common cabinetmaking tenon, nothing fancy. The problem was that the geometry was beyond minor fitting -- tenon is way too short. I will do as John Hall suggests, cut the tenon to fit, shore up the mortise and add a second bolt. It's a relief to finally have a plan...

--d.
tippie53
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Re: Tenon quandary --- where to start?

Post by tippie53 »

the way that this joint is done at Martin is the straight tenon doesn't get the dovetail till the neck setting process. That is when this joint would be fitted at Martin. Martins Guitar Makers Connection will sell the new neck and often have 2nds of the bodies that may or may not have the dovetail cut. In this case it wasn't cut for the Dovetail so making this a 3/4 in tenon will be easy
I would agree with John P had the dovetail been cut.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Danl8
Posts: 740
Joined: Mon Jul 28, 2014 7:50 am
Location: Chadds Ford, PA

Re: Tenon quandary --- where to start?

Post by Danl8 »

Thanks for the feedback. I went ahead and fitted this one. A one inch chisel and some more lampblack and repeated small adjustments did the trick; the joint is tight, centered and angled correctly. I did add the second bolt as you suggested. This thing is now rock solid and another GMC body saved from the mulcher.

Added benefit... I was able to use information from your 8/31 video on set up immediately after completing the joint.
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