Official Luthiers Forum!

This is my first post so let me first thank everyone on this forum for contributing to a great wealth of knowledge and resource for folks like me. Thanks!

Now onto my problem & question. I recently purchased the StewMac mortise & tenon templates, built a fixture to use them and proceeded to machine the body and neck joint of my current build. I understand the importance of this joint so I am quite anal about having things exactly aligned and properly clamped. You can imagine my surprise as I noticed a lot of slop between the tenon and mortise joint when dry fitting. I had expected a snug fit.

So I did what I should have done first. I checked the templates for accuracy and discovered the tenon template measured 0.731" +/- 0.001" wide and the mortise template measured 0.783" +/-0.001" wide. This produce a gap of over 0.05" between the walls of this joint. Next I called StewMac and spoke with one of their techs'. He explained this difference is to allow for final shimming to fine tune the joint. Okay. Now I know it was intentional. I have to add material to the tenon or mortise to take up the slop. Has anyone experienced this? What is the procedure for doing this? Do I glue material to the tenon and hand chisel to fit?

BTW, I used a 1/2" router bit with a 1/2" bearing guide. It would seem if my bearing guide were 17/32" I could get the fit I expected. Would this be an option next time (providing I can get a 17/32" guide for a 1/4" spindle)?

Thanks again.

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Ron

The mortise and tenon joint doesn't function like a dovetail. You can have airspace around the tenon and be just fine. In fact, I have allowed for an extra 1/8" width in the mortise to allow perfect alignment of the neck with the top and back plates.

I have the neck bolted up (without the finger board) and everything lines up fine. Like I intended it to be. I now have a gap on each side of the tenon between the mortise walls. I'm thinking I'll have less string energy transfer from the neck to the body unless this gap is closed. Does that make sense?

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Ron

I wouldn't worry about it. I've used the Stew Mac templates on all my bolt on necks and actually like the little bit of play. Makes it easier to align the neck. Once everything is bolted up I don't think it makes any difference whatsoever. No different than a bolt on without the tenon. The tenon for me just serves as a place to put the barrel nuts for the anchoring bolts.
Terry
http://www.kennedyguitars.com

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Yeah,I agree with Terry.It's nice to have a little gap for alignment.
Once you have the bolts tightened and fb.ext. glued or bolted it should be fine.

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Anderson Guitars
Clearwater,Fl. 33755

The idea that there is significant energy transfer in a neck joint is just...well, it's just weird. It's one of those things that too many people just accept in the beginning and that solidifies in their thinking without ever a critical look at the theory. I simply don't believe that there's much to it all. I've seen and built too many instruments with hardly any contact that sounded just great to believe in that old wives' tale...

Rick T.