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I am about ready to look at fitting necks to my first two. And the first thing I noticed is I can't get them in the slots. I am using a mortise and tennon joint, bolted.

Problem is, the truss rod sticks out too far so it and the back binding (where it crosses the mortise) get in the way. I began by cutting a slot in the base of the neck tennon for clearance over the binding, but it still won't go together.

My question is, should I just cut off the end of the tennon instead of using the slot? Any downside to this? Or should the tennon be full length of the heel?

Should I make the slot in the top longer (toward the sound hole) to make more clearance for the end of the truss rod?

Thanks, eagerly awaiting your answers!

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Phil

http://www.oleninstruments.com

"Those who tilt at windmills are only considered insane by those who can't see the dragon."

The mortice normally stops about 5mm or so from the base of the block. No need to go full depth - you just need enough room to get the barrel nuts or threaded inserts in there. There should be a slot cut in the top of the neck block where the truss rod slides through. It looks like you've already got it on yours, so that shouldn't be keeping it from going in. Are you sure the tenon isn't too wide?

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"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso

https://www.facebook.com/FenskeGuitars

If you have to trim a little slot in the soundboard for the truss rod to slip through it shouldn't hurt anything. You should still have plenty of material left to glue the fretboard down.

From your picture, I can't see what the problem is. As Peter said, normally the tenon is not continued
all the way to the back of the heel, it stops 3/8-1/2" from the rear threaded insert. The tenon should
drop straight down into the mortice, and the end of the truss rod should just slide into the slot in
the neck block.

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Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain

The tennon is a nice snug fit, the problem is interference at those two places. I've attached a couple more pics to show the fit.

When I cut the slot in the top, I tried to keep it as short as possible. But knowing the fingerboard gets glued to the top in this area, is this a concern?

It sounds like cutting just a bit off the tennon for clearance will get me what I need. Realistically, a small adjustment in either place will get me there I think, but since I'm new at this, I alwas like to ask to see if there are any concerns I'm not aware of!

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Phil

http://www.oleninstruments.com

"Those who tilt at windmills are only considered insane by those who can't see the dragon."

Hey, thanks for the quick replies! I was loading those last pictures while replies were coming in, so I didn't get to read them first. So I think I'm in good shape.

One question though, how long is that slot in the top, typically? Lenght of the tennnon? length of the tennon plus half/full/some of the length of the truss rod?

Thanks again

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Phil

http://www.oleninstruments.com

"Those who tilt at windmills are only considered insane by those who can't see the dragon."

Yeah you should take a little off the bottom of the tenon. There's no need for it to go all the way to the bottom of the heel. That should fix that issue. And cut a small notch for the truss rod and that will fix that issue as well. A 1/4" wide slot 1/4" long won't affect your gluing surface for the fretboard. your notch in the soundboard should be tenon shaped with a rectangle out the end for the truss rod.

It helps to glue the fretboard onto the neck shaft to help size the tenon to the right length. Mine stop half a milimeter above the binding and the heel cap covers that easily.

Some people like to fit the dovetail and glue the neck shaft onto the guitar before gluing the fretboard, but that's not necessary with the bolt M/T method, unless there's a specific reason for you doing that which I am unaware of.

Cut a notch for the truss rod, of course.

The Martin truss rods don't extend past the tenon, which eliminates that consideration, although the notch doesn't hurt anything at all.

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Old growth, shmold growth!

Todd,

Should the offcut be thick enough to contact the tennon? Or is it sufficient to double the back thickness in that area, just to stiffen it? In other words, have a gap between the added off cut and the tennon?

Thanks,

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Phil

http://www.oleninstruments.com

"Those who tilt at windmills are only considered insane by those who can't see the dragon."

There won't be a dimple there if you've removed the discontinuity.

None of my guitars have dimples, and when I went to Cumpiano's shop, none of his had dimples either.

They're all made the same way.

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Old growth, shmold growth!

You're probably right, that there will be no dimple there. I personally would just fill the space with something out of piece of mind. Just seems like good practice to not leave an area of a mortise empty.



That is interesting, something Im glad you said. I would not have been aware of this. The whole time building I have been trying to prevent from having to cut a big notch in my sound board to accept the end of the truss rod.