Thread: Headblock and neck mortice

Originally Posted by Different

Hi guys
Just working my way through Cumpianos book and my first build as you know and as far as I can see the mortice in the headblock runs through the whole height of the block (ie not stopped as a mortice would be in the leg of a chair or table) this leads me to a number of questions as follows. What concerns me is apart from the bolts pins or whatever fixing you use the only thing stopping the tennon is the backplate of the guitar.

1. Is this the normal method of construction for a M&T joint?
2. Is there a reason for this?
3. Is there a reason why the mortice cannot be stopped some distance from the bottom for both strength and registration purposes?

Ross

Hi Ross,

It seems to be done that way in most of the books I have read. Dunno why, dare I say tradition? It allows / requires a heel cap to be be fitted which can be an aesthetic point, ie it matches the headstock material. Mandos often have the back material as the heel cap in one continuous piece.

As for why not have the mortise shorter I cant see a reason. If there is plenty of strength to withstand the pull of the strings the only reason I can see is tradition. It raises the question of composite neck and block materials with much higher strength than timber.

Ross, you know Cumpiano updates his book on his website regularly, see http://www.cumpiano.com/Home/Book/textbook.html

Sebastiaan

Originally Posted by Sebastiaan56

Hi Ross,

It seems to be done that way in most of the books I have read. Dunno why, dare I say tradition? It allows / requires a heel cap to be be fitted which can be an aesthetic point, ie it matches the headstock material. Mandos often have the back material as the heel cap in one continuous piece.

As for why not have the mortise shorter I cant see a reason. If there is plenty of strength to withstand the pull of the strings the only reason I can see is tradition. It raises the question of composite neck and block materials with much higher strength than timber.

Ross, you know Cumpiano updates his book on his website regularly, see http://www.cumpiano.com/Home/Book/textbook.html

Sebastiaan

I suspected as much as it being tradition and one I intend to break.
Yep I know about his updates very good of him I feel!


Ross

I cut mine to around 5-6mm inside the binding ...and given the thickness of the binding @around 6mm I'd say the bottom of the headblock would still have 12mm of meat on it before it meets the backplate.

Originally Posted by gratay

I cut mine to around 5-6mm inside the binding ...and given the thickness of the binding @around 6mm I'd say the bottom of the headblock would still have 12mm of meat on it before it meets the backplate.

So you agree the mortice should indeed have a bottom to it?
If so what are your reasons fo doing so?

Ross

Originally Posted by Different

So you agree the mortice should indeed have a bottom to it?
If so what are your reasons fo doing so?

Ross

I don't see the point of going right through the headblock if you don't need to..
doesn't matter what joint M&T or dovetail most I have worked on and seen are similar to this picture.
This is not mine by the way. Just a googled image ...but mine is similar to this depth

Surely having the tenon bottom out snug in the mortise adds a bit of extra strength to the joint....even if the bolts are providing most of the strength in the joint.

Martin

Originally Posted by kiwigeo

Surely having the tenon bottom out snug in the mortise adds a bit of extra strength to the joint....even if the bolts are providing most of the strength in the joint.

Martin

I agree big time but the only reason I can see for it being done the other way is the ease of cutting the through joint on a tablesaw.


Ross

Correct. Note that Campiano has changed a few of his views on neck joints and other things. When reading his book also check out his website...

For a conventional dovetail M and T joint the mortise MUST stop short of the bottom of the block. The bottom of the mortise is part of the joint....if you cut the mortise right through then the tenon will pop through the back of your guitar when you tune it up to full tension.

Originally Posted by Different

I agree big time but the only reason I can see for it being done the other way is the ease of cutting the through joint on a tablesaw.


Ross