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I am using solid linings on my build, and was wondering if there is any reason not to run them to the center line where the sides meet at the neck? I would then rabbet the neck block to accommodate them instead of just butting them. Thanks!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Interesting idea Alex. Of course where the dovetail or tenon goes will have to be milled out but just the same it would seem to me that this would add rigidity to the block area where distortion happens over time leading to neck resets. Might be a cool mod and it may have functional value too.

Good thinking!

Certainly sounds like it would be worth a try to me .

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If you want to glue your blocks before your linings as is common you might be able to rout out a notch in the blocks after they are glued like we do for brace pockets and tuck them in a half inch or so. That would certainly eliminate the potential stress riser when they are butted.

Then again is it worth all the extra work? Anything that limits headblock rotation is good and this might be one of the little things that makes the construct just a bit more rigid.

I say do it!

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

I'd have to be convinced -- with some science, I see no structural advantage. I don't necessarily agree with the Martin neck block cantilever but at least that idea theoretically counter acts the neck arm lever action providing resistance at the other end of the pivot some distance away -- running the lining into the block just changes the pivot configuration -- how will that add resistance?

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Ken Cierp

http://www.kennethmichaelguitars.com/

Solid/laminated linings are exponentially stiffer than a typical kerfed lining, tying them into the neck and tail block is worth a try.

I've built with a rebate for laminated linings in the head block. I find it helpful for two main reasons:

1) On cutaway guitars especially, it helps capture the ends of the laminates where they are otherwise difficult to clamp into place. This also applies to non-cutaway guitars too, but the clamping is much easier in that situation. Works well for reverse kerf linings, too.

2) It will stiffen the joint between the linings and the head block. In the normal situation, with the head block being "pulled in" by string tension, part of the resistance to this force is supplied by the shear strength of the joint between the linings and head block. In the normal situation, there is no effective joint here. In the rebate situation the stiffness of the linings in shear adds to this if they are properly glued in.

It's not a particularly common failure, but many will be aware of the shear type failure where the fretboard slides back into the sound hole and the top panel cracks either side of the fretboard. I can see linings rebated into the head block going a long way toward minimizing that sort of occurrence and the damage caused.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

The neck joint will be a bolt-on butt joint, and the FB bolt-on as well, so there will be some of the lining lost when the pocket for the neck extension is routered out. I made a neck block a couple of days ago, but I'm not quite satisfied with it, so I'll make another tomorrow.

My thinking was eliminating, or reducing the stress riser, as Terence stated, and eliminate the chance of having a less than perfect butt joint. The thought came to me after I installed the heel block, so I'll cut a rebate for the linings, as suggested by Trevor.

I made the linings with a three piece lamination of basswood, and have one set left to go in the gluing form. This is the first time that I've used basswood for anything, and found the smell appealing, at first, but then a little overpowering, like the Patchouli one of my girlfriends used to wear!

Thanks for the responses, and the encouragement! I'm looking forward to inching my way forward on this!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

You might consider shortening the mortise for the extension. Leaves more top glued to the head block to resist rotation. Got the idea from Sylvan Wells as well as some other tweaks to increase stability of the Bourgeois style joint. It definitely helped. It is potentially not the most stable joint I have found.

In my eternal quest for even more stability I am going to start inletting the linings as well. Thanks! It is something I would never have thought of and worth a try.

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

Thank you, Terence. That looks interesting. Are the blocks with the threaded inserts just glued on the FB?

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Good question. I started with Tightbond about 9 years ago and had one lift partially so switched to epoxy. Thought that solved the issue. I recently saw an older guitar with epoxy and there was a small lift on one edge. Now I use Gorilla glue with a couple of small brads to hold it aligned during clamp up.

How do you do your fretboard tenon Alex?

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

Good question, Terence! This is my first guitar build, so everything is new to me! If I understand correctly, the neck and tenon will be one continuous piece, with the heel block a separate assembly, and the tenon narrowed and thinner where it attaches to the pocket routed in the top. I'm working from the OLF SJ plans, but with a couple of modifications. On the plans, the neck block extention stops shy of the UTB, and unless it's a dumb idea, I want to attach directly to the UTB. I'm also thinking about doing a "C" neck block, and butt the lower extention to the upper bout back brace.
Again, I'll be seeking the advice of those with experience to set me straight, if need be!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

I think it's a great idea Alex. That's got to add some longevity and rigidity to that whole upper bout, neck joint area. You better name it after yourself pretty quick before someone else jumps on it. The "Kleon Neck Block Rabbit Thingy". Sorry, it's late. I'm sure I'll awaken in the middle of the night with something a little more catchy.

I'm having a real hard time understanding how the lining material would be stronger than the neck block material.

What I like about Alex's idea is that it's not simply replacing neck block material with lining material but it's the continuance of the solid linings through the intersection of the neck block and where traditional linings terminate.

I may take a pic or two today of some of the patients in our hospital awaiting neck resets to make this point. When it's time for a neck reset you can often see from the outside of the guitar where the neck block meets the sides, the block can look pushed in a bit and the smooth transition of the sides into the block region gets broken and "kinked" for lack of a better word exactly where traditional linings terminate and the block begins, the stress riser area if you will.

Continuing the linings beyond this point is a stiffener and has to help resist deformation at least to some degree. This is the beauty of Alex's idea at least in my way of thinking. It very well could help belay the need for resets a bit longer.... or more....

Of course we would need to do some testing so who wants to build two mules one with ACL's (Alex's continued linings) and one without and then hang em and wait 30 years and report back to us? Seriously though I like this idea a great deal and would have no problem using (with Alex's permission of course) continued linings on a future build.

Good going Alex!

I'll add, since I can...., that for years now I have personally believed that the design of the traditional acoustic guitar as per Martin, G*bson, etc. is pretty good for it's intended purposes and not too much of the newer stuff that I see does much for me in making me believe that it's a leap forward. The simplicity of traditional design especially without the dependency on other parts, hardware, etc has been not only something that I admire but something that I have believed is likely so very good now that there is little that could be done to improve on it without adding mass and/or complexity and possibly reducing serviceability.

Neck blocks don't need to be removed, not often anyway.... but even still this idea does not preclude anything that may need to be done to the ax from being done in the future - by definition it's a serviceable idea. In addition the stiffening of the block area is always a good thing provided that extra mass is not added as in some ideas or complexity as in other ideas i.e. buttressing etc. Alex's idea adds stiffness in this critical area to the constant string pull but does not add any additional mass or complexity - beautiful!

PAF time Alex?

You know too there is no reason why solid linings could not also be used for the bottom of the block as well not to mention the tail block too. The result would added rim stiffness with the only complexity added being four routed channels and some precise measuring.

Thanks for the catchy name, Danny! Doesn't quite roll off the tongue like Manzer Wedge though, does it?



I planned on doing the same with the back linings as well, Hesh. I wish I hadn't already installed the heel block, but I let the linings into it, as well.

At this point, I'm having visions of my completed guitar either imploding or exploding, and only the linings and neck block surviving.
I'm sure that I'm not the first to think of, or do this. Lots of people do things, and never tell anyone. I just have a very questioning mind, and ask myself, what if..... a lot.

PAF time? Permanently attached fixture?

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

As soon as someone has a picture, I sure would like to see it. I'm having a little trouble imagining what a continuous lining inlet into the blocks looks like.

Whenever I see this type of analysis, I just wonder how many have actually grabbed a side assembly at the neck block and twisted it in their hands. It provides very little resistance (even with solid linings rabbeted into the block), for one simple reason....the sides are perpendicular to the direction of the force, and twist very easily. Remember, we are talking about a constant 180 pounds of string tension. Also consider that a movement of as little as 1/32" is enough to make the neck angle change to the point that the guitar is totally unplayable.
Solid linings will increase the stiffness some over kerfed linings, but it still won't matter much.


I also don't like Martin's L-shaped neck block, but for different reasons. On standard series Martins, the grain in the cantilever is running east-west, and does not provide much resistance to neck block rotation (wood flexes easily across the grain). The area of the cantilever that is actually glued to the top is very narrow....it is not glued to the popsicle. Finally, leaving a space between the cantilever and the UTB (as Martin does) provides no resistance to a neck blocK shift.


In order for that failure to occur, there are three joints that must come loose:
1) The neck block to the top outside of the fingerboard
2) The popsicle brace to the top under the fingerboard
3) The UTB under the fingerboard.
All three joints on a Martin style guitar are cross-grained. Most of the time, this failure is the direct result of overheating the guitar.

IMHO, the best way to prevent neck block shift is with a patch of thin spruce fitted tightly between the neck block and the UTB. If the grain in the patch is parallel with the grain in the top, it has the best chance of resisting any rotation, and the best chance of staying glued. I make this patch with angled edges, which lessen the chance of top cracks. The width of the patch is the same as the neck block where it contacts it, and widens to the width of the soundhole at the UTB. This patch is used in place of the popsicle brace.

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John

If I am understanding you correctly, John, instead of trying to butt the neck block to the UTB while bracing the top, leave a gap to be filled afterwards with a patch glued cross grain to the UTB? Or is this as a corrective measure for a finished guitar? That would be much easier than what I was going to do. I'm fitting a C shaped neck block, so should I leave a gap between the block and the upper bout back brace, and fill the same as the top? That is, if I understood what you explained, correctly. Thank you, John!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

Not continuous solid lining in this case, but I think you'll get the idea...

This guitar...

...looked like this without its top...

The reversed kerfed linings are let into the headblock, but don't go through as far as the centerline. The top plate of the head block butts to the UTB and a lot gets machined away for the double tenon neck joint, below (different guitar, clearly)

The main reason for tucking the linings on this one was the first reason I gave in the post above; it captures the ends of the linings. More beneficial when using laminated linings, of course, but when you have a stock of pre-machined headblocks...

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

This is turning into a great thread. To make sure the mortise block for the fretboard tenon is tight against the top brace I've been leaving a gap at glue up and then accessing it through the mortise cut and squeezing in a tight spacer so there is solid contact. That has helped.

Dana B does that but since he glues the top first it is easy to put in at that time.

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

Thanks for the pictures, Trevor. The picture of your M&T and bolt-on FB extention is what got the wheels turning to do something similar. I really enjoy doing bits of different joinery!
I made a new neck block, and routed out the heel block to accept the linings, and will scarf them at both ends.

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

I tend to see it like John Arnold, even with the stiffest linings, the soundboard is the major element resisting neck block rotation.
Inletting linings won't harm as long as they are a really tight fit in the neck block and don't intrude under the area supporting the top of the heel. I can't see it being worth the effort.

Any benefit derived from such a design would be dependent on excellent joinery, and anything less, it would seem, would sacrifice what stiffness and anti-twisting property the side/neck block joint would have had with the traditional design of butted linings. As far as joinery goes, fitting an inside radius rabbit to perfectly opposed surfaces (to me) is mighty difficult!

Great thread, and this is what I love about guitar luthiery--on a violin site, a suggestion for a design change gets you banned for life!

Dave