Official Luthiers Forum!

Only in math and statistics, Clinton. My preference is for

4.
Usually, parameters. limits or boundaries; guidelines: the basic parameters of our foreign policy.
5.
characteristic or factor; aspect; element: a useful parameter for judging long-term success.

However, I failed to equate perimeter. My error!

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

Sooooo, Filippo, You bolt the neck to the body, without a tenon... right? Don't even cut through the sides to the block, right?

I don't know exactly why... but that just does not seem right to me.

Mike

No problem, just couldn't pass up an opportunity to be smart a#@ !! I'm glad that we here at the OLF can joke around and not get our panties in a bunch . Is this off subject?? Clinton

Mike,

I, like Filippo, use a simple heel or butt style neck joint with two brass inserts. Check out Kathy Matsushita's website: http://home.comcast.net/~kathymatsushit ... ive22.html

She has some pictures of the process that may clarify some of your questions. The link is to one size 5 guitar she built, but if you go to the main page, there are other projects that similarly describe the process.

I really like this neck joint. Seems plenty strong, super easy to fit, and I can't tell any difference in the amount of sustain/tone from similarly built guitars with other types of neck joints like dovetail or M&T. I don't really see a downside to it. Many other builders, from Taylor to well respected members of this forum, have used such a joint to build many, many guitars.

Aaron

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Aaron Craig

I may have to give that butt joint a try... I've mostly been using the barrel bolt M&T so far, but I don't really see any advantage in it, and it's a bit more pain to cut and drill. The main contact is still just the outer rim of the heel, so the tenon is really only there to hold the barrels, rather than any useful acoustic/structural purpose.

I'm also a fan of the C-shaped headblock, with massive upper braces on the top and back, notched through the linings at full height and connected by hefty side braces. Mega solid, so any deformation leading to a neck reset has to happen further out toward the bridge, where the angular difference is much smaller. It is a bit heavy though, especially with the M&T making the headblock fairly deep. Another reason to try the butt joint I think the headblock on my current one was around 150g. Also could try the A-frame style though...

Acoustically, I'm most drawn to integral necks (with as wide of a solid connection in the middle as possible). The continuous fibers running all the way down the neck to the upper brace of the top make me happy (just a gut feeling, no real evidence to support), plus the ability to have the truss rod and/or CF reinforcements extend into the body. I also enjoy the construction style, and ability to shape heels in interesting ways. Perhaps better to stick with that, and convert later on any that need it. Doesn't look like that much trouble to saw the neck off, and then drilling the holes for the butt joint is about the same as doing it at construction time... although I suppose the long truss rod could complicate things a little bit, and odd shaped heels may not be as smooth and pretty afterward.

On the C shaped neck block, which direction does the grain run? Any chance of the neck block wood contracting at a different rate than the top causing the top to split in low humidity? I've read some folks state that splits along the fretboard are sometimes caused by the wood of the thick fretboard shrinking at a different rate than the thin spruce top in low humidity. If that's true, then could the same thing happen with a long C-shaped headblock glued to a spruce top?

A flat neck-to-body joint would sure make setting the neck angle easier! (don't have the tenon in the way of sanding)

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Formerly known as Adaboy.......

Ooo...never mind the neck joint stuff.......Nice Wood!

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

I guess I am missing the point. What does the C shaped block do for you?

Mike

What are the advantages, disadvantages of mortise tenon, dovetail , buttjoint???
I have only built 6 so far with 5 mortise and tenon and one buttjoint...I use the simpson jig, which gives good joints for neck angel, but I always wonder what is the advantage over just a buttjoint since the tenon doesn't touch the neckblock on the bottom of the tenon???
I have been using the barrel nuts as well, seem to work great , easy to install and line up..

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MK5acoustics.com

I have an excuse - I'm an engineer. Well nown ees we kant speel an makes words up

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Steve Smith
"Music is what feelings sound like"

Flippo, any chance you have a picture of the neck heel made for a butt joint? Does it use the screw-in inserts?

I too have to wonder what the purpose of the tenon is in a mortise & tenon bolt-on neck. As previously mentioned, the end of the tenon doesn't touch neck block and the side fit isn't tight either. Seems the face of the heel making contact with the body and the tension in the bolts is providing all the support........so how would that differ from a butt joint?

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Formerly known as Adaboy.......

Compared to a butt joint the mortise & tenon has more resistance and solidity in case of lateral stress or shock. It is also easier to line the neck to the centreline. It may not be very important.
I use a mortise & tenon with bolts and end grain inserts, the fretboard is glued to the top. There is no issue there and in case of a neck reset the change of angle is so slight that the issue of alignment is non existent. I drill my neck block with a 17/64" bit in any case.

I never saw the advantage of the barrel system as it adds unnecessary weight (steel or brass) and labour, and the tenon needs to be reinforced to avoid splitting. But I am probably missing something.

As for the tonal advantages of one system over another I fear this is purely anecdotal territory. For one, if one believes the connection between neck and body enhances tone, sustain or whatever, the joint itself is not the main point of contact: it is the neck heel cheeks and the upper bout sides/neck block combo. The joint itself is only there to prevent the bottom of the heel to lift up with string tension. The top of the heel is naturally pressed against the body with string tension.
Secondly I built my first few guitars with a dovetail neck joint, I then converted three dovetail guitars to a bolted tenon & mortise neck joint and noticed no loss or even change of tone on any guitar. I then decided to built the subsequent ones with bolted mortise and tenon.
Lastly, I also build with a fully adjustable Stauffer/Turner "tilt-neck" where the only points of contact between neck and body are 3 points: 2 tiny setting screws for parallelism and one 10-20 bolt for setting the neck angle. I built enough of those guitars to firmly state that they lack not in tone, sustain, complexity or otherwise compared to the "traditional" ones. As a matter of fact, without looking, there is no way a player would know what kind of neck system the guitar has. Furthermore I am almost convinced that the tilt neck actually improves sustain and resonance.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Since nobody has mentioned it. . . If you are doing the butt joint, instead of brass inserts you can use hangar bolts in the neck heel (you still should use the cross dowel like you would with the inserts) and a nut on the inside of the guitar. This way you have a smaller hole (and dowel) in the heal and less worry when carving the heal. Other than that, I see no difference.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

The timing of this thread couldn't be more perfect. I just emailed my guitar sensei last night with exactly this idea. It had come up because he has me off making some neck blanks, and I questioned why we had a tenon at all. My idea was hangar bolts epoxied into slightly oversized holes (they would still thread in but not as tightly to prevent splitting) and a nut on the inside with a spherical washer. The spherical washer makes any angle non critical, just like barrel nuts make the neck angle non critical because they can rotate.

And then here's this thread. Nice.

If he gives the OK, I am hoping to try this on one if the matching pair that we are building.

Yup no tenon. I've built probably 25 guitars like this over the last 10 years with no problems at all. I'll probably continue with this method, it really is simple.

John, I have only tried the hangar bolts once, but I was pleased. I didn't use over sized holes (in the heal). I bored a hole through the heal (from the heal cap side) and glued in a dowel (with PU glue). This allowed me to be screwing into long grain instead of end grain and makes me less concerned about splinting. I started the hangar bolt in the appropriate sized hole (just shy of final depth) then backed it out and removed a bit of the pointy end of the wood threads (to give me the length I wanted. Then I threaded it back in with some think CA and drove it in the last little bit. It is very solid. I don't even know that the spherical washers are needed. For this particular instrument, I attached and removed the neck many many times during construction (a lot of experimenting on this one). By the time I had the neck angle and heal fit properly, the washer had pretty much seated itself where it needed to be by crushing (a very small amount mind you) the wood fibers in the hole in the block. Obviously, this would not be ideal if you are way off on your neck angel to begin with, but if you have a good idea where it will be when you drill your holes the bolt angle discrepancy will be small.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

It certainly seems easier. As long as the heel is tight and able to resist the pull of the strings towards the bridge, it really doesn't matter, I guess.

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Old growth, shmold growth!

So far, Laurent's point regarding the potential superiority of the mortise & tenon joint in the event of lateral stress or shock is the point I've most often heard others argue in opposition to the use of a butt joint. I have serious doubts that any technical or mechanical difference in strength to resist lateral stress or shock would correlate to an appreciable advantage in real world situations where such strength would be tested. As a preliminary matter, has anyone ever tested this? It would be great to see some relevant empirical data.

I've been hesitant to drop guitars with various neck joints to test their resistance to lateral stress or shock. Still, I "feel" (watch out now) quite certain that any guitar I've built with a butt joint neck would weather a lateral shock resulting from a fall from a standing playing position as well as one made with a M&T joint. How well is that you ask? Well who the hello knows. Far too many variables would come into play (how tall is your player, are the neck woods the same species and of the same quality, how wide is your heel at the butt joint, how wide is your M&T, what surface is the guitar being dropped upon, etc., etc.). Common sense and, unfortunately, experience tell me the fall isn't going to be good for any guitar.

To damage the butt joint neck, the lateral force experienced would have to be sufficient to basically sheer a heel cheek or break the heel block and crack or sheer the fingerboard where it meets the body. My uneducated guess (I know, opinions are a like a certain body orifice, everyone has them) is that the same force it would take to severely damage a reasonably well designed neck using a butt joint would very likely be equally damaging to a neck made with a reasonably well designed M&T joint.

That's my opinion, and I'm stickin' to it . . . at least until someone else offers hard data or better reasoning in opposition.

Regarding the ease of aligning the neck to the centerline, this is more of a potential production/design issue that may or may not be a problem depending one's technique. A perfectly fit and centered M&T joint doesn't create itself.

Aaron

Edit: Laurent, I'm neither trying to pick a fight, nor insult your judgment or talent as a builder. Having seen your work, I will readily admit you are a far superior luthier than I.

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Aaron Craig

Thanks for that post, Laurent. Indeed, I don't see much difference between bolt-on and dovetail... you get a little more wood contact pulling the neck in, rather than the bolt contact, but it's still mostly the outer rim of the heel taking the pressure. Integral probably doesn't actually help much/any either, but it is different, putting the main connection in the center. But if even the adjustable neck-on-steel-posts doesn't make an obvious difference, I guess the joint type isn't a big player in the sound.

One advantage I remembered of the tenon versus butt joint, is that you can make a smaller heel since you don't need to leave room for the screws in the heel. Doesn't really matter unless you have a cutaway, but if you do, then shorter heel = bar chords possible at higher frets, since you have neck surface to pinch your thumb against. Without cutaway, hand bumps into the body before the start of the heel curve anyway so it's a non-issue.

As to strength, it does seem like side impacts to the butt joint could dent the sides in under the heel edge more than it would if a tightly fitted tenon took the pressure instead. But unless you fit the tenon tightly, then no difference. And in any case, such an impact could just as easily break something else, so I wouldn't worry too much about it.

I haven't. I've taken a few prototypes and beaten them to death. It's worth doing. Guitars are tougher than I thought. Suffice to say that after doing that, I have built both with butted/bolted heels and adjustable necks similar to Laurent's and have never given a thought to lateral strength.

I do reinforce my heels with a cross-grain maple spline. Never tested an un-reinforced butted heel.

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http://www.chassonguitars.com

Thanks Kent. I had a sneaking suspicion some curious mind with destructive tendencies would offer enlightenment. Since I have a limited amount of wood suitable for necks and even less time to do such testing, I think I'll take your word for it.

Aaron

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Aaron Craig

First, I read your previous comment and understood your point, but, other than the number of guitars and the time they have been in circulation, the comment lacks any real specificity. What does "nary a a [sic] field issue" mean? I doubt too many of Randy's clients have conducted destructive testing to determine the strength of his neck joint. Maybe bad things have happened to a few of those guitars that might be relevant to this discussion, but without more info - who knows? Nevertheless, your comment does logically have value: You know of 200 guitars built using a butt joint neck. Few, if any, of those guitars have exhibited problems relating to the neck joint. Therefore, few, if any, guitars built using butt joint necks will exhibit problems relating to the neck joint. Still, inductive reasoning has its limitations, which is why I asked about actual testing.

Second, I also thought Laurent's comments were great, and I enjoy reading Laurent's posts and have learned a great deal from them. As to his comment that it may make no difference, one could interpret this statement, as written, as applying only to his comment regarding the alignment of the neck. In any event, my intent was not to attack Laurent, but to comment on an idea that I have repeatedly heard, but personally question.

Third, and finally, I would never claim any particular neck joint is the "best." I never suggested Laurent was of the opinion a particular neck joint is the "best." I do what works for me, and, at least for now, that means I use a butt joint. Laurent, with much more experience and expertise than I, currently prefers a different method. That's great too.

For the record, I value your opinion also, Filippo, and I have learned a great deal from you through the information you have shared with the forum. Thanks.

Respectfully,

Aaron

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Aaron Craig

I know its a bit off topic but would you care to elaborate on this Laurent ?

Do you think the sustain could be that, because you can adjust the neck angle of your guitar perfectally AFTER the guitar
has bulged/been played in...
and that less fret work=higher frets ?

Tomas

Tomas, my opinion here is purely anecdotal: because there is no "tonesink" in the form of various pieces of wood being more or less in contact (as in any neck joint) it is possible that the tilt-neck, with its 3 pivot points, "robs" less energy from the top. Again, my experience is purely anecdotal. Note my use of almost.

Aaron, as Kent can probably testify, if you stress a neck joint in the manner of Pete Townshend, you end up with a neck attached to a neck block and various guitar parts more or less solidly attached to it. The sides tend to break right at the edge of the neck block. A mortise & tenon has more lateral strength than a butt joint, this is self-evident, but as I demonstrated it may not be relevant to acoustic guitar construction. Personally I am more comfortable with a reasonably tight M&T, I believe it is probably a more stable joint.

The value of Filippo's comment on Randy's guitars "in the field" is this: if you build and sell enough guitars, especially to working musicians, you will see them come back to the shop regularly, for maintenance, modifications, repairs and so on. Believe me, if there is a flaw in your building technique, you will change it quickly. Warranty work can hurt a company pretty badly, but it will kill a small builder.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

To add my 2 cents. I have been using a but joint since my 3rd instrument and initially used inserts but for the past three or so years have been using hanger bolts and reinforcing the heel with a maple dowel. Works great for me.