Official Luthiers Forum!

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.