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  #1  
Old 05-05-2017, 07:30 AM
Briggle Burger Briggle Burger is offline
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Default Neck Joint Fastening

Hi, newbie to the forum here, and just starting my first build. I have a question about the neck joint when I get to it...

...Why use bolts, nuts, and inserts instead of just using wood screws (in addition to a mortise and tenon and glue)? It looks to me like over-engineering and a huge waist of time doing something that requires precision; versus slapping it in, drilling some pilot holes, and screwing in some wood screws.

I can't think of any tonal or structural advantages to the system that everyone seems to use, and just using wood screws seems so much easier. Cheaper too!!! THAT'S why I'm asking the question: nobody seems to do it the easy way, and I can't think of one logical reason why not! Am I missing something...???
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Old 05-05-2017, 07:41 AM
LSemmens LSemmens is offline
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Wait until an expert chimes in but my thinking would be that wood screws can come loose over time given that, although the wood is seasoned, some shrinkage can occur as a result of humidity, or lack thereof. A Mortise and Tenon Joint is strong enough for furniture but for a precision instrument you may well be requiring the additional stability of a dovetail joint. Don't forget, you are going to have several strings putting stress on this joint 24/7.
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Old 05-05-2017, 08:01 AM
charles Tauber charles Tauber is offline
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People have tried just about everything in attaching necks to bodies. These include, an epoxied butt "joint", dovetail joints, mortise and tenon joints, Spanish construction, one-piece through construction and so on. These have been used with a variety of glues and with no glue. These have been used with and without a variety of fasteners from pins to barrel nuts/bolts, threaded inserts ...

I mostly use the system I learned more than 30 years ago from Grit Laskin: a traditional dovetail joint with no glue that is prevented by a single wood screw from sliding vertically apart. (The dovetail is a mechanical locking joint that comes apart only by sliding one part vertically relative to the other.)

If you are going to glue a mortise and tenon joint, you probably don't need any mechanical fasteners, relying on the glue to prevent motion of the parts. Mechanical fasteners can be added to a glued mortise and tenon joint as a way to clamp the joint while the glue dries, if one wishes. One of the primary reasons that modern makers use mortise and tenon joints is that they don't use glue, making it a simple matter to remove the neck or adjust its angle. If used without glue, it needs some mechanical means to keep it from coming apart, hence screws, bolts, etc.
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Old 05-05-2017, 09:05 AM
TEK TEK is offline
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Welcome to the forum, you will find a wealth of knowledge here that will help you through that first build and beyond.
You just heard from one of the most knowledgeable guys here, Charles. He is our equivalent to GOOGLE
Pay attention to him
Travis
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  #5  
Old 05-05-2017, 10:28 AM
phavriluk phavriluk is online now
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Default wood screws

I think trying to drive a wood screw from inside a soundhole would be quite an uncomfortable and perilous thing to do. Nuts and bolts assemble very easily except for that last half-turn and then that can be done with a socket wrench on an extension. Wood screws need force applied pushing on the screw for many turns, hard to do inside a soundhole.

Some folks use hangar bolts in the neck, which don't need additional hardware in the neck, and which use nuts on the inside to draw the neck tight to the neck block. Perhaps that is a compromise that might make sense to OP.
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Old 05-05-2017, 10:48 AM
M Hayden M Hayden is offline
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Wood screws are definitely kind of coarse, and I suspect that they might make removal and replacement difficult for a reset, as the holes would need to be shimmed before re-fitting.

Hardware based joints are easy, especially when using the KD fasteners available at most hardware stores. Two barrels and two bolts and a generous hole for the bolt allows a lot of adjustment.

Dovetails are harder - you have to learn to cut and fit them, and it's not intuitive at first - but they are very satisfying to make, at least for me. And with a properly fit dovetail, you don't need hardware
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Old 05-05-2017, 12:04 PM
Frank Ford Frank Ford is offline
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Wood screws will be just fine, Collings, for example, uses hanger bolts - the same kind (but smaller) that hold down toilets - with wood threads on one end and machine threads and nuts on the other.

Guitar factories, and even many small builders have fixtures that make alignment a non-issue, so they see no benefit in doing the job the way you outlined, but there's no reason it won't work just fine.

Screws driven into end grain don't hold as well as those in side grain, so it's customary and logical to build the neck heel with a vertical dowel to accept some of the wood screw threads, thus increasing overall security.



Please note that the tenon shown above tapers toward the fingerboard where it's about 1-3/4" wide.
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Old 05-05-2017, 10:04 PM
Briggle Burger Briggle Burger is offline
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I'll be using screws.

Maybe I'll find out the hard way, but my opinion is that the reason for the traditional "nut an bolt" method is because someone like Martin went with anal retentive over-engineering about a hundred years ago, and now any deviation from this standard is blasphemous, and should be feared as being a path towards failure.

I see replies ranging from "very likely a bad idea" to "I know someone who does it that way and it works just fine." I saw no reply against the idea that I couldn't argue with using my uninformed opinion, and Frank's reply proves that my arguments for using wood screws have merit. I was looking for some technical reason for not using wood screws that I couldn't think of on my own, and I got pretty much what I was hoping for and expecting.

Thanks!
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Old 05-06-2017, 06:57 AM
John Arnold John Arnold is offline
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Note the 1/2" maple dowel installed in the Collings neck. If I decided to use a wood screw, that is the way I would do it. A screw concentrates the stress, which makes a cracked heel likely in an accident. The cross dowel not only holds wood screw threads better than end grain, but it also reinforces the heel aganst breakage. Banjos use lag screws, and they pull out or crack the heel all the time.
I have installed wood screws to repair a failed neck joint, and as long as they are in the proper place, tightening them inside the body is not an issue.
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  #10  
Old 05-06-2017, 10:49 AM
printer2 printer2 is offline
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Sorry, skip it.
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