Dovetail Questions

[John Arnold]

Considering it is maple, I would just do a 5/16" dovetail. Other options are to shorten the scale, or shift the fingerboard so the nut is relocated.

[phavriluk]

Why a beginning builder voluntarily attempts to construct a dovetail is beyond my comprehension. Come the age of commonly available metal fittings, nuts and bolts came to be for good reasons. The argument that a given project would 'sound better' (and how to determine that?) goes more toward religious fixation than physics.

[rccosta]

Update: I have glued a few pieces of maple together. Wish I had done a floating tenon but panicked and here we are with 3 pieces of wood end-grain glued together with a 3/8" diameter dowel running ~2" deep through all pieces of wood at the end of the heel.

Praying that this holds up over time.

[MC5C]

A dowel or two will not hold up, in my opinion. If fixated on non-mechanical joints, do a floating tenon - the tenon will be in both the neck and the body, completely strong if fussy as heck. Make and fit the neck side, glue it, then make and fit the body side like a normal dovetail joint. But what I would do is a bolted joint. Use your protrusion of 5/16" to make a plain tenon to stabilize and locate the joint to the body, and one 1/4" bolt fairly low on the heel. My take anyway.

[redir]

It's easier to just go ahead and make it a bolt on neck now rather then having to do it in a year or two.

[John Arnold]

You could add a wood screw to the assembly for a bit of insurance. As far as doing a bolt-on, I recommend a smaller 10-32 screw, rather than 1/4". It is plenty strong enough, and less weight.

[Howard Klepper]

Originally Posted by John Arnold

You could add a wood screw to the assembly for a bit of insurance. As far as doing a bolt-on, I recommend a smaller 10-32 screw, rather than 1/4". It is plenty strong enough, and less weight.

He would be screwing into end grain, which would not add significant strength.

OP ignored good advice and went ahead with his original idea. Not unusual.

[Taylor Ham]

It seems like in any case the 5/16 long portion of the original dovetail will be doing most of the work. Subtracting the side thickness, this means 7/32 will be in contact with the neck block. How long does it have to be to work anyway? lol

[rccosta]

That's partially my question: how deep does a dovetail have to penetrate into the neck block to have a secure joint? I've seen 1/2" used a lot, but have seen as much as 7/8".

I agree with the notion that only the first portion (1/4"?) of a dovetail is actually making meaningful contact with the neck block, but not sure how much beyond that is absolutely crucial to have or not.

[charles Tauber]

Originally Posted by rccosta

That's partially my question: how deep does a dovetail have to penetrate into the neck block to have a secure joint? I've seen 1/2" used a lot, but have seen as much as 7/8".

You are asking a question to which likely no one has an answer. The minimum depth of the dovetail that is sufficiently strong enough depends upon a number of factors including wood species, height of joint (ie depth of body), taper of dovetail, angle of dovetail, grain orientation...

To determine the answer to your question would require a significant amount of testing.

I agree with the notion that only the first portion (1/4"?) of a dovetail is actually making meaningful contact with the neck block, but not sure how much beyond that is absolutely crucial to have or not.

A well executed joint has “meaningful” contact on both side faces for the full area of the faces and across the bottom of the joint. The sides are rigidly attached to the heel block and the thickness of the sides are part of the side faces of the joint.

[John Arnold]

He would be screwing into end grain, which would not add significant strength.

It is the attachment method for most banjo necks.

[Bruce Sexauer]

My standard dovetail connection uses only the last 3/8" or so on the dovetail. The rest is pared away to simplify fitting it. The point is, what is left to do the job closely resembles having only a 5/16 deep dovetail, and so I am virtually certain you could simply carry on with what you have.

Many modern makers seem to fear the dovetail and consider it VooDoo. It is actually a simple excursive in applied geometry and no more outside the average craftsman's ability than throwing disk back and forth is for any fit person.

[rccosta]

Thanks, all! Believe it or not I caved and bought new wood - haha.

I'm keeping the last neck because I'm partial to it and there's nothing wrong with it other than the frankenstein hybrid heel. Might use it on a future build for someone who won't care as much about the aesthetics.

[tadol]

Intriguing - I’d always thought that the length of the dovetail was approx equal to the distance from the fret at the body joint, to the next fret closer to the bridge -that way, when that next fret gets pulled and drilled for steaming the neck joint, it lines up with the bottom of the dovetail - hate to think these things happen by accident -

[Bruce Sexauer]

Originally Posted by tadol

Intriguing - I’d always thought that the length of the dovetail was approx equal to the distance from the fret at the body joint, to the next fret closer to the bridge -that way, when that next fret gets pulled and drilled for steaming the neck joint, it lines up with the bottom of the dovetail - hate to think these things happen by accident -

I believe the standard neck set was a McGyver type deal, and the original engineering never considered basket ball needle steam removal.