Birds beak/Bridle joint headstock

[ViolinWizard]

Somewhat of a rare sight nowadays, what are your experiences with the strength and durability of a birds beak headstock joint (also known by many names, such as bridle joint, arrow joint, etc...)?

I understand the structural benefits regarding the grain, but does the joint hold up well over time? How does its soundness in structure compare to a scarf joint or one piece neck/headstock? Why is it not used more nowadays?

[hermithollow]

I use the modified bridle joint on most of the necks I build. It is more involved to make than a simple scarf joint, which is one reason it is less used today. If you are building for profit you won't want to use this joint.
It is probably somewhat stronger than a scarf joint, but a well done scarf joint is strong enough.
I do it because it is a little bit of a challenge and looks nice when well done.

[ViolinWizard]

Originally Posted by hermithollow

I use the modified bridle joint on most of the necks I build. It is more involved to make than a simple scarf joint, which is one reason it is less used today. If you are building for profit you won't want to use this joint.
It is probably somewhat stronger than a scarf joint, but a well done scarf joint is strong enough.
I do it because it is a little bit of a challenge and looks nice when well done.

Thank you! Would you kindly explain what does "modified" refer to?

[JonWint]

Originally Posted by ViolinWizard

I understand the structural benefits regarding the grain, but does the joint hold up well over time? How does its soundness in structure compare to a scarf joint or one piece neck/headstock? Why is it not used more nowadays?

It seems to hold up fine on Martins as old as 180 years.

It's takes more time to make. Most buyers are unwilling to pay the extra. Some luthiers will use it on request.

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[hermithollow]

The typical bridle joint is a fairly straight forward straight sided open tenon type joint. The "birds beak" bridle joint has members joining at odd angles and "tenons" coming to a point - it is still a bridle joint but has been modified from what is the typical form.
https://en.wikipedia.org/wiki/Bridle_joint

[ViolinWizard]

Ok, got it. Thanks guys!

[tadol]

You might want to check the threads in Custom shop from Bruce Sexauer - he’s shown a number of guitars where he’s used that joint - give you a better sense of how its made, and whats involved -

Why isn’t it used? The joint you’re showing is not something that can be made by machine or really with jigs - it has to be laid out and cut almost entirely by hand, and requires a pretty high degree of hand tool skill. Even in the example in the picture, you can see where they’ve overcut part of it. Not a big deal functionally, and easily filled when assembled, but even for a master luthier it takes time, and few will pay for it, especially when machines and modern adhesives can make a simple machinable joint fast and easy, and quite strong - allowing their budget to go into other aspects of the build -

[hermithollow]

Not to be a contrarian, but actually some parts of the joint can be cut with a table saw and tenoning jig. A jig can be used to make a couple other cuts with a bandsaw - but some cuts are easier done with a handsaw, and the final fitting and refinement of the joint is done by hand. A careful craftsman who is familiar with his tools can make the joint in a reasonable amount of time, but not as quickly as a simple scarf joint.
There are some advantages to using the modified bridle joint. It allows you to shape the neck shaft and peghead separately and join them together later in the process. It also allows some savings of materials. You can make two necks for about the same materials cost of a one piece neck.
For some, budget may be a consideration, but there have been many professional luthiers who have done this joint or one equally demanding as a mark of their skills. The late 1800's Martin factory was what we might consider a "boutique" builder by today's standards and used this joint in their regular production.

[tadol]

We could truly geek out on the reason for all this - while I will concede that some parts of the joint \can be cut with power tools, it really calls for a skilled hand with a sharp backsaw and a couple sharp chisels and knives - In late 1800s, getting a job as a journey-level joiner, you’d be expected to lay out and cut a joint like that quickly and accurately, and I’m sure in a shop situation like Martin ran, they undoubtedly had some layout templates to make it even faster and more accurate and consistent - but that doesn’t really answer why they would use it -

Saving money on materials? Maybe. Aesthetics? IMHO - Not likely. My feeling is that increasing demand for higher string tension, and the move towards steel strings, was causing a lot of problems with necks and headstocks and grain orientation on a 1 piece neck w/ slotted headstock. The greater you increase the break angle, the shorter grain you get across that area. Adhesives were good, but a simple scarf joint in that area would not hold up well long term - even now, the headplate is installed to hide the scarf, but also to reinforce that joint - some builders even reinforce the back of the headstock with another plate as well. The birdsmouth joint not only is mechanically stronger, but string tension helps hold it tight, and the adhesive is not really a structural element. Even the dovetail at the other end of the neck is designed to structurally and mechanically hold the neck to the body with minimal reliance on adhesive. Traditional joinery never relies on adhesives - mortise and tenon, dovetail, etc, all were designed to transfer forces to the material in a way that worked with the natural strength of the material - even the box joint was designed to greatly increase the glue surface area to make it stronger.

Anyway - thats my belief on the birdsmouth joint - and I would enjoy hearing others!

[redir]

It's a beautiful joint for sure and has passed the test of time too. I jsut repaired an 1850's Ashborn that had one coming apart some 170 years or so after it was built. But as beautiful as it is it's perhaps overkill especially in a factory setting. A scarf joint well done will pass the test of time as well and they are a lot easier to manufacture.

[hermithollow]

Martin moved away from that joint and to a one piece neck construction when they started building larger bodied and steel strung instruments. They also switched from Spanish cedar to mahogany for their necks - a stronger but heavier wood, and added steel reinforcement to the necks. To my knowledge Martin never used scarf joined pegheads.
I don't know their reasons for this - increased production?, lack of skilled workers?, availability of cheap materials? a change in neck profile? cost cutting?
Maybe all these reasons or maybe none of them.

[Quickstep192]

I think the Cole Clark neck joint is cool and innovative. I imagine it's CNC'd or done in a router jig setup. I'd love to be able to figure out how to make jigs to do it.