The key to the Ridgewing system is the headstock lever, which fits into the underside of the headstock, and allows the strings to be instantly slackened or tensioned. The one shown here was insert molded in carbon fiber with a stainless steel axle. When the lever is opened, the gap between the headstock and the end of the neck shrinks by approximately 5mm, making the strings not quite slack.

This is my favorite piece to mold - quick to lay up and orient the fibers in the mold, generally comes out of the mold with no bubbles, and is easy to clean up. Plus, if there are any goobers, the lever lives out of sight, out of mind in the back of the headstock.

In addition to carbon fiber, these headstock levers can be hand-carved out of a piece of 3/8” aluminum plate and finished with hand files, sandpaper, and finally 0000 steel wool, which rubs out to a nice satin sheen. We tried having investment cast brass levers made, but they bent like hard cheese.

In this picture, the headstock lever is fully rotated out of the back of the headstock, slackening the strings. Rotating the lever back into the headstock brings the strings back up to full tension (Yes, some fine tuning is usually required – we are not magicians).

The headstock lever, despite its small size, is by far the most seriously stressed component in the assembled guitar. All of the string tension is born by the lever’s axle, which transfers it in turn to the lone contact point between the nose of the lever and the surface of the neck shaft’s end cap. The headstock dowels, which slip-fit into the neck, only apply torque to the neck joint, carrying no longitudinal stress. The neck end cap performs the same function as a dental crown, preventing the torque of the headstock dowels from splitting the end of the neck (yes it once happened on stage to one of the very early Chrysalis prototypes).

It is interesting to look closely at the physics of what happens at these contact points. The lever/neck contact area where a carbon fiber lever makes contact with the brass neck cap  looks to be on the order of 4 mm^2. To figure the pressure at the contact point, dividing the 50 kg of string tension by 4 mm^2 yields a contact pressure of 12.2 MPa (1777 psi). With an aluminum lever, the contact surface shrinks to a fraction of that, increasing the contact pressure in inverse proportion. Even higher contact pressures are experienced at tips the stainless steel set screws in the neck cavity where they make contact with the 3D-printed metal hard points in the neck.  At such pressures, materials start to undergo plastic deformation at the point of contact, effectively locking the rough micro-structure of the two surfaces together. This allows stress and vibrational energy to be transferred across these boundaries almost as if they were a solid piece.

Due to this microscopic boundary melding, an assembled Ridgewing guitar doesn’t “rattle” or have its tone negatively affected compared to solid construction, a concern which some players have expressed.

Years ago in my guitar shop in Ann Arbor, Michigan, I had a customer come in and swear up and down that putting a square pattern of 4 small ball-bearings between his bass guitar's neck and body would greatly improve the tone. So I put them in there, and he seemed pleased with the result (You have to be careful in discussions of relative tonal quality of guitars, as I have learned that these perceptions are closer to religious beliefs than physical observations).

So let's do some easy math - what is the total compressive strength of the four screws holding the neck on? I don't know the answer to that but we can do a comparison. What is the contact area of a small ball bearing surface compared to the whole neck/body contact surface?  I would guess that the total contact area for all four ball bearings is on the order of 20mm^2, compared to a typical total neck/body contact area of roughly 7,500mm^2. So using the ball bearings to hold the neck joint open increases the effective compressive force at the points of contact by a factor of 7,500/20, or 350X. Not too shabby!