I need to be able to rough tune and lock down each string separately, so the usual ones with two strings per screw won't do. According to the idea, after rough tuning, the fine tuners in the bridge take care of further adjustments.
For some time, I've been looking for a suitable locking nut. After a while without identifying anything useful off-the-shelves, I decided to make one myself.
I started with a piece of 7075 T6 aluminium. I drilled six holes for the string locking screws and two for screwing the locking nut on the headstock. I then threaded the holes (M4).
I then made six grooves; one for each string.
...and filed the grooves smooth.
Unfortunately, there was another problem as well: The pressure of the screws lifted the nut off the brass plate (the picture shows the gap between the aluminium nut and brass plate). That can probably be solved by making the nut a bit deeper and having two mounting screws on each side of the string locking screws rather than only having one set of screws.
I'm going to give it another try some day and make an improved version.
Btw, if it had worked, I would have bought six proper set screws for it and cut off the remaining headstock. In an artistic fashion, of course ;-)