This one doesn't have the screws to help turn it, to show the nubs being used instead. It could be that the screws might be an hindrance for unforeseen reasons so I'm just showing that they are still useful as is.
Balancing upside down on the music stand so you can see the bottom better.
The 90.675 degree version with the screws fitted.
Download both versions and try it for yourself. The fusion360 files are also included so you can modify them to suit yourself.