Angle limited clamp for sharpening flat hone machine

[Beltenebros]

Hello,

I've been trying to find an off the shelf articulated arm that could set an angle limit on a clamp.
It works on machines like these so you can sharpen a shear without going beyond the set angle.
The arm in general it's quite straight forward, but what is the correct name for the swivel clamp with the grade scale on it? How do you start making such a thing?


Thanks.