Hi,
I have been given a "Harris" milling machine arbour adjustable spacing collar. Picture here:

The collar is in 2 parts with a 20 TPI thread. The nut component has 50 teeth around its outside diameter. The screw part has 2 small tapped holes. Presumably for a ratchet to allow easy adjustment of the spacer by 1 tooth/thou, at a time. This ratchet mechanism is missing.
I am wondering if anyone knows of how this looked originally so that I can make a suitable replacement.
Thanks,
Steve