Good morning Bruce,
I modified Dr. D’s encoder concept just a bit. If you look at my post (Another PM-833TV Conversion - CNC Mill Conversions and Builds - Dr. D-Flo (drdflo.com) you can see that I used the same 3D printed timing pulley but mounted the encoder differently. The post also explains how I modified the shape for the timing pulley for easy 3D printing. See link below for the encoder, timing belt, timing pulley and both Fusion 360 and Step files. I used a different encoder than Dr. D. It works well with Acorn. Let me know if I can help in any way.
Best… Richard