A Rack and pinion for my Andonstar microscope base

In the previous video (link below) I built a strong and stable base and arm for the Andonstar 407. However, there was a weak part in the design; the coarse setting was not pleasant to work with. In this video I solve that with a rack and pinion. Now I really like the new base for the microscope.
Link to the previous video: • Andonstar annoyances.....
Music: Open source Mozart and Beethoven