Rack and Pinion

[kim50usc]

I am trying to create a mechanism that uses a rack and pinion mechanism that pushes an object upwards sort of like this one here.

I plan on making it with a stepper motor instead of a servo and with some off-the-shelf gear racks off of mcmaster.

I guess I have more than one question, but in regards to the gear/rack, which gear would you recommend for the motor?
This is the rack I plan on using.

I guess my question is - how does the # of teeth, the pitch diameter, and the overall diameter effect the motion of the mechanism in terms of speed and power?

 

[mechedoc]

I think google is your friend on this one:

http://members.tripod.com/kenoh_5/8.htm

Remember, rack and pinion is still a gear system - larger pitch diameter means more motion per rotation with lower force.

So - the motor you want to use and the weight you want to lift will determine the pinion you should use.