need advice, is module 2 to large of tooth size for a rack and pinion set up
It look to course, I thinking of module 1.0 or 1.5 looks ok but want to try do a split pinion using http://www.atlantadrives.com/zerobacklash.htm
A split-pinion consists of two pinion halves and an axial spring pack. The pinions halves mesh with opposite tooth flanks on the same rack, eliminating the backlash. The axial spring pack is used to preload the rack & pinions to insure that no backlash develops during the operating cycle.
only problem idealy you got to get both pinions on one rack, no problem for module 2 size but the smaller module 1 size is a problem.
what is the most popular module size for rack and pinion 1, 1.5 or 2
From my experience, a simpler solution would be to spring load the pinion into the rack. We used 20 degree pressure angle parts with 24 DP components. The necessary loading force of the pinion into the rack would be (Max Drive Force) x Tan(pressure angle). For 50# force, 20 degree PA gearing, this would be 50 X Tan(20) = 18.2# force.
If you use anti-backlash split pinion, you will need to have the "unwinding" force between the two pinion halves greater than the max drive force.