Ever since my TAZ was new it has always exhibited a little bit of error in Z, specifically it always printed out short. I finally sat down and fixed the issue. There is about .008" of lost motion in the Z Axis so in Simplify 3D I go into the starting script and take out the backlash with a G92 Z-.2 command essentially setting the Z axis to a lower value after Z Homes and then when the print starts the machine promptly removes the backlash on the first Z move. Then I went into configuration and reset the Z Steps value from 800 to 820 as this effectively eliminates the .005" shortfall every time a 1mm Z move is commanded which can accumulate over time with height. I used a Starrett indicator to measure the Z moves and compensated the Z using the Z Steps value. I plan to do the same for X and Y once I manufacture a fixture to hold an indicator so that I can use a small right angle block to measure the motion.
If anyone is having issues this may be of some assistance.
TM