Sherline CNC Mill Setup Microstepping

Hi, I used the defaults in stepconfig wizard to setup a Sherline mill. However, a command of .1" only moves the axis .05" (manual or via G commands). When I change the microstepping to 4 the movement is .1" for a command of .1". Why is 1/4 stepping needed? In multiple places on their website they mention half stepping for these motors. The spindle pitch is set to 20 rev/in which is 1 rev per .05" which is correct and the motors are set to 200 steps/rev. New to this so I'm sure I'm missing something so any help would be appreciated. Also, when I test the axis in stepconfig...and I set the travel to +/- 1" the travel seems correct using the 1/2 step setting. I only notice the error when I run the motors in manual or via G commands while using the completed config.

Problems with the unit of measure?
Have you tested the G20 and G21 commands?

Nicola.

If it helps, these are the settings for the x-axis on my Sherline 5400 Mill (inch), scaling is same for y and z. These basically came from the original Sherline supplied files with tweaks for backlash, and soft limits.