Lathe CNC conversion 

Very low cost closed loop control of my lathe using:
-linuxcnc 2.8 with pid module and stegen in velocity control mode
-Nema23 steppers
-Tb6600 stepper drivers
-5um linear glass scale encoders
-Plywood gears bolted dirctly to the handwheels
-original lead screw for X-axis (0.17mm backlash)
-original rack and pinion for the z-axis (1.2mm backlash)
-PCIe parallel port card
-21500nS base thread
-1ms servo thread
Following error +- 0.01 mm except when axis changes direction. Peak at 0.05 mm error for a brief time doing direction change.