George,

One other thing I forgot to ask... have you been through the 'motor tuning' section of the MACH3 manual? What settings do you have for steps/mm, acceleration and step pulse width (should be at least 5).

If you have a mutlimeter, check the 5v output from the BoB, confirm its 5v and its getting to the + pins on the driver (orange wire on my diagram). Also measure voltage between the ENA output and the 5v rail. This should measure close to 5v if the system is enabled. If its not, try putting J3 in place to override the chargepump and confirm that the enable output goes low (i.e. measures 5v between it and 5v rail). The 'chargepump' CP LED should be on as should the POWER LED.

A simple test ypu can do is to disconnect the 'step X' wire from the BoB, (in my diagram the blue wire to PULS-) leave everything else connected. Set the motor driver to full step. touch the step X wire to the ground terminal, the motor should step each time you do that.... if it does then the issue is with the Bob or the MACH3 configuration.