Hi captainleeward,
you have been busy! I recall the day I got my own homemade mill working, I was elated and you will be to. The degree of elation is proportional
to the effort spent building your machine so yours will be phenomenal. May pay to alert the authorities beforehand, hoax earthquake reports
are viewed dimly! A lot of users on this forum buy their machines ready made from China. They seem to report more frustration than elation.
From the pics its clear you don't use any pulleys or reduction between your steppers and the lead screws. The Steps Per calculation is easy. There is
a calibration utility in Mach3 but unless you have to use it don't bother.
If you set the microstepping to 1/8 you should be about right. Two phase steppers advance 1.8 degrees per full step or 1.8/8 degrees per microstep
at 1/8 setting. Your table will advance (1.8/8/360) *0.5 ie 0.3125 thou per microstep or taking the reciprocal 3200 microsteps per inch. If you set to
1/16 microstepping 6400 microsteps per inch. Easy!
Stepper motors are very grunty for their size at low speeds, upto about 100 rpm but lose torque thereafter down to about 5% of rated torque
at 1000 rpm. Multiphase (3 and 5) steppers do better but the same trend applies. Unless you are prepared for repeated stalls set your max speed to
be such that the steppers are doing 300-500 rpm. At 300 rpm(conservative) then 300*0.5 ie 150 inch per min.
Again as a conservative starting point set you acceleration to 15 inch/sec/sec.
What I did not see in your pics was an Estop button, it is a must have!. Plenty of suppliers will supply you with lockable and latching Estop
switches in standard colours for $$$. Any push-to-break switch will work tho. You can set it up to use push-to-make but if you have a wiring
fault you wont know until you REALLY need it. Not recommended. Many safety conscious users arrange it that an Estop will kill all electrical
power to the motors and spindle rather than relying on Mach3 to stop on command. I personally have not bothered to do so and have had
a couple of times where I regretted that choice but none the less a working Estop is a must especially when starting out and setting up as you
are.
Work on one axis at a time. Use manual G0 commands or use the jogging keys to move backwards and forwards while tuning you motors. If you
haven't found it yet there in an enable jogging/disable jogging button on various Mach3 screens. On the MDI screen hit <tab> to see the flyout
with the jog commands and modes. Have fun!
Craig