After some calculation as to the http://www.engineersedge.com/calculators/torque_calc.htm calculator for bolt torque I came up with an almost unbelievable small amount of torque needed for the Z axis steppers. It is amazing how efficient a screw mechanism can be. So,to lift 10 lb, I only need 0.5 lb/in or 8 oz/in torque (0.5 lb / in = 8 oz / in). Similar goes for the VAT tilt, but adding to that gravity and I did not even make an effort to calculate it, I have just used lower spec motors that follow:
a 25 to 35 oz/in ( estimated by comparison – could not find docs for this particular model ) from a printer
no idea what this stepper is rated at (estimate is about 70 oz/in) , but if it fails for the task I will replace with the 180 oz/in on hand.
I have chosen an old power supply from HP 32V 2.2A for the steppers since the NEMA17 is not over 0.7 and the NEMA23 will be limited to 1A. I have chosen to mount it temporarely via some washers in the channel and brackets.
Washers – wide 18mm(5mm internal)x1mm ( I will use them all over the place so get at least 50)
Bolts – any head 20mmx4mm will do ( again take at least 20 )
Brackets – 40mmx40mm right angle for wood frame
Held in place by zip ties.
You can get a dedicated power supply and depending on your motors choose a higher rated Amps.
Rule is generally add your stepper driver limit +5%~10%. No point in wasting money on more power than that.
In my case I will limit the Amps via the stepper drivers to collectively 2A and it will not be even at 25% duty cycle (calculating from 8sec exposure and 2sec tilting cycle).
