Z Axis Resolution

OK, I need someone to check my logic and math here. If I'm thinking right:

Z Resolution = Z Screw Pitch / 360 * Motor Step Angle / # of Micro-stepps of Motor Driver

M8 threaded rods have a pitch of 1.2
My motors have a step angle of 1.8
My my drivers are set for 16th steps.
My threaded rods are attached directly to my motors with a coupler. (No belts or gearing that change ratio between motor and screws.)

1.2 / 360 * 1.8 / 16 = 0.000375

My Z resolution is 0.000375 mm. That the minimum distance my Z axis can move. I want my layer height to be a multiple of this and within the constraints of my nozzle size.

Dose all that hold water?

Something wonky here...

m8 have a thread pitch of 1.25, NOT 1.2

you have a resolution of 0.000390625

you have 200 steps per revolution (1.8 degrees steppers)
you have 1/16 microstepping so 16 * 200 = 3200 steps per revolution
a revolution moves 1.25mm

1.25/3200 = 0.000390625 mm per step.

Edited 1 time(s). Last edit at 08/01/2014 11:48PM by Dust.

Check this web page out for your screw pitch.

[calculator.josefprusa.cz]

See, this is why I lean on you guys. Thanks ; )

I can't see the point of making the layer height a multiple of the minimum Z movement unless you have rods with the necessary accuracy for it to be significant which normal threaded rods are not.

If you want perfect looking prints, then the layer height has to match a multiple of the minimum Z. Or you get fractionally thin and fractionally fat layers due to rounding of the Z position. but yes if you have crap Z threads.. it wont help.