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Z Axis Resolution

Posted by appdev007 
Z Axis Resolution
August 01, 2014 10:47PM
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?
Re: Z Axis Resolution
August 01, 2014 11:47PM
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.
Re: Z Axis Resolution
August 02, 2014 06:54AM
Check this web page out for your screw pitch.

[calculator.josefprusa.cz]
Re: Z Axis Resolution
August 05, 2014 11:14PM
See, this is why I lean on you guys. Thanks ; )
Re: Z Axis Resolution
August 06, 2014 09:02AM
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.
Re: Z Axis Resolution
August 07, 2014 02:04AM
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.
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