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Minimum Z and E moves?  

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DocRuzzy
(@docruzzy)
Active Member
Minimum Z and E moves?

I am doing some research that requires very small z and e moves. 
I assumed that the minimum z and e moves would be equal to the 1/(steps/mm), which I think is 400 for both the z and the extruder, meaning the minimum z or e move would be .0025 mm.   
I think the printer is skipping moves such as
G91

G92 E0

G1 F15.
G1 Z0.0025 E0.0025

Is it possible that the printer has a minium value it will try to execute that is larger than 0.0025? 

Have I made some other error in assumption or calculation?

 

Thanks for your help.

Posted : 05/10/2024 6:11 pm
vhubbard
(@vhubbard)
Estimable Member
RE: Minimum Z and E moves?

My calculations for the MK4 show the Z minimum move is .02mm    8mm lead /400 stepper increments per revolution =.02mm  per pulse.

XY use GT16,  16 tooth pulley with 2mm belts.   16x2=32mm per rev/400 = .08mm per pulse X and Y. 

Posted : 08/11/2024 9:42 pm
DocRuzzy liked
DocRuzzy
(@docruzzy)
Active Member
Topic starter answered:
RE: Minimum Z and E moves?

Thanks, the information and your explanation were both helpful!

Posted : 09/11/2024 5:00 pm
DocRuzzy
(@docruzzy)
Active Member
Topic starter answered:
RE: Minimum Z and E moves?

actually, I think the pitch of the lead screw is 2mm, so minimum z-step is 5 microns.

Posted : 09/11/2024 10:15 pm
vhubbard
(@vhubbard)
Estimable Member
RE: Minimum Z and E moves?

If it is a single start then pitch=lead.  These are multi start lead screws, so pitch, or distance between threads does not equal Lead.    Put a piece of tape on the lead screw.  then move Z 8 mm.  You will see the lead screw makes 1  revolution, or 8mm lead.  

Same with the MK4S X, put a mark on the pulley, move 32mm and you will see it moved 1 revolution.     

With   Z moves stepped in increments of .02, why does the Prusa slicer default to some layer distances that are not evenly divisible by .02?  Example MK4S with standard .04  nozzle uses a .15mm layer.  That means the machine will move .14, .16, .14, .16 in Z for successive layers.  That is a +-7% Z error in laying the bead.   I am working on the Prusa Slicer enhancement request to add Minimum XYZ move definitions to the printers and to use them for layer distances and layer smoothing calculations.  

I would like to see XY with .02mm minimum moves also, but that may be an MK5... 

Posted : 10/11/2024 4:19 am
DocRuzzy and ssmith liked
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