Why some layer heights in gcode are not multiple of the preset layer height?
 
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Why some layer heights in gcode are not multiple of the preset layer height?  

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prusanewuser
(@prusanewuser)
Prominent Member
Why some layer heights in gcode are not multiple of the preset layer height?

Hi, I set the layer height to 0.15mm. However, when I looked at the gcode, I found that that some layer heights that are not multiple of 0.15mm were generated automatically by the slicer. For example, after layer height 1.7mm, the system should have generated:

; LAYERCHANGE

; Z: 1.85

but the gcode had "; Z: 1.81875" instead. 

Posted : 11/09/2021 8:41 pm
jsw
 jsw
(@jsw)
Famed Member

Coincidentally, I am running a print with a layer height of .15.

I inspected the gcode at the 1.7 and 1.85 layers and, at least on this print, it's as expected.

This is with PS 2.3.0 on Ubuntu with the MK3s and a very vanilla PETg filament profile.

G1 Z1.700

(several lines later ...)

G1 Z1.850

Posted : 11/09/2021 10:07 pm
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
Please check consistency

Would you please search by LAYERCHANGE in your gcode and step though to see if the increment is always 0.15 consistently throughout the file? I guess different models may have the inconsistency at different layer heights.

Posted : 11/09/2021 10:36 pm
Neophyl
(@neophyl)
Illustrious Member

Did you have support on your print ?  Support is done independently of model layer height. 

Posted : 11/09/2021 10:45 pm
jsw
 jsw
(@jsw)
Famed Member

 

Posted by: @prusanewuser

Would you please search by LAYERCHANGE in your gcode and step though to see if the increment is always 0.15 consistently throughout the file? I guess different models may have the inconsistency at different layer heights.

There's something obviously different between our setups.  Here's the line at the beginning of the file if you want to compare:

; generated by PrusaSlicer 2.3.0+linux-x64 on 2021-09-11

The word 'LAYERCHANGE', one word, all caps, does not appear at all in my .gcode file.

'AFTER_LAYER_CHANGE' three words, all caps, delimited with underbar, appears for each layer and all show consistent expected values for Z.

;AFTER_LAYER_CHANGE

;0.2

G1 Z0.200

--

;AFTER_LAYER_CHANGE

;0.35

G1 Z0.350

--

--

;AFTER_LAYER_CHANGE

;5.3

G1 Z5.300

--

;AFTER_LAYER_CHANGE

;5.45

G1 Z5.450

--

;AFTER_LAYER_CHANGE

;5.6

G1 Z5.600

Posted : 11/09/2021 11:05 pm
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE: I use support

Yes! So is that why some consecutive layers have height different from 0.15mm? So if I see a layer that is not a multiple of 0.15, it means that is it the support layer?

Posted : 12/09/2021 1:08 am
Dan Rogers
(@dan-rogers)
Noble Member

Support, or first layer.  You can have the first layer height be different than the rest of the print as well.

Posted : 12/09/2021 6:18 am
jsw
 jsw
(@jsw)
Famed Member
Posted by: @prusanewuser

Yes! So is that why some consecutive layers have height different from 0.15mm? So if I see a layer that is not a multiple of 0.15, it means that is it the support layer?

That apparently answers the question and explain the difference.  The .gcode file I used as a reference does not include any supports.

IIRC, there is, buried in the settings (not ambitious enough to look for it right now) in PS, an option to have support layers at the same heights as printed layers.

Posted : 12/09/2021 2:27 pm
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
Why is it good to have support layers at different heights than the present layer height?

Thanks. Why it is good to have support layers at different layer heights than the preset, say 0.15mm layer height in this example, for the printed layers? I suppose it is good so the developers implemented it. 

 

Posted : 12/09/2021 2:33 pm
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