Inconsistent layer height  

Re: Inconsistent layer height

Can't see the pictures.

Re: Inconsistent layer height

Sorry, I fixed the URLs, should be working now.

Re: Inconsistent layer height

Stock Prusa profiles?

Infill is barely reaching the perimeters. Are you underextruding?

Re: Inconsistent layer height/extrusion

Stock profiles, filament is Prusa's PETG.

If you look closely at the first pic you'll see that the infill on the right side is correct, so this is not a overall underextrusion. I'm not sure if this is a height or extrusion problem, but the inconsistency is clearly visible. On a single layer it can go from perfect, smooth layer lines to ones that barely stick to the bed. And it always seems to form a "shadow" from feature outlines.

Here is another picture of a different iteration of the same part where the issue is clearly visible:

Re: Inconsistent layer height

Hi,
This is the next on my list of issues to fix with my mk3. Same as you it doesn’t show where infill is done in one continuous go.

Here is prusa petg with stock profile.

Like you, I’m thinking z is shifting after it makes a jump from one section to another. I’ll look for mechanical slop later today. How did you go?
Thanks.

Re: Inconsistent layer height

A video showing layer height change on usb microscope.

Aslo does this on bottom layers.

3.2.1-576

Is present in the same locations with Lift z disabled which is surprising.

Re: Inconsistent layer height

I haven't done any larger prints recently but I noticed that all of the screws on my x-axis cover have come loose, it might or might not be related, so probably worth checking.

Re: Inconsistent layer height

Hey there!

As I have had the same issue as you guys (but way worse) I started testing a bit to find the root of the problem and maybe even solve it.

I found that the Z layer height wasn't in the right height. So after some self testing and Calibrating I ran the "first layer calibration"
As I am very new to 3D printing I was suprised about the -1.5 in live adjust because one week ago the first layer cal. was just perfect. As in the handbook recomended you have to adjust the pinda if the value is over one or under -1.
While readjusting the PINDA I found the screw holding the probe was very loose. I didn't ordered the KIT so I didn't mounted the probe but to unscrew it you needed a bit of a breath. So either the Prusa fitter was very very carefull to not destroy anything or the screw came loose after some hours of printing. As the screw preventing the probe to move was loose I guess that the probe was mooving down a little bit due to vibration and messed up my first layer height. I readjusted the Probe and redid the first layer calibration.

Afterwards I printed the same part again and saw the issue reoccuring.

Waited till the print was done to see the bottom of the part and it was mechanicaly ok but it bothers me that the leyer is so inconsistent.

From my point of view this issue could be caused by the trapezodial screw spinle. The disadvantage of those spindle types is that after a direction change the spindle needs to turn a certain distance untill the axis moves with the spindle. Normally for those small tollerances and fast movements you should use a ball screw spindle as they dont have travel these certain distances. But I could be totally wrong and this issue is caused somwhere else.

I hope this helps to solve the most problems caused by this issue.

Thank you for reading.
Happy printing!

Jonasebby

Re: Inconsistent layer height

I suspect the z-hop could be the cause of those issues. In all our cases it clearly occurs when the infill stops around a feature and jumps to a new start. I've been quite busy lately and didn't have time to do any test prints but will try doing so in the next couple days, with and without z-hop.