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Martin
(@martin-30)
New Member
Variable first layer

First of all I have to say that I am absolutely happy with my Prusa i3 MK3. Compared to my old Mendel 90 it´s a totally new feeling.
But there is one thing looking strange to me. The first layer seems to be different in different runs. The two parts in the attached photo are done with the same gcode file, just a few hours between them, no changes on the settings. The rest of the parts are completely identical.
Can anybody give me a hint what is going on there?
Thank you very much and best regards
Martin

Posted : 02/03/2018 11:17 am
haxxlinus
(@haxxlinus)
Active Member
Re: Variable first layer

A small guess: the bed and nozzle temperature were different when you started the print, and the PINDA probe gave different readings because of temperature drift.

Posted : 02/03/2018 11:33 am
Martin
(@martin-30)
New Member
Topic starter answered:
Re: Variable first layer

Bed and nozzle should have the same temperatur, as the print starts after heating up bed and nozzle. I can not influence that. But the bad first layer happend with the first print and the good layer was the second print. Could that be the reason? And if yes, what can I do to overcome this?

Posted : 02/03/2018 12:19 pm
haxxlinus
(@haxxlinus)
Active Member
Re: Variable first layer

I am far from an expert, but I would try to move the PINDA probe slightly closer to the bed, to improve the measurements (and then recalibrate).

Posted : 02/03/2018 1:39 pm
Martin
(@martin-30)
New Member
Topic starter answered:
Re: Variable first layer

I understand, I will try and report back.
Thank you very much

Posted : 02/03/2018 2:49 pm
stahlfabrik
(@stahlfabrik)
Honorable Member
Re: Variable first layer

Hi Martin,

please report back if you are able to fix your issue when you change the height of your PINDA probe!

I just want to make you know about another very current thread in this forum where we are discussing seemingly the same problem.
https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/different-first-layer-results-every-new-print-t14474.html

To me personally it looks like that the MK3 Pinda, which registers its own temperature (so it can account for influence of temperature on trigger-height) does not work reliably for all MK3s. I seems that the system is hyper sensitive to temperature (so exactly the opposite of what the goal is of the thermistor in the PINDA). When it is cold, my live z values are more negative. The warmer it gets I have to dial in live z higher.
Currently I think it is a firmware issue (see the linked thread) - I just wonder why it seems to not affect every MK3 in the same way

Best regards

Posted : 02/03/2018 3:36 pm
Dewey79
(@dewey79)
Honorable Member
Re: Variable first layer

First of all which one is "More Correct"? Second are you in an area where it's still cold? I've read in this forum when I first joined that "air flows" can affect your print.
One print is good, and then on the next one you have a cool breeze going through and makes it harder. This is why people recommend an enclosure.

Posted : 02/03/2018 3:42 pm
Chris
(@chris-16)
Reputable Member
Re: Variable first layer


The two parts in the attached photo are done with the same gcode file, just a few hours between them, no changes on the settings.

which is first which is second?

Posted : 03/03/2018 6:09 am
stahlfabrik
(@stahlfabrik)
Honorable Member
Re: Variable first layer

Please see this post where I propose a bugfix firmware that seems to solve this issue for me!

https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/different-first-layer-results-every-new-print-t14474-s20.html#p69203

🙂

Posted : 03/03/2018 12:25 pm
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