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Inconsistent first layer print - thermal impact on PINDA?  

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Sebastian W
(@sebastian-w)
New Member
Inconsistent first layer print - thermal impact on PINDA?

Hi,

Couple weeks ago I have assembled my kit MK3S+ and still have problem with first layer calibration.

I can't adjust the proper Z height. I am printing one layer square in the center of the bed. I observed situation that after I have adjusted live Z value that square was printed perfectly, cooled down the printer for about 5-10 min and started to print again there were gaps between lines. But when I start printing just after first print there are no gaps. Seems the PINDA probe is affected by temperature, any thermal expansion?

Did anybody faced the same issue and how to solve it? Please help, I have realy enough to print and calibrat ethe first layer.

This topic was modified 2 months ago by Sebastian W
Posted : 30/11/2021 10:27 pm
Neophyl
(@neophyl)
Famed Member
RE: Inconsistent first layer print - thermal impact on PINDA?

Yes, the pinda probe (depending on version) can be effected by temperature to a greater or lesser extent.  Also the mechanical parts of the printer like the bed can contract or expand depending on temperature.  Even more important now with colder weather on us as the effect is much more noticeable.

This is why some people preheat the bed before any printing operation.  Basically soak heat it for 10 minutes at the printing bed temp before any printing session.  Do the same before doing your live z calibration, that way its consistent.

Yes it can be a pain waiting for the soak heating but whats a few minutes worth when you get far more repeatable prints.  

Posted : 01/12/2021 6:37 am
adarmit
(@adarmit)
Active Member
RE: Inconsistent first layer print - thermal impact on PINDA?

Hi Sebastian W

Agree With Neophyl. and like you I am only 10 weeks into printing

I am in Australia coming into our summer. found Air Con a pain caused some issues in early days.

My fixes were:

Make sure filament is dry, Good quality, 

no fan or Air con blowing on Bed

Preheat worked most times (not a real 3D'er until you have grabed head at 250 deg Plus with bare fingers) after rebuild or modify.

Clean bed, Clean bed and clean bed again (I use IPA and clean microfibre cloth)

Make sure head is clean and no dags stuck to it

I found if I set hardware accoring to manual My Z live would go  down as far as -2.00, apparently this is within tolorance see page 27 of Prusa 3d Printing handbook V3.16

took abit of time but i feel I have got it now

good luck

Posted : 08/12/2021 11:16 am
This_Dude_Jay
(@this_dude_jay)
Eminent Member
RE: Inconsistent first layer print - thermal impact on PINDA?

I noticed this one with a MK3S (PINDA v2 instead of SuperPINDA) too. Interesting to see it on a SuperPINDA as well.

https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/an-empirical-insight-into-a-major-flaw-of-pinda-v2-bed-level-probing-and-why-7x7-makes-things-even-worse/

My workaround was a preheating sequence in the Starting G-code, but since the SuperPINDA has no more thermistor this wouldn't work, at least automatically. Maybe it is still interessting for you, especially the verdict in part 3.

Posted : 12/12/2021 7:23 pm
Sebastian W
(@sebastian-w)
New Member
Topic starter answered:
RE:

I made a lot of test, meshing bed, in different conditions, all this week. Excluded thermal impact on SuperPINDA and proven it is insensitive to temperature. The issue is thermal impact on the bed. Another important conclusion analysing my graphs is that to have stable, reapating condition for printing first layer for calibration or any model you shall keep your bed warmed the best at least 10 min in printing temperature before the print. Period. 🙂

Attached some slides I did quickly do give you aflavour on which I am basing my conclusions.

This post was modified 1 month ago 3 times by Sebastian W
Posted : 13/12/2021 12:32 am
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