first layer issue  

Re: first layer issue

The PINDA probe seems to be very sensitive to temperature, that may explain the difference. (Ie. first time it's cold, second time it's warm, or vice-versa.)

I put the extruder far from the bed (Move Z to around 100mm) before heating up the bed and that has greatly reduced the variability for me.

Re: first layer issue

Some people relate that the PINDA is heat sensitive so it may be that when you initially set yesterdays prints were startd from different levels.
I suspect that the first print was pre heated with the extruder / Pinda at the height that the previous job finished, and the second print was started off with the extruder / Pinda, virtually on the heated bed!, so the second time, the Pinda may have been at a higher temperature, so there may be some expansion issues, or sesitivity issues.

if you also set up the original Live Z settings starting from a low level, this could explain the differences...

next time, consider committing an auto home before you start the print so that the extruder / Pinda, are both nerer tot he heatbed...
(auto home is just over half way down the calibration menu. )

regards Joan

Re: first layer issue

As Gab says,

I also tend to run the z axis up high at the end of a print. I typically send it to 190mm... just short of full height.

but this would probably mean that you need to re adjust your live z to match,

trying the autohome, option first may help confirm the hypothosis...
regards Joan

Re: first layer issue

I only did a few test but I think you guys are right. when the probe is hot, it seems to squish less. I lifted it up, cooled it down and adjusted the z by about 0.1mm and I think it it is working well now. I chose to calibrate it cool and lifted instead on homed because I think it is easier to be consistently lifted instead of homing every time. I will update this thread if something changes.

Re: first layer issue

Good news Calan

regards Joan

Re: first layer issue

This for me is design flaw in the firmware. When you do the bed calibration after build, you do it with the heated bed disabled and the PINDA probe cold.

Then when you print, it heats the bed and nozzle to the full temperature required for the print, then probe the bed with the PINDA probe. If the probe is heat sensitive (and most sensitive electronic parts are), then why doesn't it perform the measurement prior to heating the bed or perform the full printer calibration with the bed heated?

Re: first layer issue

This for me is design flaw in the firmware. When you do the bed calibration after build, you do it with the heated bed disabled and the PINDA probe cold.

Then when you print, it heats the bed and nozzle to the full temperature required for the print, then probe the bed with the PINDA probe. If the probe is heat sensitive (and most sensitive electronic parts are), then why doesn't it perform the measurement prior to heating the bed or perform the full printer calibration with the bed heated?

Well that's not actually a firmware thing but a gcode thing. You can change the order of the starting gcode in your slicer of choice. Move the "G28 W" and "G80" code to happen before the "M104 S" command. I haven't tried this so I can't recommend it but it will what you were suggesting

Re: first layer issue

or insert a

G1 Z190 command at the beginning, to make sure the PINDA is always away from the heatbed, before heating starts.

regards Joan