RE: An empirical insight into a major flaw of PINDA (v2) bed level probing… and why 7x7 makes things even worse
@this_dude_jay
The bottom line is the Spinda is different and it does have superior performance. I have been using one for a few weeks. I was going to hold off installation until one crapped out. I am glad I did not. I am getting a better first layer with more consitance.
Sounds promissing 🙂 But I still believe this could also be achieved with less sophisticated hardware, but a clever error cancelling solution
RE: An empirical insight into a major flaw of PINDA (v2) bed level probing… and why 7x7 makes things even worse
One thing I have noticed is a tendency for my PLA prints to adhere with more difficulty to the top right quadrant than the rest of the sheet. I have one of those powder-coated textured steel sheets, though, and PLA doesn't stick well to it in the first place. However, this thread makes me wonder if I'm experiencing the effects of temperature changes in my PINDA (the gray-tipped one) as the 7x7 calibration progresses.
If I do the z calibration, I can look closely at the line printed in that quadrant and I can imagine that it isn't as squished as the rest (suggesting a calibration error), but that could easily be my imagination.
It's hard to say with that powder-coated steel sheet.
When a print comes loose from the top right quadrant, I know it's time to wash my sheet in warm soapy water. That fixes it for quite a while... the interval between washings has increased since I got the printer in 2019, I assume because my sheet is getting "seasoned" like a well-used cast-iron skillet (and I print only on one side of the sheet). Oddly, 99% isopropyl alcohol does nothing to improve adhesion in this event. Only warm soapy water does the trick.
I guess the best way to test whether the weaker adhesion in the top right quadrant is due to calibration, is to rotate the sheet 180 degrees and print with the sheet upside down and see if adhesion continues to be weak in the top right (suggesting the problem is the PINDA and not the coating on the sheet) although that redistributes the steel on the top and bottom edges, and I don't know if that messes with the PINDA sensing.
Difficult to tell, if it this is due to a some kind of worn out/malfunctioning bed or a sensing problem. Have you done the 3x3 first layer test to see if there are any differences?
Will be interesting to see if the flip does change something
RE:
I found out the hard way also. My probe is direct behind the hotend because i like less offset. I ran into problems. I don't know if the gcode is compatible because I am using a Duet board. But it looks like this is working. You can read more here. I came to the same factor of 0.02 although it's not lineair. I never realized this nor it was a problem because i was printing at lower temperatures and used also a switch for Z-offset. Only the pinda for bedlevel.
https://forum.duet3d.com/topic/26298/hidden-z-offset-duet3/2?_=1638921487473