pre print Bed Leveling behavior change?
I have only been printing for a few months, so bear with me! 🙂
I noticed a few days ago, that when my i3Mk3s+ (3.11.0-4995) does the pre-print first layer calibration, at the 5th and 9th points, it hesitates and raises and lowers the print head (Z axis) 5mm or so.
I'm using octoPrint (1.8.6), and if I run a bed visualizer "update mesh now", it runs as I am used to. (the head moves to the 9 points, pauses for a second with a little wiggle, and does the next. Only recently, the calibration runs when a print starts, acts as noted above.
I have tried checking the GCODE for any differences from when it was not doing it, and I'm not seeing any but let's be realistic, it's not that easy to read.
I'm not saying anything is wrong, but I'm trying to understand what is causing the behavior change. I thought maybe it was part of the process for the calibration if the measurement was more or less than an expected value or maybe the sensor was having an issue, but it is very consistent and the printer seems to be working well still.
Any insight would be appreciated.
Best Answer by Tim Weston:
This is pretty normal behaviour - my printer sometimes does this too. I think the bed-levelling software routine is 'double-tapping' some points because it did not get a good reading on the first try.
There is nothing to really see in the G-code related to bed levelling as the routine is part of the printers firmware. There is just a G80 command that initiates the routine and an optional G81 that can send the results to OctoPrint (see here for more info).
That said, it might be worth checking the height of the SuperPINDA probe just to make sure it is still has an optimal setting. If you built the printer from the kit, then just use the tie-wrap spacer method that is mentioned in the assembly manual. There are also quite a lot of simple spacer jigs on Printables that you can use. This one from fuchsr for example: https://www.printables.com/model/57192-super-pinda-spinda-spinda-height-adjustment-tool-m
If you are printing larger objects, you might also want to consider switching to 7x7 pre-print bed levelling in the printer's menu. It takes a little longer to run but is generally worth the extra time. If you do switch to that, note that OctoPrint will probably still do 3x3 though.
Hope that helps,
Tim
RE: pre print Bed Leveling behavior change?
This is pretty normal behaviour - my printer sometimes does this too. I think the bed-levelling software routine is 'double-tapping' some points because it did not get a good reading on the first try.
There is nothing to really see in the G-code related to bed levelling as the routine is part of the printers firmware. There is just a G80 command that initiates the routine and an optional G81 that can send the results to OctoPrint (see here for more info).
That said, it might be worth checking the height of the SuperPINDA probe just to make sure it is still has an optimal setting. If you built the printer from the kit, then just use the tie-wrap spacer method that is mentioned in the assembly manual. There are also quite a lot of simple spacer jigs on Printables that you can use. This one from fuchsr for example: https://www.printables.com/model/57192-super-pinda-spinda-spinda-height-adjustment-tool-m
If you are printing larger objects, you might also want to consider switching to 7x7 pre-print bed levelling in the printer's menu. It takes a little longer to run but is generally worth the extra time. If you do switch to that, note that OctoPrint will probably still do 3x3 though.
Hope that helps,
Tim
RE:
The measured height at that point is slightly different to the stored value but not enough to prevent printing. If the plate is clean and there are no debris or filament fragments beneath and the bounce recurs then it's tme to do another first layer Z calibration and so update the stored values.
The cause is most likely to be gradual wearing of your nozzle, it probably hasn't gone far enough to need replacing, just recalibration; inspect it anyway.
Cheerio,
RE: pre print Bed Leveling behavior change?
Thanks for the information and education. I re-did the SuperPINDA sensor calibration, and it was not at the 1mm mark, so I must have bumped it working on the hot end.
I have redone all the calibrations, and it is much happier now, even via Octoprint, which is happy with the 7x7.
I'm going to do one of those first-layer calibration prints out of curiosity and see how it turns out.