7x7 Bed Levelling Head, Z moving up and back down 30mm Randomly.
I have been running my new MK3S+ for 3-4 weeks now after build, and so far except for some minor printing issues that were explainable (Mostly due to me challenging it TBH) has been running very well.
I was trying to do a particularly difficult print past few days, and the supports were not coming out well in PS 2.3.0+, so I transferred over to Cura and sliced and it printed much better. However about 4 or 5 times during the 7x7 level at the start the Z axis would lift around 20-30mm off the normal trajectory (Far more than usual) and go back down and continue.
Initially I thought it was something strange within Cura GCode that was causing this to occur, however I have just started another print (This Heart Box) Heart Box (Fixed) by gaellafond - Thingiverse Which I sliced with Prusa Slicer and it did the same at the start of this as well.
Has anyone ever had this before?
I can post a video in a few hours after this print finishes, its a bit strange.
Tank you very much!
RE: 7x7 Bed Levelling Head, Z moving up and back down 30mm Randomly.
I have reset the calibration dats on the mc, did the self test, then XYZ calibration again (Got Perpendicular still so frame still square)
Before the reset did it about 4 or 5 times during 2 consecutive prints (Ok maybe not rising 30mm, probably nearer 15mm up then down)
Then did 7x7 calibration from the menu and it did it again, but only once, all reads at normal speed.
Then did 75x75mm test square from Life adjust my way and was ok, and the hesrt print started again and did not do it.
Then I did the internal 7x7 bed level from the menu again and now is taking the 3 readings at each point at a very slow speed compared to above. But 1 of the points reads at nornal fast speed.
Have also tried reseating the connector into the board fornthe SPINDA.
Any ideas anyone? Its very random and rather confusing.
Tank you very much!
RE: 7x7 Bed Levelling Head, Z moving up and back down 30mm Randomly.
After scratching my head for well over a day with this I think I may have found the solution.
While searching the web I found this tech insider article on Prusa Blog relating to bed leveling (very interesting read)
https://blog.prusaprinters.org/prusa-tech-insider-1-mesh-bed-leveling_30817/
In it there is an in depth description of the methods used in bed levelling with PINDA.
One of the sections says "So what happens if the measured value is out of bounds? The printer will try to correct the situation automatically – it will move the extruder up and slowly down again, which is the original measuring procedure. Only if this doesn’t help, it’s necessary to perform Z-leveling."
So I took this to mean good chance my bed variance was causing this randomly to occur.
Found using g80 and g81 that the bed was roughly 0.3 to 0.4mm variance side to side, so I have manually levelled the bed now to within .02mm, this so far seems to have resolved the issue.
Only time will tell, but seems this is a normal procedure, I readjusted the bearing clips on the bed and rod holders for, parallel, I wonder if this could be due to the bearings etc settling after build and just went over the limit.
I have now enabled 5 points at each 7x7, see how it goes, hopefully head scratching over.....
Tank you very much!
RE: 7x7 Bed Levelling Head, Z moving up and back down 30mm Randomly.
I get that about every 4th or 5th print. It's not an issue - it found a bump, it's trying to make sure it's not too close to the sheet. I now rotate between two sheets (3 sides, one side is ruined) and just let the 7x7 play itself out. Sometimes the same sheet will test out with no inter-test raise/lower for two or three prints in a row - and if I turn it over, the next one tests out with a few of those pauses.
It's part of the program.
RE: 7x7 Bed Levelling Head, Z moving up and back down 30mm Randomly.
@dan-rogers
Thanks Dan.
Had me scratching my head for while, thought maybe something wrong with SPINDA at first.
Appreciate the feedback, was looking for a reason to level the bed properly anyway 😁
Tank you very much!