Z Axis Calibration - Problems
We recently upgraded the MK3 with the MMU2 and up to now, haven't had any issues.
Issue #1 - All of sudden, the printer (hot end and/or P.I.N.D.A) started catching the the print. I decided to do another Z-Calibration and this began my problem. The extruder would stop at the +10.0 height and give me a 'Calibration failed check the axis' error message and began the trouble shooting. The short version is I exhausted all searches on the internet related to this problem and performed numerous Factory Resets and and re-calibrations. After reading one particular thread someone mentioned flashing the printer with the wrong firmware. So i flashed the MK3 printer with the MK3S firmware and that solved my 'axis error'. Question: when you get the upgrade kit with MMUs, does that now make it a MK3s or does it remain an MK3?
Issue #2 - XYZ calibration. I noticed that the print head would stop short of the build plate. Again, to make a long story short i performed every action that has been recommended to solve this issue but to no avail. I flashed back to MK3 and tried again and i keep getting the same problem. Once i felt that the calibration actually worked and I went to do my First Layer Calibration i ended up having to lower the P.I.N.D.A probe down to -2.8 which is obliviously way lower than the recommended height -0.500 to -0.800.
I am at my whits end with this one. I even thought it was the P.I.N.D.A probe so i get a new one and replaced it but again, Issue #2 still remains.
Any help would be greatly appreciated.
RE: Z Axis Calibration - Problems
Isn't -2.800 a clue the PINDA isn't set properly?
RE: Z Axis Calibration - Problems
Indeed it does however i lowered it an few notches (threads) to see if i could see a change in the Live -Z Adjust number which i didn't.
RE: Z Axis Calibration - Problems
It appears that no matter what i do i am ~1.700 away from the steel sheet. When it does the -Z Calibration actually hitting the steel sheet (bouncing). When it gets finished, it does it homing and when i do a Move Axis -Z to 0.0 i am still 1.700 away from the steel sheet.
How would it be able to measure a Skew when it doesn't even touch the sheet?
RE: Z Axis Calibration - Problems
Just a thought - is the PINDA sitting vertical in its slot? If you had been printing high temperature stuff the PINDA bracket can sag and the PINDA winds up sitting at a noticeable angle to vertical and things can get wonky quickly. Sometimes you'll get sensible readings and sometimes not. I just rebuilt my extruder assembly because I had that problem after printing a bunch of PC items that kept the hot end near the bed for long periods of time and when I took things apart the sag in the holder was pretty amazing. The R5 parts are supposed to prevent this in the future but I actually went one step further and printed the R5 version in Polycarbonate which should definitely be more heat tolerant than the PETG was.
RE: Z Axis Calibration - Problems
Live-Z does NOT change because of PINDA height. But Live-Z MUST be changed when you change PINDA height.
The PINDA triggers at 2.0 mm. Live-Z adjusts for the height difference between the nozzle tip and the PINDA trigger point.
When you move the PINDA, you must adjust Live-Z accordingly.
e.g.
If the nozzle to PINDA difference is 0.8 mm Live-Z is about -1.200
If the nozzle to PINDA difference is 1.2 mm Live-Z is about -0.800
If the nozzle to PINDA difference is 0.0 mm Live-Z is about -2.000 (PINDA and nozzle touch the bed surface at the same time).
RE: Z Axis Calibration - Problems
Thanks for the explanation. So does that mean
1) i set P.I.N.D.A hieght
2) Adjust Live -Z accordingly
3) Run XYZ calibration
4) 1st layer calibration
RE: Z Axis Calibration - Problems
The normal process is to set your pinda height as described in the manual. run the calibration process and SAVE the values. The you run the first layer calibration, preferably using the Live Z method which is superior to the built in one. At that point you would have adjusted the live Z to get the correct perfect first layer.
Every time ANYTHING alters the physical pinda position or you change nozzles, rebuild the extruder, fit a new print sheet etc you should run calibration and redo the live z process so its dialled in for that setup.
RE: Z Axis Calibration - Problems
We recently upgraded the MK3 with the MMU2 and up to now, haven't had any issues.
Question: when you get the upgrade kit with MMUs, does that now make it a MK3s or does it remain an MK3?
The MMU2 kits ship with all the parts to upgrade the MK3 extruder to the MK3S setup. So, assuming you installed all the parts including changing out the filament sensor, that makes your MK3 printer into a MK3S now so you should have flashed it with the MK3S firmware when you finished assembling it. Sounds like you already did that now.
After assembly, did you run the full calibration wizard from the beginning, sheet of paper and all?
As neophyl wrote, you can't run live Z calibration until after you run the wizard on a newly assembled or reassembled printer. You might want to start at chapter 9 of the printer assembly manual before running the wizard though? I'm concerned that you may have skipped steps in the pre-flight check.
https://manual.prusa3d.com/Guide/9.+Preflight+check/1053?lang=en
RE: Z Axis Calibration - Problems
Thank you both.. I am confused though.. What is the difference between the Live -Z method and the builtin one?
RE: Z Axis Calibration - Problems
The “Life Z method”
Involves using a larger square to set the live Z instead of the little square of the built in live z program. It’s easier to see what you’re doing with the larger square pattern. I prefer a 12mm x 80mm x 0.2mm rectangle myself. Moves the print head to the right quicker so I can see how it looks as I adjust.
RE: Z Axis Calibration - Problems
Ah, Yes.. I was just unfamiliar with the use of the term. I used a 70x70 square but i like yours better because It is difficult to see the print until it moves about 1/4 to 1/2 through..
Thanks again
RE: Z Axis Calibration - Problems
What is not clear - is there seems to be a requirement that you first run the built in first layer calibration (the zig-zag with pad). That sets the initial Live-Z offset. Once set, it can then be adjusted using Tune/Live-Z, and those subsequent adjusted are properly kept in EEPROM memory.
RE: Z Axis Calibration - Problems
What is not clear - is there seems to be a requirement that you first run the built in first layer calibration (the zig-zag with pad). That sets the initial Live-Z offset. Once set, it can then be adjusted using Tune/Live-Z, and those subsequent adjusted are properly kept in EEPROM memory.
That’s good to know! I run the built-in live Z to get the nozzle low enough that the filament sticks in the zig zags, let it finish, and then go do my own rectangle. I did not know it was a requirement to run the built-in program first though. Thanks!
RE: Z Axis Calibration - Problems
So far so good. I did the built-in Live -Z adjust and then printed out a rectangle and adjusted the Live -Z again. My -Z height is about 1/2 of what it was before. Thanks to everyone for their feedback and suggestions. I am going to run a test print on something to see if everything is good to go.
RE: Z Axis Calibration - Problems
Question? Is the nozzle supposed to make contact with the steel sheet during the mesh bed level?
RE: Z Axis Calibration - Problems
no it should be above it as the mesh bed level should move the extruder down to the pinda detect height at each point and the pinda detect height should be liveZ+.2mm above the sheet
RE: Z Axis Calibration - Problems
David is correct but said it in a way that might be misunderstood:
When the PINDA height is correct, and after Live-Z is calibrated, the PINDA should sense the metal sheet and stop so that the nozzle is about 0.20 mm above the bed. The nozzle should never contact the sheet during a home operation nor during mesh leveling (neither 3x3 or 7x7).