MK3S+ Some Problem Encountered. Z-Leveling Enforced
Operating a MK3S+, currently running firmware 3.14.1. Was running a previous version before this problem started. I believe the MK3S+ was placed into service in 2019. I'm unsure of the total/cumulative hours, since factory resets have been executed over time, but imagine it has been more than 5,000 hours with minimal maintenance & repairs. In the time leading up to this, i'd rarely had any print issues in hundreds, if not thousands of prints. Shortly before this, there were a couple issues. 1) a small part came loose from the print-bed and attached to the hot-end. It turned into a sizeable mess and tripped an axis error. 2) an object got too close to the left hand z-axis. when a new print was started, the x-axis motor lowered, it came to rest on the object and lifted the edge of the printer off the table. After these, i reset everything and the next prints were executed normally. Within about a week of the last event, the error message occurred at random, generally after a few successful prints. Recently the failure has become repetitive to the point where it has consistently failed the first layer calibrations during the pre-print checks as well as at the end of the Wizard calibration. The error occurs shortly after initiating the first layer calibration. "Calibrating Z : 9" this fails, then the LDC reads "Some problem encountered. Z-leveling enforced. It then attempts "calibrating Z". The x-axis assembly rises to the top; the stepper motors hammer and the assembly lowers approximately 10mm. Periodically it retries "Calibrating Z". When i reset, or power off/on, the X, Y & Z attempt to home. X & Y behave normally. Z increments and "homes" at a height approximately 10mm higher than the previous. LCD indicates that it the Z elevation is 0.15 (mm) regardless of where the actual value is (200 mm, 5mm etc). I've tried two methods to reset it. 1) After a reset, manually adjust Z using the control panel knob, forcing it to 210mm. I can then use Z-axis to lower the assembly to Z = 0, but the nozzle tip is still approximately 5 mm above the hot-bed. Method 2: power-off. manually rotate the Z-axis until the nozzle tip is separated from the print bed at all x-values by the thickness of a piece of printer paper (~.0035 in / ~.09mm)
Troubleshooting: Flashed current firmware 3.14.1 (3 times). Forced a factory reset to clear ALL data (multiple times). Removed and replaced trapezoidal nuts. Removed Z-axis linear bearings and cleaned the smooth shafts. Damage and/or excess wear were not observed on the smooth rods or the linear bearings. Lubed the inside of the linear bearings & reassembled. Loosened z-axis motor fasteners common to the lower brackets and loosened brackets at the top of the Z-axis, moved the z-axis thru the full range of motion, and re-torqued fasteners at the top and bottom. Adjusted the Super-Pinda. When the hot-end tip is separated from the plate by a piece of paper (.0035" / .09mm) from the print surface, the Pinda is set to the thickness of a debit card (.030" / .762mm) . Ran tests to see if the Pinda is functioning (e.g. make sure that moving a metal (spatula) under it triggers the PINDA from 0 to 1. I then set the hot-end tip the thickness of a piece of paper (.0035" /.09mm) above the print surface and ran the print head in a grid across the print bed using Pronterface controls to see if it toggles unexpectedly from 1 to 0. Using Pronterface controls, I periodically raised it .1-.2 mm to verify that it toggled to 0. Ran the G80/G81 commands from Pronterface 3 times and analyzed the data. Didn't see any point that deviated by more than 0.06mm. Reviewed X/Y/Z set-up data. Measured skew: 0.02deg.
I'm at a loss for what to try next. I'm considering ordering a replacement PINDA as well as linear bearings. Suggestions are appreciated.