Modes Normal, Stealth, power panic resend gcode
I tried some forum searches and did not find any threads regarding my experience. I've found a work-around for my issue but wondered if anyone else has observed or heard of this.
I received my MK3S+ on May 2, 2022. I updated to firmware 3.11.0-4955 that day. After two successful test prints from gcode on the included SD card I connected the printer to a Raspberry Pi 4B running OctoPrint. I had been successfully driving an Ender3 V2 with the same Pi 4B and OctoPrint and using PrusaSlicer successfully for several weeks prior. Everything worked great for several days as I printed several models all day everyday (I'm retired so have plenty of time for this).
On May 4, about four hours into a seven hour print job, the printer's hot end would quickly move completely to the left of the X axis, the print bed would quickly move to the rear of the Y axis, a resend request would be sent to OctoPrint, the hot end would quickly move back to previous print position and resume printing. This happened seven times and the print job finished successfully. The model looked fine, no defects or anything to indicate a problem.
I contacted Prusa Support via chat when this began happening. The advisor's suggestion was to open up the power supply unit and disconnect the "Power Panic" cable (see attached image). I doubted the likelihood of a power issue since I have the MK3S+ plugged into a UPS power supply that has worked perfectly for months. The UPS conditions the power so no spikes, brownouts or power hits would effect the printer. During this time I did not observe any issues such as flickering lights so don't suspect there were any commercially supplied power issues at my home.
Since the printer was only two days old I was reluctant to open up the PSU and disconnect any cable. I had read that in "Normal mode" there is detection of lost steps. Here is a quote from the Prusa Knowledge Base:
Normal vs. Stealth mode
MK3 series printers offer two print modes. Normal mode is required for the detection of lost steps (shifted layers), while still being quieter than the silent mode on MK2/S. There is also the Stealth mode,which utilizes Trinamic StealthChop technology. This makes the printer almost inaudible where the print cooling fan is the noisiest part of the printer.
I switched from Normal mode to Stealth mode and the issue with resend requests to OctoPrint and the hot end homing and returning have ceased. It appears I have found a work-around. I have not tried printing directly from an SD card to determine if OctoPrint is playing a role in the issue.
Has anyone else observed or heard of this issue?
Thanks,
Jake