We have a brand new Mini and we’re gaining experience with it. Using the included Cura slicer software on Win7.
The nozzle temperature seems to have a selective calibration problem. When we set the temperature in Cura’s manual window (where you can manually “set” the nozzle and bed temperature), the nozzle goes right to that temperature and stays within +/- 1 degree. Works perfectly.
But when we put a target temperature into the setup screens, and then turn it loose to print, it begins printing when the head is exactly 10C below the target temperature (as reported in the window title). And it holds that -10C temperature during the entire print.
The bed temperature is rock-solid, manual or automatic. Always within a degree of the target value.
So… what’s happening here? It seems clear that the hardware and software CAN set and maintain a target temperature (based on the manual results). Why does it hold the head 10C cooler than the target temperature when automatically printing? Is there an offset adjustment somewhere in the software that I should play with?
Starting the print process at -10 from target is normal. The initial heatup of the extruder is done with a “M109 Rxxx” command, which “waits” (meaning firmware won’t accept further commands) until it reaches the target temperature. However, there are parameters in the firmware build that define a “window” of 10c for the extruder temp, meaning once it is within 10c the M109 command ends, and that allows the print to begin. In general, this isn’t a problem – because it typically takes only a few seconds to finish heating that last 10C, and by the time the head actually starts laying down extrusion it is at the target temperature.
It would not be normal to stay -10c from the target. One thought, which wouldn’t fully explain what you’re seeing but I’ll mention it anyway: Beware that if you have the Print Control window open in Cura, any changes you make to temp (or any other settings) in the main window will NOT be reflected when starting the print – unless you first Close and Re-Open the Print Control window.
That makes perfect sense. However, as you note, it doesn’t explain why the nozzle STAYS at -10C from the target temp.
One thought, which wouldn’t fully explain what you’re seeing but I’ll mention it anyway: Beware that if you have the Print Control window open in Cura, any changes you make to temp (or any other settings) in the main window will NOT be reflected when starting the print – unless you first Close and Re-Open the Print Control window.
I considered that, and was very careful to change NOTHING (not even clicking the mouse, so the window focus didn’t change) during my prints that were testing this condition.
I have since (re)confirmed that it doesn’t matter what the temp setting is in the “control” dialog box. I had wondered if it wasn’t zero if there might be some sort of interplay there. It does not appear so, and I certainly wouldn’t expect it, but worth the test.
So far, I don’t know why it happens. But it’s 100% repeatable. Question is: Do I trust the setting, or the temperature display in the dialog box’s title line? 10C is enough of a difference to have an effect on some filaments.
My best guess is the actual temperature is correct, but Cura isn’t properly sending/receiving/interpreting the periodic M105 commands during the print. Cura normally sends one of those every few seconds, and interprets the response to get the extruder/bed temps and update them in the GUI.
What version of Cura? PC or Mac? I haven’t seen a bug like that reported, but who knows… I currently use 21.02 on PC, and have not seen any issues like that with it or the previous versions I used. But I haven’t used every single version.
It could also be a firmware issue. You could try flashing default firmware (from Cura menu, it’s “Machine, Install default firmware”), then reset all settings to default (send M502, then M500), and try again.
Do you have any other control software to try? It would be nice to send a manual M105 command and look at the result. Unfortunately, Cura filters out the response to the M105 (i.e., does not show it in the terminal window) so I don’t think there is any way to send a manual M105 and see the reply. Not sure about standalone Pronterface; I know Octoprint and S3D allow sending manual M105 and seeing the responses, but that doesn’t help if you don’t have them. :-/
Win7, running Cura V19.08. This was the version included on the USB stick with the Mini. I haven’t tried later versions, yet.
Do you have any other control software to try?
I am considering grabbing a copy of Slic3r to see what happens there. I haven’t dug into how to configure each of these slicing programs for a different printer, though… since there is a Mini-specific version of Cura that suggests there may be some customization/configuration required. Sounds like YALC (Yet Another Learning Curve)!
Slic3r doesn’t include a “controller”, it is a slicer only, so you will still need Cura or Pronterface to communicate with the printer. But I don’t think your issue is with the slicer.
I’d suggest updating to the latest Cura from Lulzbot downloads – 21.03. It will have all the latest Lulzbot-provided profiles, and the latest firmware if you want to flash it (and I recommend you do). Basically an up-to-date version of what was provided on the USB stick that came with the printer.
Yep, we’ll do that this morning. I hadn’t bothered to check for a later version, presuming that a brand-new printer shipping direct to me would have shipped with the latest . If the present version is V21.xx, then they shipped us a MUCH older version (19.08). Wow.
I saw something kind of like this on my Mini a while back, but I suspected it was due to a bit of melting on the part cooling fan duct. Try disabling the cooling fan and see if that helps. Mine was blowing a bit on the heater block and would make it so the printer had a hard time maintaining temp above 240C. I fixed it for now by shimming the duct a little so it points a little more away from the heater. I need to print a new one, but would prefer to do a dual.
. If the present version is V21.xx, then they shipped us a MUCH older version (19.08). Wow.