CoreOne+ - Bed not moving to bottom position after print finishes.
Hi everyone,
yesterday I did a first print on my new Core One+ (factory assembled). The print turned out nicely. However I noticed that after the print finished the bed stayed at about half height. The panel indicated that the print finished (100%) the LED strip did light up green. It seems that the only way to get the bed back to the bottom is to navigate to the menu and adjust the Z-axis height manually with the rotary knob. This seems a bit odd to me. I'd expect the printer to move the bed all the way down by itself after finishing a print. Is this normal on a Core One+, is there any setting that makes the printer move the bed back down automatically once a print finishes?
RE: CoreOne+ - Bed not moving to bottom position after print finishes.
The position of the bed after printing depends on the height of the model and the bed only moves down a certain height so that the model can be comfortably removed from the printer, not completely to the bottom. This is in no way a bug. If you need this, you can set it in the final gcode model. But that's after you learn something!
RE: CoreOne+ - Bed not moving to bottom position after print finishes.
It is actually undesirable to move the bed all the way down after a print, unless it is necessary to accommodate a very tall model: When you load and unload filament, the firmware likes to move the bed down a few centimeters, then performs a quick XY homing. If the bed already starts in a low position, it will drive into its bottom end stops and lose knowledge of its actual Z position, requiring new leveling and homing. Better to keep enough safety distance from the base plate if you can.
RE: CoreOne+ - Bed not moving to bottom position after print finishes.
Thank you for the quick response miroslav and Jürgen. I don't know why but I just expected the bed to move back into the bottom position automatically once a print finishes. I guess it seems reasonable because usually you want to remove the sheet and/or the print and for that it is just good to have as much clearance as possible. In the mean time I had a quick chat with the support to see if there is an option in the printer firmware to move the bed back down once a print finishes automatically, apparently there is none.
the firmware likes to move the bed down a few centimeters, then performs a quick XY homing. If the bed already starts in a low position, it will drive into its bottom end stops and lose knowledge of its actual Z position, requiring new leveling and homing. Better to keep enough safety distance from the base plate if you can.
Okay I did not know that. I did move the bed down using the rotary knob and manual Z-axis adjust in the menu before I turned it off. Also after initial setup and calibration the Core One moved the bed to the bottom position automatically. Looking at the menu it seems the printer remembers the Z-height. So theoretically it should know that it is already at the bottom location and not try to move down any further.
RE: CoreOne+ - Bed not moving to bottom position after print finishes.
Unless it has been changed in the most recent firmware, the printer does not remember its X/Y/Z positions over a power cycle.
If you power up the printer when the bed is in a low position, you can do an Auto Homing from the menu before you load/unload filament. Then the printer will know its positions again and will not move the bed too far down.
RE: CoreOne+ - Bed not moving to bottom position after print finishes.
Unless it has been changed in the most recent firmware, the printer does not remember its X/Y/Z positions over a power cycle.
If you power up the printer when the bed is in a low position, you can do an Auto Homing from the menu before you load/unload filament. Then the printer will know its positions again and will not move the bed too far down.
As far as I'm aware, the only feature that implements saving coordinates on power-down is the power panic feature. However, before it continues, it has to do a precision home first.
RE:
@Jürgen, @hyiger: If the bed is in a certain position, e.g. the bottom position (Z=275mm) and I turn the printer of and then on again, navigate to Control > Move axis > Move Z, the printer still shows the value set from before the restart. I'm not sure if the printer/firmware actually considers this setting when processing G-Code for a new print but the position is persisted in memory and could, at least in theory, be used to determine the bed position even after a restart.
RE:
@Jürgen, @hyiger: If the bed is in a certain position, e.g. the bottom position (Z=275mm) and I turn the printer of and then on again, navigate to Control > Move axis > Move Z, the printer still shows the value set from before the restart. I'm not sure if the printer/firmware actually considers this setting when processing G-Code for a new print but the position is persisted in memory and could, at least in theory, be used to determine the bed position even after a restart.
Down is always safe. Any other direction isn't. When the power is off I can manually turn the z-axis lead screws and move the bed to any position I want. So if you move the bed to the bottom, turn the printer off. Then move the bed up by manually turning the screws by some amount. Then turn the printer back on, what does the stored number 275 actually mean? I think Prusa is storing the last Z position because the bed will generally stay in place between power cycles unless it gets manually moved. So it's somewhat safe. But you will notice that until you do an auto-home you can only move the bed down and not up.