Ultimaker 3 print head pauses after core switch

[Kief 2]

Hi,

 

Im printing with TPLA in core 1 and PVA in core 2. Everytime it switches to core 2 the print head pauses for 5-10 seconds before continuing. What is the reason for this and how can i fix it? seems like a huge time waste.

[GregValiant 1,261]

If there are M109 temperature commands (likely) in the gcode then that will usually cause a delay before printing resumes.  If both cores are printing at the same temperature, and if the stand-by temperature for both cores is the same as the printing temperature, then you could (if you are brave) use Search and Replace to change all the "M109" lines to "M104"'s.

 

BUT...If the temperatures are not the same, then you need to let the printer adjust temperatures and that will mean a short wait every time there is a tool change.

[Kief 2]

7 hours ago, GregValiant said:

If there are M109 temperature commands (likely) in the gcode then that will usually cause a delay before printing resumes.  If both cores are printing at the same temperature, and if the stand-by temperature for both cores is the same as the printing temperature, then you could (if you are brave) use Search and Replace to change all the "M109" lines to "M104"'s.

 

BUT...If the temperatures are not the same, then you need to let the printer adjust temperatures and that will mean a short wait every time there is a tool change.

Yes i figured something like this was the reason, however I thought that the temperature was adjusted to the correct level while the opposite core was finishing its layer so that it was ready by the time the cores switch?

[GregValiant 1,261]

"I thought that the temperature was adjusted to the correct level while the opposite core was finishing its layer"

 

It does work that way but it's dependent on "Heat Up Speed" and "Cool Down Speed" which are not exactly consistent (they are affected by a lot of things including flow-rate of material through the nozzle).  There is also the question of how long the layer takes to print.  For quick layers there may not be enough time for the temp to adjust before the next tool change.  The M109 is a safety to insure that the printing temperature is reached.

 

As a side note - A change I made in the PauseAtHeight plugin was to add an option to use either M109 or M104 when the print resumes.  If the "Standby" temperature is the same as the "Printing Temperature" then M104 is fine and the print immediately continues after the pause.  If the temperatures are different, then the use of M109 is indicated so the printer waits for the new temperature to be achieved before printing resumes.

 

One thing I have noticed is that if the current nozzle temperature is the same as the resume temperature then M109 may or may not cause a 10 second dwell in the print.  It appears to be a function of when the M109 appeared in the Printer/Planner queue as to whether a dwell occurs or not.  It might have something to do with the clock cycle of the Printer/Planner or whether the reported temperature is slightly above or slightly below the set point temperature.  It certainly isn't consistent.

Edited October 21, 2023 by GregValiant

[Kief 2]

1 hour ago, GregValiant said:

"I thought that the temperature was adjusted to the correct level while the opposite core was finishing its layer"

 

It does work that way but it's dependent on "Heat Up Speed" and "Cool Down Speed" which are not exactly consistent (they are affected by a lot of things including flow-rate of material through the nozzle).  There is also the question of how long the layer takes to print.  For quick layers there may not be enough time for the temp to adjust before the next tool change.  The M109 is a safety to insure that the printing temperature is reached.

 

As a side note - A change I made in the PauseAtHeight plugin was to add an option to use either M109 or M104 when the print resumes.  If the "Standby" temperature is the same as the "Printing Temperature" then M104 is fine and the print immediately continues after the pause.  If the temperatures are different, then the use of M109 is indicated so the printer waits for the new temperature to be achieved before printing resumes.

 

One thing I have noticed is that if the current nozzle temperature is the same as the resume temperature then M109 may or may not cause a 10 second dwell in the print.  It appears to be a function of when the M109 appeared in the Printer/Planner queue as to whether a dwell occurs or not.  It might have something to do with the clock cycle of the Printer/Planner or whether the reported temperature is slightly above or slightly below the set point temperature.  It certainly isn't consistent.

Thanks for clarifying! It is a fairly small model with quick layers and i run most parameters that i think would affect heat up and cool down speed at default setting. So the most likely explanation seem to be the one you provide. I'm not confident enough to mess with the g-code manually yet but will look in to this more 🙂

[GregValiant 1,261]

If you search through the Gcode for "T0" and "T1" you should see where the temps are changed at any tool changes.

If you search for "M104" and "M109" you will come across other temperature changes.  Between the two you will get a feel for what Cura is doing.

On long prints you won't want to be dragging an oozing nozzle around your print so the standby temperature is important.