(Humor must be obeyed.)
You might want to review your OctoPrint -> Settings -> Gcode Scripts in the areas of before/after pause.
You should know if you sliced this with absolute or relative movements and extrusion. This is critical for this to work. In a case like this, it's good to visit the Gcode Viewer tab, have it sync up with the printer and use this to know precisely which layer you're printing at any given moment. In some cases if the pause/resume goes badly you can cancel the job. You could potentially then create a new GCODE file which starts at the aborted layer, for the win.
Working on the assumption that you don't need to actually cancel the job, it's important to validate your OctoPrint's pause/resume Gcode scripts. I couldn't tell you if it pulls those in at the moment of truth of if it already cached them at the job start. If it's the latter, then your efforts to adjust the scripts mid-job won't work.
If these two scripts are wrong or absent, some side effects may occur:
- Hotend could just sit there at the top of your part, melting the plastic
- Hotend could move and then return in such a way that it's now crashed into the top layer badly, even knocking over a tall part
- Hotend could ooze plastic onto the top of a "for show" surface, ruining the appearance
- Hotend could return to the wrong place and try to finish the job a few millimeters off from where it should be
- The hotend filament audit could get off by the amount which you retract/extrude during your filament changeout. This then would either under/over-extrude on the resumed printing.
(You really should have dialed this in before starting such a long print job.)
My best guess would be that you should initiate both pause/resume from OctoPrint.
Here are my pair of scripts, noting that I'm running on a fork of Marlin on a printer with an unheated bed and one extruder and I assume absolute mode on movement and relative mode on the extruder:
After Print Job Paused:
M117 Print Paused
G91 Z # Set to relative positioning on the Z axis
G1 Z15 # Move my bed down 15mm (or the hotend up 15mm)
G90 Z # Set to absolute positioning on the Z axis
Before Print Job is Resumed:
M117 Print Resumed
G91 Z # Set to relative positioning on the Z axis
G1 Z-15 # Put the bed back
G90 Z # Set to absolute positioning on the Z axis
Mine is simple. Since I always use relative extrusion for slicing, I never have to worry about a filament change causing problems for the filament audit which goes on in absolute mode.
If your GCODE uses absolute mode, then you're going to want to add some M82/M83 behavior before/after. By temporarily going into relative mode, you can adjust the filament feed all you want. Then you set it back to absolute mode before printing and the audit will be happy.
