My extruder failed. Is there any hope to recover print?

Question

Yesterday I had filament that entangled on the spool and before I knew it, the printer told me to eject the filament. Unfortunately, then the filament broke. There is no way to fully unload it, no way to load new piece.

Long story short, I need to disassemble extruder-hotend assembly and fix whatever is broken. I'll manage, it's simple mechanical and electrical issue and I know my way around it. But, is there any chance to recover that print?

I'm lucky it failed at about the end of a layer. It's 0.3 mm layer height, so I can even use calipers to find out how many layers I do have. But how would I go about it now?

I used PrusaSlicer and the printer is a Prusa i3 MK3s+ so any specific guidance would be appreciated, but general guidance is also welcome.

Answer 1

In order to "resume" a failed print like this, you can edit the prints .gcode file accordingly.

1. Measure the height at which the print failed

2. Open the file, and search for when the printer starts the corresponding layer. How to search for this differs from slicer to slicer. In SuperSlicer, it's "move to next layer (XYZ)". Searching for moves to the desired Z height might work too, but beware of false positives if you still use "Z hop" for some reason. You may want to choose the layer above the measured height as a starting point since the nozzle might scrape over the printed parts if you try to print the same layer again.

3. Delete everything from the line which moves the printer to the first layer up to when it moves to the layer you wish to resume printing from.
   If you use mesh bed leveling, you'll need to remove that too - or the printer might probe into the existing print. If your start G-code contains moves that might make the print head interfere with the existing print, remove that too.
   Also: Make sure the print head moves to the desired Z height before starting to move to the print area (on X and Y) - otherwise, it might again crash into the print.

4. Start the print as usual and pray.

You'll be likely to see some defects/imperfections on the failed layer, but the print as a whole should be salvageable in most cases.