Extruder > Ooze control > [
] RetractionExtruder > Ooze control > Retraction distance: 0.5mm
Extruder > Ooze control > Retraction Vertical Lift: 2mm
I need the vertical lift settings because of my printer's geometry; prints will fail otherwise. And generally speaking this feature works great, I use it to avoid the print head knocking loose delicate prints.
But, there's one area where this feature is an absolute nightmare and is a common cause of print failure - outer shells. The generate g-code instructs the printer to do the vertical lift (and retraction) when switching between adjacent layers of outer or inner shells.
Let me clarify. Let's say I'm printing a cube with 3 outer shells (that is, Layer > Outline/Perimeter Shells: 3). I also have it set to do the innermost shell first.
Here's an ascii diagram of one of the cube's corners in the first layer. It's meant to show the 3 shell extrusions forming a corner:
Code: Select all
+----------
|+---------
||+--------
|||
|||
|||
1. The printer homes .
2. The printer moves to the bottom right "+" symbol in my diagram and begins the extrusion.
3. Eventually, the 1st shell finishes and the print head has returned to the "+" symbol in step 2
4. The printer stops moving at the "+"
5. The Z-axis raises by my Vertical Lift amount
6. The printer moves to the middle "+" symbol (to start the next shell)
7. The Z-axis returns to its initial position
8. It begins the printing extrusion for the 2nd shell.
Steps 3-8 repeat for the next shell in the 1st layer.
Why is this a problem?
Depending on how well your print is stuck to the bed, it sometimes pulls the print right off the bed! This is most common when printing ABS or PLA on glass. Furthermore, the time delay seems to "cook" the plastic too long and the next extrusion typically doesn't adhere to the bed for a few MMs. This problem is especially noticeable on small inside shells e.g. if the cube I'm printing has any screw holes.
Have I also discovered an emoji bug?
