Luban settings (J1) - tool paths resulting in model being struck by nozzle

I’ve spent at least 7 hours now trying every setting I could find documentation for or think of myself. It simply refuses pass over the same part that’s being printed without striking it.

I’ve ruled out physical issues - bed level, bed flatness, even manually verified that the right nozzle Z-offset is absolutely identical using machinist’s blocks and shim gauges since the printer won’t let you jog the Z-axis far enough to do a paper test.

The forum will not let me upload a video, so here’s an imgur link to a recording of what’s happening. Nothing fancy here, PLA+ with mostly default settings. This happens with default settings, but anything non-flat gets knocked off the plate without a brim.

Am I missing something crucial here?

Try enabling Z-hop in material settings…

Tall and narrow parts are harder to print, for this reason. ZHop should help, but it’s not a guarantee. Increasing layer height can help, slowing down can help, and some pieces printing it by itself can help. The last one depends on the part though. Those parts look like if they were printed individually, the print head would always stay inside the part.

Try enabling Z-hop in material settings…

When I tried Z-Hop, it hops between parts, but still strikes when jogging around the same part.

Ok interesting… Did you try different combing modes or disabling it completely?

My suggestion:

retraction: enabled
z-hop when retracted:yes
combing mode: off
max comb distance with no retract: try very low value like 1 mm or something or maybe it doesnt matter when combing mode is off…

I tried this, tried every combing setting, and realized that Luban does not respect the combing setting at all. This appears to be a bug in Luban.

Ok. Then I would suggest switching to another slicer. It’s easy to get started with Cura for example. Just remember to lower the retraction distance to a reasonable value becaause the default is way to high…

Also, the start gcode primes the nozzle on top of the wiper and wich can cause blob on nozzle and failed starts. You might want to get rid of that and use skirts/brim instead.

You could just take my start gcode and copy paste it into cura machine settings:

;— Start G-code Begin —

M140 S{material_bed_temperature_layer_0} ;Set Bed Temperature

G28 ;Home

G1 Z0.8

M190 S{material_bed_temperature_layer_0}

M104 S{material_print_temperature_layer_0} ;Set Hotend Temperature

M109 S{material_print_temperature_layer_0}

G1 Z0.8 F6000

M201 X10000 Y10000 Z500 E5000

M593 P1 F50

M205 V5

G92 E0

;— Start G-code End —