Mini 2 kills when calibrating before a print

I have a Mini 2 that kills when calibrating during bed leveling. I never really noticed it until I was forced to revert to Cura because Cura LE is no longer supported for me. It happens when the head is calibrating against one of the corner pads - it may happen on the first, second, or less often, the third pad.

I’ve contacted Lulzbot support and they can’t help because I’m not using Cura LE. Are Lulzbot printers really only meant to work with Cura LE and nothing else?

In any case, I’ve noticed if I preheat the extruder, it helps get past this issue (sometimes), but I’m wondering if it’s just a script or something that I can run in Cura which Cura LE does automatically?

Also on a seemingly related note, it often won’t lay down PLA when I go through these kills (I usually have to reset two or three times). When that happens, I need to do a filament change, then it usually works. For a while.

I assume you are running Cura on something other than Windows, correct? Lulzbot printers are not CuraLE only, but CuraLE has some features that are not easy to duplicate with other slicers.

In any case, your problem appears to be a dirty nozzle and/or dirty corner washers. The corner washers can be cleaned with Isopropyl Alcohol, a Scotchbrite pad, and/or very fine grit sandpaper or pad (1600 grit or higher). The nozzle should be heated to the temperature used for the filament and then carefully cleaned with a non-conducting tool like the above Scotchbrite pad. If you want to use a conducting tool like a brass brush, then heat the nozzle, turn the printer off, and then clean the nozzle. If the conducting tool shorts out the heater or thermistor wires while power is applied, you can damage the controller board.

The leveling sequence (G29) should be run with the nozzle heated to around 140 degrees. One of the things CuraLE provides is the start (and end) gcode sequence(s). Also the ability to update the firmware (there are other ways but nowhere near as simple as using CuraLE).

On my LulzBot TAZ 6, I use Ultimaker Cura, Simplify 3D, Prusaslicer, and other slicers but I copied the start and end gcode sequences from CuraLE. There should be a series of wiping commands in the start gcode as well.

Another useful item to use is cleaning filament, eSun is one brand but there are others. This can be used to clean any filament stuck in the path by doing cold pulls. You can cold pull regular filament, but the cleaning filament just does a better job, IMO.

I realize I’m reviving my first post which is really old, but it still ranks high in search results when I google this problem, so…

In the intervening months, this issue has come and gone. Recently, I’ve replaced my nozzle and began printing with ABS. Now it happens when the nozzle touches the first leveling pad every time. I could try to preheat to 200-ish, but with ABS, heat creep is so bad I get filament grinding pretty quickly, so I’m trying to keep the temperatures down.

I’m running the latest Cura release under Linux. I don’t run CuraLE because it’s been unstable (crashes on initial startup).

So, to make it work under Cura, I acquired the beginning and ending g-code for the Mini2 and added it to my Cura profile.

It’s clear there are commands to raise the probe temperature prior to wiping and bed leveling, but I don’t see the probe temp change when the printer runs through the initial g-code. The M109 / M190 commands at the end of the startup phase do run, however.

Is the variable reference for the other M109 calls invalid?

For reference, here’s the starting g-code I have in the custom printer I created in Cura:

;This G-Code has been generated specifically for the LulzBot Mini 2 with SE 0.5mm Tool Head
M73 P0                  ; clear GLCD progress bar
M75 					; Start GLCD Print Timer
G26 					; clear potential 'probe fail' condition
M107 					; disable fans
M420 S0                 ; disable leveling matrix
G90 					; absolute positioning
M82 					; set extruder to absolute mode
G92 E0 					; set extruder position to 0
M140 S{material_bed_temperature_layer_0} ; start bed heating up
G28 					; home all axes
G0 X0 Y187 Z156 F200 			; move away from endstops
M117 Mini 2 Wiping...			; progress indicator message on LCD
M109 R{material_soften_temperature} 	; soften filament before retraction
G1 E-15 F75 				; retract filament
M109 R{material_wipe_temperature} 	; wait for extruder to reach wiping temp
G1 X45 Y176 F11520 			; move above wiper pad
G1 Z0 F1200 				; push nozzle into wiper
G1 X45 Y178 Z-.5 F4000		; wiping
G1 X55 Y176 Z-.5 F4000		; wiping
G1 X45 Y177 Z0 F4000		; wiping
G1 X55 Y176 F4000		; wiping
G1 X45 Y178 F4000		; wiping
G1 X55 Y176 F4000		; wiping
G1 X45 Y178 F4000		; wiping
G1 X55 Y176 F4000		; wiping
G1 X60 Y178 F4000		; wiping
G1 X80 Y176 F4000		; wiping
G1 X60 Y178 F4000		; wiping
G1 X80 Y176 F4000		; wiping
G1 X60 Y178 F4000		; wiping
G1 X90 Y176 F4000		; wiping
G1 X80 Y178 F4000		; wiping
G1 X100 Y176 F4000		; wiping
G1 X80 Y178 F4000		; wiping
G1 X100 Y176 F4000		; wiping
G1 X80 Y178 F4000		; wiping
G1 X100 Y176 F4000		; wiping
G1 X110 Y178 F4000		; wiping
G1 X100 Y176 F4000		; wiping
G1 X110 Y178 F4000		; wiping
G1 X100 Y176 F4000		; wiping
G1 X110 Y178 F4000		; wiping
G1 X115 Y176 Z-0.5 F1000	; wiping
G1 Z10					; raise extruder
G28 X0 Y0				; home X and Y
M109 R{material_probe_temperature}	; wait for extruder to reach probe temp
M204 S300				; set probing acceleration
G29					; start auto-leveling sequence
M420 S1                     ; enable leveling matrix
M425 Z			     		; use measured Z backlash for compensation
M425 Z F0		     		; turn off measured Z backlash compensation. (if activated in the quality settings, this command will automatically be ignored)
M204 S2000				; restore standard acceleration
G1 X5 Y15 Z10 F5000			; move up off last probe point
G4 S1					; pause
M400					; wait for moves to finish
M117 Heating...				; progress indicator message on LCD
M109 R{material_print_temperature_layer_0} ; wait for extruder to reach initial printing temp
M190 R{material_bed_temperature_layer_0} ; wait for bed to reach printing temp
G1 Z2 E0 F75				; prime tiny bit of filment into the nozzle
M117 Mini 2 Printing...		; progress indicator message on LCD

You should substitute temperatures for the variables that are unknown in Ultimaker Cura. I believe those are {material_probe_temperature}, {material_soften_temperature}, and {material_wipe_temperature}. Easy to tell by looking at the output gcode.

See http://files.fieldofview.com/cura/Replacement_Patterns.html for the list of variables Ultimaker Cura does support.

Failure of the G29 is probably still due to a dirty nozzle. Since {material_wipe_temperature} is undefined, the wipe sequence probably isn’t doing its job.

While CuraLE isn’t usable for you, you may be able to look at the installed files for the values to use for the undefined variables. On the Windows install, C:\Program Files (x86)\cura-lulzbot 3.6\resources\materials contains XML files for each of the materials CuraLE supports. For example, ABS_(Chroma_Strand).xml.fdm_material contains:

    <setting key="print temperature">240</setting>
    <setting key="heated bed temperature">110</setting>
    <setting key="standby temperature">175</setting>
    <setting key="soften temperature">170</setting>
    <setting key="probe temperature">170</setting>
    <setting key="wipe temperature">170</setting>
    <setting key="part removal temperature">60</setting>

Material XML’s are at: /usr/share/cura-lulzbot
(On the rare chance a linux user shows up and wonders where these files are…)

Still seeing the printer kill during G29 with temps added, but less often. Also, sometimes it happens on the 2nd, 3rd, or 4th pads. It’s progress. And yes, all pads are clean and the nozzle has been scrubbed several times. I replaced the factory nozzle some time ago. Granted, I bought a 10-pack off Amazon, so I won’t claim they’re high quality. Didn’t make an appreciable difference in the kill behavior, though.