Possible bed-levelling issue?

General LulzBot Mini
1

So I think I have a bed leveling issue. I printed out the first layer of 50 of a small part I’ve designed and inspected the results. There were significant gaps on the right and more solid layers on the left.

I’m printing the first layer 10% thinner than the default layer height (0.18 mm) and setting the flow rate to 115% for the initial layer as well as increasing the temperature from 205 to 210 deg C.

The goal, of course, is to get a smooth bottom, but now I’m more interested in just getting a consistent print. I clean my nozzle and level the x-axis before every print.

The printer, by the way, is a Lulzbot Mini 2

IMG_1308
IMG_13084032×3024 2.19 MB

2

Classic mini 2 print! :wink: The mini 2 is designed so that the left side of the X gantry carries a lot more weight than the right side: not one but two large (and tightly-routed) cable chains, along with a parked extruder. As a result, any time that the stepper motors are turned off, or even just when the necessary holding torque is overcome, the left side of the gantry will tend to sag. The end result is the nozzle will be closest to the bed on the left side, and will get increasingly further away as you move to the right. The solution is levelling the x gantry, which is accessible from the LCD menu if you’re running stock firmware. The G-code looks something like this:

G28; Home Axis G0 X160 F9999 ;move toolhead to right
G0 Z5 F6000 ; Move to bottom of printer
G91         ; Set relative motion mode
M211 S0	; Turn off soft endstops
M400 ; Finish moves
M906 Z600 ; Lower current to 600mA
G0 Z-15 F500 ; Skip steppers against lower Z mounts
G90 ; Return to absolute mode
M400 ; Finish moves
M906 Z960 ; Restore default current
M211 S1	; Turn soft endstops back on
M400 ; Finish moves
G28 ; Rehome
M117 X-Axis Leveled

Sadly, my Mini 2 has to have the x axis automatically leveled before every print. Other people are able to get away with doing it periodically.

3

I level the X-axis before every print…

I’m going to guess that the problem is I’m printing 50 small pieces at 10 mm/s and it throws itself out of level as it goes. Seems the only reasonable explanation, unless there’s another potential cause.