Mini 2 with magnetic bed not wiping

I’ve had the magnetic bed for some time now, but recently I’m getting a lot of probing/leveling failures when starting prints and I just noticed that the nozzle is not actually making contact with the wipe pad. I’m wondering if the z-height adjustment for the bed caused this. Does this sound normal, and does it sound like something that I can fix while keeping the bed height position the same?

Try adding M400 after this command in the start gcode:

G0 Z5 F6000; Move to bottom of printer

I’ve noticed the printer never makes it to Z5 sometimes before it starts G12. Probably won’t make a difference.

On the mini2, the initial z height is measured from the top of the Z axis and measuring down from there. Until it’s measured the washers, that is how it calculates its Z height. What does the screen read for the Z when the wiping is attempted? Since some versions of Cura do the wipe entirely with GCODE movements instead of issuing a wipe command, it’s possible that the Z got changed in your startup GCODE.

Beyond that, is something causing it to mis-read where the top is? i.e. gantry not level, a physical obstruction, failing Z max limit switch?

It could also be a loose set screw on the Z so the movement down is missing some part of the rotation, causing some extreme backlash in Z movement.

Or, perhaps your Z steps/mm got changed (should be 100 steps/mm).

I believe the screen doesn’t get updated once G12 is sent, and will instead display the last Z height which should be Z5 according to the standard start gcode.

It may not be using a G12 for the wipe, depending on the Cura version, so it may give proper Z height on the screen.

It’s at least worth a try. If it’s reading Z10 when it’s wiping, we know something’s off.

While G12 makes wiping the nozzle a firmware function, I don’t think it is “better” than the old method of embedding the wiping commands in the start gcode. I’ve removed the G12 from my TAZ 6 start gcode and replaced it with the original wiping commands.

In theory, G12 is a better option, since a failed probe initiates the G12 wipe macro.

If you set a good G12 wipe procedure in the firmware, it will always be used if an error requests a nozzle wipe - such as probe failure. If your G12 is a quick back and forth instead (I believe earlier Marlin only allowed a simple line instead of programmed zigzag or other pattern) then an error is going to get a “bad” wipe instead of the good one you have that only exists as startup GCODE.

It’s one of the firmware/CuraLE incompatibilities that pops up, when newer startup GCODE just includes G12 and the old 1.x firmware translates that to a simple line that may or may not be in the right place, based on your toolhead.

Who is the “you” in this statement?

Not all users compile their own firmware. The G12 default for my TAZ 6 was nothing more than a back and forth on the Y axis and even worse, G12 P1 (zigzag pattern) was exactly the same because the firmware didn’t define the parameters to allow anything but a straight line.

The “you” is definitely who writes the firmware, which should be LulzBot. Just like most people don’t change their startup GCODE, when you pay premium prices for a printer, it should absolutely work with its own software without intervention so long as you’re not modding things.

LulzBot definitely isn’t the only one to blame. I recently got a Stacker S4, which dwarfs the Taz in price, but out of the box, Stacker’s special version of Repetier-host (Stacker Run), it doesn’t even put temperatures in the gcode. At all. If you dropped a test file into the software, told it to slice and send to the printer, you’d get nothing. Even the bed size was set up so if you had more than one extruder connected it would ram them into the frame.
This is what they give you for over $13,000:

Missing a

M190 S{BED}
M109 S{TEMP0}

in there.

And no, it’s not like PrusaSlicer where it will add temp codes if they’re not part of your startup.

Anyway, these are the things that are minor hiccups for the experienced, but are the reason that I couldn’t recommend a LulzBot to a new user. For somebody who knows how to work a machine though? Lulzbot are solid. My Mini2 has been printing virtually non-stop for over two months now. It’s set to clear parts with the toolhead into a bin underneath, and I just have to put a new spool on every 80 hours or so.

1 Like