Probe Failure with Mini 2

All of a sudden, my Mini 2 is sticking me with a probing failure every time I try to print. It seems like it might be an issue of the X axis not being level (see photo), but I cannot adjust it through automatic leveling procedures available via the LCD. I am at my wit’s end with this. I have scoured the Internet far and wide and tried many suggested solutions including but not limited to cleaning the washers and nozzle, replacing the wiper pad, taking apart the tool head to make sure nothing is stuck, etc. I even took the cover off the control box to check wiring and nothing looked off, but I’m not an electrical engineer.
I am attaching photos showing the errors I get on the LCD and on Cura as well as the video of what happens when I try to start a print. Can anybody help, please?

Level:


Cura Error (sorry for screen photo):

LCD Error:

Video: Lulzbot Mini 2 Probe/Bed Leveling Error - YouTube

On my Mini 2 at work, I have put G34 after the G28 homing and before the wipe command in the startup GCODE. It counters the sagging of the right side that happens when the steppers aren’t powered.

But the video looks like you’ve got a massive Z offset being set somewhere.

What is the z offset set on the machine?
Is there one set in your slicer?
What does M503 report when sent via the console? M206 can screw up offsets too.

Thank you so much for your help and clarifying questions. I did notice that the z offset looked worse than usual, but wasn’t sure how that could suddenly be so. I’ll do my best to clarify:

What I get when I send M206:
M206
What I get when I send M503:

There’s a lot going on here and I’m not sure what to look for exactly.

The Z offset was set to -1.20. I changed it to -1.10 but can’t tell if anything really changed.

I’m not sure how to tell if there is one west in my slicer; I tried searching “offset” in CuraLE but couldn’t find an option for it.

I’ll try adding G34 to the startup GCODE in the future. Thanks for the tip.

Everything in there seems to be in order.

I watched the video a bit closer, and at 12s in, it’s obvious your gantry is not moving in sync. The right side lifts significantly before the left side starts lifting. It seems to stay out of alignment when it lifts to the top as well. With the gantry that out of alignment, it could be jamming or at least slowing things down enough that it’s not going all the way down.

When it does the mechanical alignment at the bottom, the left side looks like it’s stopping too soon.

Thank you so much for your help.

I’ve observed what you’ve identified, but I’m not sure whether this is something I can fix myself or would need to send it in for. I’ve done mechanical fixes for this machine and my Workhorse before, but those were mostly involving the tool head; nothing like the gantry. Any advice on how to fix this or keep this from happening in the future?

You might take a look at the OHAI for the Mini 2.

A loose belt, or maybe the z brake board are the only likely things I can think would cause the problem. Maybe an out of square frame, to but that’s very unlikely with a mini. Also check for loose screws that would allow enough play in the frame to let it sag.

I have, and I appreciate the link, but I can’t find any guides that mention the gantry except instructions for the TAZ. I’ll look around the pages for the mini, though.

I’ve checked for loose screws but will check again. I’m going to see if I can realign the gantry manually as described here: https://all3dp.com/2/3d-printer-gantry-simply-explained/
I’m not sure what I’d do to fix a loose belt or z brake board, though. I’ll keep researching. Thank you for your help!

One problem I see is that the Igus bearing on the right rear Z axis rod is out the bottom of the right X end piece a bit. It needs to be pushed back up to the top. Then there are two screws you can tighten a bit to clamp it better.

Check the Z belt tensions - since you don’t have a tool for this, I’d just say push on them sideways and feel the tension, and if they feel similar one has probably not slipped and they are OK.

You want to get rid of how the right side goes up before the left after it hits the bottom. Look for anything that is obstructing the movement on the left side. One thing that sometimes causes this is the cable chain hitting the wires at the bottom or the plastic guard piece around the hole where the wires come out at the bottom left. Another thing is having the two screws that clamp the left side bearing too tight, so there is too much drag on the left side.

The Z brake board isn’t the problem. If it wasn’t working you would have much worse movement issues.

I don’t know if the G34 even works on the Mini 2. Try homing the printer with the GLCD menu, then run the “Auto Z-Align” or “Level X-axis” from the move menu. Those are the same leveling function, just named differently depending on what firmware you have. Then start your print.

Thank you so much for your help. I only just got around to looking more into this (I am a computer science/design teacher and this is just one of many responsibilities!) so I just fixed the Igus bearing on the back right (good catch; thanks).

I looked into what might be obstructing movement, but I can’t seem to do much to move the wires/plastic guard at the bottom left, and when I hold them so they’re definitely not hitting the cable chain, the problem still persists. The right side is still going up before the left after hitting the bottom, and probing still fails. I also checked the left bearing screws and loosening them a bit did not help. Is there anything else I could look at to see what is causing the problem? Thanks.

I guess what I would do is unplug the Z motors so you can move the Z axis up and down by hand, and I would push it up and down and feel how much force it takes. If it gets tighter at the bottom or top that means the X axis rods and X end pieces aren’t aligned with the Z rods properly. To fix this, you have to take all the tesion off the X belt so it literally hangs loose, then push the Z axis it all the way down to the bottom on both sides, then loosen the set screws in the back of the right X end piece that hold the two X axis rods so that the rods can be moved in and out of the X ends.

Often when you loosen the X rod set screws with the Z pushed to the bottom, you will see that it releases tension and the X ends move a bit. This happens when the tension on the X belt pulls the X ends inward a bit because the set screws aren’t tight, so the rods don’t hold them outward in alignment.

It is critcal that he X belt be completely loose, if it is not, it will do the opposite of what we want and will pull the X ends inward instead of letting them find their natural position.

After they realign, you need to lightly push the X rods toward the left X end to make sure they are seated all the way down in the holes on the left side. Then tighten the two set screws to make sure everything is locked in position, then re-tension the X belt. Then it should be able to go all the way up and down without binding up at the top or bottom.

One issue with this process is that the tension adjustment screws for the X belt tensioner on the back of the X carriage often don’t have enough length to loosen the X belt all the way to hanging loose and they will come out of the tensioner block. If this happens it can be quite difficult to get them back into the nuts inside the tensioner block.

This is a more advanced process than is usually done by an end user, so please think about if it sounds like something you feel comfortable attempting.

Mine is doing the same thing. How did you fix yours?