Bed Leveling and Z Height Problem

I’ve had my mini for a few months now and everything was going great. All of a sudden, the bed leveling had made my z-offset too high and the first layer wasn’t adhering.

I should mention, that I’ve scrubbed the nozzle clean and cleaned the washers (and replaced the cleaning pad). When the leveling was working correctly, it would deflect the washers a little during the leveling process, and it isn’t doing that now.

I’ve sorted the first layer issue by changing my z-offset in cura to -1.1, but I’m wondering if there is a better long term solution to this problem in case I use a different computer to control it. Is there a mechanical adjustment I can do on the machine to fix the offset issue?

The deflecting the washers seems odd. If you have set the z offset and used the other M code command to save it to the firmware then that setting should stay with your printer even if you switch to another computer.

Have you double checked to see if your x-axis is perfectly level? On one print i had my machine mysteriously only turned one z-axis screw for a few seconds and it totally screwed up my x-axis level. So i had to manually turn one of my screws (while the machine was off) to relevel my x-axis.

I haven’t tried any mechanical changes to the machine. Not exactly sure how to check that it is level, but I’ll go through and make sure everything is tight.

Strange thing, is that today, that z-offset seems to have changed and it is now too low. There was almost no offset and the filament wouldn’t extrude because it was touching the build plate.

You can change the z-offset by changing what is stored in Mini’s firmware by entering the appropriate g-codes, or changing the setting in Cura -> Machine -> Machine Settings and entering an adjustment in the “Z-Offset (mm)” box. The setting in Cura is not an absolute setting, it modifies what is in the firmware. So if you have -1.35 stored in the Mini, and 0.1 entered in Cura, your resulting z-offset will be -1.35 + 0.1 = -1.25mm.

Since the Cura setting is in the software, and not saved to the Mini, it will not follow you from computer to computer. The value stored in the Mini will be there regardless of what computer you are running Cura on (and subject to modification from whatever Z-offset adjustment is entered in that copy of Cura).

Here’s a link to a thread with directions on the g-codes needed to reset the z-offset stored in the Mini.

One note (which I discovered the hard way) is that updating the your firmware will mean you have to re-enter your z-offset setting.

+1 Yes, follow the above link to directions on how to change your z-offset AND keep those changes in your firmware for the next time you print. It sounds like you are having the same problem that i was having a while back. Mine was also too close. Changing the z-offset to not too close and not too far away made a big difference for me.

Also double check your belts to make sure they are tight.

Find a bubble level like one might find in a garage toolbox and place it on top of you x-carriage. You would want to know if your table is level before doing this just in case your table is not level as not to throw your readings off. But a crooked table in and of itself should cause no problems. But a wonky level machine might. But i doubt that is your problem, just thought it was worth a look.

Thats terrible advice. You level the x carriage to the aluminum bed plate by measuring. Not using a level. Measure the distance to the smooth rod on one side then check the other side. if its off you can manually turn the coupler while motors are off and get them to be same on each side

I use a digital level to check that the frame, bed and gantry are level…

Well perhaps not the best advice, sure, but to say that it is terrible advice is not very nice. I actually do both, i was just in a rush so i forgot to mention that. But that particular advice was meant more for this statement made by the OP:

I should mention, that I’ve scrubbed the nozzle clean and cleaned the washers (and replaced the cleaning pad). When the leveling was working correctly, it would deflect the washers a little during the leveling process

But to fair there are calibration spacers and jigs that lulzbot uses that probably would be useful. I just haven’t gotten them printed myself just yet. But he’s right, you should adjust each z screw to the same height on both sides and that should have your x-carriage level, but double check with a level if you so wish.

This looks like the z leveling spacer lulzbot uses. No STL file apparently, so open in FreeCAD and then export into STL.
https://download.lulzbot.com/Mini/1.03/jigs/z-low3r_spacer_v0.1.fcstd

and although these files are probably not helpful to your current problem you may be interested to know that they exist:
https://download.lulzbot.com/Mini/1.03/production_parts/assy_jigs/3.3mm_x_motor_spacer.stl
https://download.lulzbot.com/Mini/1.03/production_parts/assy_jigs/y-motor_pulley_spacer_7mm_0.1.stl

and i have printed this one, and i like it as a test piece.
https://download.lulzbot.com/Mini/1.03/novelties/make_test_parts/dimensional_accuracy_test.stl