LulzBot TAZ Pro Auto-Leveling Issue - Seeking Urgent Help

Hello All,

I hope this message finds you well. I’m back with an issue that has been giving me quite a headache. My LulzBot TAZ Pro is still experiencing an auto-leveling failure, and I’m in desperate need of assistance.

Despite my previous attempts, the problem persists, and I’m stumped about what to do next. Tech support over at LulzBot has suggested sending in the printer for repairs, but the thought of shelling out $700 in repair costs is a tough pill to swallow.

I’ve tried cleaning the nozzle and ensuring the washers are in place tightly, but the issue lingers. If anyone has encountered and successfully resolved an auto-leveling failure on their TAZ Pro or has any insights into potential solutions, I would greatly appreciate your guidance.

I’ve followed various troubleshooting steps, but it seems like I’m missing something, and the problem just won’t go away. Please share your experience and advice on how to troubleshoot and rectify this issue, especially if there are more cost-effective alternatives to sending it in for repairs.

Thanks in advance for your assistance.

Best thing to help us help you is to post a video to youtube of the entire homing and leveling process.

Also, a good close-up picture of the printer’s nozzle to help judge how “clean” it is.

But a few quick questions:

Does it complete the attempt to level using the washers, or quit halfway through?

When it hits the washers, is there any visible deflection of the bed at any of them?

If it does complete the leveling, how does your first layer look? (pictures!)

What are the symptoms you’re seeing of the bad bed leveling?

What firmware are you using? What version of Cura LE are you using?

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Will post pics.

It is the latest software and firmware.

It makes contact with the first washer and then go into a loop (rewiping both nozzles and then auto level 3x before failure)

what do you mean by deflection?

Video link here:

There’s some definite deflection - the nozzle is pushing the entire bed down in an attempt to get a reading. It doesn’t read a connection before it hits the limit of how far it will go. Goes into zero failure state, which re-homes the Z axis, cleans the nozzle and tries again. Upon consecutive failure to get a reading it errors out.

So, there’s a break in the probing loop.

The nozzle isn’t exactly clean, but it should give a (bad) reading even with some plastic on it. You’ll still want to eliminate the nozzle as a failure point and get a short length of wire. Get a length of wire, about 300mm or so. Connect one end to the zero sense ground wire on the toolhead - the red wire here:

Once the toolhead starts to lower over the first washer, touch the other end of the wire to the washer. It will do one of these things:

A) Stop moving down, lift up and start moving down again (in which case, touch the washer with the wire again - it should then try to probe the next washer).
B) Immediately error out without contacting the washer (because it thinks it touched too high). It might re-home the Z if this happens.
C) Continue moving, hitting the washer, and doing exactly as it was before you tried using the wire.

If A or B, your nozzle to ground wire connection is failing, clean the heck out of the nozzle and make sure that zero ground wire is well-connected to the radiator. Check for break in that wire where it connects to the radiator too.

If C, your test wire isn’t making good connection, or you have a break in one of your zero ground wire. Usually in the harness that connects to the toolhead. If you have a multimeter, you can connect to the red ground wire at the toolhead and check for continuity working your way back to the motherboard. If there’s continuity the whole way, check from the washer back to the motherboard.

Question: how do you typically do a cleaning of the nozzle???

Heat to about 20c under normal melt temp, then shut off the machine. Pull off as much as possible with tweezers, picks, and such. Turn on and warm back up. Shut off and scrub with brass bristle brush.

Key thing is you don’t want to accidentally have one of those brass bristles, tweezers, or picks short the heater wires while there’s power applied. You want below melting temp so the plastic still is gooey, not runny. It sticks together better so it’s easier to clean. Turning it too hot and you’ll start breaking it down and carbonizing the plastic , making it harder to remove.

Excellent advice. I got it to work!!

Seems there was some rust on thre screw connecting to the red wire. See picture.

I cleaned it and now it’s working!! However now it’s convince my boss that my Makerspace should not be located in a high humidity environment. Possibly get a climate controlled system installed.

Darn it. It’s started to do the bed fail again.

Something else to try, if you haven’t, is replacing the wiper pads. They don’t have to look particularly dirty to leave residue on the nozzle. One test you can make to see if the issue is the wiper pad is to remove the wiper pad and test it after cleaning by hand. You can go through the whole deep cleaning process, but I usually just heat up the nozzle, retract the filament, and wipe it with a red scotch-brite pad (like the one included with my printer). If you run through the process with a clean nozzle and no wiper without issue, you will know where the problem lie.

Already did that. Issue is still present. It was a fluke that it worked when I loosen/together the red wire. It printed a great test print. But now the issue has returned.

There could be an internal break in your wire that had a temporary connection after you messed with it, but then standard movement of the head stretched the wire again, causing a separation.