Mini fails bed level wipe test first button. Rear left

First off, this is not my printer and have very little experience. A shared maker space, but regular repair guy is away for 6 months, so I am trying to get it working. After a web search I found and followed the instructions, and continuity between 4 corner buttons and metal bed plate is good. However, the print head was swapped at some point with an Aerostruder I believe. So the instructions for the nozzle continuity are not the same. Any ideas on next step? Not keen to dismantle the thing, if its not needed.

I noticed you also posted regarding the thermal runaway. Getting both a thermal runaway and bed level failure at the same time suggests the wire harness to the printhead doesn’t have a good connection (it just seems unlikely that two things would randomly fail at the same time … but what they both have in common is the wire harness needs to be securely connected.)

Do you happen to know if the print-head is built by IT-Works 3D? They make parts for LulzBot printers and if this is their toolhead, then possibly you can reach out to them if you have questions about the wiring.

Yep. The thermal runawy problem is on a TAZ6. A different printer. Trying to get them working again. We also have a second MINI that works fine.

This is the TAZ6m Fails thermal runaway.

Is this a Mini 1 or a Mini 2? (The v2 has an LCD display in the upper right corner and uses belt-driven Z-axis. The Mini 1 wont have the LCD display and the Z-axis uses screw-drive.)

LulzBot documents the assembly process at:

The development documentation is located at:

The pic above is a TAZ, related to another issue I posted elsewhere. Our mini has no LCD, and this print head. Need to know how to test continuity from the nozzle, because it fails bed level.

The nozzle is where the filament comes out and testing continuity between the nozzle on this print head should be the same as any other print head. You are checking continuity between the nozzle and the controller board (you can find a diagram / picture on the LulzBot website). If this test fails, you need to check from the board to the pin on the connector at the head (again, diagram / picture on the LulzBot website, and the nozzle to the pin on the connector on the print head (which should match up with the connector from the controller board). If required, fix the connection that fails.

The nozzle needs to be clean for the auto level to work. To clean it, heat it up to the temperature of the filament last used and use a non-conducting pad (scotch brite). If the only thing you have is a (conducting) brass brush, then turn off the power after heating the nozzle and before using the brush.

The four corners also need to be clean. Wiping with an alcohol rag (paper towel, wipe) is usually good enough but a light wipe with the scotch brite pad, brass brush, or a very fine (1000+) sand paper may be needed.

Since your printer does not have an LCD, you have a “Mini 1”.
Your print-head was upgraded to the LulzBot Mini AeroStruder Toolhead (this didn’t come standard with the printer, but is an upgrade part sold by LulzBot for your printer).

IT-Works 3D (the maker of your toolhead) is a LulzBot reseller & service center. They sell upgrades, replacement parts, etc.

The board on the Mini has a section where the “end stop” wires are all connected. There are end-stops for each axis. The Z-min should be wired to the bed and print-head so the circuit is completed when they (the nozzle and bed washer) make contact.

I looked for a schematic but was not able to find one for the Mini 1.

In any case, see this page – specifically Section 5 labeled “Plug in Endstops” which shows the location of all the end-stop cables. The Z-min end-stop is a molex connector with one green wire and one white wire.

Unfortunately I do not know which wire is attached to the bed frame vs. which wire is attached to the print-head. You’ll probably need to trace the wire back to the board (or from the board to the head – either direction) and test that the wire is connected all the way through with no breaks in continuity.

E3D makes the Titan AeroStruder. But the AeroStruder has to be assembled into a toolhead that can mount to the X-axis carriage. LulzBot sources the extruder from E3D ( when they build the toolhead. But you toolhead was built by IT-Works 3D ( – again, also using the very same E3D Titan AeroStruder. All the wiring that controls the heater, thermistor, z-axis minimum probe, fans, and extruder motor … all have to go into a modular connector that matches up with what LulzBot has on the X-axis carriage.

One of the pins on that wiring harness (I’m not sure which) will be wired to the zero-sense wire used by the Z-axis min connector back on your board.

On my printer (a TAZ Workhorse with a Titan Aerostruder toolhead – though not the same as yours) the zero-sense wire used to probe the bed washers is connected to one of the screws that holes the aluminum heat-sink in place. I’m not sure where IT-Works 3D attaches their wire (it would not necessarily have to be in the same place) but you certainly could phone and ask.

There is a Facebook group called “LulzBot Mini & TAZ”. It is a private group so you’ll have to request to be added. Here is the URL:

A lot of folks hang out there – including folks from IT Works 3D (Zach Ruder is from IT Works 3D). You can probably ask for guidance on that group to cast a wider net on solving your issue.

Be safe & stay healthy,

I also have a Lulzbot Mini 1 and have had this issue in the past for me it was the fact the grounding wire had come detached. The single wire on the underside of the print bed on the front left. Check that as well.