Lulzbot Mini - Did I get a lemon

So I’m on my third or fourth non-octopus print, and 80% of the way through a 7-hour print it goes haywire, and starts laying filament all over the place. I cancel and restart everything, and when it goes to clean the print head it drops down on the cleaning pad, and just wiggles in one spot. It then acts like it’s going to do the bed leveling process, but moves VERY slowly side to side, and ends up above the BED, well short of the front left corner disk.

Because of this, it starts traveling down to find the conductive surface but since it never finds the disk, it hits the bed and begins pressing into it - so I immediately stopped it all before it damages anything else.

It appears to me that the product no longer moves freely from side to side…shouldn’t I get more than 3 or 4 prints out of a machine before it needs service? I am thinking that I need it to be serviced, but should I just return it for a refund? I will confess that I am not interested in the internal workings of the product – I bought this specific model because it was supposed to be easy to use so I wouldn’t have to be rebuilding it constantly. If this product isn’t consumer ready and is more about people who want to fiddle and hack their printers, then I was told the wrong things and need to get something else.

Sounds like your belt pulley is loose on the X motor. Check the 2 small set screws, they sometimes work loose in shipping or after a few initial prints. 3d printing involves some small knowledge of the machine, just like operating a clothes washer requires knowledge, or bike ownership requires familiarity with basic maintenance tasks. The Mini is one of the most reliable and maintenance free printers out there, but all printers require a small amount of maintenance and troubleshooting from time to time. It is the nature of the hobby. Lulzbot has a very good and thurough tech support department, and there are plenty of people in certain forums such as this to help set issues right.

Is there a video or other resources to show me how to do it?

My related concern is that there is only a 30 day window for me to return this and get a competitor’s model. If this is something that does end up occurring every 4 prints or so that means I could potentially be wasting 20-25% of my prints, and when prints take hours that’s also a lot of wasted time.

No problem with some routine maintenance, but not that frequently. (Edit) noticed two recent reviews have had this problem as well…perhaps the quality they have been known for is slipping?

It does not happen frequently. I have hundreds of prints on my Mini. Cleaning off the nozzle is the extent of the maintenance at this point.

There are small set screws on the belt pulleys. Follow the belt to the pulley, rotate the pulley until you see the set screw. Make sure one of the set screws is over the flat on the motor shaft and tighten them both against the motor shaft.

I envy your experience. When I get home tonight I will see if I can figure out how to do what you say - as noted, my intent was to get a 3D Printer that doesn’t require a lot of fiddling (which so far is not MY experience), but maybe such a 3D Printer doesn’t exist yet…find myself wondering if the Makerbots are more consumer oriented.

So assuming that I do try to repair this, here are my concerns:

  1. When I attempted the print after the failure, during the leveling process it brought the head down ATTEMPTING to find the disks in the corners, but it wasn’t in the right place, and so before I could cancel and stop the motors, it was pressing…HARD…on the bed. What are the risks that this has damaged/shifted the bed in an excessive way? What are the risks that the motors have now suffered excessive wear from this resistance? Same question for other parts? Basically, has this failure mode now either added new issues, or shortened the life of my product? (Asking as someone who had a car with a transmission fluid leak out in the third month, which then had a complete transmission failure just outside of warranty)

  2. How does the Mini “know” or “remember” where the head is located? Right now it THINKS that it’s positioned over the corner disk…when/if I can resolve the pulley issue, will I still be hosed because it has no idea where it is, and no way of re-learning its position?

  3. Since lots of people who are not me seem to think these things are reliable, I am worried that while it may not be a DESIGN issue, my product seems to have a BUILD issue, and I’m wondering how many other pieces were not fully seated/secured when it was sent…I don’t want to get into a long process that ends with me unable to actually return the machine when I realize that this one is no good.

It’s the 1st two that have me thinking of having this serviced/replaced or returned.


  1. If the glass did not crack, and if the PEI layer is intact, chances are that your alignment is still the same as it was. You can verify this with a set of calipers, a bubble level and or a dial indicator gauge. If you cracked the glasss it would be highly visible. There is zero chance you damaged the motors. They can take a lot more force and punishment than that print head can dish out. Same with the other parts.

  2. Head position is based off of distance from the limit switches. When you turn on the printer and connect it, the printer usually homes its axis before it prints. It uses that position with the values embedded in the firmware to tell the motors “0,0,0 is here, you can go 200mm that way until you run out of room, etc.” Every time you re-home the machine it re-registers that position.

  3. All filament 3d printers on the market share common mechanical and controller aspects. Anything with a belt and pulley system, regardless of manufacture origin is going to have the same potential issues that will occur from time to time. The Mini is one of the more robust and bullet proof designs, but ANY precision instrument that travels long distances in a truck with suspension built by the lowest bidder is going to potentially have issues. It probably was fully seated and secured when it was sent. Any 3d printer you choose is going to potentially have similar issues. Many of them have much worse issues to deal with. If you are unwilling to put in the time and effort to learn your machine and learn how to resolve basic mechanical issues, 3d printing might not be a great hobby for you.

  1. Not sure how I can test the PEI layer for being intact - - just visual inspection? Good to hear about the motors.

  2. I am a bit dense, but I’m interpreting this as “It basically doesn’t matter where it was, it starts fresh each time, so it should be fine” - - let me know if I got that right.

  3. I had hoped my experience would be more like others who had hundreds of prints without issues. The reviews seemed to make it think my experience would be that. But this response does actually make me lean toward just returning the unit and waiting until there are 3D printers that actually don’t require a lot of personal repair tasks. But it also makes me think the right answer is getting Lulzbot to take this back and EXCHANGE it for one that is like the one you have. I don’t have a problem turning a couple of screws, but you’re right in that I’m not that interested in learning how to adjust components - there were much cheaper printers I could have purchased as a KIT, but I went with an assembled product to avoid having to be Mr. Fixit. But point taken…may just have to put my $1350 in the bank for a few years.

Positive note: While I’m not sure how this relates to ever being able to just return it, apparently they want it back for repair…good that they are stepping up. Good sign of a good company.

Again, I don’t have a problem adjusting a few screws, but as someone who does a lot of work with manufacturing, it’s the kind of thing that SOMETIMES indicates a general lack of care on that one day/build/line/worker, so hopefully they can take care of it.

The Mini is a low fiddle printer for sure. If you can’t find anything wrong, contact Lulzbot support. They will make it right. There support for these printers is fantastic. It makes the price worth it.

I like them so much, I have a Taz 5 on the way to keep the modded Taz 2 and Mini company!

In the long term picture of things, loose set screws happen on new or old machines. 3D printing is not plug and play and requires a learning curve and some problem solving skills. But yes, you would expect a new printer out of the box to work. I had a problem with my refurbished Mini when purchased and a lot of it was user error. But the crew stuck with me and its works great now. I think its the best 3D printer on the market today. And this was not my first CNC machine, but first 3D adventure.