lulzbot mini smashing the sensor washers, again.

The same thing that happened to my first printer is starting with my second. My first printer had many successful prints using PLA until it eventually started smashing the sensor pads and grinding the motor. Eventually the printer got worse and worse getting more and more problems.

Fast forward a year or so and I decided to get another lulzbot mini. I used PLA again and everything was going great. I decided to try nylon and got 1 good print out of it before it started smashing the sensor washers and grinding the motors. Is there any way to fix this or do I need to send it in for maintenance?

Have you attempted to clean the tip of the nozzle? This problem is usually due to a dirty nozzle or corner washer. Wiring issues could come in to play but if this started following a nylon print, I would suspect a dirty nozzle tip.

You would be correct. My main problem was how do I get the gunk off without messing it up. The first printer I had I used a wire brush and messed it up bad. This time I shut the power off and disconnected it. Then I hit it up with some alcohol and fine grit sandpaper. Worked like a charm. Thanks for the idea.

Great! Green or blue Scotchbrite usually does the job for me. It is non-conductive and can be used while the nozzle heater is on.

update: I can get 1 out of 5 prints to work. Sometimes it smashes the first sensor, sometimes others. I clean it as good as I can and it seems to still be doing it. Maybe higher grit sand paper? New print head?

What is the condition of the wiper pad? What temps are you wiping and probing at? What plastic are you attempting to print when it fails?

Are the corner washer screws tight? Try backing them out a little and retighten.

You might want to check the black ground wire that attaches to the underside of the bed plate. It allows the electrical connection to be made between the nozzle and the auto level washers during the leveling routine. I had those go bad on 2 Minis. The crimp connector will sometimes loosen over time making an intermittent connection. I just soldered the wire in the crimp connector and it fixed the leveling problems on both Minis.

I purchase my Mini used and not working. I repaired a broken wire and got it working but then the nozzle would hit the washers ver hard. After a while I realized that the nozzle was loose and gradually unscrewing. I tightened it when it was hot and that solved my problem. Sometimes I get buildup on the nozzle which I have to clean off but I have found that when the nozzle homes in on the second washer I usually here 3 faint ticks, if I hear more, I abort the print and clean the nozzle. I usually find that there is a buildup of plastic on the far side that I can’t see easily.

I put some words about my similar problem and what worked for me on this thread:

I hope it helps