Lulzbot Mini ABS adhesion compared


We are operating 4 printers remotely using Octoprint with exactly the same setup:

  • same machine (Lulzbot-Mini)
  • same model and gcode generated by Cura (same bed temperature, head temperature)
  • no Octoprint configuration
  • same filament ( from eSun that is working really well with the printer and has reduced warping
  • same room and temperature
  • same bed with PEI sheet
  • same color

We have 2 printers where model is sticking too much to the bed, one that is perfect and one that is sticking slightly not enough. PEI sheets are changed regularly and rolls also (same color). However, prints are still sticking too much to the same printer. For this reason, it is unlikely that PEI sheet or filament is the culprit.

We have tried glue, alcohol on the print bed to slightly influence adhesion but with limited result. Right now we increase bed temperature up to 80C to be able to remove the part. However, this still does not explain why we have such a difference we other printers.

Something to notice is that the parts that are sticking too much to the bed are slightly whiter that other parts. We can remove those spots with a torch. First, I thought these white spots were caused to humidity in the filament. However, it is not the case as we can switch filament from one printer to another and the whiter color is caused by the printer.

I think this comparison is really interesting as we have a very similar setup, filament and printed part.

Do you have any clue what I should investigate to have a similar adhesion behavior on each printer?

Probably just ending up closer to the bed on that one printer. A small adjustment to z-offset in firmware settings is probably the best fix.

On the printer where you are getting “too much stick”, send a “M851” command. It will respond with the current z-offset stored in firmware (will be a negative number; I believe the default is -1.43).

Whatever number you get, add +0.1 to it (i.e., making the absolute value smaller, so if it was -1.43 then you now have -1.33).

Next, use the M851 command to set that value in the firmware. For example, “M851 Z-1.33”. Follow that with a M500 command to store the value (if you don’t use M500, the value will be lost at the next printer reset).

Now try your print again, and repeat the process if needed. As long as you are getting good fill on the bottom layer, you can reduce this value further until adhesion is reduced to the desired amount.

Hello Scott,

I am going to test. Right now, I am unclogging an hot end :cry:

However, I am pretty sure you’ve got the solution. I will let you know. Thanks.

Hello Scott,

I can confirm this work perfectly! Thank you.

Great! Out of curiosity, how much did you need to change the offset to get good results?

Sorry for the late reply.

I’ve got -1.10, -1.10, -1.37 and -1.5 for the 4 machines.

However, I am going to adjust a little bit the one with -1.10 offset since I see stripes on the face that sticks to the bed and a really slight warping.

Calibration must be done each time the PEI sheet is changed.