Tips on prints that fit together

A consistent problem I’ve had with my Lulzbot Mini is printing objects that are supposed to fit together. These are usually designs created by someone else, so I know they are being designed for different slicers and printers.

Does anyone have any tips on how to achieve better prints that will actually fit together like they should? I use Cura for slicing and printing. What settings should I be adjusting? Is there some component of the actual hardware I should be adjusting? I’m sure there are ways to improve my results but I’m just not sure what they are, so any suggestions are appreciated.

You could change the X and Y steps to 100 instead of the 100.5, slightly lower extrusion multiplier, verify e-steps are accurate, slightly raise z-height so the fist few layers arent smooshed

Thanks, I will definitely try this. I’ve also had some issues with fitting beyond just the bottom layers.

Another thing you can try if you are using Cura 3.2.21 is a setting under the Shell section of the Custom settings. The Outer Before Inner Walls option will help you get a more precise outer wall, which will help these parts fit together, especially on the lower layers.

There is also the “horizontal expansion” setting under the Custom shell selections. That changes the X/Y to increase/decrease gaps between external parts walls (Think print-in place joint fit.)

  • = tighter/- = looser fit

I too am having trouble with my Lulzbot Mini. It used to print mechanical parts that had 0.5 mm clearance just fine, but now those prints don’t fit together. I don’t know the answer, but the Slic3r page on dimensional errors has given me a few good hints:

I noticed on my latest prints that the inner walls of objects seem wobbly - so I’m looking at a few things: belt tension, bed auto-leveling (that’s another story), and extruder idler screws’ tension. I’ve recently found the extruder idler screws’ tension can make surprising difference in the quality of the print.

Update September 10: I seem to have fixed the problem (or at least a significant part of it). First, my right X carriage height was about 1/8" lower than the left, so I turned off the printer and manually turned the right screw until the two X carriage mounts were at the same height from the top of the printer. Then I found that Slic3r page on dimensional errors, and it got me thinking about the ripples I’d seen sometimes in the first layer. I then adjusted the extruder idler tension, the ripples disappeared, and now the printer prints parts that fit together fine!

My complete notes on adjusting the extruder idler tension on my Lulzbot Mini are at

Update: see my notes on how, on the Lulzbot Mini, the nozzle missing the wiping area can be caused by Y scale problems:

In short, since version 1.0.4 of the Mini, the nozzle wiping is a Y dimensional accuracy test. If your nozzle hits the back or front of the wiping area while wiping, it suggests a Y scale problem.