Minor issue with leveling

The mini does the leveling probe and seems to work well overall. What I’m seeing looks like the nozzle is too close to the bed, in some areas. Almost like the bed is warped. It’s more noticeable with small layer height. At 0.2mm I can see it if I look for it, at 0.1mm it’s bad enough that I cancel the print. Adjusting the Z offset doesn’t help, if I’m still too close in one area and too far in the other. I tested in Cura, including the beta, and simplify3d. It doesn’t appear to be a slicer issue. I also tried modifying the start script to heat the bed before leveling just to see if perhaps heat expansion was throwing off the probe. No change. I also manually cleaned up the nozzle and washers.

Obviously, 0.1mm is quite small. I only tried it as the designer of a part I wanted to try printing suggested it. But I would like to get higher resolution eventually. I have a 0.3mm nozzle on the way as well. From reading around it seems like the common causes are the bed actually being warped or the rods holding the X axis and extruder are flexing slightly. I thought I’d see if anyone has experienced either on a mini before I get out feeler gauges and such.

It would be helpful to know the distrubution of your height offsets. If you are too close in the middle of the bed and to far away on the edges, it’s most likely due to flexing rods. But as long as you don’t need the complete print bed area and you z-offset is well calibrated, you should be able to print at 0.1mm 1st layer height.
I have this problem on my TAZ 5, which limits the max. area I can use for a 0.1mm print. I would say, it’s very hard to get a perfect 1st layer @ 0.1mm when I need more than ~50% of the bed area. At 0.2mm, the problem is visible but does not lead to a print problem… It should be better on the Mini due to shorter rods.

It’s worst in the middle. At the far left, looking towards the front of the machine, it’s a bit too far. Center is way too close. Right gets better, but I haven’t gone all the way to the edge. Perhaps I should print out a single layer grid at 1cm or so to better visualize it. I don’t suppose someone has an STL for that sitting around? I could probably work something up for it. I also noticed that the front of the plate seems a little bit worse, but I haven’t done any real testing for that yet.

Honestly, 0.2mm is probably what I’ll print most of the time. It would be nice to have 0.1mm for special cases though.

Clean the nozzle manually as well as the touch points… there could be build up of filament causing bad contact.