I just bought myself an Ultimaker 3 to replace my Prusa MK3. But I have problems with the print quality.
As I'm going to print many mechanical parts for RC cars which require tight tolerances I decided to compare those two printers with the Maker's Muse Tolerance Test.
While the test on the Prusa MK3 (which currently has a slightly broken X-Axis motor mount) with stock profiles (0.2mm layer height) results in all except the 0.15 tolerance to get free (some with a bit of force) but the test on the UM3 shows different results.
First I used the stock profiles that came with Cura 3.6 (0.2 layer height again) and only changed the "Initial Layer Horizontal Expansion" to -0.25 to compensate for an elephant foot. The result was, that only the 0.5 tolerance came free. Even the 0.4 tolerance I couldn't get loose. It only broke by the amount of force I used.
So I turned down the print speed to 35mm/sec. Now I could get all tolerances except 0.2 and 0.15 free.
What can I do to get such good print results to also get the 0.2 tolerance free? I think it might be that the layer seam is the problem or overshooting at corners.
At the moment my Prusa MK3 is giving me better results than the UM3. I'm a little disappointed in the printer right now. Only positive things for me are the camera, WiFi and the Dual Extrusion.
Here is the video from Maker's Muse where he explains the tolerance test