I actually have an update: I printed 3 (Three) wooden objects without any problems now.
The trick in the end was to set the speed even higher.
I now have:
First layer: 20mm/sec (I think you might need to raise this for larger objects when the first layer takes very long)
Layer 0.2mm
Outer shell layer: 50mm/sec
Rest: 80mm/sec
Retraction: 5.5mm @ 40mm/sec
Layer 0.15mm
Outer shell layer: 50mm/sec
Rest: 100mm/sec
Retraction: 5.5mm @ 40mm/sec
For the rest of the settings I used the standard Cura Normal Print settings.
I noticed that even though I set 80 as overall printing speed and set the others to 0, that top and bottom still had variable speed. When I set the speed on 80 manually (so not on 0) it seems better and less risk of getting stuck at the final layers.
I tried the outer shell @ 80mm/sec but that gave a very ugly result.
Another trick I learned: In cura, you can add a second Ultimaker to your machines, but in stead of ultigcode you choose the Reprap / m… something. This gives you more options in the gcode, like printing temperatures, retract settings etc., so you don’t have to set them manually on the printer. I added a line to the starting gcode to make sure 30mm of material is extruded though, since in the default settings there is NO extrusion at the beginning. I’ll upload my profile later, so you can simply open it in Cura after adding and selecting the UM2 with different gcode setting.
