Some of the parts on the printer are showing their old age and may reduce the quality. These are cheap parts to replace:
1. linear shaft 0.8mm
2. polymere bearer
3. gear belt
4. Z-axis stop
maybe more parts to come..
Resolving the leveling issue:
1. Z-axis stop
The z-axis stop is now a normal switch. It seems not to respond as expected. Therefor I will replace it with an optical stop which should be more precise.
2. In my case when the hot end pushes on the glas the horizontal shaft and bed bend a little. I'm not sure if it bends back exactly the way it was. Also it seems that the whole extruder is leaning forward a bit which could imbalance the printer. For this i want to change the horizontal x - ax shaft. See pic 1 and 2 (pic 1 is the way i want it, pic 2 is the way i have it)
Even if everything is in balance I know humans can't level 100% correct, although the paper method works quit well... For that autoleveling can be installed. This only needs a proximity sensor (4$ on ali) and a nice way to attach it to the extruder.
When al this is done I am considering installing the bowen construction. This will increase the quality of the print but not all materials are supported. Since i mostly print with PLA and ABS that may not be a problem for me.
Carriage facing down
Maybe usefull upgrades
Maybe this is a useful upgrade for your printer as well. https://www.thingiverse.com/thing:547706. There is a funnel part in there for cooling fans mounted to the extruder to improve print quality. This video shows the thing in action, though I think this guy is putting the temperature way too high :)
I did a test with a loose fan that I put next one side of my printer and printed a small object with thin walls. The side where the fan was blowing was printed in much better quality. Need to see now if I can make this work on my uDelta printer...