I was having problems with the print becoming “squished”. It resulted in a part (say) 10mm high ending up (say) 8mm high with one or more layers being chewed up by the nozzle because the Z-axis wasn’t moving up the correct distance between layers. The fault was intermittent and seemed to occur about 40% of the time I ran the printer. After trying all sorts of software fixes (none of which worked), greasing the threaded Z-axis rods (lithium grease) and cleaning the smooth rods with IPA, the problem remained. However, I think I have finally found the problem. I carefully removed the plugs that go into the base of the two Z-axis stepping motors and cleaned them (these white plugs simply pull out). I then repeated the cleaning operation on the black z-axis plugs that go onto the Rambo control board. (You’ll have to open up the case).Fortunately the cables are labeled. (Note to remove the two black Z-axis plugs on the Rambo board you have to depress a tab under the plug (you can’t see it easily, but you can feel it). Don’t just keep pulling at the plug, and certainly do NOT pull the wires entering the plug). Work slowly and carefully. Cleaning method: Add a few drops of 91% IPA to the pins in the socket, and a few drops into the holes in the plug. Wait 10 - 20 seconds and blow away any remaining liquid with compressed air. Repeat. Carefully replace the plug in the correct socket. Be gentle and don’t force the plug or you might bend a pin which could mean a new Rambo board! The plugs go in very easily.
So far this seems to have resolved the problem.
Here is a" before and after" photo of part of a key holder:
At first I thought this “Squishing problem” was related to the way the printing head retracted after the print had finished (in multiple vertical steps, rather than one continuous action), but it doesn’t seem to be. For more details on this see my posting of about a week ago.