Fixing a badly skewed X-axis  

Fixing a badly skewed X-axis

I have a Mk2s that I upgraded from a Mk1.  After I did the upgrade (which was a complete rebuild), I had some difficulty getting it calibrated, but I was able to eventually get it to work.  Time passes where I am happily and successfully printing a bunch of stuff.

At some point Octoprint added a plugin to visualize mesh bed leveling offsets, and I generated an image.  (I'm not allowed to upload files and I am feeling lazy, so you get a verbal description...)  The X-axis is pretty near zero on the left side, but as we move to the right (coordinate points marked on the print bed get larger) the offset exceeds -2 mm.  But my prints were fine so I said to myself "That bed leveling compensation is pretty impressive!" and "Meh, I should fix that, that's terrible."  But I am lazy and so I didn't.  My prints were working beautifully.

And then (duh duh DUH!!!) I printed (or rather, tried to) print some taller items.  The all kept failing a few inches above the print bed. I tightened my belts and screws and that helped a bit, but I still ket getting weird artifacts and constant failures.  So I got serious about trying to fix the X-axis skew.

I tried the things I find suggestions for online.  I checked the threaded rod frame to be sure it was square and seated properly in the punched metal plate Z frame.  I checked the connection of the print bed to it's mount and the bearings.  I checked the level of the rods that the X slides on.

All I could do is make the skew worse.  Eventually I got it back to my original range of 0 to -2.4 mm offset.