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.
Getting x (which carries the extruder) parallel to the bed is normally achieved by running the z axis to the top till both motors stutter against the top brackets.
Getting y- square and removing skew is done by adjusting the frame distance from the rear corners using the M10 nuts where the threaded rods meet the frame. It is essential to keep the threaded rod fully inserted into the frame slots while making these adjustments. The y distances are shown on the LCD through the support menu.
Hope that helps you.
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