My Creality K1 bed is actually in pretty good shape (max deviation of 0.7mm left to right, 0.1mm back to front), but I recognize that many folks might have beds that are off as much as 1.5 or more mm. The K1 has 3 lead screws, but not proper 3 point leveling (maybe someone will create a daughter board and a 3 point conversion kit in the future, after Creality open sources their firmware for the K1 series -- anyone out there that does this, I'd probably throw some small amount of money at you).
As far as I understand it, there are currently two methods to properly tram your bed:
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Follow the creality way, which is essentially immobilize the bed with shipping screws and retension the belt that synchronizes the 3 Z screws. To do this, you must turn the printer on it's side, remove the bottom panel, and fight the tensioner. Reports are mixed luck doing this.
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Skip teeth. You still have to do the bottom removal, but instead of completely removing the belt and detensioning, you slip the teeth on the belt drive (I think this is something like 0.4mm for each slipped tooth). There is less information about this, but there's a video in Chinese showing someone doing it. Perhaps a more helpful guide would democratize this more, and it might have more success than 1?
My question is: there are grub screws on the 3 lead screws, on the top side, accessible from the printer cabinet -- would it be possible to loosen the grub screws, so the z rod in that position spins freely, turn that z rod just slightly, then reseat the grub screw? That would seem a lot easier to relevel the bed, than doing either of the above procedures. Am I missing something?
I can't find very good images of the bed mechanism in the machine, but it looks to me like there's a separate piece for the machine that mounts the nut for the leadscrew to the bed. The easiest way to make it more adjustable might be to design and print a replacement for this part that allows you to use a screw to offset this connection slightly. You could probably get away with just making the front two adjustable and leaving the back one fixed.
Ah this sounds interesting. If I ever get around to taking the bottom plate off, I’m definitely going to check that out. The only other idea I had was to get metal shim washers and put them below the stand-off mounts for the bed, but I was worried it would befuddle the strain gauges somehow.
Oh, that's a thought, I'm not sure how the strain gauges factor in.