Quote Originally Posted by ixlr8 View Post
2mm is enough to show up if you put a known straight edge on the platform to inspect gaps, like a perfectly straight tool (even ruler side of a caliper) to see if the platform is warped.

Have I done this? No. What did I do? I attached a dial indicator on my extruders and ran them in the X and Y direction to test a theory. It turns out that the extruders are as much as 0.005" (0.127mm) closer to the build platform at X center. It's not 2mm by any means, but it's enough to make you want to slightly change your leveling process, like making sure the paper you are using as a clearance guide has some friction between the extruder and the build plate at the platform center, but is more free-sliding near the platform edges.

The next question is: What is warped? The build plate or the X guide rods? Is the simple weight of the extruders enough to cause a slight deflection of the X-rods when the extruder is near the center of the platform? (At an atomic level that answer will always be "yes", the question is...how much?) Are both plate and rod warped?

I haven't taken a straight edge to my build platform yet, but I doubt I would see much if any gaps with only 0.005" warpage (a sheet of copy paper is about 0.003"). Your situation may be different.
Yep, couldnt have said it better myself.

After some 1000 hours of printing, my hotbed has slightly risen on the edges, to the naked eye it's flat, but yeah it definitely has warped slightly over time. My brother in law is cooking me up a new build plate in his workshop, he used to be a fitter and turner in the navy so he's got some seriously good know how on metals, heat transaference etc..