RE: Different Z lead screw travel between MK4S upgrade screws and Core One kit — 2 mm mismatch
Kinda wish I’d bought an inclinometer instead of a small level now, they’re only a few £/$/€ more.
So am I right in thinking as long as the motors are mounted correctly, and there’s no damage or bending to the lead screws themselves, any tilt is going to be the result of mismatched lead screws?
I guess damaged/worn trapezoidal nuts could be a factor, or skipping steps due to binding, but both of those seem highly unlikely here.
I really wish there was a way to identify the out of tolerance screws easier than the tracing method, my first attempt at that did not yield very good or convincing results 😂
RE: Different Z lead screw travel between MK4S upgrade screws and Core One kit — 2 mm mismatch
You can use a clinometer app; for example, ClinoScope on iOS provides 0.01° resolution and displays the tilt digitally. I’m not sure whether there’s an equivalent for Android, but there’s likely a similar option.
RE: Different Z lead screw travel between MK4S upgrade screws and Core One kit — 2 mm mismatch
Hi Albert, it was really your concern about layer adhesion which threw me off. As long as we are talking about a linear distortion of the overall object shape, we are on the same page.
As an aside, it would actually be possible to compensate for this skew in firmware -- even with all three motors wired in parallel. The software-based bed leveling correction already moves the bed dynamically during the print, as a function of X and Y. It would "only" need to be enhanced to move as a function of X, Y, and Z: As the print progresses, there would be a gradually increasing contribution which compensates for the tilt caused by the screw pitch difference. It would be difficult to calibrate though: It can't rely only on automated bed probing, but needs to know the screw pitch difference in addition.
But let's not go down that rabbit hole. It looks like Prusa has decided not to go for software compensation, but rather provide replacement screws to the limited number of users who notice this flaw.
Glad we converged 🙂
Yes, I completely agree, mechanically correcting the root cause is by far the cleanest solution. Software compensation would quickly become complex and fragile compared to simply having matched screws.
Thanks for the thoughtful discussion - it helped clarify the different models.