Different Z lead screw travel between MK4S upgrade screws and Core One kit — 2 mm mismatch
Hi,
My Core One comes from a MK4S upgrade kit, and I’ve found a mechanical mismatch in the Z axis.
The two lead screws reused from the MK4S rotate exactly the same number of turns as the new lead screw included in the Core One kit, but their trapezoidal nuts move about 2 mm less over the full travel.
To compensate, I had to add a 2 mm spacer at the lower left Z calibration stop so the bed is level near the top of the travel.However, as the bed moves down, the tilt appears progressively, reaching about 2 mm out of level near Z = 0 on the MK4S screw side.
Small prints are fine, but tall prints show increasing layer issues as Z increases.This suggests a different effective pitch or cumulative tolerance between screws.
I’m attaching two photos of a bubble level showing the bed level at the start and at the end of the travel.
Has anyone else seen differences in lead screw pitch or effective travel between MK4S and Core One screws?
RE: Different Z lead screw travel between MK4S upgrade screws and Core One kit — 2 mm mismatch
Oh yes... Here's the original thread about this. The link goes to the post where @pavel-brych has identified the root cause.
Prusa support will send you a replacement lead screw or two, but it takes some back & forth to convince them. Your pictures of the spirit level will be helpful; that's a demonstration they have asked me to provide (in a video, showing the change while the bed is travelling upwards).
RE: Different Z lead screw travel between MK4S upgrade screws and Core One kit — 2 mm mismatch
Are the lead screws replaceable? I always thought they’re fixed to the Z motors ?
RE: Different Z lead screw travel between MK4S upgrade screws and Core One kit — 2 mm mismatch
They are fixed. When Prusa agrees to provide remplacements, you get the complete replacement units: lead screw, motor and cable. It's a bit of a hassle to swap them on a fully built printer -- front and side skirts around the base plate need to come off so you can pull the motors out towards the bottom.
RE: Different Z lead screw travel between MK4S upgrade screws and Core One kit — 2 mm mismatch
They are fixed. When Prusa agrees to provide remplacements, you get the complete replacement units: lead screw, motor and cable. It's a bit of a hassle to swap them on a fully built printer -- front and side skirts around the base plate need to come off so you can pull the motors out towards the bottom.
Jesus Ive just read the beginning of that thread and think I might have that issue ! I was batch one also.
Sorry to be a pain mate but is there a tldr to find out if Im affected? I have decent callipers but thats about it regarding measuring tools.