Skewed XY-Plane (Z Rods, Heatbed)  

RE: Skewed XY-Plane (Z Rods, Heatbed)

After what I can only assume must have been lengthy deliberations at Prusa HQ, I finally got new motors today. As far as I can see, their spindles finally do have the same pitches. Between the right and left front spindle, I now measure 0.4mm difference (see first post). Probably good enough.

This whole spindly "experience" took me way longer than assembling the kit...

RE: Skewed XY-Plane (Z Rods, Heatbed)

Just adding in here that it appears that I have a similar XY skew as well. Measuring the base at z=275 I'm coming up with all measurements being equal, but when raising the bed to z=0, there is a X axis skew between the front screws of 1.4 mm.

This photo is X=-2, Z=0. Y remains constant at 10.

While this is at x=252, z=0

I had the mk4s>CoreOne upgrade kit, but it originally started as a mk4 several years ago.

RE: Skewed XY-Plane (Z Rods, Heatbed)

Hi,

Decided to check the pitch of the Z lead-screws on my Core One batch 2 Kit, and I got similar results to previously presented in this thread.

Procedure

1. Paper strip with center line marked out, tape to fasten and limit measurement area to 150mm
2. Attach Strip to lead screw
3. Pinch tape on one end with fingers
4. Lighly trace out the threads with pencil away from pinched side
5. Photograph (flat bed scanner would have been better) and count pixels and threads

Results

L = Left front Screw

R = Right front Screw

C = Center Rear Screw

Sanity check by aligning the threads and miss-match in pitch after 21 turns is clearly visible

RE: Skewed XY-Plane (Z Rods, Heatbed)

Nice job on the measurements. Make sure to notify Prusa via chat.

I might do the same trick to get accurate measurements!

RE: Skewed XY-Plane (Z Rods, Heatbed)

Petulf, now that's a clever way to take the measurements!

RE: Skewed XY-Plane (Z Rods, Heatbed)

Very smart.

That's quite a difference for tall prints.

RE: Skewed XY-Plane (Z Rods, Heatbed)

What’s the latest status on this?  I cancelled my conversion order over this issue; doesn’t look like much progress has been made since.

RE: Skewed XY-Plane (Z Rods, Heatbed)

I upgraded an MK4 from late 2021 with one of the Batch 1 upgrade kits . Using @petulf's measuring method (very satisfying for its simplicity), both front screws have 100 ridges in 200mm. In my instance the kit motor seems to match the MK4 ones.
I did use this mod to level up the left front of the frame. I think that's an artifact of the modular frame design.
FWIW, printing 50mmx200mm cylinders near the three lead screws match within a few hundredths of a millimeter on mine.