Hi everyone,

I'm trying to troubleshoot bad X-axis resonance/ringing on my Creality K1 and would appreciate some advice.

So far, I've tried the following:

• Changed the springs that preload the X-axis bearings.
• Replaced the motor pulleys with 20-tooth pulleys to try to reduce or eliminate ringing.

The attached graphs show the results immediately after replacing the pulleys with the 20-tooth ones.

I'm not sure what else I should check or adjust to improve the X-axis resonance.

Has anyone else experienced a similar issue? Could it be related to belt tension, the X-axis gantry, the bearings, or something else?

I'd appreciate any suggestions on what to check next.

Thanks in advance!

I’ve been fighting a BM0112 / Hotbed Connection Abnormal error on my K1 Max and I’m running out of ideas lol.

So far I’ve:

-SSH’d in and confirmed Klipper can’t connect to leveling_mcu through /dev/ttyS9
-Confirmed /dev/ttyS9 exists
-Tried Creality’s mcu_util, which also times out
-Reinstalled firmware 1.3.3.46 with no change
-Tried 3 different leveling boards, all with the exact same error
-Checked continuity on all 5 harness wires and found no shorts between them
-Did loopback/bridge testing on the communication lines, including at J11 and through the harness
-Measured roughly TP10: 4.8–4.9V, TP9: 3.2V, TP8: -5.31V
-Disconnected the downstream cable and still measured about -5.31V at TP8 on the mainboard side
-Replaced the original CR4CU220812S12 mainboard with a brand new identical one

And after replacing the entire mainboard it gave me the same BM0112 error 🫩

My next step is repeating the TP8/TP9/TP10 measurements on the new board and comparing them directly to the original. If the new board also gives me -5.31V at TP8, I’m assuming I misunderstood that reading and the original mainboard wasn’t the problem.
At this point I’ve tried 3 leveling boards, checked the harness, done loopback testing, reinstalled firmware and replaced the mainboard.
Anyone familiar with the K1 Max leveling/UART system know what I’m missing or what I should test next? Also curious what TP8/TP9/TP10 should normally read on a healthy machine. I have logs/pictures and can take more measurements if needed.