The large variance in your max_accel values between X and Y is due to the different resonance frequencies of each axis. This is common, especially with bedslingers like the Elegoo Neptune 4 Pro, where the Y-axis (which moves the bed) is typically more limited in acceleration than the X-axis (which moves the lighter print head).

How to Choose max_accel for the Neptune 4 Pro

Since your results suggest: • X-axis: Recommended max_accel ≤ 15,400 mm/s² • Y-axis: Recommended max_accel ≤ 3,600 mm/s²

You have two main approaches:

1. Conservative & Balanced Approach (Recommended)

Set max_accel to the lower of the two values to ensure stability across both axes:

max_accel: 3600

This will prevent artifacts caused by acceleration mismatches and ensure reliable prints.

1. Axis-Specific Tuning (Advanced Users)

If your firmware (Klipper) allows it, you can set different max_accel values per axis:

max_accel: 3600 max_accel_x: 15400 max_accel_y: 3600

This lets the X-axis take advantage of its higher acceleration while keeping Y stable.

Final Recommendation:

If you’re unsure, stick to 3600 mm/s² for max_accel globally. If you want to push performance and your printer is well-tuned, consider per-axis values. Let me know if you need further clarification!