Stock XY motor specs / 0.9° stepper swap on the U1

Hi all,

I’m looking into swapping the U1’s two XY steppers for 0.9° motors to further reduce VFAs, following up on the ideas from the “Eliminate VFA on the Snapmaker U1 (for free)” thread. I’m already running the Extended Firmware, so the Klipper side is straightforward (full_steps_per_rotation: 400 in [stepper_x]/[stepper_y], then re-run vibration compensation). The open questions are purely mechanical/electrical, since Snapmaker doesn’t publish motor specs and the XY motor isn’t available as a spare part in the store yet:

  1. Stock XY motor specs: frame size, body length, shaft diameter and length, rated current — or ideally a photo of the label with the model number.
  2. Pulley: removable via grub screw, or press-fitted onto the shaft?
  3. Motor-side connector: which type, and is the pinout documented anywhere?
  4. Clearance: is there room behind the inner panels for a 48 mm body (e.g. LDO-42STH48-2004MAH, the usual 0.9° CoreXY choice)? The wiki replacement guide mentions the motor can be blocked by the inner panel during removal, so I suspect it’s tight.

If nobody has done this yet, I’m willing to be the first: I’d pull one motor, measure and photograph everything, and document the full swap (including TMC2240 current settings and before/after VFA test prints) in this thread.

Any data points, teardown photos or measurements would be much appreciated. Thanks!

Link?

OK, found it: Eliminate VFA on the Snapmaker U1 (for free)

Unfortunately, nowhere can I see it explain what “VFA” means (for any of us who don’t know).

VFA is short for “Vertical Fine Artifacts”.

It’s the slight vertical ripples which sometimes are visible across walls (best shown on glossy materials) and which unfortunately can have a multitude of sources and therefore are hard to eliminate.

Possible sources include:

  • Stepper pitch (1.8° in normal steppers, 0.9° in finer steppers)
  • Belt pitch (2.5mm in normal belts, 1.5mm in finer belts)
  • Resonances dependent on belt tension
  • Resonances dependent print speed
  • Idlers and pulleys
  • …and a lot more

Note that this ripple is different from ringing (which only happens on velocity changes).

Open a ticket and see if you get some information about, maybe you got luck:
https://snapmaker.formcrafts.com/u1-troubleshooting-request

But I don’t have a problem; I’m just looking for information about the stepper motors used in the system.

Sounds like you’ve been nominated guinea pig.

Someone on the SM Discord did this a couple of days ago and it didn’t produce good results.

Link?

Yes!

This links directly to the comment that mentions it.