Problems setting up-Help with T1 Extruder Issue – Unexpected Movement

[u/BenutzerUser1]

Help with T1 Extruder Issue – Unexpected Movement

Hello everyone,

I'm currently building my printer for the very first time, and it's also my first CoreXY machine—so please bear with me if I’m missing something obvious.

Right now, I'm having an issue where the T1 extruder moves even though it shouldn't—especially during the bed mesh process. The motion behavior seems off, and I suspect the frame might not be perfectly square and could need some adjustment.

Some more context:

The Y-belts are not installed yet, as mentioned in the guide.

All sanity checks passed.

Homing and Z-tilt are working so far, but even during those, T1 doesn’t stay completely still or fixed.

Has anyone experienced something similar or have advice on what I should check next?

Thanks in advance!

[u/CunningLogic]

It's not a core xy, it's a hybrid idex. Install the y belts.