Sharing a gotcha from a long cutting session this week in case it saves someone a faulted cut. Maslow 4, FluidNC v1.15, cutting 2" foam.
Short version: the controller can report State 7 (Ready To Cut) with GRBL Idle — web UI all green, everything looks ready — while a belt is actually ~15 mm out of position. State 7 only means the belts are tensioned, not that they’re where the kinematics think they are.
How it bit me: after loading a fresh sheet I tensioned, and the UI showed Ready To Cut. But $MINFO told a different story:
extension drift (mm): etl=0.35 etr=3.07 ebr=-15.45 ebl=3.98
Bottom-right belt 15 mm off. Hitting Run there is a position-error → E-stop mid-cut waiting to happen (same failure class as the position-error reboots in [25789]). Earlier in the same session, a recovery left the belts ~110 mm off while still reading tensioned.
What I now check before every $SD/Run: the four $MINFO extension-drift values (etl/etr/ebr/ebl), not just the banner. On a seated machine they sit near zero (mine are typically < 0.1–0.2 mm). Millimeters = a belt isn’t where the controller thinks it is.
Recovery that worked: release tension → apply tension → jog the machine around a little. That re-synced position and dropped the drift from −15 mm back to ~0.02 mm, steady. (Jogging alone cleared the 110 mm case too — moving re-establishes the belt/position relationship.)
Takeaways: (1) read the $MINFO drift before cutting; treat anything past a fraction of a mm as “re-seat first.” (2) It’d be great if “Ready to Cut” weren’t green when a belt is several mm out of position.
Anyone else seen as-cut belt drift after a sheet change / sled bump — what’s your threshold for re-seating before a cut?
Maslow-serial (16).log (6.0 KB)