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Macro: Servo Cutter

What it does

EREC filament cutter

Tunes a servo-actuated cutter mounted at the MMU end of the bowden - originally the EREC design, but this covers any similar servo-actuated cutter at the MMU end of the bowden. Additive to tip forming rather than a replacement for it: a decent tip still needs to exist going into the cut. Fully native now: enable Have servo cutter at MMU? under menuconfig's Tip Forming / Cutting screen, wire the servo pin, and tune it below - this isn't a separate [include ...] file to copy in any more. You'll still need the physical build/wiring instructions from EREC's own project page. See Feature: Tip Forming and Purging for how it fits alongside whichever tip-forming method is active.

Where it's applied

Defined in mmu_servo_cutter.cfg as SERVO_CUTTER_ACTION - after the filament parks in the gate, it advances the filament, activates the cutter, then parks again, firing a filament_cut event (Feature: Statistics & Consumption Counters can count these). Unlike most of the macros on this site, enabling the capability in menuconfig does not wire this one up automatically - the Kconfig prompt's own help text says as much ("after enabling this be sure to edit Macro variables"). Add it as a post-unload extension hook yourself:

variable_user_post_unload_extension : 'SERVO_CUTTER_ACTION'

Note

mmu_macro_vars.cfg's own section banner for this block describes it as a "post_load_extension" - that's stale relative to the macro file's own header comment and the hook it's actually written to receive (user_post_unload_extension); wire it up per the macro file's own instruction above, not the banner text.

Configuration

menuconfig: Servo cutter at MMU (_MMU_SERVO_CUTTER) screen, showing servo angles/timing and feed/cut length settings

_MMU_SERVO_CUTTER_VARS in mmu_macro_vars.cfg, reachable from menuconfig's Macro Variables → Servo cutter at MMU (_MMU_SERVO_CUTTER) screen shown above, once Have servo cutter at MMU? is enabled under Tip Forming / Cutting. Full variable table: Macro Variables: Servo cutter, MMU-mounted.

feed_length - the distance from the gate parking position to the blade - is the one setting worth calibrating carefully rather than guessing: 48mm covers ERCF v2 and most other designs, 58mm is the ERCF v1.1 value.

See also