XL Nozzle Cleaning Brush+GCode

Ever had prints not start because the stupid nozzle refuses to be clean enough for levelling? Or had the distinct feeling that your filament's temperature difference from “soft enough to clean” to “starts oozing” is negative? Or a multi-head print where stray filament cling-ons, well, cling off at the very worst place within the print?

This mod fixes all that. (Mostly.)

Installation

Print the holder, attach the silicone brush (it's originally for a Bambu A1). Chip a spare slider in, find a spare screw. Don't tighten up yet, in fact tilt the holder forward so it's out of the way. (I don't have to mention that it definitely shouldn't block the print bed as it moves up, do I?)

Move one of the tool head to X=340 Y=-7 and adjust the holder so it actually cleans the nozzle instead of merely kissing it lightly. Moving from X=320 to X=360 should now nicely clean the nozzle.

Software

Open the attached start.gcode file (it's zipped because Printables analyzes gcode and doesn't like the content for no good reason) in an editor, copy, open PrusaSlicer, go to Printer / Custom G-Code, click into the Start G-Code area, select all, paste. This replaces Prusa's start code with a version that (a) uses the brush to actually clean the nozzle used for levelling, (b) avoids the right-hand area for purging because our brush is in the way.

Operation

The replacement g-code heats the primary extruder to first-layer temperature, then moves it across the brush a few times while allowing it to cool back down to the same bed-levelling temperature as the original Prusa g-code. This should clean the nozzle well enough for levelling to succeed.

For multi-head prints, the other extruders are simply brushed off lightly before purging.