[FEATURE REQUEST] Add "Clean nozzle" to Filament menu (XL multi-tool)

[tg73]

If it makes sense, enter what type of printer or upgrade the feature request applies to. Printer type - XL multi-tool, maybe other variants.

Is your feature request related to an existing problem? Please describe. It's very important for the nozzle to be clean before starting a print so that load cell MBL works reliably. In the old days of the MK3, there was often plenty of time and physical access to scrub the nozzle during the normal heat-up routine, but there's no such opportunity with the XL. Also, when the XL decides to start moving, it goes like a beast and will hurt you, so you quickly learn not to get involved unless the machine is idle. So, manually cleaning the nozzle(s) before a print can be a tedious procedure, requiring to pick up the right tool, bring the nozzle to the right temp, clean it, park it, set the temp back to zero - for each tool involved in the print. It seems that a "Clean nozzle" action, alongside the other actions like "Unload filament" would be really useful.

Describe the expected functionality A Clean Nozzle action in the Filament menu would list all tools with loaded filament, and allow the user to select a tool to clean. Upon selection, the tool would be picked, moved to the front of the machine, the bed dropped a bit to give access, and the nozzle bought to temperature. The UI would then wait for the user to clean the nozzle. The user would then use for example tweezers or a brass brush to clean the nozzle, and then click "Done". The target nozzle temp would be set to zero and the tool would be parked. This should be repeatable for other tools without requiring rehoming each time (at least if the machine is not left idle for a while between selections).

Update: Tools without filament loaded should also be supported. This would help when preparing for nozzle alignment calibration, and also when using a tool without filament loaded for probing/MBL as per prusa3d/PrusaSlicer#12151.

[mix579]

Excellent idea. I've been underwhelmed by the lack of resilience of the load cell and its sensitivity to dirt on the nozzle, with the "nozzle cleaning" at the beginning of the print sheer hit or miss. A way to get the nozzle positioned to properly clean with a brush may help deal with a lot of the "everything-but-perfect-first-layer-unless-it's-PLA-on-a-smooth-sheet" issues I'm seeing

[mix579]

Which I do. For example, with PC-CF I wouldn't be able to make it past the Cleaning Nozzle step without constantly peeling the filament off.

[tg73]

For clarity (and given some comments that appear to have been deleted), let me note that the MK4 and Mini, as bedslingers, give easy access to the (one and only) nozzle during the normal heating cycle for the user to clean the nozzle with tweezers. And if the bedslinger starts to move, the extruder will only move at speed in the X axis - so you can position your hand/tweezers fairly safely when cleaning with tweezers. In contrast, the XL is a CoreXY machine, and it can have multiple tools. It tends to keep the active tool near the back of the machine when heating, and quite close to the print bed, which is hard to reach. And if it starts moving, the toolhead can move towards you with great speed and force - it is no joke, and it's not safe to try and reach to the back of the machine and use tweezers. Then there's the issue of multiple tools, and it can be desirable to clean all the tools that will be used in a print. Only the first tool used in a print is picked and heated and used for probing and MBL.

So - this feature request is likely specific to the XL, and may not make much sense to non-XL users.

[tg73]

I'll also second @mix579 that probing/MBL does not mix will with filaments containing fillers (eg PC-CF and wood-fill). I've suggested allowing a different tool to be used only for probing/MBL, even if it's not used in the print and even if it doesn't have filament loaded - see #3722 and prusa3d/PrusaSlicer#12151.

[dhyananbho]

To clarify: I am a user of an MK4 and of an XL with 5 tool heads (otherwise I wouldn't be reading here). First I switched from the MK3S to the MK4. I had to relearn a few things about how to best handle the printer when loading filament, cleaning nozzles, etc. This relearning is now also helpful with the XL. However, I usually change the filament when I start a new print, the print head moves forward anyway and I can clean the nozzle easily. Using tweezers, I always have a perfect first layer with PETG and TPU, but I have no experience with PC-CF or wood filament.

My misunderstanding was that I thought I had clicked on my feature request #3717 and that mix579's reply was meant ironically regarding the problem I described there. Sorry, that probably caused some confusion here.

Your feature request seems well thought out and helpful, especially for nozzle alignment calibration.

[mix579]

Thanks for your explanation. I didn't really see why my comment was interpreted as ironic. Makes sense now.

[nealzip]

This does sound like a great feature to add.

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[tg73]

Waiting for Prusa to respond.