Material changer with S5: gratuitous material extrusion at end of job

[TheOldCodger 0]

Okay, I did a cursory search of the posted topics and didn't immediately see my issue.  However, I'm more than willing to concede that I failed to find it...

 

Just installed the material station on the S5, and it works as advertised.  However, "as advertised" includes having the station not only retract the filament at the end of a job, but also extrude a bunch of filament through the head prior to retracting.  The rationale for extracting the filament is, apparently, that the material station can't control the humidity in the Bowden tube.. which is a questionable point, but at least "a point."  However, extruding prior to retracting seems just excessive, in terms of job time, waste, and (ultimately) the potential for the rat's nest of waste filament getting into a big job that involves the platen dropping near the bottom of the print volume.

 

I'm open to explanations that expose my ignorance.  Thanks for your patience.  I love the Ultimaker product, so please don't take my comments as anything other than constructive feedback!

[Carla_Birch 115]

My understanding is it extrudes filament as the end to make a tip on the end of the filament so that it s able to feed in and out from the feeder without blobs getting broke off inside and making it unable to load again. It's also why other brand of filaments need to be confirmed because the process needed for other brands might not be 100% the same to make a nice tip.

[TheOldCodger 0]

Thank you Carla!

 

I suppose that makes sense, but in all the time I was using my S5 without the material station I had no problems with blobs broken off, etc.  Furthermore, it seems like the printer spends an inordinate amount of time extruding at the end, if just for that purpose.

 

As a retired engineering director I feel that one of the major issues is the debris accumulating at the bottom of the printer.  I've already had a case where extruded filament got caught up in the print head fan, jamming it, and another instance where the waste filament started wrapping itself aggressively around the Z-axis table screw.

 

I am thinking of prototyping several solutions to this; one involving a collapsing "shield" and another involving a pair of chutes that vacuum the waste filament out.