What is the current state of the art wiping solution?

Discussion in 'Getting Started' started by John Meacham, Dec 7, 2020.

  1. John Meacham

    John Meacham Well-Known Member

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    All my print heads have fairly different heights (hemera plus Bowden with some volcanos thrown in) so the basic wipers on the side don't work that well. So far I have been using the silicone brush method with a high brush on the left and a low one on the right. The volcano just goes deep and the v6 gets tickled by the top. It just doesn't work that well, my mutimaterial prints have strings of infill material sticking out of the sides of them or deposit blobs that are ugly at best and lead to the print head jamming on them ripping off the print at worst. It's still usable, but requires baby sitting for things that change materials within a layer.

    So looking for what the current state of the art is, things I have seen mentioned on the forums have been

    Stringing a silicone line across the whole back so they hit it while being docked or undocked. (Doesn't solve height issue but I can rig something up probably)

    A razor blade positioned to slice the nozzle tip and seal it while docked (seems promising but will be a little design work. Open question, will slicing stainless steel blades over the tip remove the nozzle x coating?)

    A silicone silkscreening pad the nozzle wipes into. (I have only seen this as side wipers, maybe it can be done per extruder to continually seal while docked?)

    Another issue with the current wipers is the purged filament drops onto the spools below which led to my singular jam on the TC, a petg whisker from purging got pulled into the pla tube and rode it all the way to the nozzle where the combination jammed up the works. Not much point in solving this until I can get the purge threads to not be dragged all over the print in progress though.

    Any thoughts or pointers to more recent work would be appreciated.
     
  2. blarbles

    blarbles Well-Known Member

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    I've been using a tiny (1cm x 1cm) purge block on the edge of the bed. It adds very little time to the print job and works every time. As a result my wipe command is extremely quick. It just flicks over the silicone once and moves to purge block. I came to this decision after a lot of trial and error with retraction settings and various wipe moves and methods.

    Unless you are a wizard at extrusion/retraction timing I think even the seal method for docked tool heads has issues like as soon as it is released that pressure blobs out.

    I have had success with a wipe only print, but it was not reliable enough to leave alone and the purge block + quick wipe is almost as fast as a full wipe.

    The above would not work if you were using 2 different materials that did not stick to each other (PETG and PLA for example). You could fake purge blocks by adding 1cm x 1cm stacked cubes for each material on the edge. I'm not sure how you would force the slicer to print those first though.
     
  3. John Meacham

    John Meacham Well-Known Member

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    Thanks! Although I probably won't use a wipe block in general for now since SuperSlicer ones are a little wonky I was able to do a few test prints with them that turned out perfectly (despite wasting a ton of filament) that gave me a baseline to work towards and compare behavior between it and my wiping to figure out where errors were sneaking in.

    I ended up making a few changes that made it much more reliable. I completely disabled purging in tfree, this saves a ton of time and leaves me with half as much plastic that might become strings or blobs to worry about. Is there any particular reason to purge on tfree? I can't think of why its useful. I tightened up my priming to do a little less extruding and more wiping and put in a fast retraction right at the end to encourage the string to break off. The biggest change was noting that the travel move from the wiper back to the print was very slow as it was inheriting the feedrate of whatever slow print move happened before the toolchange, this gave a lot of time for oozing out of the nozzle before it got back to my print which invariably caught on the perimeter. I modified my post processing script to quickly move back into position after a toolchange and that helped dramatically.

    assuming this continues to work okay, I'm going to design some stepped wipers on the side so nozzles can hit the one of the appropriate height for them as the wiping isn't 100% at removing the strings and ooze (but much better than before)
     

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