ColorFab XT CF20

Discussion in 'Filament' started by mike01hu, Jul 6, 2016.

  1. mike01hu

    mike01hu Well-Known Member

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    I have now used two reels of CF20 with reasonable results at the specified temperatures (250C/70C) and hardened standard 0.4mm nozzle and 0.2mm or 0.25mm layers. My biggest issue has been with collecting filament on the nozzle such that blobs tended to drop off and, in one case, caused a total print failure. First layer results have always been very good and adhesion no problem on PVA juice prepared glass or on the PEI coated aluminium plate discussed elsewhere. What I did notice was that I could reduce the pick up by reducing the flow rate and finally arrived at 86% as a sensible figure but still getting pick up. What is strange is that the last jobs done pick up occurred but did not drop but stayed as an ever-growing blob, like a mushroom, on the nozzle. I can't explain why such a large reduction in flow rate does not show in the filled layers, perimeter overlap and inter-layer adhesion but it did show up in the reduced weight of the parts.

    To achieve the results I have I left the extrusion width on Auto, extrusion multiplier at 85% and used the Tune menu to finely adjust the flow rate; I used 1.5mm retraction with 0.25mm Z-lift with infill at varying percentages, depending on job, and always with full honeycomb and definitely not triangular as this dramatically increased pick up due to crossing the same tracks twice on the same layer; infill to outline overlap was at 30% as I needed to be sure that the strength of the part was maintained.
    6-7-16 (7-6-16 US)

    The next job did not fare as well; this time the blob grew quickly and deposited itself right in the middle of an enclosed slot, making the part unusable:(. I am going to try reducing the extrusion multiplier by another 10%. Any thoughts are welcome.
    7-7-16
    I'll update this later.
     
    #1 mike01hu, Jul 6, 2016
    Last edited: Jul 8, 2016
    Paul Winter likes this.
  2. Henry feldman

    Henry feldman Well-Known Member

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    We so desperately need those silicone caps... Not sure why a simple piece of injection molded silicone can take many, many months. I mean really...
     
  3. fpex

    fpex Well-Known Member

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    What do you mean by these caps?
     
  4. Alex9779

    Alex9779 Moderator
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  5. fpex

    fpex Well-Known Member

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  6. mike01hu

    mike01hu Well-Known Member

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    I suspect there are a couple of issues, one being the high temperatures that can be achieved and two, the cartridge cable exits that will vary depending on printer application unless the cut-outs are on both sides. We shall see.
     
    #6 mike01hu, Jul 6, 2016
    Last edited: Jul 6, 2016
  7. mike01hu

    mike01hu Well-Known Member

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    If you look at Sanjay's image you will see the sleeve covers the whole of the nozzle right up to the tip so that pick up problems should be reduced.
     
  8. fpex

    fpex Well-Known Member

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    And? can be done already and in the end it will not solve all problems.
     
  9. Paul Winter

    Paul Winter Well-Known Member

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    Hmmmmm....I'm wondering if I can paint a silicone RTV covering on my nozzle in the short term, until the nozzle sleeves become available.
     
  10. Paul Winter

    Paul Winter Well-Known Member

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    Hi Mike
    I was going to suggest reducing the infill to outline overlap, to give the nozzle less opportunity to dive into the outline, but it seems you beat me to it, and have already considered it. Though with the increased stickiness of the new filaments giving a better bond to the outline, strength of the part may be maintained if you reduce the overlap?
    You could also up the infill density a little to compensate, and give the infill more points of attachment to the outline.

    Or, thinking about it, for large areas of infill, keep the infill to outline overlap at 30%, and reduce the amount of infill, giving the nozzle less time hitting the outline and picking up plastic.
     
  11. mike01hu

    mike01hu Well-Known Member

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    Thanks Paul, I'll wire that in to the next job although I have been down that road before but not together. I have watched this closely and the pickup occurs more on perimeter runs but there are no ridges to pick up from. I said elsewhere that I suspect that it is the carbon fibre that is creating the problem as it leaves a furry surface that is easy to pickup. I was hoping the materials guys, including @Sanjay might have a view.
     
  12. eca

    eca Well-Known Member

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    I just did a few prints with this and while a great finish and strength, the globs were driving me crazy. I kept going in every 30 mins or so and using tweezers to free the globs before they dropped off on the print. The biggest problem is that this stuff gets so hard that a glob will lift the whole carriage if the glob is high enough to hit a fan or IR sensor shroud. Not to mention the high melting temperature doesn't allow the nozzle to just melt its way through the glob easily.
    I printed the bottom of my carriage and the one piece LCD enclosure with this stuff. Looks amazing as long as you don't see the spots where the blobs dropped off...
     
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  13. R Design

    R Design Well-Known Member

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    @mike01hu you can e-mail colorfabb directly. They have a ticket system and will get back. support@colorfabb.com

    With blobs in general (not carbon fibre specifically), I find Z-lift actually makes things WORSE.

    Why?

    Because keeping the nozzle low as it moves over the part means that even the tiniest blob gets wiped off. With Z-lift tiny blobs have time to grow into a big blobs which then either results in a significant deposit at the arrival point or a build up higher up the nozzle, as is the case here.
     
  14. mike01hu

    mike01hu Well-Known Member

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    Thanks for that, I'll try without Z lift for the next job but the pickup was increasing anyway while doing long infill that did not involve lift either. I will contact Colorfabb to get their view.
     
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  15. mike01hu

    mike01hu Well-Known Member

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    ColorFabb Support have offered a couple of things to try that I have not tried but I will add their response here if anyone is having the same problem:

    (19 July 2016)
    The accumulation around the nozzle could be related to oozing. You might also spot this during a print, liquid material that ejects the nozzle during travel moves might hit the product and attach to the nozzle then.


    I advise you to try 3 things:

    - Reduce retraction speed. When you retract the filament too fast, the melt can break and cause a big blob of molten material inside the nozzle which oozes during travel moves. Try to reduce the retraction speed by half.

    - Uncheck "Avoid crossing outline for travel moves" under the tab "Advanced". In your gcode I found some travel moves that go along the outer perimeter. This will contact oozed material and force it to go to the outside of the nozzle. Unchecking this will makes the print head going a direct way with less chance of this issue.

    - Increase the speed of travel moves. The faster the print head moves, the less time to ooze. The BigBox is capable of going to 150mm/s, set this value to "X/Y Axis Movement Speed" under "Other".

    Item 1 is interesting as the hardened nozzle has a longer path from the melt chamber to the nozzle tip (that's from E3D pictures) and the additional friction in the path could cause the break to occur . . . but any break has to be filled by something and as it can't be air the vacuum must be filled by something e.g. melted filament. Hmm . . . we can but try!
     
    eca likes this.
  16. R Design

    R Design Well-Known Member

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    Thanks for sharing Mike.

    I'll be interested to know what comes of your retraction tests. For me retraction speed and distance is one of the great mysteries of the universe. Like boiling an egg you can't see what's going on inside!

    I tried 150mm/s XY speeds for some time for proportional ooze reduction. But in the end decided it was too detrimental to print quality. However maybe someone using Chases' low-slung carriage with a pancake motor will find they can zip about with less distortion?
     
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  17. Rob65

    Rob65 Member

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    Hi Mike,

    indeed: reduce retraction speed - something I tested with different materials. A friend got better results that I did, my retraction was set to 4500 mm/min, he had 1800mm/min and that really improved a lot of oozing during travel moves.

    Uncheck "avoid crossing outline" is like not lifting the pen from the paper when writing....
    This is like having no Z-lift during travel moves: you just drop excess material on the way, preventing bigger blobs. But in the end this will result in visible markings on top layers and may also result in small blobs at start/end-points of perimeters being printed.
    And yes - I did this and it indeed reduces a lot of oozing, blobbing and stringing - especially with materials like XT_CF and PETG but I did notice some imperfections in the outer perimeter (I admit to be using a jewelers eye lens to look at this)

    I like to test with increased travel moves, high acceleration during those moves is - I think - a must. My printer can go up to 12000 mm/min with a acceleration of 8000 mm/s^2 but I need to bolt it down before testing this o_O

    I think higher travel moves and trying to lower the nozzle temperature is the solution I'll end up with.
    Lower nozzle temperatures result in lower max. printing speeds - but when I go for quality that's okay with me.
     
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  18. mike01hu

    mike01hu Well-Known Member

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    Thanks for that input Rob. I have not been using XT-CF20 for a while but will be shortly, so I'll run a couple of test pieces with settings reflecting your suggestions.
     

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