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  1. #1
    Super Moderator curious aardvark's Avatar
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    Finally decided to sort out flexibles on my creator

    I reckon i can strip down a flashforge mk8 extruder with my eyes closed.

    Stick some flexible filament in there and print it just a smidge faster than it wants and it will wrap itself round the extruder and jam.
    And the only way out is to take it apart and remove the filament.

    I've finally had enough - lol
    By rights if setup correctly the ff should be able to print flexibles almost as fast as rigids.

    Bought some cheap flexible pla this week. And I have to say it's pretty impressive stuff. Maybe a tad stiffer than polyflex and at least as strong. £22 a KILO ! and comes in lots of colours. So a proper polyflex killer. I keep asking polymaker to mak more colours of polyflex and they just offer to make me a custom bulk batch up. Which isn't the point at all :-)

    I started a print off with the sienoc stuff, the same settings I use for esun flexible pla. Started great, got about 4 or 5 layers in before I started to hear that dreaded clicking noise.
    Turns out the sienoc is a smidgen less firm than the esun. Not enough for a human being to tell, but clearly enough to jam an extruder !

    Now sebastien told me he'd just inserted a short length of ptfe tubing and that had sorted his problems out.
    For that you have to drill out the current feed holes to fit the tubing and then insert from top and bottom till there is no gap between the top and bottom of the bolt and bearing.

    I don't want to drill my original extruder - just yet.
    So currently I'm printing out this: https://www.thingiverse.com/thing:169086
    On Alexa - the ff is in bits.
    I'm hoping this will work with the existing metal parts, if not I'll go the drill and tube route.

    I do have the extruder from the right side (which currently only boasts a plastic print of a stepper motor) as a backup if i bollox this up.

    More later

  2. #2
    Super Moderator curious aardvark's Avatar
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    That extruder doesn't use the same parts as the original - seems stupid, but maybe he had his reasons.

    So I went with drilling out the feed holes with a 3mm drill and inserting a very short length of ptfe tube at the bottom and a slightly longer one at the top.
    The idea is to remove any gaps that flexible filament can warp into.

    Currently reprinting part it jammed on with original settings.
    (should probably have recalibrated :-) )
    Fingers crossed :-)

    ***
    Looking good :-)
    Last edited by curious aardvark; 12-21-2017 at 01:02 PM.

  3. #3
    Engineer-in-Training
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    I thought that Flashforge and clones use mk10 extruders.

  4. #4
    Super Moderator curious aardvark's Avatar
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    not if they're 4 years old :-)

    It is kind f weird that someone would design an upgrade but not use the existing hobbed bolt, guide-rolley-thing and screws.
    But if a few mm of ptfe tube does the same job - all to the good :-)

    The sionec stuff is actually a little floppier than than polyflex too - which is good for the flexible prints I make a lot of.

    Two clean prints at 30mm/s, so I'll see if i can punch the print speed up a bit. I'll try the next one at 50 :-)

  5. #5
    Super Moderator curious aardvark's Avatar
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    Hot diggity !
    Clean sharp print at 50mm/s - to be fair I am just printing a flat shape, but even so .
    I've gone from printing these in 2 colours that took over 3 hours, to a stronger, better, one colour design that takes 30 minutes :-)

    Oh yeah and this prints on a cold bed with the first layer at 100% speed.

    60mm/s looking quite good too :-)

    Going to try some filaflex next. Never had any luck with it on the rep clones before.

    ***

    Hot diggity indeed !
    Currently printing filaflex at 50mm/s 230c, unheated bed.
    Looking good !

    So for the sake of a piece of ptfe tubing that costs a few cents, the basic rep clone extruder can be turned into a flexible printing superstar :-)

    Should have done this years ago !

    Guess the next job is to do the same mod on the Knp.
    Maybe after christmas lol

    The weird thing is I haven't moved from my chair and I've lost the third one I did at 60mm/s with a slightly varied design. Just vanished.
    Last edited by curious aardvark; 12-22-2017 at 03:03 PM.

  6. #6
    Super Moderator curious aardvark's Avatar
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    Okay filaflex will print at 50 - but it's not happy.

    So for the really floppy filaments 30 is about right.

    Which is still 30mm/s faster than I used to be able to print it :-)

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