Flexible filament & purging filament pathway

Discussion in 'Titan' started by TheCure, Nov 28, 2017.

  1. TheCure

    TheCure Member

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    Hello all,

    I'm new here. I am hoping you might be able to help me with a question I have.
    I've been into 3D printing for a few years, but recently bought an FT-5, and upgraded with a Titan aero.
    It's been abit rocky so far. I still haven't got the printing quality up to the point of the stock extruder.

    One of the main reasons for the Aero was to be able to print flexible filaments.
    I finally ripped into my Ninjaflex spool, and attempted to load the extruder. I had previously printed in ABS, so I ran PLA through to remove the ABS, then attempted to run the ninjaflex through to purge the PLA. Instead of cutting the PLA, I retracted the filament so most of it has come out. I suspect there is still molten/semi molten PLA in the nozzle/lower heatbreak.
    Keeping the temperature at 220C, i attemped to load the extruder with no success at all. The filament keeps wrapping itself around the extruder gears. It seems there is not enough pressure to push out the remaining PLA using the ninjaflex filament. I've tried manually pushing it down too. It always meets resistance presumably near the bottom of the pathway.

    What are the best practices for loading this type of filament in general?
    What are the best practices for loading this type of filament after other types have been printed previously?

    I hope I don't need to clean the nozzle and heatbreak each time I change to TPU/ninjaflex.

    Thank-you in advance,

    -TheCure
     
  2. Old_Tafr

    Old_Tafr Well-Known Member

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    Although I would love a technique for loading a new reel or a different filament without disassembling the whole heat-sink to nozzle assembly, after a certain amount of use it would seem like a good idea to clean out the whole assembly.

    In the past I had looked online at devices for melting/welding two pieces of filament together, this may work with different types of filament, I may have another look and buy one of these if I can't find a manual way to do this.

    I had hoped that Titan would provide an easy way to extract the whole assembly from heat sink to nozzle, this is a TOTAL pain on the original BigBox, but Titan for BB is different than other printers in that there is an extra part fitted where the groove mount at the top of the heat-sink fits, so I assume that with the assembly mounted below it is maybe not as bad as the original but still a pain. I'm not familiar with the Aero assembly.

    The new Titan install instructions on the WiKi show the assembly process, alas not for the BigBox any more.

    Maybe try welding the old and new filament together heat the nozzle and then use Octoprint or whatever to feed filament through until the new emerges?
     
  3. TheCure

    TheCure Member

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    I ended up taking the extruder apart. Turns out there was a layer of plastic lining the inside of the nozzle, and heatbreak, so the ninjaflex filament wouldnt quite make it down the throat. i replaced the nozzle and cleaned the heatbreak tube, then gently, manually extruded the ninjaflex. it worked.
    not only that, but i even started a print. twice. both times it failed in approximately the same spot, maybe after the 1st or second layer it stopped extruding. on both occasions the filament was cut, and came out of the extruder (see picture).

    IMG_20171129_135137-small.jpg

    Any idea what is happening? I know this is going to be a long process before solid prints are achieved with this.
     
  4. Ed Neugebauer

    Ed Neugebauer Member

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    I have the same problem using a Titan Extruder with a direct drive setup. I've slowed it way down and loosened the knob on the Titan Extruder so there is hardly any pressure. I'm using Inland TPE.
     
  5. Antoine

    Antoine Well-Known Member
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    Regarding cleaning the hotend: the easiest and quickest way is probably the cold pull/.atomic pull. This involves heating up your hotend to 100°C or so and then pulling on the filament so that you get it out "cold". This allows you to avoid cross-contamination. There are a lot of tutorials online regarding this technique.

    Regarding printing with flexibles: be very careful with the idler tension, as the flexible filaments can be "squashed" much more easily, which leads to the issues you describe. You would want to start printing with very slow accelerations and speed, and with the temperature above what is considered the print temperature. Once you get your hotend to extrude, gradually reduce the temperature or increase the speed/accelerations. Flexibles are probably one of the hardest material to print, and require nerves of steel, but it works, trust me!
     
  6. Ed Neugebauer

    Ed Neugebauer Member

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