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Is there anything better then PTFE

Discussion in 'Mods and Upgrades' started by tonycstech, Dec 22, 2013.

  1. tonycstech

    tonycstech Active Member

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    All extrusion and retraction problems are the cause of the nozzle setup.
    When motor turns backward, filament suppose to retract from the nozzle but it doesnt because so much of it is melted inside it keeps extruding.
    Making retraction to turn back much more will create problem as well.

    PTFE Tube is there to keep the filament centered going straight to the tip of the nozzle.
    I see PTFE is still getting deformed and melt allowing filament to flood the nozzle.
    This create SO MUCH nozzle problems.

    I was thinking of MAYBE a different tubing that will transfer heat even WORSE then PTFE.
    Plastic is not very good at heat transfer, thats why PTFE is used. But is there something worse (in that case less heat transfer) material for the tubing ?
    Something stronger ?

    I was also thinking about drilling small holes inside the nozzle above the tip to keep the heat focused on the tip rather then the whole nozzle.
    Maye even replace the hot end with some other that has more of a direct heat rather then entire nozzle heat ?

    If heat distribution was directly at the tip of the nozzle, life would be so much better
     
  2. Melody Bliss

    Melody Bliss New Member

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    PTFE (teflon) is used because it's slick. Very Very slick. Allows the filament to move from the extruder to the hot-end easily.

    If you're routinely melting the PTFE tube, you may be getting the hot-end too hot. If it's cracking, however, that's a different problem.

    Why don't you move to an all metal hot-end like the E3D? No PTFE tube to fail then.
     
  3. tonycstech

    tonycstech Active Member

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    Because all metal=more heat distribution where you dont want it.
    I want entire filament to be solid (cold enough to be solid) as close to the nozzle hole as possible before it melts. This will make "Filament Retract Function" to work much much better and more precise.

    Surely i can increase retraction rate, but its not the same. It will have to pull melted filament causing somewhat negative pressure and then pushing it back. Thats not optimal solution.


    With "all metal" i suspect heat transfer will make it even more likely to clog (i assume)

    Do you have all metal hot end ? Whats your expirience with it ?
    Is the feeding diameter good all the way or is it expanded at some point allowing melted filament to expand inside potentially causing it to clog ?
     
  4. Printed Solid

    Printed Solid Volunteer Admin
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    Your concerns are exactly what the all metal hot ends are designed to address.

    You're 100% right that you need to keep that heat in a small area. If heat starts to get further up the filament, the filament (especially something like PLA with essentially no leathery zone) melts and becomes a plug.

    Rather than going to an insulation concept like you describe, the E3D and other all metal hot ends go for a heatsinking approach. Same intent, different method. The E3D advertises (I believe) a 5mm hot zone. A lot of people use them on this forum and are happy with them.
     
  5. Melody Bliss

    Melody Bliss New Member

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    I think you may be a little confused about the all-metal hot-ends.

    Yes, metal transmits heat significantly more efficiently than plastic. But that is a Good Thing(tm) if the hot-end is designed well.

    The all metal E3D is designed to heat the heater block that the nozzle is attached, but then the heater block is attached (using an all metal transport tube) to a gigantic heat sink that has a fan attached. This fan is attached using a mount that is 3D printed plastic.

    By using a fan on the heat sink, it decreases the heat level of the all metal portion significantly (since metal is an excellent transport for heat) and thereby keeps the plastic that is contained within the hot-end from melting and clogging.

    The reasons for using an all metal hot-end is multifold. You may want to print in other materials that require more heat than a stock hot-end can provide (for example Nylon). You want a hot-end that is better performing and less prone to clogs. Yes, the E3D and other all metal hot-ends can clog. Any hot-end can. But, the clog will tend to be at the nozzle end instead of higher up the transport mechanism.

    Let's look at the E3D hot-end versus the stock Robo 3D one.
    [​IMG]

    You can see that the nozzle on both are attached to the heater block. In the case of the stock one it's permanently attached.

    On the E3D hot-end, see the metal tube under the heater block? This minimal amount of metal means that heat transfer will be minimized. If you read the assembly instructions of the E3D, it specifies that the heater block should not be directly touching the heat sink but there should instead be a small gap. Air is an excellent insulator and this prevents the heater block from directly transferring large amounts of heat to the heat sink, which is a good thing. That means the heat mostly stays inside the heater block which heats the nozzle.

    The stock one has the heater block mostly directly attached to the plastic section (which contains the PTFE tube). This means this heater block cannot be allowed to reach the melt temperature of the plastic (or PTFE) pieces. If you do you ruin the hot-end.

    If the all-metal hot-end does get clogged, since it is the heater block area that is the most likely spot of this clog, you can actually increase the heat level to the point where you carbonize the plastic that you're extruding. This will then allow you to push either new filament through or a wire, thus unclogging the hot-end. You cannot use this method with the stock hot-end.

    Yes, I do have an all metal hot-end. In fact I have two since at some point I'm going to try to design/build a dual extruder. My experience with it is that it has been outstanding. I'm so glad I upgraded.
    As for feeding diameter, it is, as far as I know, constant. But I have yet to experience a clog on this hot-end. I'm sure it'll happen at some point. But I've been running this hot-end for probably several hundred hours and no issues as of yet.
     
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  6. tonycstech

    tonycstech Active Member

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    I see the heatsink design is awesome.
    I could use existing fan to angle it to it making it colder thus keeping the heat very direct.
    Do u have a link to their product page ?
    I think i saw it somewhere but it wont hurt to have it on more then one place.

    From the looks of it, it seems like i could swap the nozzle size quickly on this model. Is that correct ?

    Thanks.
     
  7. Printed Solid

    Printed Solid Volunteer Admin
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    Melody, you should copy your explanation into your FAQ!
    tonycstech, I'm going to be buying a few and putting them in my shop, but it won't be for another few weeks. If you don't want to wait (and I don't blame you) Tim has them in stock and on sale at filastruder.com. I'll probably have the same prices, just getting a few on hand since I'm selling high temp materials (nylons) that will benefit from the all metal hot end.
     
  8. tonycstech

    tonycstech Active Member

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    They have E3D Direct Feed - 1.75mm and
    E3D Bowden Feed - 1.75mm
    Which one do i need ?
     
  9. Melody Bliss

    Melody Bliss New Member

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    Direct feed. Robo 3D is a direct feed printer


    Sent from my iPhone using Tapatalk
     

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