The Nimble

Discussion in 'Tool heads & ToolChanger' started by Amr, Aug 9, 2019.

  1. Springfield-Jack

    Springfield-Jack Well-Known Member

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    The hobbed wheel is driven by the internal cable the outer sheath is fixed at both ends Does the cable rotate any more than a bowden tube or power cables?I've been unable to find anyone suggesting this happens!
     
  2. orcinus

    orcinus Well-Known Member

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    The outer sheath is fixed, yes.
    So what? The cable is not fixed. It rotates.
    Its rotation drives the extruder.
     
  3. Springfield-Jack

    Springfield-Jack Well-Known Member

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    So what " issues with the cable rotating at its "pivot points" are there?
     
  4. orcinus

    orcinus Well-Known Member

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    Does this make it clearer?

    [​IMG]
    (Top view, simplified)

    Moving the gantry along X causes the drive cable to rotate.
    This causes additional extrusion or retraction.
     
  5. Springfield-Jack

    Springfield-Jack Well-Known Member

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    The internal cable doesn't rotate dependent on the position of the head or at least the effect is inconsequential.Can you point to anyone who has commented on this?
     
  6. orcinus

    orcinus Well-Known Member

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    Yes it does. I've just shown you it does.
    What is there to comment? It's simple geometry.

    And yes, it's not very significant, unless you print large objects - which i've literally said here:
    https://forum.e3d-online.com/threads/the-nimble.3284/#post-33168

    Why do you think people build printers with flying extruders and gimbals?
    For fun?
     
  7. orcinus

    orcinus Well-Known Member

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    If you still don't trust me, do an experiment yourself.

    Get a rotary tool with a cable attachment.
    Fix the rotary tool in one corner, put something that makes it easy to observe rotation on the end of the cable (like a cutting disc with a piece of sticky tape). Move the end around the tool-end and observe the disc.
     
  8. Springfield-Jack

    Springfield-Jack Well-Known Member

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    Doing your test with an actual Zesty Nimble shows no discernible movement of the hobbed wheel. Flying extruders and gimbals are far from the norm with Nimble installations. The five gimbal designs on Thingiverse show only one "make"(if that is anything to go by).The one gimbal design I've seen on Youtube seemed to introduce a lot of vibration (on a delta).
    Again, can you point me to a link that suggests that this is a problem with the Nimble ?
     
  9. orcinus

    orcinus Well-Known Member

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    That's because of the high gear ratio.

    Can you point me to where i've said this is a problem?
    It happens. It's simple geometry, as i've stated numerous times.
    You've claimed it doesn't happen.
    Now you've moved the goalposts to "is it really a problem".

    And just to remind you, this started with you asking how cable rotating is different than a bowden tube or electrical cable rotating. Which i've answered. Repeatedly.
     
    #29 orcinus, Aug 29, 2019
    Last edited: Aug 29, 2019
  10. Springfield-Jack

    Springfield-Jack Well-Known Member

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    "Installing it at the back causes issues with the cable rotating at its "pivot" points." That's where you said it was a problem.Also here
    "Why do you think people build printers with flying extruders and gimbals?
    For fun?"
    "or at least the effect is inconsequential"..is where I didn't claim it " doesn't happen"
    My original question -"Why would this be different from a standard Nimble installation ?The Nimble will be moving in X and Y just as it does on most Cartesian printers.Am I misunderstanding something?" No goalpost moving!
     
  11. orcinus

    orcinus Well-Known Member

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    Did you somehow miss me posting this, and citing it twice on top of that?
    But i've replied to that, rather directly.
    I said, and i quote: "Because bowden tubes and power cables rotating don't move the hobbed wheel. Nimble's cable does."

    Was that unclear in some way, or did not answer the question?

    You've then claimed that such rotation is not possible because the outer sleeve does not move, to which i've replied by explaining how that has absolutely no bearing to the cable.

    You've then continued to claim that such rotation does not exist, to which i've shown you, again quite clearly, that it does and why.

    You've then switched to "but it's negligible".
    Moving the goalposts.

    I've told you "the sky is blue", you've repeatedly said "nope, that cannot be true, i've seen it red just now". When shown a photo of a blue sky, you said "nope, that's not happening". When explained what Rayleigh scatter is and how it works, you've said "oh, but it's not always blue, you kept saying it's always blue".

    I'm done with this child play, go troll someone else.
     
  12. Springfield-Jack

    Springfield-Jack Well-Known Member

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    Try deep breathing!
     
  13. Andy Cohen

    Andy Cohen Well-Known Member

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    Finally made it to this thread now that the Bowdens are limiting what I want to do. I HATE BOWDENS!!!
    I do not understand why there's an argument about it working... We have tested one and we do not see radial cable motion as a function of cable movement in X unless of course it is stretched to an extreme position and the cable is stressed.
    The Nimble DOES come with some pretty long cable lengths and mounting one on top of the TC may work. Brian sent us one awhile back to review, but I have asked him if they have thought about the TC. Hopefully they have. I'll report back here when I hear back from him. IMO the longer cable will work at least better then what I am seeing with these craptastic Bowden setups!

    BTW... I have also contacted Roy at Techild to see if his DD UDrive is anywhere close to delivery. We'll see.
     
    #33 Andy Cohen, Oct 5, 2019
    Last edited: Oct 5, 2019
  14. Andy Cohen

    Andy Cohen Well-Known Member

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    I love a good argument! It's been way too long since MOGG!

    OK Orcinus I did EXACTLY as you suggested. I went out to my garage and took out the Dremel box with the radial cable extension which operates just like the Zesty products... like a speedometer cable.
    I connected the extension and held the Dremel in one hand and moved the other end of the cable away from the Dremel in a straight line. YES you ARE correct. The cable DOES rotate. That is until I push the little button that locks the Dremel. Then the other end does not rotate. Not at all! So.... Unless the stepper that drives the Nimble is disabled during tool path motion I do not think this is a problem. Nor do all the Creality users that are buying these things because their Bowden extruders are poop.
     
  15. Andy Cohen

    Andy Cohen Well-Known Member

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    Brackets to hold the stepper with armature pointing up and into the Nimble can easily be mounted to the back of the top of the enclosure next to or even behind the docks. There are even holes there already! Though they are a bit small. As such the Nimble cable would go straight up and arc 180 degrees and then down into the tool while parked. With the right length of cable this should not be a problem. Yes, the filament would have to move out of the enclosure... which is probably better anyways from a systems standpoint. Yes, the longer the cable the less accurate the control will be... but it will still be better than the Bowdens we have now, by quite a bit.
     
  16. Cullman

    Cullman Member

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    I am a zesty and ToolChanger owner however I haven't fimished my ToolChanger build yet, but it's my hope that I could eventually use my Zesty with the TC system.
    I believe the theoretical problem of the zesty being more fixed in relation to the carriage is likely a real one. My question is, could this not potentially be solved in software? Sort of a specialized pressure advanced that is taking the Zesty/ToolChanger kinematics into consideration. Basically, just adjust the extruder movements to take the XY movements into account. I am a big fan of the Duet products this my third printer where I have used them. One of the reasons I am a fan is DC42 seems very responsive when it comes to adding things to the firmware, see CoreXYUVAB. I can see this kind of extrusion adjustment based on XY movement would be useful even outside of TC/Zesty combos. Who knows it might even already exist in some form, or alternatively if enough of us expressed a need DC42 might implement it.
     
  17. Jai Stanley

    Jai Stanley Well-Known Member

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    Looking forward to seeing some results!

    I have to say, it was fun reading the heated back and forth (deep breathing should help: this is either a hobby or work and neither are worth increased blood pressure IMO).

    My educated but still uneducated, finger in the air, total guestimate makes me feel like the rotation of the cable will produce negligible effects on the print due to the high gear ratio of the drive; but might cause a bit of havoc if you tune pressure advance.
     

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