Zesty Nimble

Discussion in 'Tool heads & ToolChanger' started by Andy Cohen, Nov 1, 2019.

  1. Andy Cohen

    Andy Cohen Well-Known Member

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    I decided to start a new thread.

    So right when the power comes back on and the winds have died down I finally get my longer Zesty Cable. The one that came with our eval unit was not long enough.

    Thanks to Blarbles for the design of the Tool top bracket it was really not hard to put it all together. I had to use melt in brass inserts to bolt the top bracket to the tool bracket and I had to design a motor mount (see pics).

    Seems to print nicely. The cal cube came out perfect. Currently printing the 3DBenchy and will post here afterward. If anyone has an idea as to how to test for unwanted cable rotation please tell me but from what I see in moving the tool around by hand and while the stepper is enabled, there's no unwanted rotation at all. The result I get is an optimal DIRECT DRIVE extrusion with retraction set to 1.0mm. IMG_6146.jpg IMG_6143.jpg
     
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  2. Andy Cohen

    Andy Cohen Well-Known Member

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    The 3DBenchy came out nominal, but it does show I need to adjust the steps a bit. The real test though is with a multiple tool print which I'll try next. IMG_6149.jpg IMG_6150.jpg
     
  3. Amr

    Amr Well-Known Member

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    I just saw zesty post a design on thingiverse I think there block mount the stepper and stepper bracket to the top plate of the printer at the back my be better if you intend to use more than one. but @blarbles design for the zesty it self is better IMHO https://www.thingiverse.com/thing:3898187
     
  4. Andy Cohen

    Andy Cohen Well-Known Member

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    Note that the Tverse post is a rendering and has yet to actually be printed and installed.
    Not too sure about that motor mount design. My design is much simpler, has loose tolerances for fit and won't be effected by any heat from the motor. I'll be redesigning it to fit the 2 holes behind each dock. The rotating cable is long enough for the motor to be mounted back there and have the cables ride the Nimble rotating cable casing.
    I keep trying to find a way to test for small tool paths. I've yet to see if it solves the problem. As soon as I get a print which demonstrates I'll post. However, one thing I definitely do see in the 3DBenchy... Its a heckalot better consistency in the extrusion. Each layer line is the exact same width and there are no layers out of line at all. I saw this kind of improvement when I switched other machines to Bondtech feeders. The Titans are way suboptimal. I also get a much smaller blob at the start/end of each tool path which makes for a much easier to hide zipper.
    However the real purpose for doing the mod is to see if I can get better control on small tool paths. Much of the issues I have seen are also evident with lots of tool changing. As such I'll have to print objects with the 3 Titans and the Nimble in one. I'll need to use the Nimble on parts which are real small or have tiny areas and the Titan based tools everywhere else.

    I also need to try prints with combined PLA and TPU. No doubt the Nimble works fine with TPU.
     
  5. Andy Cohen

    Andy Cohen Well-Known Member

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    I found a good test for small tool paths. It is printing now, but the parts with the tiny tool paths (which would have totally distorted with the craptastic Bowden/Titans) have already printed and the result was perfection. I'll post comparison pics here tomorrow after the print is completed. No distortions anywhere in the path. The extruder had command authority on the flow of the material. Thumbs up!

    The good news: The nimble works and solves the tiny tool path problem. I am also seeing extrusion reliability that is almost as good as my 5 Bondtechs. I get Direct Drive performance without weight added to the carriage.
    The not so good news...
    They are sold out on their website of the previous version... the version that we have an adaptor for. V2 will be shipping in Dec and they are taking discounted preorders now. So it'll be a wait and another adapter design will be needed.

    Adding a BMG or waiting for the Herme's IMO is not an optimal solution here. These will add a LOT of weight on to a carriage which is already weight challenged. It should also be noted that the approach using a bmg from Bondtech extends the length from the contact point on the carriage down to the hot end. This makes for a significant source of potential unwanted motion I.e., slop. The Nimble IMO and IME solves the problem and works optimally with zero compromise on result.
     
    #5 Andy Cohen, Nov 3, 2019
    Last edited: Nov 3, 2019
  6. Andy Cohen

    Andy Cohen Well-Known Member

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    Look at the buttons...
    The cancelled print on the left is one of my first attempts.
    The center print was after tweaking and tuning and experimenting... basically this was the best I could do with the Bowden/Titans.
    The right side is with the Zesty Nimble... yes I still need to adjust my steps which look a bit low to me, but zoom in on the brown buttons and you'll see how well the Nimble controlled the extrusion when it's a minimal tool path for the layer.
    There are still a few kinks to figure out such as the Extrusion UI. If I go faster then 5mm/sec I get a message back about a problem with the stepper and 5mm/sec is way more then 5mm/sec. So the extrusion control on the UI panel needs to be set correctly for the Nimble. Otherwise It's working well. Next is TPU.
    IMG_6152.jpg
     
  7. Cullman

    Cullman Member

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    I have been thinking about the Zesty and the ToolChanger quite a bit. I have been thinking about an implementation where instead of placing the Zesty gearbox on the Tool, it would save some money and potentially reduce complexity if the gearbox was permanently attached to the Tool Changer/X-Carriage. Since then I have discovered the Blackbox open source tool changer that implements a similar idea but with a permanently installed and shared direct drive mechanism. The "may be too difficult to be worth it"additional idea I had was whether or not we could get rid of the C-Stepper that actuates the T-bar. I am imagining an X, Y location right before the tool banks that phsycially pushes a lever that changes gears, making the Zesty motor responsible for the T-bar locking and unlocking until it has a new tool and then goes back to the "Lever pusher" or goes to a different X, Y location that implements a "Lever puller" putting the tool head back in extruder mode. The end result is a tool carrier that would be very light, a potential cost saving of 4x on motors, additionally different tools could also take advantage of the tool head's built-in rotational movement. A pen plotter tool could interface with the gear to move the pen on and off paper, a laser could use it for a focus, a lightweight milling tool could use it for power, a heavier milling tool could use it to change the angle of the end mill/drill bit. And not to go too crazy, but a two motor gearbox could be implemented at the motor side. For instance a high power stepper and an ODrive for CNC stuff (I have another remote drive technology I am playing with in case the Zesty isn't versatile enough for all of this) While this design would not be easy to figure out in an afternoon, my gut says an elegant solution is likely possible. I'm wrapping up a Voron build and then I am going to start working on some of this stuff, but it would be great if anyone else exists that doesn't think this is madness and wants to get a head start.
     
  8. Ntesla66

    Ntesla66 Active Member

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    Nifty! With the bed dropped to around the 130 mark and a scale placed in the middle of the bed, what does the Zesty toolhead weigh resting on the scale?
     
  9. JanHouwers

    JanHouwers Member

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    How did you do the cable management with the Nimble in place?
     
  10. Andy Cohen

    Andy Cohen Well-Known Member

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    "With the bed dropped to around the 130 mark"
    I do not understand... what does it matter where the bed is in Z? The Tool stays up on the carriage and does not go down in Z. Now perhaps if the tool (#4 on the far right) is placed at the home positions of X and Y which would expose the tool to the more of the weight of the rotating cable, that is where it should be weighed.
    The Nimble itself weighs 45 grams. If I can find a scale I'll measure. No doubt the rotating cable adds a bit of weight. With the motor mount higher then the tool the motor mount will handle more of the weight of the rotating cable then the tool will.
    But compared to a stepper? I'd say it's not much at all.

    It printed TPU like a champ. Full speed at 235C. Currently attempting to print the Mosaic pliers which combines rigid with TPU. I'm doing it with PETG and TPU.
     
    #10 Andy Cohen, Nov 3, 2019
    Last edited: Nov 3, 2019
  11. Andy Cohen

    Andy Cohen Well-Known Member

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    I zip tied the cables to the red casing at the top of the tool and a loose zip tie at the back. When I move the motor to the back of the parking spot the cables will fit against the rotating cable's red casing.
     
    #11 Andy Cohen, Nov 3, 2019
    Last edited: Nov 3, 2019
  12. Andy Cohen

    Andy Cohen Well-Known Member

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    Here's the Mosaic multi material pliers. The gray is PETG, the green is TPU. A very weird thing. TPU over time starts to get weird within the V6. It's not the Nimble that is the issue it's in the V6 where the stuff starts to bind. Next prints I will have to slow it down. Never saw this with the Mk8/Bondtech setups I have on other machines.
    IMG_6153.jpg
     
  13. Andy Cohen

    Andy Cohen Well-Known Member

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    Update...
    I designed a new motor mount so that it sits behind the parking space. It just seemed to make sense... easier cable mgmt and it looks a lot neater.
    Well... It did not work. Not at all.
    Seems the rotating cable when bent 180 degrees with the 2 ends are brought close creates downward pressure on to the tool. The tolerances on the parking pins in the bracket are enough to make the tool tilt downward and subsequently unable to mate with the toolhead on the carriage. I put the motor back on the side and it works fine again, but...Unfortunately mounts on the back will not work IME.
     
  14. Rob Xaos

    Rob Xaos Member

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    What length of Nimble are you using / would you recommend?
    Any useful advice you have picked up using Nimbles in the last month?

    Having ready yours, and other, replies to my Hemera thread I am very much moving in the direction of 4 x Nimble V2 right from first build on my Toolchanger. I had planned to use Nimble on an alternate head for flexibles, but given that you and others expressed dissatisfation with the bowden drives, I now feel I would rather take the time to implement all Nimbles initially.
     
  15. Joe Pomo

    Joe Pomo Active Member

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    Hey, what is your reasoning for using the Nimbles over Hemera?
     
  16. Rob Xaos

    Rob Xaos Member

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    Mass

    The Nimble is a fraction of the mass of a direct drive Hemera mounted on the tool. I am sure there could be issues with the Nimble, as rarely in engineering do you get anything without a trade off, but I am hoping Andy Cohen might tip me off on those before I commit.
     
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  17. cj.matthes

    cj.matthes Member

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    The nimble is intriguing. The price is quite high thou. Looking forward to see more results.
     
  18. Andy Cohen

    Andy Cohen Well-Known Member

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    You all may want me to get my next 3 V2s and see how well they all work with all 4 tools as Nimble's. Zesty says delivery mid Dec. We all know how that goes with stated delivery dates so it may be a wait.

    I am using the middle length. Keep in mind that the mount for the motors should be on the side of the machine and not behind the parking spots because when the rotating cable is bent the whole 90% it pushes downward which will put the parked tool out of position for capture. I'd say that is a downside.

    The upsides of the Nimble is Weight/mass which IME means more X/Y determinism and as such increased speed is possible. It also will not have a flying stepper nor the stepper's 4 conductor cable. It also only needs 1 part on the tool for mounting and one part to mount the motor on the side (Zesty's mount IMO will not work because it is behind the parking place).

    On the side of the Hemera... It IS a dual hobbed gear kinda like the Bondtech and IME these are optimal. After Greg posted his latest tool design for the Hemera I may try 1.

    In my opinion... if one was about to order a TC I would recommend buy only 1 Titan and the 4 tools and build it with a single Bowden for now and get it printing. By the time you are all confident with the many aspects of setting it up and printing with a single tool THEN go order either Hemera or Nimble (or whatever becomes available between now and then!) rather than committing now.
     
  19. Beat

    Beat Active Member

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    Currently, there are three points that keep me from ordering a Nimble:
    • I wonder why Zesty doesn't use a dual hobbed gear - the basic design with the worm gear really lends itself to it, doesn't it?. I will look into this first before investing and finding out afterwards that Zesty or a competitor was just about to release a dual version.
    • While the 30:1 gear ratio largely mitigates the problem of the elasticity and play of the drive cable, the need for a faster-turning motor creates another problem. I'm not an engineer, but since the (rotational) energy increases by the square of the (angular) velocity, I imagine that fast rotation is really not what you want if you need to switch direction quickly. This problem could probably be mitigated in turn by a gearbox on the other end, but that adds to the complexity and increases inertia again. Ideally, the extruder gear itself with its low mass and speed could be designed to switch direction without the motor and the drive cable needing to. But I'll have to think about how this could be implemented elegantly
    • Having the motor on the side will require a significantly larger enclosure (but that's not a big issue).
     
  20. Rob Xaos

    Rob Xaos Member

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    @Andy Cohen
    Thank you for your prompt reply. I will go with the 950mm, I'm going to bite the bullet and buy 4 from the start. It is clear to me that the Titan though the length of bowden required for the TC isn't working for many. One factor in this is that I have a mostly clear December and January, but after that chaos stalks my world, and any time for tinkering about with 3D printers might be very restricted.

    @Beat
    • I wonder why Zesty doesn't use a dual hobbed gear. Not sure why, but I think it unlikely that Zesty will be releasing a dual gear in the near future as the Nimble V2 has only just come out. Who knows what a competitor might have in their sekrit squirrel lab?
    • The V2 uses 20:1 which I think helps with the angular momentum issues and afaik this has not been an issue even in the V1 with the 30:1 ratio
    • Side or rear mounted lumps are not an issue to me
     

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