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  1. #13
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    Sep 2009
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    Quote Originally Posted by stewi View Post
    ...The name "chip shooter" is likely reserved by turret head placement machines, which have a stationary rotary head and moving X and Y PCB to be populated....
    That's what I thought as well, but also heard many times a machine being called a chip shooter to designate a particular machine in an assembly line where there is also another machine(s) that is dedicated to place odd shape and high pitch components. In those cases the "chip shooter" was either an eight-head or a rotary head used to quickly place small passives.

  2. #14
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    "chip shooter" is not in Wikipedia, so I take your word for it.

    By adding the turning station, motor mounts and cams, I wrap up this project and return to paid business.
    Whoever wants to build this, I will provide logistic support and step drawings.

    Multiple nozzle heads will also require:
    Fast automatic component feeders
    Feeder set up optimization software
    Tricky multitasking software
    Large air compressor for hungry venturi generators
    Hefty gantry and motors on a solid machine base.

    With multiple nozzle head, regardless if in-line or revolver, we get likely a gain in 50% machine performance, from single nozzle.
    Adding another gantry will add another 90%.

    For Nails and others, I would propose again a dual gantry and one nozzle each head.
    The design is fairly easy, even with nozzle changer.
    The gantries are light weight and can likely be designed as a table top machine.
    The feeders are not demanding high speed.

    However, it was a fun project for me and I love to be involved in this technology.
    Attached Thumbnails Attached Thumbnails revolve40.jpg   revolve41.jpg   revolve42.jpg   revolve43.jpg   revolve44.jpg  


  3. #15
    Erfahrener Benutzer
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    Feb 2005
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    122
    Like you have presented it until now seems to be doable by a hobbyist ...
    I see it like a lasercut base board and few stepper on it. I suppose that troubles are coming on the moment when you start to build the nozzles mechanism.

  4. #16
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    Getting started could be a big hurdle too.
    I am only proposing a design plan, which can be modified.

    Also, I am a great fan of this open source concept. We could discuss any obstacles in this project and help each other to resolve issues.
    I have quite some knowledge about failure analysis http://www.steering-inc.com/about.html but admit finding bottlenecks in my own design is most difficult.

    However, I don't mind critique if it is constructive.

    Here is another thought of building the "star wheel" with 4 mm linear shafts.
    Attached Thumbnails Attached Thumbnails revolve50.jpg  

  5. #17
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    Feb 2007
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    I don't know whether to thank you or curse you for this information. I've been going round and round with ideas about how to make things a little better and easier for building. But I keep coming back to the conclusion that many elements of this design do indeed work out the best.

    Things I have changed are using 7mm wide linear rails/blocks to guide the nozzles, air cylinders for the up/down motion and rotational station engagement (with linear rails), timing pulleys and belt for the rotational motion, and an encoder on the shaft so I can use the index pulse to know the orientation at start-up. I still have details to work out, so I can't post a picture.

    I have a few questions.

    How small were you able to get the revolving wheel? I've gotten it down to 4 inches. With my lightning nozzle holders and nozzles hanging off of it, it ends up being just shy of 6 inches from tip to opposing tip on the other side. I can't see it getting any smaller.

    About fine pitch components; I found some Siemens literature that says the rotational accuracy for the 12 station head is +/- 0.7 degrees, and the 6 station head is +/- 0.3 degrees. It appears the rotational accuracy of the rotary head design is a function of the disk diameter located on the nozzle.

    http://www.automation.siemens.co.uk/...0606_final.pdf

    So there is some limitations for very fine pitch, large BGA's such as FPGAs. Hence the option of the "TwinHead" mechanism for these parts, which has +/- 0.07 degrees accuracy.

    The spring on the nozzle...it doesn't make much sense to me for how it is drawn. Can you include a post showing a transparent body housing with the bearings and spring?

    About only picking up 7 components on the first round. You could check the fudicials first and then load the parts to avoid this. But I suppose this is just an optimization so you can already pick up parts while the next board is loading, right?

  6. #18
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    Looking at the wire frame ACAD drawing, I get a 142 mm diameter. 4" is very nice.
    I anticipated a spring which forces the pins in the hollow shaft against the lower bushing. Upon placement, pick up and rotation pin and shaft will deflect the spring.

    Wish you'll a happy and successful new year!!
    Attached Thumbnails Attached Thumbnails revolve20.jpg   revolve21.jpg  

  7. #19
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    Adding one more thought to your discomfort.
    Although I like the idea with linear tracks and re-circulating ball carriers, it makes the head quite expensive and heavy. I would rather consider less expensive slides and easy head exchange feature. Ideally you plug the entire head into a single connector, using alignment pins and a single latch holding the head in place.
    Into the same place you can plug in another spare head within seconds or even a single nozzle head, while maintaining the other head.
    If your placement head becomes too expensive, you'll likely not effort an extra head.

  8. #20
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    Yeah, linear tracks add about $450, but the added precision and virtually frictionless travel are appealing to me. I was afraid there might be a chance for binding without it, as the extending air cylinder (in my modified design) needs to be offset from center and spring loaded.

    >>Ideally you plug the entire head into a single connector, using alignment pins and a single latch holding the head in place.

    Definately one more thought for my discomfort.....I'm not sure I want to tackle that.

  9. #21
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    Further considering the costs of the linear guides, they are actually only required for the z-axis. If you keep the segments seated with conical pins at the wheel with spring force and drive the segment down with a foot shaped guide, than you would require only one expensive linear guide.
    Attached Thumbnails Attached Thumbnails revolve30.jpg   revolve35.jpg  

  10. #22
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    oops, feet need to be wider, else the segments don't fit through the z-axis rods.
    Attached Thumbnails Attached Thumbnails revolve36.jpg  

  11. #23
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    Mar 2011
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    Re: Open source P&P revolver head

    Hi,

    actually i am confused in the vacuum distribution design.
    how it work actually?
    Possible to share me the detail?

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