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Thread: Prototype Scara Robot Arm

  1. #1
    Administrator CLaNZeR's Avatar
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    Default Prototype Scara Robot Arm

    Thought this may interest someone


  2. #2
    Member cnc_dragon's Avatar
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    Wow. That's great Sean !
    I'll be very interested to see where you take it from here.

  3. #3
    Administrator CLaNZeR's Avatar
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    Hi Eoin

    That was MK1 of the Scara Arm and we are now on MK3 !

    It is coming along well in the background and working on it in between the usual day to day builds.

    One of the main problems is getting the resolution and backlash out of the system.

    With the MK1 we used 50:1 planetary gearboxes but we just kept stripping them with the speeds we were running the stepper motors.

    So with the MK2 we actually built an arm with a combination of belts and pulleys to build up the ratio, But again backlash was appearing.

    With the MK3 we are now going for Harmonic gearboxes. These are not only compact but give us zero backlash.
    But harmonic drives costs a fortune and on the scale of up to 1000 each. We have picked up some second hand from good old ebay for testing, but looks like we will end up going down the road of having the drives made up for us in quantities to get the price down.

    The next step that is not so easy is the firmware as we need to use Inverse Kinematics to turn the X/Y target position into arc movements on each of the motors.
    These calcs are pretty well finished and proved, but now it is sourcing a low cost controller that has enough processing power to do these calcs in real time as such.

    So all good fun and will update this thread as we progress.

    Cheers

    Sean.
    Last edited by CLaNZeR; 04-05-2014 at 12:27 PM.

  4. #4
    Administrator CLaNZeR's Avatar
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    Here are some pictures of the MK3 Prototype Scara Arm 3D Printer

















    Cheers

    Sean

  5. #5
    Member cnc_dragon's Avatar
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    This is great to see Sean ! Excellent work. Any video to follow ?

  6. #6
    Administrator CLaNZeR's Avatar
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    Hi Eoin

    Videos coming soon !

    I was playing all day with the Smoothie board for controlling it, but I am not 100% convinced it is going to be fast enough.
    Even though using a controller like this would allow people to use existing 3D printing software out there.

    So I am attaching our own hardware next week that is proven and we know it can create nice clean pulses to get the speed and accuracy we need.
    Software development would then be down to us, even though we are mostly there if honest about it. But some of the mature open source 3D printing software does have a lot of bells and whistles.

    But on the plus side of using our own hardware/firmware and software we can change things to suit the users requirements.

    The heated bed pulls a fair bit of current, so a new power supply arrived today which will be more than man enough to run the hotend and heated bed. So again next week it should be squirting out PLA !

    More to come soon.

    Cheers

    Sean.

  7. #7
    Junior Member midnight30's Avatar
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    Has there been any progress on the Scara bot?

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