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wheel to servo — Parallax Forums

wheel to servo

ltmhallltmhall Posts: 102
edited 2006-10-18 11:22 in Learn with BlocklyProp
If I wanted to mount a servo motor to a Dubro wheel could I just drill two holes in to both making sure their centers are aligned. Then place a 1” machine screw through the center of the wheel to the servo and screw it in.. Will this idea work.

Post Edited (ltmhall) : 10/16/2006 6:31:31 PM GMT

Comments

  • dandreaedandreae Posts: 1,375
    edited 2006-10-16 18:40
    You'll need to verify that the threads are the same and that the length is okay.· Do you have a link to a picture of the wheel that you want to use?

    Dave

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    Dave Andreae

    Parallax Tech Support·
  • Ken GraceyKen Gracey Posts: 7,392
    edited 2006-10-17 01:56
    ltmhall:

    This task is harder than it looks and can be very frustrating. My advice would be to get some wheels from Lynxmotion. The time and frustration could make the alternatives worth pursuing.

    If you still want to drill your own wheels, then I have a couple of ideas to help you along. Drilling a servo horn is tough - either it'll want to spin around the drill bit or it will crack. One way you can avoid this is by taking incrementally larger drill passes. This will reduce the stress on the plastic and could prevent it from taking off with the drill bit. Most servo horns are either 2-56 screw sizes or smaller, so drilling the horn and the wheel is often necessary.

    To drill the wheel you need to find the center and measure to each hole which will match up with the servo spline. A pair of calipers would help, but even better would be an optical edge finder and a mill. Assuming you don't have a mill around, at least you can find a pair of calipers to measure the distance. Two screws would work, but four is better.

    Ken Gracey
    Parallax, Inc.
  • BeanBean Posts: 8,129
    edited 2006-10-17 11:58
    Not to hijack this thead, but I wanted to make a wheel that looks like a "gear" for a robot that runs in the grass.
    I cannot find anyone that makes anything similar, and I'm wondering why...
    Is there a reason this wouldn't work ?

    I was going to make it out of 0.062" FR-4 material on my LPKF mill.

    [noparse][[/noparse]edit] This picture is NOT solid black. You have to click on it to see the "gear".

    Bean.

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    Post Edited (Bean (Hitt Consulting)) : 10/17/2006 2:14:55 PM GMT
    Gear Wheel.jpg
    411 x 407 - 12K
  • Steve JoblinSteve Joblin Posts: 784
    edited 2006-10-17 13:18
    Bean - surprised at you.... you are one of the thought leaders here and you want to make a big "gear"?· Whegs are the way to go
  • BeanBean Posts: 8,129
    edited 2006-10-17 14:15
    Whegs are too slow.
    Think about "Grass cutting robot with legs"... I don't think so.

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Cheap used 4-digit LED display with driver IC·www.hc4led.com

    Low power SD Data Logger www.sddatalogger.com
    SX-Video Display Modules www.sxvm.com

    "People who are willing to trade their freedom for·security deserve neither and will lose both." Benjamin Franklin
    ·
  • Ken GraceyKen Gracey Posts: 7,392
    edited 2006-10-17 15:44
    Bean,

    Your idea shall absolutely work, provided you have a hub with substatial z-axis depth which would serve as slop reduction to the motor shaft.

    In fact, your approach is the same as the one used by RoboCut. They're about 8" in diameter and 1/4" thick Delrin. RoboCut has mowed my yard for quite some time with this wheel design. Whegs are cool, but they could introduce a lot of friction if not designed right as they turn your lawnmower into an aerator.

    Ken Gracey
    Parallax, Inc.
  • BeanBean Posts: 8,129
    edited 2006-10-18 11:22
    Ken,
    That must be where I saw it !
    I knew I had seen wheels like this before somewhere.
    I wonder why nobody sells wheels like this ?

    I was planning on putting 4 holes in the center and bolt them to the "X" hub that comes with the servos.
    Do you think that will hold up ?

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Cheap used 4-digit LED display with driver IC·www.hc4led.com

    Low power SD Data Logger www.sddatalogger.com
    SX-Video Display Modules www.sxvm.com

    "People who are willing to trade their freedom for·security deserve neither and will lose both." Benjamin Franklin
    ·
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