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Hex head motor shaft

  1. Jan 11, 2006 #1
    on a smaller electric motor
    the motor output shaft is cylindrical with a hex head insert
    i am just directly attaching it to a small tire
    is there a certain type of drive shaft that anyone could recommend
    i thought about using an old allen wrench
    but had nothing to hold the drive shaft into the motor output shaft
    any suggestions?
    thank you
     

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  3. Jan 11, 2006 #2

    Danger

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    It would be helpful if you knew what the motor came out of in the first place. If you can find one, there might be a proprietary hook-up that you can salvage. The closest that I've seen to something like that is the power seat motor pack from a car, which has a square inset for a speedometer-type of cable to dock with.
    In any event, if the hex socket is deep enough, and the shaft big enough around, I look at drilling and tapping a hole in the shaft at right angles to the axis and running in a set-screw to clamp the hex rod in place. It would work even better if you notch the rod where the screw intercepts it.
    If that isn't practical, you could epoxy it in place with something like JB Weld. It probably won't be removeable after, though, so make sure that you have it properly aligned the first time.
     
  4. Jan 11, 2006 #3
    it is a Denso motor DC 12volt 1.5 amp 160 rpm
    with a gear casing on it
    seems to be a worm attached to a helical gear
    so the motor shaft is perpendicular to the motor casing
    i picked it up from a science surplus store
    i feel like its a windshield wiper motor...
    yeah i thought about using JB weld. but i eventually want to use it on another project
    drilling/tapping should work. the OD of the shaft is approx 7/16ths inch
    you think this is too small to drill/tap it out?
    thanks for the reply
     
  5. Jan 11, 2006 #4

    Danger

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    7/16ths is a lot bigger than I was expecting, actually. You should have no trouble drilling up to 3/16ths, but 1/8th is probably adequate.
     
  6. Jan 11, 2006 #5

    FredGarvin

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    I may be missing the point here. Why do you need to have the drive shaft fixed at the motor end? Why not let it float between the wheel and the motor shaft? The wheel should be mounted on static structure. The wheel can control the distance the drive shaft needs to be. If you used an allen wrench that has a ball end on it, like this
    [​IMG]
    you could let the wheel hold it in place. The ball end would allow for misalignment.

    Explain your set up a bit more.
     
  7. Jan 12, 2006 #6
    what the final project is going to be is a R/C cart to drive a high powered rocket to the launch pad (think NASA shuttle crawler but much smaller)
    its just a fun project for a competition
    i am looking to keep it as simple as possible, so as to not take too much time away from the actual competition

    i am going to have 2 motors for each side of the cart
    that way it can skid steer and simplify this project a little
    i just have 10 inch diameter plastic wheels and was thinking of just directly attaching them to the drive shaft
    and running the shaft through a cartridge bearing in the frame
    and then to the motor output shaft
    i hope this clears up some questions
    thanks for the help
     
  8. Jan 12, 2006 #7

    FredGarvin

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    Ahhh... I see now. That makes sense. Does the wheel have a hub that you can insert a larger diameter dowel in? Here's what I am thinking:

    Drill out the center hub of the wheel and insert a solid round piece to extend the hub. It should be a tight fit and then use an adhesive to hold in place. Then drill out the center of the piece that you put in the wheel slightly oversized for the motor shaft. You want it to be a bit of a snug fit, so I'd say the next drill bit larger than the 7/16. On the outside of the insert, you can drill and tap a radial hole to accept a set screw. You can put 2 180° apart if you want to use two of them. Insert the motor shaft and use the set screws to hold the motor shaft in place and to transmit the torque to the wheel hub. Since it's low speed and torque, it should hold fine. You may want to file a couple of flats on the motor shaft for the set screws.

    That's my first suggestion. If that's not doable, we can come up with other ways.
     
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