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I Give Up-- what's It called?? — Parallax Forums

I Give Up-- what's It called??

Jerry ElyaJerry Elya Posts: 16
edited 2010-07-30 16:59 in General Discussion
Got a bunch of those really cheap (price) 12V gearhead motors that are flooding the market. Slowest 5RPM, all the way up to 300 RPM.

I have large (6 to 62 tooth, 1/4in thick!) Kelvin plastic gears, and I've been attaching them to the motor shaft by drilling them out to 1/4in and press-fitting the gears on. So far, so good, but if I don't run into a problem with load exceeding friction, I'll have one in October after 1, hopefully 2 weeks (if I place in the top 10 after the first week is up).

The motors all have flatted shafts. I can't find the matching connector because I have no idea what it's called! It's a disk with a hole that has the matching part of the flat filled in to keep itself from spinning on the shaft. The dish has some way of attaching to a gear or wheel.

And, how do I spec it for an order, and here do I get a bunch? I guess I'd use diameter across a round dimension, but is the flat a "standard", or do I have to measure that too? Diameter at flat. or width of flat?

Comments

  • W9GFOW9GFO Posts: 4,010
    edited 2010-07-29 05:30
    Not sure, may be called something like a "D" shaft. Typically the connector, or adapter piece will have a set screw that engages the flat, then the gear attaches to that.

    Rich H

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  • ElectricAyeElectricAye Posts: 4,561
    edited 2010-07-29 06:42
    Mcmaster sells something called a D-profile shaft.

    www.mcmaster.com/#catalog/116/1069/=8617br




    Or are you talking about a keyway on a shaft?

    shaft.jpg

    Post Edited (ElectricAye) : 7/29/2010 6:54:56 AM GMT
  • khd00khd00 Posts: 13
    edited 2010-07-29 10:41
    Morning:

    Its just a hub with a set screw meant for attaching to a D shaft. Measure the diameter of the motor shaft only as if it were fully round. I doubt you will find a hub with a D hole, the set screw will secure it fully.

    ServoCity has them www.servocity.com/html/set_screw_hubs.html The holes in the face of the hub are for attaching your gears/sprockets.

    Kevin
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-07-29 11:09
    It is all about torque. As a motor outputs more power, the size of the shaft increases (so that it won't break off) and the problem of transferring the power to a gear or a pulley requires more grip.

    Tiny shafts use collets or set screws on a round shaft, sometimes just a friction fit (toy gear motors).
    The next size up often use a set screw of a shaft that has a flat spot (you can make your own flat spot with a file).
    Really powerful motors have a keyway slot in the shaft and the pulleys or gears have a matching keyway. A piece of metal called a shear pin is inserted to transfer the torque. Sometimes these have set screws as well.

    If you get any large (like the drive shaft on an automobile to a universal joint) the shaft and mate are splines (cut with a series of matching grooves).

    Often you can enhance the grip of the smaller shafts with a glue - like epoxy. Locktite has specific products for this.

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    Ain't gadetry a wonderful thing?

    aka G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan
  • Jerry ElyaJerry Elya Posts: 16
    edited 2010-07-30 16:49
    The Servo City set screw hubs are exactly what I need! Already have a bunch on order. Thanks a million--- it's hard to google something when clueless as to what it's called.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2010-07-30 16:59
    You can find good collet adapters for small shafts from R/C controlled airplane suppliers. The make them to attach the propeller to electric motors.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Ain't gadetry a wonderful thing?

    aka G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan
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