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61299RE: Cheapo linear actuator using a pager motor?

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  • robots42
    Feb 6 12:55 PM
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      The restoring spring is going to subtract from the available pull. The steam engines I have seen used gravity acting on the balls for the restoring force rather than a spring and the govenor didn't do much work, it just closed down a valve for the steam.
      You could calculate the available pull from the assemble but for a pager motor it won't be much at all and you would need a very low friction thrust bearing to do the pulling.
      Back in the early 1960s Peter Holland in Radio Control Models and Electronics used a similar flyball design to drive the steering winch on a 6 inch long radio controlled car. The flyballs driven by a Kako-1 (IIRC) worked as a friction clutch inside a cup which turned the 1/32 inch diameter winch which wound in thread to pull on an Akerman steering rod to steer the wheels. A spring returned the wheels to the opposite lock when the flyballs disengaged. The 1/2 inch diameter cup and 1/32 inch winch gave a 16:1 mechanical advantage which was still only just enough to steer the wheels when the car was moving.

      There are small linear servo using pager motors and leadscrews, see
      http://www.hobbyking.com/hobbyking/store/__11737__hobbyking_ultra_micro_servo_1_7g_for_3d_flight_left_.html
      with an 80g pull for $4.29

      A simple leadscrew actuator is going to much easier to make.

      David
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