Using two channel radios with Battery Eliminator
Circuitry (BEC) as servo will propel a small model boat. In this
example the servo is used to power a Lindberg Model tug. Everything is powered by
four AA rechargeable batteries.
It takes a little bit of time to modify, but they save a lot
of space and weight (not necessary in the Lindberg tug but crucial
in smaller models) and they eliminate the need for a separate speed
control.
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1.)
I
have modified several Tower Hobbies TS-53 standard servos to make
them into motors. They
cost about $10.00 (plus shipping).
I assume that other servos can be modified in the same way.
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2.)
The
first step is to remove the servo arm or horn.
Remove one screw and remove the horn from the splined shaft.
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3.)
Loosen
the 4 screws on the back and remove the gear housing.
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(4.)
Remove
the gears and the pins that they rotate on.
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5.)
Carefully pry the electronics out of the servo case.
Very carefully pry the pressed-on gear off the motor shaft. I
use a small flat bladed screwdriver for this.
Left is the motor- right is the
potentiometer which is used to adjust the motor.
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6.)
On the servo case, there is a housing that covers the end of the
motor where the gear (just removed) used to project into the gear
case. With a hobby knife, cut the housing off so that the motor
shaft is completely accessible.
The right servo has the housing cut away, while the left one
shows the housing to be cut.
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(Picture
completed servo)
Reinstall
the electronics into the housing. Press a small piece of rubber
tubing (or the insulation from household wiring) onto the motor
shaft. This tubing
will later attach to a propeller shaft of about the same size.
The back cover of the housing can be held in place with
small bolts or with a rubber band.
The other shaft sticking out of the case is a
potentiometer. This
is used to adjust the dead stop position of the servo-motor once
it is hooked up to the radio receiver.
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Typical
installation
This
shows a typical installation. The motor shaft must be located
directly in line with the stern tube.
This can be done by removing the propeller shaft and looking
thru the stern tube towards the motor shaft.
I make a simple motor mount out of scrap styrene glued to the
hull and use a rubber band (not shown) to hold the motor in place.
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