How to Modify a Servo 
Using an inexpensive servo you can power your R/C model 
 

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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.

SERVO MODIFICATION

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.

 

2.)
The first step is to remove the servo arm or horn.  Remove one screw and remove the horn from the splined shaft.

 

3.)
Loosen the 4 screws on the back and remove the gear housing.

 

(4.)  
Remove the gears and the pins that they rotate on.

 

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.

 

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.

 

(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. 

     

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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