Servo - November 2015

SERVO 11.2015 29

also known as a

1230 motor — packs 30 watts of continuous power. For reference, a common 13 mm Maxon brushed motor is rated for only three watts continuous power.

Figure 2 is an example of a 1230 brushless motor with a 4,800 KV wind.

The 1230 motor has a very small mounting face pattern that appears to be designed for a single stage plastic spur gear. A metal planetary gearbox with several stages of reduction would provide a better solution. The 13 mm Maxon gearbox would be perfect as there is a large number of used 13 mm Maxon gearmotors on eBay; the gearboxes rarely have any wear, but some customization is required.

Both the 13 mm Maxon brushed motor and brushless 1230 motor share the same 1.5 mm diameter shaft. You just need to core out the Maxon motor and use the motor frame as a mount for the brushless motor. Figure 3 shows the thread mount the motor uses to interface to the gearbox.

To remove the pinion from the motor shaft and allow the motor shaft and rotor to be removed from the motor, a small torch or soldering iron can be used to loosen permanent Loctite. This is shown in Figure 4.

Figure 5 provides a sum of all the motor components. To continue the process of removing the rotor, the rear brush assembly and cover can be removed by inserting a small nail or peg into the cover hole and forcibly breaking it out. Once the brushes are out of the way, the rotor can be removed by using a small peg to hammer the pinion side of the shaft down and through the motor.

In Figure 6, use the same peg enlisted to push out the shaft and rotor to push out the center magnet assembly. The magnet assembly should come out leaving only the motor can and front thread mount as shown in Figure 7. The inside diameter of the motor can is slightly less than 12 mm in diameter, so it must be opened up with a 12 mm drill bit. This can be done in a metal lathe or even a drill press. It is preferable to grip only the thick thread mount body area. A drill collet could be used to apply equal force in holding the motor can. Figure 8 demonstrates a lathe setup. Finally, after test-fitting the brushless motor into the Maxon motor body, use permanent Loctite to secure the brushless motor into the body. Apply the Loctite to the upper circumference of the brushless motor and slide it into the Maxon motor body. Use the permanent Loctite to Figure 3.