Timing a motor...need information, please - RC Groups
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Jul 06, 2001, 08:03 AM
The Great and Powerful Oz
Woody's Avatar

Timing a motor...need information, please

Would someone please outline the steps of how to properly time a motor, or re-time it for better performance. List the step-by-step details, along with what equipment is needed, and the end results a person should be looking for.

Thank you to all who reply.
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Jul 06, 2001, 08:13 AM
H301 Libelle Pilot
Dr. Jet's Avatar
To time a motor:

You need a constant Voltage {not "current", AW} power supply. For small, brushed motors, I use a 4-cell pack of "D" sized rechargeable alkaline cells.

Mark the current position of the endbell with a felt pen or something. Loosen the screws until you can rotate the endbell.

Use a Whattmeter and measure the no-load current

Rotate the endbell (VERY small amounts - 1/8" is a LOT!) until you get the lowest current. Note that the current goes up from this point no matter which way you rotate the endbell. This is the neutral point. Note what the current is.

This is where it gets tricky. In order to ADVANCE the timing, the endbell must be rotated in the OPPOSITE direction from the rotation of the motor. Think about itů.you want the brush to hit the commutator segment sooner. ADVANCE the timing until the no-load reads 10 percent higher (15% for "competition" motors). A motor I timed today for a Zagi had a no load current of 3.1 amps. I advanced it to 3.4 amps.

Tighten everything up and see what happens.

[This message has been edited by Andy W (edited 07-06-2001).]
Jul 06, 2001, 08:15 AM
Old Guy
Ron Cichowski's Avatar
Any timing change is a trade in performance/duration. With the model cars we were always running timed races. 4 minute heats and an 8 minute main. We would adjust timing and gearing to give us the best performance for the race and heve the battery empty at the end of the race. If you had an extra lap or two left in the pack at the end you weren't using all your potential. With the aircraft your test conditions aren't as easily duplicatable because you are not operating on a constant course against similar opponents for a fixed duration. You also have the variables of gear ratio prop diameter and pitch and cell counts. Probably a good starting point would be to establish a performance gage of what you have at conventional timing and keep serious notes (I still have the car notebook). Then start making your changes and see if any of them yield improvements. Some might become improvements as you get into a more efficient profile, others might be just trades where you give up one attribute for an improvement in another. If you are doing duration on a 1 minute motor run then maximum run time would be a feature you'd be giving up for maximum climb performance. As long as the pack made the 60 second mark you'd be okay. Etc... Have fun!