well, that's an annoying thing to do ...!
But definitely rewarding.
My test bench was actually the arducopter arm, on which i mounted the prop to be balanced.
i hesitated how to balance them, as ordering a balancer now and waiting for it to arrive for a month would piss me off....
as i tried to run an un-balanced prop, the vibration were so noticeable that i decided to test it on the frame itself.
the before and after difference is HUGE.
and finally this is the testing setup:
Comments
@Jack,
The motor mass has a very small moment arm compared to the propeller. When I used to build slot cars, I would balance the motor armatures on knife edges. We did a comparison of balanced versus out of the box brushed motors of the period and could not tell any real difference. However, I have run 12" dia props, balanced and unbalanced, and there was a substatial amount of vibration with the unbalanced prop. I am proposing that the propeller is the source of most of the vibration encountered in the frame. And, by the way, when you come up with a cheap motor/propeller dynamic balancer, I will be the first in line to buy it. Notice, that I said cheap.
Just a thougth.
Regards,
TCIII
You have convinced me about buying a proper prop balancer ;)
How about this one?
@AR
Very selfexplanatory vdo. Thanks.
Looking for your maiden flight.
i was thinking that too,
actually i ran the motors only, at full speed, they were perfect - no vibrations at all.
when adding the shaft and prop and spinner, and running slowly, it seemed like the spinner is not perfectly centered....
then i decided to associate a shaft and spinner to every prop, balance them on quad, and keep them together so i have prop+shafts pairs balanced.
the most complete way will be balancing after tightening the prop on the motor, sanding the prop without taking it off the motor, so the tiny gaps (micro) between the prop and the shaft couldn't change while removing the prop....
but eh, let me fly it before that :)
No one is arguing that it is "wrong" to balance off the quad. I was just saying that balancing on the quad can be considered a more complete technique.
It will account for motors that may not be "perfect".No matter how perfect your motors were out of the factory , they are only new once. Unless you have NEVER crashed , which is a very very small subset of pilots. The most likely reason you are replacing a prop is because of a crash of some sort. Making assumptions about the motor condition after an event , is not the safest assumption to make.
Similar to how you can have your car tires balanced off the car , or on the car. On the car is more complete , but requires a bit more work to do properly.
i thought i would add to this. found a reasonable priced magnetic balancer.
http://www.hobbypeople.net/index.php/rc-airplanes/airplane-propelle...
@Jack,
The assumption is that the motor + shaft has been "reasonably" balanced by the manufacturer so it will not come apart within the "warranty" period. I use quality motors that have insignificat runout unlike some foreign products. On the other hand, neither APC or MAS makes any effort to balance their products. I have balanced many APC and MAS props. Some (slow flyer) hardly needed any compensation where others (thin electric) took several hours to become balanced. The props are large mass moment arms with mass profiles that are reflected in thier pitch, length and type. Just balancing a long moment arm mass will greatly reduce vibration.
Just a thought.
Regards,
TCIII
@ Dany Thivierge
I think it can be argued that balancing the prop while on the quad is more precise .. Perhaps precise is the wrong word. More 'complete' maybe. .
While its on the quad , you are balancing the whole "system" .. when off all you are balancing is the prop. And really , thats what needs to be balanced. Not ONLY the prop, but the entire rotating mass of prop + shaft + motor.
I am looking for some dirty cheap props for inminent breaking
Has anyone tried these 10x6 props?
Thanks Dany.
TCIII,
I have the cheaper props because they came with the frame kit.
http://store.jdrones.com/product_p/ac1245bl.htm
after upgrading to Hexa, i will probably order these ones which are said to be stronger
http://store.jdrones.com/product_p/ac1245comp.htm
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