12 replies to this topic

[Dave_12]

Does it make sense that the rotor on a brushless motor should be balanced?
Because if it isn't this would affect performance greatly.

[Hot Slots]

Dale have you tried balancing one of these rotors using your tire balancing process?

[Hot Slots]

It's the can that would need balanced. If you pressed the shaft out and had it balanced then put the shaft back in, I believe that would be the correct process.

Or if there was a jig you could slide the can shaft over to balance the whole thing without removing the shaft.

[Dave Crevie]

Any spinning component will be enhanced by balancing. Don't know how you would balance stationary parts of a motor. 

[Wink Hackman]

Yes they benefit from balancing.  The higher the revs the more you notice imbalance i.e. vibration.  So the 4000kv motors generally seem pretty good but dynamic balancing really helps 11000kv and upwards. You have to balance the entire rotor with the shaft in place - actually re-shafting the rotor can easily change the balance as the new shaft may not be perfectly straight or be perfectly aligned with the rotor.  You might think that the shaft can only be aligned exactly the same every time but it isn't so - I've seen rotors have visibly different out-of-round after re-shafting.  If you don't have access to anyone who can dynamically balance the rotor, you could grind points on the ends of the shaft and use a static balancer e.g. tyre balancer. In which case your balance will only be as good as your points are concentric. Good luck with that - grinding them with the dremel is not good enough.  Best free option is probably to skim the outside of the rotor with the motor spinning - you can feel the improvement in vibration straight away.

[Ken Lenz]

Her you will find a factory tour of a BLDC plant.  There is a short video on computer balancing.

https://www.facebook...8262554194665/?

[stoo23]

As far as I am aware a number of the Better quality / Performance brands, like the Emax RS series etc were Balanced.

[bbr]

ask a balancer guy to do one n see if it makes a difference

[jimht]

Mass production equals lower cost. Mass production also means better control of tolerances, which is why nuts mostly fit bolts with a very small percentage of error.

 

The tolerances of brushless motors are comparable to the tolerances in any other slot car motor I've ever seen, whether it cost dozens of dollars or hundreds. They certainly offer high performance at a lower cost than built ceramic or cobalt motors.

 

 Most people "playing" with slot cars are quite happy with the motors that are available. There are some people here that are really focused on "racing" and they really don't care much about how anyone else's motor runs as long as theirs is faster. These people will never be satisfied; it's their nature. 

 

 

 

 

[dalek]

Dale have you tried balancing one of these rotors using your tire balancing process?

The few brushless motors that I have worked with have seemed so smooth (especially compared to brushed motors in general) that it hasn't crossed my mind as to balancing them.

[Dave_12]

Stoo there is no sign of any balancing on my KC motor 

[stoo23]

You may Not see it, as it is Not like what you have come to expect on a normal 3-pole brushed armature.

If you dis-assemble the motor, you may see extra amounts of epoxy-like material in between the various Magnet segments, which is the balancing, ... much like some very old arm's that had added epoxy, before material removal via dynamic balancing was a 'thing'

 

I have not dis-assembled a KC motor but I am sure someone here could confirm or deny whether they are or not.

There are quite a few Brands of Racing style Drone motors, that are !!

[Ken Lenz]

Stoo there is no sign of any balancing on my KC motor 

Dave,
Stoo is correct the motor balance epoxy is applied one the inside of the rotor.  You will see a dark gray color for the balance material.  If you follow the link I added earlier you will see how the balancing is done - https://www.facebook...8262554194665/?