Thread: Discussion Change sun 12 bladed 70mm
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Old Feb 03, 2013, 01:50 AM
mopetista is offline
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Vienna, Austria
Joined Apr 2007
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how to balance: static at all? what order the diff. parts?

Originally Posted by PAPE View Post
Peter, here is a hint...

If you static balance the fan firsts, then when you go to do your dynamic balance, your added weight will mess up the 2 plane balance. I hope you understood that, what I am trying to say is, if your going to dynamic balance beter start with no added weight.

and when you dynamic balance move your weight from the back of the rotor to the front, And on anothere note, I use an iphone 4S to do my balancing and my jig will register 0.10g
I dont know if an android based jig will be the same.
We have three parts: motor, rotor and spinner (and the adapter, that has to run true)

What others have found -.and I agree 100% - is that you first have to dynamically balance your motor. I was not successful with the balancer and now just run it, mounted in the housing, c-clip removed in my hand to feel the vibrations, peel the sticker off, put small stripes of tape on the bell at diffferent places and run it up each time to feel the balance - in the end add thick CA and kicker in the bell between the magnets where it is needed. Not difficult to get it to run nicely, especially the L-2855 series seem to need that.

If you DO NOT dynamically balance the (out-of balance outrunner - inrunners are unsually balanced) then you will never get the assembly dynamically balanced right because an imbalance in the rear (motor) can only be balanced by an appropriate imbalance in front in one dimension (rotation) but then it will wobble in the transverse axis. Also I have found that it is a lot easier to balance the setup once the motor is balanced.

Now for rotor and spinner: Ideally, you would not balace statically either of them separately at all but just both of them together dynamically. Problem is, the spinners are imprecise in their seat on the rotor, and in order to turn the rotor, you need to take off the spinner...
So I think it is still best to NOT statically balance the rotor (for the 10- and 12-bladers which are pretty good, in the case of cheap 5-bladers, e.g., you would need some crude static balancing to get the worst out). Then balance the rotor dynamically, e.g., by the clock method, and then adding the spinner - and only add weight to the spinner if you don't find a spinner position which balances the assembly nicely.

That's what works for me now without any fancy technology. Comments and suggestions welcome. I am quite frustrated that I am not able to use the dynamic balancer for the motor, and also the rotor I prefer to balance with the clock method. I put it on Bob's balancer only at the very end with the spinner on to get the very last bit out if needed.

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Last edited by mopetista; Feb 03, 2013 at 01:57 AM.
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