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Old Feb 05, 2013, 08:11 AM
we can take off without that
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Quote:
Originally Posted by Odysis View Post
Nice! It's been too long since I looked at it from 1st principles. ISO 1940/1 gives the international standard for balancing grades (and "silky" doesn't appear anywhere )

Here's a quick rundown It'd be nice to get to G3 or so, but even G10 is pretty good for these little things.

We have the tools, we have the knowledge, there is a Standard way to do things, why must the EDF fraternity ignore the lessons of those who have been doing this since 1940?
Thanks! that's really good info. I still haven't moved over to 70mm fans, waiting for HK to get some. I do a lot of hand-and-ear balancing of 50mm fans.
So for example 0.006kg rotor, 50,000rpm, 25mm radius, standard G10,
using equations from the article I would need to detect g=0.00048
is that even possible to detect using phone accelerometers?
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Old Feb 05, 2013, 04:53 PM
Life begins at transition
Australia, VIC, Sale
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Probably not. I have a different accelerometer, analouge piezo jobby. No minimum acceleration (in theory).

That shows how far out of balance (by Standard measurements) these things are, and why "smooth" means nothing.
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Old Feb 05, 2013, 08:41 PM
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Jeez, I just can't seem to get those optional aluminum spinners right. All three in my possesion cause the same vibration and "out of round" noise. Without the spinners the 12 blades are smooth and quiet.
Maybe I should try using one these iphone apps to balance them?
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Old Feb 05, 2013, 08:42 PM
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Quote:
Originally Posted by Tartago View Post
Is it the aluminum spinner?

Make sure the spinner is seating properly. It took me some time to make it click on the right position.
Can you elaborate on this? Why did it take you some time to seat them correctly. I put them on and they appear to sit flush on the rotors. Is there a trick to it?
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Old Feb 05, 2013, 09:39 PM
Bond, Hotglue Bond
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Quote:
Originally Posted by WhalleyB0Y View Post
Can you elaborate on this? Why did it take you some time to seat them correctly. I put them on and they appear to sit flush on the rotors. Is there a trick to it?
The aluminum spinner fit is very tight, in my EDF I first seated it but a ver small gap was present noticeable when looking at the assembly from the side and rotating the rotor by hand. By gently pressing from every side I managed to click it in place. Now it's true.
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Old Feb 06, 2013, 05:28 AM
Extreme CNC Alloy EDF
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Australia
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If you line it up then use the bolt to pull it down it should seat against the rotor evenly.
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Old Feb 06, 2013, 06:06 AM
Bond, Hotglue Bond
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Originally Posted by Extreme_RC View Post
If you line it up then use the bolt to pull it down it should seat against the rotor evenly.
Tried that the first time. With the plastic one it works, but the alum can dent the rotor seat.
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Old Feb 06, 2013, 07:23 AM
we can take off without that
green_flyer's Avatar
London, UK
Joined Nov 2008
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Quote:
Originally Posted by Odysis View Post
Probably not. I have a different accelerometer, analouge piezo jobby. No minimum acceleration (in theory).

That shows how far out of balance (by Standard measurements) these things are, and why "smooth" means nothing.
I have this one
https://www.sparkfun.com/products/9198

it does register a reading, of about 8mV, but I dont know how that translates to g-force. I started to use it with my most recent fan, but gave up because I realised I need a throttle stop to balance at less than full throttle, so I can eliminate throttle position as a variable. So I finished balancing by hand.
My main concern when balancing/reason for balancing is always motor bearings (noise, slightly higher current wouldnt bother me if there were no bearings to fail).
I guess those industry standards are formulated with beating longevity in mind.
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Old Feb 06, 2013, 10:41 AM
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I've been looking and can't find one of these iphone vibration programs. Can anyone point one or two out for me? I've ordered my CS10 (didn't know the 12 was available) and would like to check it when it gets here.
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Old Feb 06, 2013, 03:29 PM
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I use this one...

http://www.macworld.com/article/1140872/vibration.html

its cazlled vibration and cost $5

Here is some one using it on you tube...

How to use an iPhone app to balance your motors (1 min 46 sec)
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Old Feb 06, 2013, 07:33 PM
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I couldn't live with what I was hearing as vibration and poor balancing. I removed my rotors and spinners and spent the last couple nights hell bent on finding good balance.
I would static balance the rotors first, then the spinners. Then I would static balance them together before putting them back on. Right away I noticed a much better sound and much much less vibration.

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I also took a suggestion on using the iphone as a tool for balancing. Here is snapshot of some of my results after balancing.

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Old Feb 08, 2013, 05:13 AM
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Well my fan showed up a few days ago, and tonight I got around to making a little stand so I could bench test it and get it running smooth.

Static bench test results are;
75A @1100W
Using;
Turnigy 4S 3300 30C pack
Hobbywing 80A esc
HET 2W-25 motor

I think that my little vampire will boogie along quite nicely
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Old Feb 08, 2013, 06:14 AM
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Fairborn, OH
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With the HET 2-25 motor, shouldn't you be able to use 5S?
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Old Feb 08, 2013, 06:16 AM
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Australia, VIC, Melbourne
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The poor battery will be under a bit of duress in that!
Though you can stay well down from that level of WOT and it will fly fine still anyway. eg 50% throttle in that.
That is the sort of combo that needs 45C, and even preferably 65C. Because of the high Amps it is using to get the power number.
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Old Feb 08, 2013, 06:51 AM
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Fairborn, OH
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I use that fan/motor set-up but with a 5S 1800 40C battery in my EF-16, but you are right. I really don't need to use full throttle. It's a very powerful, light set-up.
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