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Jul 18, 2009, 11:14 PM
Indoor Free Flight Modeler
Thread OP

EDF Dynamic rotor balancing

Thought I would post a photo or two of my latest toy. It is a dynamic rotor balancer from Bob Blackburn.

I ordered it less than two weeks ago, Bob emailed right away and said it would take a week before it would ship (I assume he builds them to order) and one week later I got an email saying it was shipped! Took about 5 days to arrive from the UK, and when the postman handed a box to me today I knew exactly what it was.

I had to try it out right away so I downloaded and printed a copy of the manual from his website then grabbed a fan unit, ESC, and lipo. He says to run low rpm so I used a 2S lipo to make life easy. After about 30 minutes I had my first fan balanced. Most of that time was learning what to do. But this unit is great as it tells you where to place the weight, the only thing you have to do is figure out how much weight, and that is where the trial and error comes in. Balancing was something I always hated to do as you are guessing both the spot and weight amount. Knowing the location is 90% of the battle, then adding and subtracting weight is not that hard.

The fan I balanced was a 64mm 5 blade EDO fan like that is in many of the stock ARF EDFs that are sold these days. I have flown this fan unit before and I was amazed to see how out of balance it actually was. The photo shows the tape I applied and now it runs like a top. I am quite impressed with this unit and highly recommend it. The total cost was about $230 shipped from the UK which may seem high but in reality the amount of money we spend on our EDF models it is not a large cost at all. Not to mention the time you will save balancing your rotors. I expect that a fan can be done in about 5 minutes once you are use to the process. I know I have spent a LOT or time and frustration trying to balance a fan and to me this unit is worth every penny!

I will post photos the next time a balance a rotor you can all see it in action.
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Jul 18, 2009, 11:40 PM
Dont forget the velcro straps
corsair nut's Avatar
that is sweet! id love to have one of those!
Jul 19, 2009, 12:09 AM
ozzi supercub's Avatar
That is awesome Don. Nothing sounds sweeter than a well balanced EDF. Most EDF's your hear scream and don't sound quite right. A well balanced fan should have a beautiful sound.
Would love to learn more about the process. The videos on the site don't really make it clear.
Jul 19, 2009, 04:58 AM
Registered User
Bob Blackburn's Avatar

You can download the manual it is a bit clearer what the videos are showing once you know what is going on.
Jul 19, 2009, 08:32 AM
Software always has bugs
Just have an additional idea to improve the current design. That is if a PLL circuit is implemented with a few strain gauges, the weight could be defined easier.
Jul 19, 2009, 05:29 PM
life is an oyster. shuck it!
istandalone's Avatar
i was under the impression that dynamic balancers were in the $10,000's range?? or is that harmonic balancers?
Jul 20, 2009, 08:20 AM
Software always has bugs
It could be called a harmonic balancer when your strobe light locked at the rotor's harmonic frequency.
Jul 20, 2009, 09:52 AM
"Marcy" VF-A
wekenav8r's Avatar
That's very nice Don!
Will you be offering motor/fan combos that have been balanced for sale in the future?
Thanks, Tim
Jul 20, 2009, 05:04 PM
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lavochkin's Avatar
I just received mine over the weekend. Now let the balancing begin!!!!! LOL!!!
I have talked to Bob about a year ago and he said he will offfer these again. Luckily again was now. So I jumped onto it. Don do you know how big of a fan it can handle??? I am hoping at least up to a 90mm.
Jul 22, 2009, 06:58 PM
Indoor Free Flight Modeler
Thread OP
Well I know it will hold a 70mm HET fan but I do not have any bigger fans.

Jul 23, 2009, 09:56 AM
Registered User
Bob Blackburn's Avatar
it should be possible to do 100mm and larger.

I have done 90mm fans no problem!
Aug 09, 2009, 10:10 AM
Indoor Free Flight Modeler
Thread OP

I hope you do not mind, I have resized the embedded photos as they were huge in size (memory wise). The manual looks identical now but went from 16MB down to 111kb! Much easier to download.

Aug 10, 2009, 02:04 AM
Registered User
Bob Blackburn's Avatar
Sorry folks I had missed that one.

The download from the website is now the small version.
Aug 10, 2009, 04:23 PM
Purchased a balanced fan unit from Don. 64mm fan with a wicked 4000 on 4s.
All I can say is wow!!!!!!!!!!!!!!!! very smooth. Thanks Don!!
Aug 10, 2009, 11:59 PM
Indoor Free Flight Modeler
Thread OP
Amazing the difference it makes!!!

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