Balancing Propeller

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I'm new to the hobby and still building my first trainer. I would really
appreciate any comments regarding methods of balancing propellers. From what
I'm reading, it appears that balance can be achieved by addition or
subtraction of weight. Do you have to buy fixture to balance a prop? How and
where do you take weight off a prop? How do you add weight? Any other tips
or comments?

Harlan



Re: Balancing Propeller

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As a newbie prop balancing will be the least of your worries, especially as
you'll liable to break it sooner rather than later. However, most modern
props will only require a little removal or addition of weight. I've known
colleagues just add paint to a tip or sand the edge just to remove or add
weight.



Re: Balancing Propeller
For all information on propellers, refer to sub section "Propellers" at
Alan's Hobby, Model & RC Web Links
http://homepages.ihug.co.nz/~atong /

APC Props
Bolly Book (The)  [  http://www.bolly.com.au/book/title2.html being the
starting point.]
Bolly Products Showroom
Choosing A Prop for best performance
Classic Props
Doppler Effect - RPM on Ground and in Air
Garvon Products Ltd
Master Airscrew
Prop Balancing - Joe Wagner - [March 9, 1998 re Giant scale props - a
different balancing method]
Props, Balancing, Engine_Prop Ratio
SuperCool Racing Propellers
Tornado Propellers by Grish Products

Preferred method of balancing is to use fine sand paper and smooth all, if
any, molding flash (sharp edges) from around the edge of prop. Lightly sand
the back of the light tip, add a little bit of epoxy and sand that epoxy
back until prop balances. much like balancing your car tires.
The prop if in effect a wing lifting the plane forwards, do not sand the
front of the propeller.
regards
Alan T.
Alan's Hobby, Model & RC Web Links
http://homepages.ihug.co.nz/~atong /
.................................................................



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what
and



Re: Balancing Propeller
I should have known that Alan's pages would provide information regarding
this subject.

Harlan

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Re: Balancing Propeller
Alan has given you fair instructions with one major item glossed over.
REMOVE ALL EVIDENCE OF THE FLASHING down to the blade itself!  That means
remove the ridge that the flashing comes from to help reduce the cutting
edge most non wood props have.  This will not prevent injury, just reduce it
when you get you digits entangled trying to tach the running engine.  Oh, by
the way do not do that, it hurts - a lot.  Learn to tune the engine from
behind the fan, it does not hurt as much.



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Re: Balancing Propeller

> Many years ago one method used was to find a dowel which fitted snugl

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Thats all you need.  When you can get the prop to rest horizontal t
the bench w/o one blade dropping, its balanced.

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Bingo! ;)  Two blades are easy, try four, or a six blade EDF impellor.
:

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Ralph Breka
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Re: Balancing Propeller

Ralph Brekan Wrote:

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Not really, if you then rotate the prop 180 degrees and if it will g
back to its original position, then still heavier on side.

When the prop is able to sit still in ANY position, then it is mas
balanced properly.

OTOH, Does it really make a difference ?  Probably not much unless i
is way to heavy one one side.  One thing you can do is balnce it lik
suggested, then rotate 180 and check how fast it rotates back.  I
fast, too heavy on one side.  If rather slow, then probably OK

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Re: Balancing Propeller

Oh, I'm always half-cooked.... :rolleyes:  I think you're right though

it never hurts to check both sides. Too bad the guys atteh tire sho
arent so thorough.  ;

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Re: Balancing Propeller

They can only be as thourough as their machine is set up to be.  Thos

machines do need to be calibrated once and a while and who knows whe
the last time it was done ??  When you really want to be thorough, the
you have to check everything that rotates !!

They (I did, when I worked part time when in college a very long tim
ago) used to do it "on the car", with this gadget that spun the tire
like mad (those that were not engine driven), and then you had to twea
these three knobs in the middle of the attachment that was clamped o
the wheel.  Only told you how much and where on the diameter, but neve
on which side of the wheel (inside or outside)

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Re: Balancing Propeller

Wild. :eek:  Well, I use the primative dowel method and in the field

spin it on a screw driver.  It's good enough; albeit NOT perfect

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Re: Balancing Propeller
AT that's the worst advice ever given regarding prop balancing.

For the rest of you, the prop should remain stationary in any position.
To achieve this using a Dubro or TF balancer:

1. Remove or add material from heavy or light side respectively until
the prop remains in a horizontal position. Check it 180 degrees away.

2. Remove or add material from hub until prop remains in a vertical
position. Check it 180 degrees away.

3. Check prop to remain in any position on 360 degree circle.

Now how does one remove or add material? In the horizontal, you can
take a little off the tip or the back face or you can add material
using epoxy, nail polish, or tape.

In the vertical, you can file down the hub or add material. If there
are slots in the back face, you can pour in nail polish or epoxy. Some
people lose material by drilling holes!

Whatever you do, don't fly with an unbalanced prop. The vibration can
loosen every nut and glue joint and take a toll on the radio gear.
Finally prop balancing is a real art, and it takes time to learn how to
do it right.

Ciao,

Mr Akimoto


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