kuplo

So, out of curiosity, I bought a prop balancer. Just the little finger balancer for about $5.00 to see just how balanced the props are that Im flying with. On a couple different message forums I've had people comment that it doesn't make a difference, especially for the planes that I fly but I now think differently.

I use the APC 8x6E prop on my Rascal 400 and quite a few people told me on the forums that the APC props are pretty well balanced and that I dont need to even check them because they are balanced so well. But aparently with the 20 different APC props that I have laying around in my tool box, ALL of them were unbalanced to a certain degree. I found that the APC 8X6E props that I have (6 of them) were extremely unbalanced. I say extremely because of how fast the heavier side dropped on the balancer.

So after balancing one of the props by sanding the backside of the heavier blade until the prop sat balanced on the balancer and putting it on the Rascal 400 I noticed a major difference. The plane had far less vibration and the vibrational resonance sound was greatly reduced. It use to vibrate so much that I think if I was able to sit inside of the plane with the motor on, it would have vibrated out the fillings in my teeth.

Now Im balancing any unbalanced props that I have that will fit on this prop balancer. I have a bunch of GWS props of varying sizes for my slowstick, but they dont fit on the handheld prop balancer so until I can make my own they will have to wait.

bigchap

i never used one until 2 months ago,i always buy apc props and thought they were such good quality that they wouldn't need to be balanced,i was wrong.

APIA

I use a DuBro balancer and I agree with bigchap, APC's are bad but Master Airscrews are worse. Instead of all the sanding, (been there for hours doing that) I use polyeurthane in a spray can to balance props and works pretty good. APC and MA need to have all of the sharp edges removed via sandpaper before spraying. It is a lot less time consuming this way anyway for me. Vibration is the enemy of your onboard electronics...

kuplo

It really makes me wonder if the people that have told me that there is no need to balance my props are people that are getting some really good quality props that never need balancing, or people that just dont wish to spend at least $5.00 and get a prop balancer.

I was wondering why my recent planes instruction book said to secure the receiver in the receiver area of the plane with some foam. I figured it just barely fits in the area for the receiver and weighs next to nothing so a slight shift of 1/4" wouldnt hurt anything, but they must have mentioned securing it with foam so that the foam absorbs some of the vibration then.

Skinny Bob

My Feedback: (12)

kuplo, I agree with APIA. The best way to balance is by painting the lighter side with clear. On wood props I even sand them smooth and clear coat the whole prop. I may be wrong, but I feel a smooth prop is more efficient. Just my 2 cents. Bob

Richard L.

My Feedback: (24)

I use clear fingernail polish to balance props. Fingernail polish is rock hard and relatively heavy, so it doesn't take much to add some weight to the lighter blade.

kuplo

Do you guys sand your props in the area where you are either spraying on clear coat or applying fingernail polish? Because I would think in the long run that it would eventually come off because it would be like painting on top of a cars clear coat that is shiny and doesnt really offer the paint anywhere to adhere to the painted surface so in the case of a prop, it's shiny smooth plastic.

APIA

For plastic/composite (APC & MA) the only thing that I sand are the sharp edges. I wipe the prop down with alcohol and spray away. I have never had the finish come off. I use spray polyurethane.

MinnFlyer

My Feedback: (4)

I don't fly electrics, so I can't comment on any aspect of how vibrations may effect them, but as far as glow engines go...

I have a prop balancer, and I have used it 4 times in the 14 years that I have owned it - So I don't say not to worry about balancing just because I'm too cheap to buy a prop balancer... Well, ok, I AM too cheap to buy one - it was a gift - but I still don't use it.

Look at it this way, even if you had a prop that was PERFECTLY balanced, you STILL have a piston that is moving up and down 166 times per second (At 10,000 RPM). Don't you think that THAT is going to cause some vibration?

A test was done a few years ago that proved that a prop with the heavy side opposite the piston's travel actually caused LESS vibration than a balanced prop.

So......

Should you balance your props? Sure, why not

Do you NEED to balance your props? No, Even though I own a Prop Balancer, I still don't bother.

OldScaleGuy

My Feedback: (2)

I always balance all my props using the sanding method. In 27 years of flying, it is a habit. As far as is it worth? Beats me, but it can't hurt to take a little time to do every thing as best we can. It is sort of like the old question should I shake my fuel.... answer,,, why not!

Richard L.

My Feedback: (24)

Ditto. An unbalanced prop would cause more vibration than an unbalanced engine. For one thing, the prop blades have longer moment arms and higher rotational inertia, so being slightly unbalanced will be noticeable. It's like an unbalanced tire/wheel on your car versus and unbalanced wheel axle.

flipstart

In a hobby like ours where there are so many things that can go wrong-just seems like good sense to eliminate all the known variables possible-do everything you can to keep "Murphy" locked in his closet. Will an unbalanced prop cause excessive vibration-absolutely-easy enough to check. Do all props come balanced-absolutely not. Seems like removing unwanted flash from a prop and balancing is a easy way to eliminate any potential problems.