Prop balancing

[nosedive]

When people say to sand down the back side of the prop to remove weight do they mean the bottom side of top side of the prop if looking at one that is mounted on a multirotor?
Thanks

 

[mailman35]

from RCG. also the google would give the same.

"From the Vibration and Balancing Soulitions section in the Quadrocopter and Tricopter Mega Link Index

--TIP 4: Balancing props and motors first separately and then together dynamically is important for reducing vibrations which can interfere with gyros and accelerometers and cause fuzzy photos and video. Magnetic balancers are best for static balancing props. There are various techniques for dynamic balancing of the prop and motor combination, such as the procedure suggested by OMM here: http://www.rcgroups.com/forums/showp...&postcount=228. **Laser motor balancing is recommended and can also be used to assist in the dynamic motor and prop balancing using OMM's method: How to balance a brushless motor using a Laser Prop balancing video tutorials: Prop balancing video tutorial and HorizonHobby.com How To - Prop Balancing and Motor balancing by sound by Alllbe and Balancing 3-bladed props. Prop balancing threads: http://www.rcgroups.com/forums/showthread.php?t=1377953 and http://www.rcgroups.com/forums/showt...4#post20203295 ""

 

[nosedive]

ive searched and watched the tutorials I just do not know what the definition of the "back side" of the prop is, when looking at a prop thats attached to a multirotor is it underneath or on top?

 

[piscaj]

ive searched and watched the tutorials I just do not know what the definition of the "back side" of the prop is, when looking at a prop thats attached to a multirotor is it underneath or on top?

I believe the answer your looking for is the concave side the side that make a slight curve inward or you could also say the side that meets the motor not the nut. :tennis:

 

[MEWERT]

When people say to sand down the back side of the prop to remove weight do they mean the bottom side of top side of the prop if looking at one that is mounted on a multirotor?
Thanks

The backside is the biteing surface, not the back edge.

I was taught not to disturb the backside, so I do my adding or subtracting of weight to the front side. I spray a bit of clear satin Lusterkote (Tower Hobbies) on the front of the light blade until it overbalances a bit. As the spray dries, it will become lighter and balance out. As you get the hang of it, you will achieve balance in one application. It usually only takes a small light shot of spray to balance.

 

[piscaj]

The backside is the biteing surface, not the back edge.

I was taught not to disturb the backside, so I do my adding or subtracting of weight to the front side. I spray a bit of clear satin Lusterkote (Tower Hobbies) on the front of the light blade until it overbalances a bit. As the spray dries, it will become lighter and balance out. As you get the hang of it, you will achieve balance in one application. It usually only takes a small light shot of spray to balance.

Subtracting some material from the back side should be done closer to the hub and not the tip of the propeller, because if you remove to much material from the tip, it will degrade performance. I'm not an aerodynamics expert, but I'm sure someone in this forum is and could explain why. I wish I had your patients with the spray paint, I'm sure you get a better end product. The back side of my props are all scratched up. :tennis:

 

[MEWERT]

Subtracting some material from the back side should be done closer to the hub and not the tip of the propeller, because if you remove to much material from the tip, it will degrade performance. I'm not an aerodynamics expert, but I'm sure someone in this forum is and could explain why. I wish I had your patients with the spray paint, I'm sure you get a better end product. The back side of my props are all scratched up. :tennis:

It only took me 30-40 minutes to balance 12 new props. That dosen't require too much patience. In my line of work, unless I produce at least 99%, I don't get paid. So, that kind of shapes your life in all you do.:strawberry:

 

[BerndM]

I've been flying various forms of RC aircraft for 40 years and if there's ONE thing I learned in all that time is to NEVER sand on ANY part of a prop. That prop's strength is the result of a lot of complicated design parameters and doing ANY sanding will alter that. Furthermore, when you remove material from a prop, you invariably compromise the structural integrity of it. Why take such a risk?
I have found that applying a small piece of vinyl electrical tape folded over the LEADING edge of the prop is all that's usually required. On the remote chance of it coming off in flight, you're no worse off than you were to begin with. Even when I was flying very high speed, high performance nitro engined planes, I NEVER had a piece of tape come off.
Just my 2 cents worth.
YMMV