I have been often asked, “Do I need to balance my prop?” and the quick answer is always “Yes!” A properly balanced prop will give you more rpm from gas, glow and electric engines. A balanced prop will reduce the wear and tear on your aircraft by greatly reducing vibration, which leads to reducing premature failure to all the components and thereby giving your aircraft a longer life. You need to do it on every prop, every single one. There are several types of balancers on the market today that will do a great job of getting different size props balanced. No matter which you use, the balancing procedure will be the same for all.
1: HOLE SIZING
The first step is to enlarge the shaft hole to a size that fits your engine. If you balance the prop first, then enlarge the hole, you will have to come back and balance the prop again, so save some time by balancing afterward. The best way to do this is by using a good prop hand reamer because this will keep the hole concentric.
2: FINDING THE HEAVY BLADE
The second step is to place the prop on the balancer in the horizontal position to find out which side has the heavy blade.
3: REMOVING MATERIAL
Two methods are commonly used to balance the propeller. The first involves lightening the heavy blade until the propeller balances close to the horizontal position. Use a razor blade or sand paper to remove small amounts of material while rechecking the balance. Don’t forget to wipe off any dust or shavings before re-checking the balance.
4: ADDING MATERIAL
The second requires adding material, generally clear spray paint or thin CA glue with a little kicker to the lighter side of the blade until it balances in the horizontal position. You want to use a fast drying paint and wait until it is dry, because it will be a little lighter when dry. To speed up this drying process I use a blow dryer. Both ways will work well; I generally will remove material from fiberglass/nylon and carbon fiber blades, while using the addition method to the wood blades.
5: PRELIMINARY BALANCE
Once the heavy blade is identified and the prop balanced level or within five to 10 degrees in the horizontal plane you can move to the next step.
6: HUB BALANCING
Place the heavy blade down so the prop is sitting in a vertical position. Check to see which way the prop wants to drop towards horizontal, whichever way it drops, you will need to add some thick CA and kicker to the opposite side so that the prop can balance in the vertical position.
7: FINAL BALANCE
Now move the prop to any position and see if it stays there, if it does then you have a balanced prop. If not keep adjust the amount of CA on the hub by adding or sanding off (in case you over did it) until it does. You may also have to adjust the blade weight to fine-tune the balance.
8: MARKING THE BALANCED PROP
After the prop is balanced, put some type of mark on it so you know it is ready for flight. I use a felt-tip marker to write a “B” on the hub for balance.