Balancing 3-Blade Propellers
The information presented here will grow. It's current form is made available to get folks moving towards saving another Bebop from vibrational induced death. More details will be added as time allows. Corrections and suggestions are always welcomed. Now.. On to the topic...
Balancing propellers greatly reduces vibrations that cause component damage and jello in video recordings. A perfect bench task for rainy days. Balancing is not difficult but does require a little patience and a bit of time..however, the results are well worth the effort.
Parrot Bebop 3-blade props are a patented proprietary design with hubs (holes & w/o holes) that help users install the correct props onto the correct motors. The props without center-holes present a problem for balancing. Balancing 3-Blade Propellers without center holes is possible using one of these optional methods and their tricks.
Starting with new parts is preferred. Balancing damaged parts may not have the desired result. If a rotor cage is warpped, or a motor shaft is bent, or a prop is damaged/bent..you are wasting your time balancing them into the mix. New parts are not balanced. Damaged parts shouldn't be used. Inspect every part very thoroughly before balancing them.
The Optional Balancing Methods...
1. Non-Powered Dynamic Balancing
Using a Bebop motor bearing shaft to support an uninstalled rotor with a prop attached. Hand-spin and gravity isolating. May be the most inexpensive method to employ..if a sacrificial motor can donate it's bearing shaft.
Using a Bebop motor bearing shaft to support an uninstalled rotor with a prop attached. Hand-spin and gravity isolating. May be the most inexpensive method to employ..if a sacrificial motor can donate it's bearing shaft.
Startup cost may be free or $10-$30 USD.
Supplies: one sacrificial motor. See video below.
Pros: Simple process. Low startup skill-level required. Quick to setup and use.
Cons: Analog, one motor sacrificed. Motor not powered through operational range.
Supplies: one sacrificial motor. See video below.
Pros: Simple process. Low startup skill-level required. Quick to setup and use.
Cons: Analog, one motor sacrificed. Motor not powered through operational range.
Video: https://youtu.be/YVUnvHZTyGI
2. Dynamic Laser Balancing
Uses laser reflection to visualize vibrations of one assembled motor/rotor/prop mounted on its arm and independently powered through its operational range. Vibrations are isolated while one motor is running as speed is increased. Requires motor circuit isolation and independent power via a 3S LiPo battery, electronic speed control, and a servo motor controller.
Startup cost is about $40 USD.
Supplies: laser, small mirror or piece of a CD-ROM disk, 3S LiPo, ESC, Servo Motor Controller.
Pros: Balances through powered range.
Cons: Motor circuit isolation. Moderate setup, startup skills, and equipment costs.
Uses laser reflection to visualize vibrations of one assembled motor/rotor/prop mounted on its arm and independently powered through its operational range. Vibrations are isolated while one motor is running as speed is increased. Requires motor circuit isolation and independent power via a 3S LiPo battery, electronic speed control, and a servo motor controller.
Startup cost is about $40 USD.
Supplies: laser, small mirror or piece of a CD-ROM disk, 3S LiPo, ESC, Servo Motor Controller.
Pros: Balances through powered range.
Cons: Motor circuit isolation. Moderate setup, startup skills, and equipment costs.
Video: coming soon
3. Dynamic Vibration Reduction
Uses a vibration detection and imaging smart phone app to visualize vibrations of an assembled motor/rotor/prop mounted on its arm and independently powered through its operational range. Requires disconnecting one motor for independent power. Vibrations are isolated while one motor is running as speed is increased.
Startup cost is approximately $40 USD before smart phone costs.
Supplies: Smart Phone, 3S LiPo, a 5-6v battery, brushless ESC, Servo Motor Controller.
Pros: Balances through powered range.
Cons: Motor circuit isolation. Moderate setup, startup skills, and equipment costs.
Uses a vibration detection and imaging smart phone app to visualize vibrations of an assembled motor/rotor/prop mounted on its arm and independently powered through its operational range. Requires disconnecting one motor for independent power. Vibrations are isolated while one motor is running as speed is increased.
Startup cost is approximately $40 USD before smart phone costs.
Supplies: Smart Phone, 3S LiPo, a 5-6v battery, brushless ESC, Servo Motor Controller.
Pros: Balances through powered range.
Cons: Motor circuit isolation. Moderate setup, startup skills, and equipment costs.
Video: coming soon
Pic of Typical Balancer:
A typical balancing jig uses a central support rod through a prop's center-hole. Good for props with center-holes..impossible for props w/o center-holes. I wouldn't recommend drilling a hole. Fracturing the plastic hub is easy and risks failure mid-flight.
posted by Christopher R. Smith (Littlehorn) @ 9:16 PM
2 Comments:
Very nice article !!!
Hope to see others videos methods soon :D
Just a thought here, but if you sacrifice a motor to do a vibration test, go one step further and remove the blade holder hub (with the 3 screws) that would be balanced and use the center hole for a conventional blade balancer. After all that " hub " has to be balanced right, just use it in the blade balancer with the prop that requires a center hole. Note that I am not familiar with using the conventional blade balancer and don't know if there is a required minimum " thickness " needed to use it.
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