Hi All,

I'm not sure if this is the forum to place this, but it just might be interesting to some of us..

A while ago I was waiting for having my car-tires balanced when I thought that must be possible with my motor-prop combination as well.
So what I did...
Got an old 9DOF razor board from Sparkfun, a motormount, a laserpointer, old transistor uses as light sensitive element, ESC and some programming skills and assembled this into a "Dynamic outrunner and propellor balancing Unit".
The razor board is equiped with an 8 MHz Atmega 328 chip that drives the ESC and reads the light sensitive transistor. Communication to a PC application is done by serial I/O
How it basically works:

- connect the razor serial port to your PC running the visual basic application.
- place the outrunner with propellor mounted on the stand. This stand is flexible mounted on the wooden base plate.
- mark one blade of the propeller with a marker. With each succesive balancing-run this marked blade should be on the same starting position.
- on the pc-application click the "RUN" button.
- now the motor runs from 1000 to 3000 RPM while the accelerometers on the razor board are constantly read. The measurements are sent to the PC-app.
- this pc-app shows the place where a counterweight should be put. It also kind of indicates the mass of it.

Done this several times to test the system and till now it works very well :-) I noticed that not only propellors need balancing, but also the outrunner itself. Could just be poor chinese quality as well :-(
All video's I shoot with my quad are without any halo-vibration-effect since and the quad is vibration free.

What else did I do:
- motors are mounted with shock absorbing supports.
- I removed the circlip from the outrunner-axle. This not only makes the balancing action very easy (just pull off the propellor unit) but also saves the bottom ball-bearing from excessive wear. I know some people may say
this is dangerous, but I never experienced a lost propellor. Every 50 flying hours I replace all bearings with quality european bearings.

Config:
motors: 4 X KDA 20-22L from Hobby King
Prop: APC SF 4,7 * 10
APM 1.4 Hotel & Oilpan with selfmade MS5611 baro-modification
ESC: Turnigy 25A basic 3.1 met simonk firmware, all calibrated manual
3DR radios 900 Mhz, HF decoupled by ferrite ring
sparkfun compass removed from frame by Starship Enterprise construction, shielded cable
Ublox LEA-6 GPS
RX/TX 40Mhz Robbe/Futaba F14 8 channel, ch5:6-way diy-mode-switch, ch6:potty, ch7 extra switch
No sonar
Lipo 4000 1p3s
2 X ubec DE-SW050 Fixed 5V switching regulator(http://www.dimensionengineering.com/products/de-sw050) both with 220uF, 10uF tantal and 100nF parallel. One system for apm + RX, the other for, leds, 3DR radio
4 Ledstrips, discrete driver 2n2222 (yes, leftovers from the stone age)
quad made of: carbon en forex (= foamed PCV). The carbon arms are two crossed rods of 1 meter each.
motors on flexi mounts
apm, dampening with 2 millimeter neoprene + aluminum.
Powerboard: diy 2 * Y, wires to motors not yet twisted, but no effect on compass
No bullet connectors to ESC and motors, all soldered
Camera Canon A3300 with CHDK hack for interval shots and RAW images, even movies are good (love it)
Camera gimball: some chinese carbon thing, works well. 2 X Hitec HS-322HD servo

Total weight: 1.8 Kg w/ camera & gimball, Flighttime 10 min, without camera 12 minutes.
Size M2M diagonal 75 cm

See attached files for pictures and pc app screen dump

Off course, I'll be happy to share code and more insight information if anyone is interested.

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Hi,

I am a newbie and I struggle to balance my motors/propellers. Unfortunately, I can't make my system working so I will appreciate any help. These are my questions:

1. Is the dpb2 software working on win7 64 bits?

2. Could I use an Arduino Nano board (16MHz) if I set the ATmega328P clock prescaller to 1/2 in order to reach the 8MHz target?

Thank you in advance for your help!!!

Hi, 

It's me again...

Can someone tell me why I can,t see any communication on COM port? I had modify the dpb.conf file to match the COM port number I could read on Device Manager window. Is it something I did not understand about installing the dpb3 software?

Hi Frank,

My name Is Yves Arbour and I live in eastern Canada. I have been flying model aircraft for few dozen years... but recently started building my first drone. I am also a retired aircraft mechanic from the Canadian forces and spent over 15 years working on various type helicopter (Kiowa, Twin huey and bell 412) I spent several hours balancing main and tail rotors and I find your prop balancing project very interesting... I would love to attempt building a similar rig to yours... Is your project still active and do you have files you could share at least to get me going in the right direction

Have a nice day

Yves Arbour

There is a commercial solution from Dynex Hobby in Oz.

The Impulse has a support thread on RC Groups. References to Vortex are for the older product.

It is not a home grown solution, but it is current and up to date...unlike this original post.

EDF balancing is the predominate topic of late, but dynamic balancing of props and rotors should be in scope.

The product videos show several applications. The test rig design is key to obtaining good data. 

-=Doug

Hi Doug,

Thanks a lot for the info I checked the links you mentioned and the Dynex commercial solution is really interesting and I find it very affordable

Have a nice day

Yves



R. D. Starwalt said:

There is a commercial solution from Dynex Hobby in Oz.

The Impulse has a support thread on RC Groups. References to Vortex are for the older product.

It is not a home grown solution, but it is current and up to date...unlike this original post.

EDF balancing is the predominate topic of late, but dynamic balancing of props and rotors should be in scope.

The product videos show several applications. The test rig design is key to obtaining good data. 

-=Doug

Hello Frank
I hope you're still looking at these posts! I appreciate the work you've done here.
I'd like to try building a similar balancing system. Could you please make the code available, perhaps as another attachment or by download from some website?
Right now, having looked at the screenshot, I'm wondering what quantities you are actually plotting in the strip-chart graph and also in the circular graph?
Thanks very much.

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