Hi,
In my spare time I race model cars for fun. I race both off- and on-road cars, all electric 1/10th scale.
I have three on-road cars, all Tamiya:
I also have some off-road cars:
This is not a racer but it's so nice to look at.
Also a Team Associated RC10B5M and a Team Associated RC10 classic re-release.
My question concerns the last two.
I would like to balance the wheels of the buggies to improve handling, I think there is a lot to be gained by balancing.
The front wheels can be statically balanced so I don't need a fancy tool to do it.
The rear wheels however have more width and I would like to build a tool to dynamically balance them.
Does anybody know if a tool like this was already made and shared? As I don't know how and where to start I post this thread hoping you can help me.
I think I need a tool that is driven by a motor (old brushed motor from RC car, or even new, some cost next to nothing). I have old motors and some left over esc's (electronic speed controls) which I can command using the servo command in Arduino.
The angular position needs to be measured with respect to the imbalance of the wheel in the tool so some form of encoder and start angle device are needed.
Furthermore 2 supports for the balancing shaft are needed housing accelerometers to measure the imbalance. How should they be positioned and how to program it?
Thanks in advance for your answers and interest!
Leo
You don't need a full encoder. Just a single sensor on the shaft like you are measuring RPM. To get intermediate angles, you can assume speed is constant so just do it by time.
Have you looked into the physics of how much weight a wheel that small in diameter and light in weight at full RPM would be off by? From years of personal experience, I know a competition go-kart tire which is approximately 11" across, 5" wide and 35" in circumference, rarely takes more than 1/4 ounce to balance. Competition kart tires spin more than 2000 RPM.
I would be more concerned about eccentricity than weight imbalance. Are the outside of the tires circular and concentric with the bolt hole in the center? The car doesn't have a lot of weight to help press the tire down, unlike real cars. Automotive tires are not perfect circles, and neither are their rims. Combined, these factors cause the tires to be egg-shpaed and have a high spot. One of the reasons automotive tires go out of balance after installation is the weight of the car causes the high section of the tire to wear more than the rest of the tire. Thereby removing material (weight) and causing the tire to now be out of balance. The RC car doesn't have enough weight to cause this self-centering effect. Getting the tires concentric with the hub hole would keep the tire in contact with the ground better.
adwsystems:
Have you looked into the physics of how much weight a wheel that small in diameter and light in weight at full RPM would be off by? From years of personal experience, I know a competition go-kart tire which is approximately 11" across, 5" wide and 35" in circumference, rarely takes more than 1/4 ounce to balance. Competition kart tires spin more than 2000 RPM.
I would be more concerned about eccentricity than weight imbalance. Are the outside of the tires circular and concentric with the bolt hole in the center? The car doesn't have a lot of weight to help press the tire down, unlike real cars. Automotive tires are not perfect circles, and neither are their rims. Combined, these factors cause the tires to be egg-shpaed and have a high spot. One of the reasons automotive tires go out of balance after installation is the weight of the car causes the high section of the tire to wear more than the rest of the tire. Thereby removing material (weight) and causing the tire to now be out of balance. The RC car doesn't have enough weight to cause this self-centering effect. Getting the tires concentric with the hub hole would keep the tire in contact with the ground better.
I have to agree, the masses concerned are very small.
I use to service and repair "real" wheel balancers, althought the physics is fairly basic, the implementation is not.
I would first be mounting the RC wheel rim on a hub, the way it would on the model and check for any out of round or warp in the inner and outer rims.
Then there is the physical shape of the tyre to consider.
Your vibrations may not be due mass but shape of the tyre.
To dynamically balance the whole wheel would require some sensitive and fast responsive force sensors and a rotary position system.
I'm not saying its impossible, but will it make that much of a difference?
Tom..... 
PS. I used to have an operator manual for an analog electronic wheel balancer around somewhere, it had a really good graphic of the phyical and physics of a wheel balancer. (I might go foraging in the garage. :o :o )