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Author Topic: Comparing brushless motors  (Read 317 times)

AmbientChaos

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Comparing brushless motors
« on: October 16, 2016, 11:30:33 pm »
I'm considering changing out the brushless motor that I am using to drive my weapon, but I would like some confirmation on my guesswork as to how I've been trying to compare the motors.  If I was comparing two brushless motors that had the same Kv rating but a different rating for Power (w), would the one with the higher power rating have more torque and be able to get the weapon up to speed faster?   Also, what is a good speed for antweight weapons to get the best bite, 5,000 rpm?  Or is it more a matter of the tip speed of the weapon than the rpm?

Jeff Gier

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Re: Comparing brushless motors
« Reply #1 on: October 17, 2016, 06:47:24 pm »
Theoretically, yes more torque.
However, advertised motor ratings are often not very realistic.  Typically, weight and motor size can be used for comparison.  Motor quality matters to some extent as well.  I am not sure what motors you are looking to compare, but I wouldn't expect two motors of the same size and weight to have different power outputs.  That being said, you probably need to go to a larger motor or lower KV to increase your torque. 

You can calculate the length of the bite your bot will get by knowing the closing speed between the two bots and the RPM of the weapon. As closing speed goes up, bite goes up.  As rpm goes up, bite goes down.  I'd shoot for ~10k rpm for an ant. 
More aggressive (positive rake) and harder teeth will also bite better than flat or negative rake and softer materials.