Torque curves

[BionicAlumni]

So I have a question about torque curves. I have purchased this motor:
http://www.lynxmotion.com/Product.as...&CategoryID=11

I have asked the seller for a torque curve for the motor and they tell me they don't have one. Can I make my own torque curve for the motor without testing it? I was thinking a linear fit between the stall torque and the no load RPM. Would this work? Should I use a different fit? Any help would be awesome.

thanks.

[Ian Mackenzie]

Actually, linear interpolation does work (Adam - I actually took the time once and worked through all the equations and theory you mentioned, and it works out very nicely - at least for the drill motor, which is what I compared my theoretical results to).

Anyways, don't take my word for it - Joe Johnson posted a spreadsheet a couple of years ago which asks you for a few simple parameters (voltage, stall torque, stall current, free speed, free current) and comes up with plots of speed, torque, power, and efficiency. It also has a sheet of information on FIRST motors (although be careful; the Fisher-Price motor is certainly out of date, and others may be as well).

[Adam Y.]

Originally Posted by Ian Mackenzie

Actually, linear interpolation does work (Adam - I actually took the time once and worked through all the equations and theory you mentioned, and it works out very nicely - at least for the drill motor, which is what I compared my theoretical results to).

Sorry your right. It will work. I have a picture of one of those graphs in my book and it has the relationship between motor torque and RPM. Definately linear. Its just one of those duh moments.

[JVN]

Originally Posted by Ian Mackenzie

Anyways, don't take my word for it - Joe Johnson posted a spreadsheet a couple of years ago which asks you for a few simple parameters (voltage, stall torque, stall current, free speed, free current) and comes up with plots of speed, torque, power, and efficiency. It also has a sheet of information on FIRST motors (although be careful; the Fisher-Price motor is certainly out of date, and others may be as well).

My design calculator whitepaper has all of this stuff, including an updated version of Joe's paper, most of it has been updated for 2004.

John

[BionicAlumni]

You guys ROCK!!!!!

Thanks to all