Can someone please help me find the RPM for high-speed, torque, and regular motors? I couldn’t find it on the Vex page, and I may just be looking in the wrong place, but help would be greatly appreciated!! Thanks!
At the bottom of : VEX EDR Motors - VEX Robotics
I saw that they had regular and high-speed, but I’m still not able to find torque, so I was just wondering if anyone had the knowledge for some reason. Thank you, though.
The regular motors are considered to be the torque motors.
True. I guess I was talking more about gear ratios than anything, and if anyone knew the specific RPM for any of the gear ratios.
That depends on what size gears you’ll be using, how well they’ll fit together and what speed you coded it with. When I built a drag car for an assignment a while back, I think I used a gear ratio of 1:16, for more speed. Didn’t calculate the RPM, though.
Free speed for:
Torque: 100 rpm
Speed: 160 rpm
Turbo: 240 rpm
This is a fantastic exercise for you to do yourself in a spreadsheet, that way you will get what you want and learn about it. You can put in every combination of motors, internal gears, external gear/sprockets, and find the theoretical speed. For example, a 100rpm motor axle with a 12t gear meshes with a 36t gear on another axle. the 36t gear axle rotates at 100*12/36 rpm, == 33rpm; With this type of 12:36 ratio, the rpm is one third and the torque is 3x (in theory).
http://motors.vex.com/ has some other information about rpm vs torque for DC motors in general, but it is FRC centric, so though they don’t list their own Vex motors there.
https://www.vexrobotics.com/wiki/2-Wire_Motor_393 has more information
Thanks so much to everyone who has helped me!! This has made it easier for me to see what I will be doing.
Correct me if I’m wrong, but motors don’t actually operate at free speed/stall torque right? I remember reading that a 70% estimate of the VEX values will give typical results in an actual situation (where the motor still turns, it isn’t stalled).
Oldie but goodie from @jpearman
https://vexforum.com/t/motor-torque-speed-curves-rev2/21868/1
https://vexforum.com/index.php/attachment/56464d7f91a13_torque_speed_393.jpg
I try and tell the kids use 7 in-lb of torque as your calculation for what you want out of the motors in order to not get in trouble. (But so few do the calculations)
Even if you calculate the theoretical torque, reality may differ.
Once you build it, it is still hard to measure torque.
It is relatively easier to measure actual motor rpm speed, then think about doing a different gear ratio if it is way different than 50% free speed.
This was also my recommendation to the base-bot gear-ratio guy. Rather than estimate the friction forces without any data, take the speed of the initial configuration and back-calculate from that.