Hard Disks motors!

Hi guys! can anybody tell me how to use hard disks motors in my robotics projects. I want to build a robotic arm and i have plenty of broken hard disks i want to know if they are usefull. Thank u in advance.
Please if any of you has a step by step tutorial for building a robotic arm please sent it to me. I am very new to robotics and electronic but i learn fast and i am determined to finiosh this job. Please help me! :roll:

Hello

Hard disk motors are brushless DC motors. Brushless DC motors require more electronics to control them but have higher torque and are more efficient than Brushed motors.

Robotic arms require a great deal of constant torque to overcome gravity. I'm not sure if Hard disk motors will be able to handle the constant currents required.

Motors with a large gear ratios are easiest to use for robotic manipulators. Jameco.com has a bunch of cheap geared motors that would be much more suited to a simple robot arm.

In addition to the motors you need to be able to measure the position of each motor in the arm. Optical encoders are the easiest way to do this. Commercial optical encoders tend to be expensive ~100$ each. You can make your own with LED's and phototransistors. The a standard mouse wheel uses an optical encoder also which you might be able to canibalize.
Both of these homemade encoders should be mounted on the ungeared side of the motor to increase your resolution.

For control use a simple Digital PID controller programed into a Microcontroller of your choice.

Good Luck

Brent

How about useing servos, you can use geared motors, replace the DC motor there with a stepper.