Hi everyone,I bought two motors from RobotShop: http://www.robotshop.com/en/solarbotics-regular-pager-motor-rpm2.html and they are both pager motors for my very small robots (5 x 7 centimeters) and I was soldering some solid core wire for easy breadboard use, and the wire snapped off from the motor, and now I can't power it in any way. Also, I found that no wheel can fit on the shaft of the motor, and I've tried making my own adapter and trying to connect them. Now I'm reluctant to use these small motors. I want to know if a small robot like mine can use servos, or if there any other small motors out there that can be used for small robots like mine.
Cool about the servos, but would they work with a dual motor driver? I have spark fun's dual motor driver: https://www.sparkfun.com/products/9457 and I'm just wondering if the servo can be controlled that way.
You don't need a motor driver for a servo. You just send a stream of pulses out on one pin per servo using the Servo library. You send a value between 0 and 180 to each servo. With continuous-rotation servos, 90 is 'stop', 0 is full speed in one direction and 180 is full speed in the other direction.The servos have 3 wires, one for signal from the Arduino, and two for connection to a 5V power supply. Then you connect the power supply's ground to the Arduino ground and Bob's your uncle.Still, there's no special reason to change to servos. I only mentioned it because you did.
Ok, but I wanted to change to a servo because the small dc motors don't have a wheel to fit on, and that's really the main reason why I wanted to change.
2) Attach a servo horn to the servo, then attach the wheel to the servo horn using a small drop or two of hot glue.
Still a matter of finding a servo horn that's sold separately and fits the shaft. It does give a wider range of options though.
Most servos come with several different horns. I imagine zoomkat's suggestion was to use one of these horns.Some servos come with half a dozen horns. The micro servos I've purchased usually some with three servo horns.Some horns lend themselves to be attached to wheels more than others. If the servo comes with a nice "X" shaped horn, they're usually the easiest to attach to wheels.Make sure the horn can be removed with the wheel attached. You don't want to have to undo the wheel/horn connection to remove a wheel. I've almost made this mistake several times.
The original motors you purchased didn't have a gearbox. It's very unusual for a DC motor to have enough torque to propel a robot without a gearbox.Pololu sells all sorts of nice little motors. They sell some without a gearbox but these are intended to be as replacements to be used with a gearbox. IMO, you shouldn't purchase motors to power a robot unless the motor includes a gearbox.Oldsteve's strategy of purchasing a combination of wheel with gearmotor is a good one unless you know how to adapt wheels to various output shafts. It's harder than one would first expect to attach a wheel to a motor not specifically designed to fit on the motor.
Those coreless motors are designed for small quadcopters and RC helicopter tail props - you'll findprops that fit the shaft easily - gear trains even, if you look for RC helicopter parts. Not myfirst choice for robotics - micrometal motors are available in several voltages and many reductionratios and have metal gears, and are good value on eBay, for instance:http://www.ebay.co.uk/itm/1Pcs-6V-100RPM-Micro-Torque-Gear-Box-Motor-Hot-Sale-/231466738662?hash=item35e47e23e6:g:r8wAAOSw1vlUyzNEBut first work out what speed and torque you actually need before choosing a motor, there's little needfor guesswork.