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[on:]

Hi everyone. I am an inexperienced electronics hobbyist, so please don't assume I know something--I probably don't. I want to make a crane or "claw" game like you can find in the arcade (just for fun, so I don't care how big or small it ends up being). I'm afraid I have the most basic question... ... what type of motors should I look at to get started?

* I have an Arduino Uno and a Makershed motor shield
* I've played around with controlling very small servos both directly from the Arduino and connected to the motor shield with success.
* I have used transistor circuits to control larger DC motors with success.
* I would like to use a 2-axis joystick potentiometer to control the crane's movements. I'm imagining it working kind of like some of those great home-built cnc machines I've seen (with some type or rail system that the "head" slides on).
* I know it's a dumb question, but what kind of motor would be best to move the crane in the x and y axes? I'm thinking probably a DC motor. I could control its speed and direction from the joystick's input. However, I wonder if I should be looking at stepper motors instead.

I'm looking forward to any feedback I can get!

[Reply #1 on:]

stepper would be great but do you need the joystick to control each step? i do think that using 2 DC motor will add to the fun due to the fact that they are almost unpredictable. anyway if you decided to make one using stepper i got 2 link that may help
http://arduino.cc/forum/index.php/topic,133819.msg1006780.html#msg1006780
http://arduino.cc/forum/index.php/topic,135739.0.html

he had manage to use both type of joystick to work with his setup.
for the mechanical part i think it is best if you follow this set up
http://www.tantillus.org/
it will give you the fullest travel you can get
how ever for the claw. you need to design one or use any of the servo type claw you can find, this one i'm sorry i dont have any link

[Reply #2 on:]

An RC servo converted to continuous rotation would be what I'd recommend. That would give you gear reduction, the motor driver, and a simple interface. The sweep tutorial gives an example of how to code for one, but in the case of a continuous motion servo turning the potentiometer farther results in the servo spinning faster ... which sounds like what you want.

You would use a stepper motor only if you wanted to be able to programmatically determine the position of the claw (e.g. "move exactly 10 centimeters"). In your case you have a operator at the joystick and don't really care where the claw moves -- just that the operator can move it.

Timing pulley that fits servos: http://www.lynxmotion.com/p-332-hitec-servo-mxl-timing-belt-pulley-32-tooth.aspx
Makerslide would make a good rail system: http://www.ulule.com/makerslide/
Converting servos to continuous rotation: http://www.societyofrobots.com/actuators_modifyservo.shtml

[Reply #3 on:]

Thank you both! I think I will take a look at modifying an RC servo for continuous rotation as a place to start.

[Reply #4 on:]

The below is an inexpensive servo that is easy to modify for continous rotation.

http://www.hobbyking.com/hobbyking/store/__3743__HXT_6_9kg_39_2g_16sec_Twin_bearing_servo.html

[Reply #5 on:]

Thank you both! I think I will take a look at modifying an RC servo for continuous rotation as a place to start.

If you have to buy a servo anyway then many vendors sell them already modified.
https://www.sparkfun.com/products/9347

Lefty

[Reply #6 on:]

they also have the claw...
https://www.sparkfun.com/products/10332