Good source for inexpensive servos?

[Rcnewcomb]

I'm assisting a high school student with a robotics project. I'll be meeting him for the first time later this week. He is trying to build a robotic arm. He's trying to keep the project under $200. One of the challenges he is running into is finding a source for inexpensive servos. Does anyone have suggestions on where to find lighter duty servo motors that might be useful in this application?

[Timvmax]

Does it have to be servo's? If he can use stepper motors, there's usually plenty of old printers & plotters around to strip down for parts

[Mogal]

Not sure what scale your working on, but Tower Hobbies has a good selection of RC servos.
Lowest I saw was 10 bucks each, but thats a slow, low power one.
Price goes up according to speed and power required.

http://www3.towerhobbies.com/cgi-bin/WT ... ARCH=servo

[Rod Williamson]

The cheapest around is from www.hobbyking.com. They are a China company, but they do have a warehouse in the US. Shipping time and cost can be an issue if you purchase from the China warehouse.

[Rcnewcomb]

For those who weren't following this thread on the ShopBot forum I figured I post an update.

Brady Watson suggested using an Arduino for this project along with a motor shield. We ultimately decided to hack an Arduino interface onto an OWI robotic arm. We were able to do the project for well under his $200 limit.

The OWI arm comes completely unassembled. Putting it together helped the student understand how each joint and motor combination operated

While the Arduino Uno board came fully assembled the motor shield was just a PC board, components, and instructions on how to solder the components onto the circuit board. He also got to figure out how to write the program to control the arm.

He hooked 4 of the 5 motors to the interface. He was programming it to pick up a block and move it to a new location. He was making good progress on the software but, alas, at 4AM the day of the presentation the motor shield failed. We haven't done a failure analysis yet, but I'm sure it will be an easy fix.

All in all he learned a lot on this project and most everything will be reusable for subsequent projects. We've already discussed how to improve the design of the arm. He's is very bright and hard-working. He'll make a great engineer. I truly enjoyed helping with this project.

I was pretty impressed with the capabilities of the Arduino boards. If you need a basic controller for digital or analog it seems to have a lot of bang for the buck. The software is free and runs on a variety of platforms. I tested it on both Win7 and Mac OSX. Once the board is programmed it doesn't have to stay connected to a computer -- it just needs a different power source.

For $16 you can get a board which has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, etc. It contains everything needed to support the microcontroller; you can connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery.

For $47 you can get a board that has 54 digital input/output pins (of which 14 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button.

At a Meetup recently there was a guy building very basic CNC machines using an Arduino controller that could accept G code. He was using V-Carve to create the files and G Code.

Go to YouTube and search for Arduino. You'll be amazed at the variety of things people are doing with these boards.

[dan_barber]

Lenze is a good source for inexpensive servos.

http://www.ctiautomation.net/Lenze-Drives-Motors.htm