Using that formula I may definitely need bigger shoulder servos.

Using the formula with round figures for the shoulder servo: Moment = can_weight * arm_length + arm_weight * 1/2 * arm_length 5oz * 20in + 32oz * 1/2 * 20 100oz-in + 320oz-in total torque required for a light 2lb arm lifting a 5oz object is 420oz-in. sick

Now the elbow requires much less. Less than a third of the shoulder. 5oz * 10in + 16oz * 1/2 * 10 50oz-in + 80oz-in Obviously I didnt subtract the elbow's servo weight but.... the elbow needs only 130oz-in

Thank you for the link!

Thanks everyone for the input.

I think arms are the coolest part of a robot design

If you type in robot arm on Google and search under images you can get tons of ideas on different types of designs just by looking at the pictures. What I would like to do is pick ...say...4 of the most popular robot toys that people like to hack and come up with step by step plans or a kit to utilize for arms and give them a choice of different types of hands, claws, grippers, etc. Also maybe a generic type of arm that people could use on homemade robots.

My ultimate dream though would be to come up with a good heavy duty arm for large robots like the full size B9.

@Glickclik---How's Pinhead coming along? I really like the head. Gives him personality Reminds me of the robot from the cartoon movie "The Iron Giant." Did you say you were going to try servos for the arms? Have you done any tests yet?

Unfortunately Im still waiting for the pan/tilt mount. After reading this Im going to have to invest in high dollar servos too. I finally gave in and gutted the brain out and I ordered cheap S3003 servos to harvest the control boards. I tested it using the one I had for the neck and it worked fine. I hooked the board to the existing motor and potentiometer in the neck and it worked great. Even made a script for random movement personality (ie random interval, random speed, random position). He seemed alive just with THAT. I cant wait to get the other servos in. I also took apart the eyes and test fit the MinM RGB led board and they fit too! They have little light scripts that can run in them too and you can make a few just by sending an I2C string. I probably wont do much with that though.

@sfoy---Yeah keeping the cost down is a priority. Thank everyone who is participating

All input and ideas are welcome.

@bret,

Sorry, been busy and away form the forum. I am kicking myself now for not getting a picture of the ice cream robot arm.....but i hit paydirt with youtube!.....I love this arm!

I checked that MinM led link when I posted. I saw that it didnt list the EZ-B as a product requirement list but it has the arduino there! NO WAY! They even sell EZ-B. A quick email to them and it was fixed right away.

We got your back DJ!!

@kkeast- Thanks for finding the video. That's really neat. All input is helpful.