I like that design rgordon! to save ez-b ports connect couples with a "Y" cable, but first we must reverse the rotation of a servo in each pair and investing the wires of the motor and servo potentiometer. I have also read any comments that two servos acting on the same axis produces a struggle between the two sevos to reach an exact position, perhaps some good quality servos might be appropriate.

I had wondered about that. See I'm learning all kinds of good stuff from this post.

I had better just try to come up with a new plan to only use one servo for each joint. It's just frustrating because so much torque is needed just to lift the weight of the arm itself. I may have to resort to using DC gear-motors and doing it like Glickclik said.

Oh well, I was outbid on Ebay for a RAD Robot 2.0 in good working condition with remote and battery charger. I didn't check on it at the last minute. Someone else got it for $51.00 stress

It looked like it was in great shape.

tired

@rgordon, I have a RAD 2.0 in great condition I'd be willing to part with, email me at nlkdavid AT pinnacle175 DOT com if your interested.

@rgordon Remember the board will only take the current draw the original servo took! idk actual figure but im guessing 1-2 amps. My bot's head only had tiny servo sized motors to power. You are better off with single high torque servo.

Rgordon, I am working on a design for arms in my B9. They will be very heavy duty, but not too, too expensive. They might be suitable for something the size of Magnus. I think that I mentioned before that I bought a case of surplus windshield wiper motors. They will be the muscle. I plan on having one joint just beyond the torso with a universal joint that will allow motion in all directions. Two motors will power that from inside the torso, using cables. Beyond that, he will have about an 18 inch "forearm" with a wrist that only bends up and down. That will be moved by a push/pull cable, again, originating in the torso. I am doing it this way to keep the weight of the motors within his center of gravity, and to reduce weight on the arms. I will need small motors in his wrists to rotate them. As far as keeping track of the motion, I will be installing something like this at the origin of each cable.

I am taking some vacation in a few weeks, and hope to get started on that phase. I will send some pictures when I make a little progress.

Hi Danger! Sounds great. I am looking forward to seeing it! I have struggled for some time to come up with arms for Magnus. They always ended up being to heavy. The elbow gear motor would droop whenever there was no power going to it. The shoulder motors are no problem. Got them surplus. They were used to unfurl camper awnings. They have each have 400 in-lbs of torque. Made my own chain and sprocket drives for the shoulder joints. The wrist and claw I think will not be to much of a problem. It has always been the elbow that eludes me. I thought by using a worm gear motor it would work but it still has issues with torque and droop.:(

Another thing I have never been sure of is, how do you remove the B9 torso to work on the Central Support Structure? Will you have to remove the arms each time you do this? For my bots torso I used a clothes dryer drum and made custom arm sockets. I came up with a quick disconnect to remove the arms so I could lift the torso up and off of the robot. I will get pictures for you to look at tomorrow.

You mentioned cables. Are you going to use some method similar to the way power seat motors work? Or how about small linear actuators?

I look forward to your reply.

GLICKCLICK looking at this post about using servo for ams and your formula is off if you go to servo city it tell you that oz-in ,like as 200 oz per one inch lift if a 12 inch arm you divide by 12 = 16.6 oz lift if like on the omnibot you have more then 24 inches so you have 6.3 oz lift you need to understand what the term meens OZ-IN second there is servo's are rated at stall torque (smoke) so it about 75% rating of the servo torque we test motors witch are close to servo's with a feedback and gear box,and the test come out almost the same we put weights on a long bar attached to a motor and see how it lifts it,it has up to 36 inches long ,also has a scope ,amp meter ,volt meter,high precision torque tester and calibrated power supply,electronics all my design,engineering lab had machinst design and built it we dont use servo's but the test is still the same

check my post on using servo's for projects has long info on selecting servo's