This project has evolved some , the basic rundown is I'm modding two Omnibots , one a regular the other a larger 2000 model. I will have two ezb kits , rad base idea was thrown out because of so much noise but could go back on the table if the omnibot drivetrain is too weak to pull it.
By jstarne1
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I think normal servos are really the wrong choice for Shoulder & Elbow joints up/down movement. You'd be better off putting together a custom servo that either utilizes a worm gear or threaded rod & chain final stage. You can even use a regular servo as the motor & electronics, just have to wire an external potentiometer to it.
yep thats what i keep tryinng to say ,but i guess others need to learn the hard way and try it i learn the hard way while back too
I'll draw up these 2 methods if your interested josh.
wish i was good at drawing ,but mostly i know electrical and mechanic engineering part of it
worm gear best of those 2 because of size,but the gears are hard to find car window motors use that type and most robot builders use it for shoulder part of the arms ,but the size is too big to fit inside the omnibot 2000
here is a simple idea JOSH
SMALL 534 OZ MOTOR $15 and if you want double the torque just plus a small gear on the motor and a larger gear on the shoulder arm with a 5k feedback pot and $4 servo board ,like THOMAS is using on is annabot or use a h-bridge to control it 2-1 ratio will give you over 1000 oz,2-1 is small gear like 12 teeth or so and twice that much on the larger gear,you want to keep the larger gear as small as you can servocity has many gears aluminum and plastic
servocity gears
also thats my design for my robot shoulder design also
If this was a bigger bot I would used linear actuators but there is not enough room for that , movement is 90 percent for gestures , and bring a can of coke or long neck to me which is faorl.light. using three servos in tandem with a special syncing module used in rc planes allows the use of two 240 oz in servos or even three if needed.
yes ,servo city does that module if 3 ,triple the current, i guess a lot of recharging at home base you will need,and i dont see why you would want to use tandem ,really no sense to it you need much more room i bought a small linear actuator for my johnny five design also what is faorl.light
Link me this actuator there was no room based on measurements for the motor and gearbox thing.
the motor and gear box takes up about the same size as 1 servo on the small actuator only need 4 oz lift and i think it has a 10 oz max,it for the antenna that comes out of the top of the johnny five he uses to change channel on tv and to control a airplane in short circuit 2,so it does have as much powerr to lift much weight only need a small plate just a little bigger then a servo,use a small pinon gear on motor and fairly small gear on shoulder part 2 inch by 2 inch square plate or less ,height about same as a servo plus gear about .5 inch, lynxmotion has some close to it here is a photo of the design only gears are different
this is the idea,only cant use this because its a 1-1 ratio might try to change the gears to give you more then 2-1 but it gives you a idea on how to make the plate and by using pinion gear servo will be much closer