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Need Help! On Ametek Pittman Gm9213-3 12/24 Vdc Gear Motor

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wanting to know if this motor will work with ez-b and will be stronger thaan my robo servo im using for the shoulders of LeXI. I figure I will need another sabertooth, but I wanted to run them off of 12v instead of the 24v. don't know much at all of this gear motor, was looking over the LOKI robots arm design and saw this motor working the chain setup. there on ebay for 5 for $125. if you know of a cheaper motor with the same power let me know. this is the final step in my LeXI's completion.
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That is the same motor that I have on my LEAF robot. It works good. I bought two of them years ago for I think $65 each. They should run fine on 12v.


This looks like a regular dc motor with a gear head attached. Are you replaceing a servo with this? If it is a dc motor with no feedback pot built in you will not have any way for EZB to know where yout arm is. You will have to have some sort of feedback device like limit switches or a multi turn pot attached to your ADC ports on EZB if you want to stop them where you want them with scripts.

Also if it is just a DC motor you will need to run it through a H-Bridge or controller like the sabortooth you mentioned to get it to be controlled both ways.

You can run DC motors on lower voltages then they are rated for. They will just run slower. Just dont run them on voltages hugher then they are rated for.

Considdering your arm desigh youmay want to stick to a Heavy Duty servos. They have the feedback pots already built into them.


@aamerlis , you can use them , they will have less than half the torque and speed rating when you run them on 12 volts so take that in mind. You will basically be making your own giant servo , you could hack a small Standard Servo and pull the pot out and use it to send signals to your motor controller.


@jstarne1 do you think this will be strong enough to handle my arm at 12v? Do you have a better alternative? I want power and torque. i figured out what to do on the elbow. Along with the spring assist i am 3d printing a dual servo bracket. 2 x hd servos to move the lower arm up and down.


Illustration to take advantage of a Standard Servo control to make a bigger servo.
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, yea this should be plenty of holding power , it will draw several amps because of it's size when "holding"

The tandem servo joint I suggested would be like this...
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The only real way to know if this motor is right for your Lexi is to give it try. It should be strong enough but hard to tell unless you see is in action. Also will it be fast enough for you?

How about doing the same thing with your sholder that your doing with the elbow. Do you have room to do dual servos up there? Of course DC motors are nice as they are a lot more quiet then servos under load.


@dschulpius to be honest, im tired of the servo troubles. they are only useful on small projects. i've spent over $400 on servos since i started and they require too much to get so little in return. the dc motors i posted should do the trick. i ordered 5 for $125 on ebay. 2 for LeXI and 2 for the Next Bot (Purple and White colored guy, havnt figured out a name yet.) and 1 left over as a spare.


In the photo you can see the ratio 7:1, just need to know the Revolutions per minute of the engine without gear reduction in any case seems to be a driving too fast for my taste.


@R2D2 the motors in the pic are from the LOKI build. they were used for the chain pully that moved his arms from the shoulder point. what do you mean by "fast" couldn't I adjust the speed with EZ-Builder?