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How to modify a servo motor for continuous rotation ( One motor walker robot )

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Picture of How to modify a servo motor for continuous rotation ( One motor walker robot )
This instructable is part of the one motor walker.
http://www.instructables.com/id/How-to-build-the-one-motor-walker/

There are trillions of tutorial like this, I know :-)

They where taking at school during lunch break with a Sony Mavica camera ( floppy disk )!
5 febuary 2001, 12:18:50

Step 1: How to modify a servo motor for continuous rotation ( One motor walker robot )

Picture of How to modify a servo motor for continuous rotation ( One motor walker robot )
The recommended tools for this project:
1 x safety glasses!!
1 x soldering iron
1 x desoldering pump
1 x wire strippers
1 x side cutter
1 x scissors, knife, x-acto, etc

You will need a set of screw driver to remove the four screws on the back of the servo.
 
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so there is no pulse pin instead you program it like a dc motor but no motor driver right

robomaniac (author)  DIY_lover1231 month ago
yes, no pulse pin.

It's a DC motor. You use it like any motor.
Depending of your application you will need a motordriver to control it.
It's call an H-bridge for example.
ShrvanW8 months ago

Can a servo make continuous rotation very acuurately (say 533 degrees 56 ' 00")

robomaniac (author)  ShrvanW8 months ago
no, get yourself a stepper motor.

cna i also know the acuurate position of the motor after movt??

a servo motor returns back to it's orginal position, ya? this is the EXACT same thing, but without the tab, so you can keep turning whatever it is you are turning before returning back to it's normal position.

robomaniac (author)  AtlasTanker4 months ago

remember that the potentiometer inside the servo motor is not design to turn more then 1 turn. He wanted to turn 533deg. A winch servo motor could work since they turn more then 360deg.

Ah, I see. I haven't really delved into the nitty gritty of how some of my rc equipment works, so I only know what they can do because I've had to troubleshoot them a lot.

can it make continous rotations say 20 rotations and what's the cost??

thnx for the reply

robomaniac (author)  ShrvanW8 months ago

have you google "stepper motor" or "stepper motor tutorials" before asking your questions?

Stepper motors are exactly what you are asking for. You know the precise position of your motor after movement and you can say turn 20 turns.
It will cost you 17.95$. No, the price of a motor can varie a lot. You need special electric components to drive stepper motors. Check pololu, adafruit and sparkfun to buy the motors and electric components.

ShrvanW ShrvanW8 months ago

Urgent

Karanjeet969 months ago

what is the rpm ofthe servo when used as motor?

swatih9 months ago

i want to know the program code used in the rotation of arm of humanoid robot urgently

my email is- hansswati63@gmail.com

robomaniac (author)  swatih9 months ago
here

#include

Servo myservo; // create servo object to control a servo
// a maximum of eight servo objects can be created

int pos = 0; // variable to store the servo position

void setup()
{
myservo.attach(9); // attaches the servo on pin 9 to the servo object
}


void loop()
{
for(pos = 0; pos < 180; pos += 1) // goes from 0 degrees to 180 degrees
{ // in steps of 1 degree
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
}
for(pos = 180; pos>=1; pos-=1) // goes from 180 degrees to 0 degrees
{
myservo.write(pos); // tell servo to go to position in variable 'pos'
delay(15); // waits 15ms for the servo to reach the position
}
}
swatih9 months ago

i want to know the program code used in the rotation of arm of humanoid robot urgently

my email is- hansswati63@gmail.com

swatih9 months ago

i want to know the program code used in the rotation of arm of humanoid robot urgently

my email is- hansswati63@gmail.com

swatih9 months ago

i want to know the program code used in the rotation of arm of humanoid robot urgently

my email is- hansswati63@gmail.com

Sumanta.Bee11 months ago

It is converting a servo motor into an ordinary dc motor. WTH! Stupid project

its just what i needed to do, since a servo is 5 euro, and the gearbox gives it torque and low rpm, and a dc motor is also 5ish euro, with zero torque and 20.000 rpm's that i do not need.

great project!

hal-zubaydi2 years ago
i have got a question, if i cut this part off and everything is going to be fine will i be able to write something like 360 in the program?

this is stupid buddy. He just removed the encoder and messed up the servo

Sumanta.Bee11 months ago

It is converting a servo motor into an ordinary dc motor. WTH! Stupid project

bro robomaniac i m not able to understand that how is the circit and the motor to be connected to each other in the servo motor after modification plzz help me out..
toywizard5 years ago
I have used a wood burner / solder iron and melted these off before.
I've done that too, and would rather stick to the clipper/file method.. You don't have to make a massive deep cut to remove the entire stop from the drive gear, I think the person breaking the gear in this mod, might've been cutting down too deep (below the gear side), or the gear itself was a fairly brittle plastic. A sharp pair of diagonal cutters, just about at the gear side surface, then careful filing (or even sandpaper, though I would wash all grease off the gear afterwards, to remove sand or plastic grit)(then again, you should even after filing to remove the plastic grit that could fall between the gear teeth.) to bring the old stop point level to the side of the gear. (no need to cut it deeper, nothing is going into the recess between the side & the shaft.) Melting, as I'm sure you've seen, leaves a blob on the sides of the place it melted, and unless you carefully remove them (screw driver tip, or clippers (yes, clippers) you run the risk of widening the stop point, instead of removing it. Careful scraping with a hobby knife (X-acto, or even a single-edge razor blade used with care) you could whittle the stop down too.
or one could use a dremel. thats what i did
toywizard3 years ago
I know this is a little off topic but................Besides modifying servos, I have modified antenna rotor motors so I could rotate them 360° non stop so I could mount a spot light on my roof and rotate it from inside via rotor controller.

Took out the stop key. Like cutting off the stop horn on a servo. Gotta love our toys.

These motors have some real b@lls too. I used one to open and close driveway gates.

Sorry to be off topic. Have a great Thanks giving!
aurbindnair4 years ago
why do you have to modify it. wouldn't it work with out one you know the fore legged 'walker' robot?
Most servos are only 180-degree rotation. (0-180, 90 being centered.) These servos also make for a simple single-wire controllable (using Pulse-Width Modulation (PWM) output from a microcontroller.) drive motor that could be stopped, ramped from stop to forward, or ramped from stop to reverse, by changing the pulses to the signal wire. The gearbox also pre-made, so you already have a high torque drive, you simply connect the output to a wheel, or gear, and you're ready to move. Not everyone is making a walker robot. Wheeled robots are a little simpler, and don't require (a) multiple joints to move, (b) extensive code to move those joints in a logical pattern.
I would just use a continuous rotation servo...much easier
I think this is what the modder is trying to do.. There are other mods for converting 180-rotation servos to continuous rotation, simply removing the stop tab as this way shows, but replacing the potentiometer with a pair of 2.2K resistors wired in a "W" (or "M") to simulate the 5K potentiometer centered.
scottsbots4 years ago
I've created a video of how to hack a servo on my site. Hopefully you find it useful.

http://www.scottsbots.com/videos.php
bertus52x114 years ago
I found an old comparable servo hack here on Instructables before seeing yours (sorry!). However, it is really old and the person does not seem to be very active anymore, hence my question to you.
Just not to flood this site with the same questions over again, here is the link: 

http://www.instructables.com/id/HiTec-Servo-Hack/?comments=all#C0MB712GJ289SX1

In brief, I'm looking for a servo that can be rotated more than 360 degrees, while maintaining it's accuracy. 
I think what you want is a stepper motor.
Can you control a stepper motor accurately? I mean, could I have it turn 425 degrees for example?
Yes. Though you tell it to turn a specific number of steps which aren't exactly equal to degrees. For example a stepper I was using has 200 steps in one revolution, so 425 degrees would be 236.1 steps, but you can only move in whole steps so you would round it to 236 steps.

Here is a guide I did a while back that has a little more information.

Controlling a stepper motor with an arduino
Thanks! That's great. I'll have to study it in more detail though. Can I contact you if I have more questions?
How is the size and the prize of a stepper motor compared to a servo?
 thanks, it worked great!
hi i need one clarification from u  now i am converting servo motor into continuous  running motor futaba s3003 but i seen some sites they are removing the pot and inserting a 2.2 resisters i need why they  remove what is the function of pot in that circuit and tell me about the usage of 2.2 resestors also..




azega murugan4 years ago
Probably to trick the circuit into thinking it's never there. A servo uses the pot to know what angle it's pointing but by replacing it with a fixed resistor it would think it's always pointing in the same direction.

The reason I would think they would do this is so they could still use the circuit board to control the servo. You could could give it a signal to start rotating in either direction and it would just keep going until you told it to stop or reverse. You would tell it to stop by sending the signal that corresponds to the 2.2k? resistor (90 degrees?).

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