Instructables
loading
Create an Instructable

With Instructables you can share what you make with the world, and tap into an ever-growing community of creative experts.

How it Works »
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 )

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.
<p>If you modify it for continuous motion can you still get the servo to return to its original position? I can get it to move with a flex sensor but once i stop it will not return to its original position before it was modified. Help</p>
<p>so there is no pulse pin instead you program it like a dc motor but no motor driver right</p>
yes, no pulse pin.<br><br>It's a DC motor. You use it like any motor.<br>Depending of your application you will need a motordriver to control it.<br>It's call an H-bridge for example.
<p>Can a servo make continuous rotation very acuurately (say 533 degrees 56 ' 00&quot;) </p>
no, get yourself a stepper motor.
<p>cna i also know the acuurate position of the motor after movt??</p>
<p>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.</p>
<p>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.</p>
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.
<p>can it make continous rotations say 20 rotations and what's the cost??</p><p>thnx for the reply</p>
<p>have you google &quot;stepper motor&quot; or &quot;stepper motor tutorials&quot; before asking your questions?<br><br>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.<br>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.</p>
<p>Urgent</p>
<p>what is the rpm ofthe servo when used as motor?</p>
<p>i want to know the program code used in the rotation of arm of humanoid robot urgently</p><p>my email is- hansswati63@gmail.com</p>
here <br><br>#include <br> <br>Servo myservo; // create servo object to control a servo <br> // a maximum of eight servo objects can be created <br> <br>int pos = 0; // variable to store the servo position <br> <br>void setup() <br>{ <br> myservo.attach(9); // attaches the servo on pin 9 to the servo object <br>} <br> <br> <br>void loop() <br>{ <br> for(pos = 0; pos &lt; 180; pos += 1) // goes from 0 degrees to 180 degrees <br> { // in steps of 1 degree <br> myservo.write(pos); // tell servo to go to position in variable 'pos' <br> delay(15); // waits 15ms for the servo to reach the position <br> } <br> for(pos = 180; pos&gt;=1; pos-=1) // goes from 180 degrees to 0 degrees <br> { <br> myservo.write(pos); // tell servo to go to position in variable 'pos' <br> delay(15); // waits 15ms for the servo to reach the position <br> } <br>}
<p>i want to know the program code used in the rotation of arm of humanoid robot urgently</p><p>my email is- hansswati63@gmail.com</p>
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..
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?
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 &amp; 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
I know this is a little off topic but................Besides modifying servos, I have modified antenna rotor motors so I could rotate them 360&deg; non stop so I could mount a spot light on my roof and rotate it from inside via rotor controller.<br><br>Took out the stop key. Like cutting off the stop horn on a servo. Gotta love our toys.<br><br>These motors have some real b@lls too. I used one to open and close driveway gates.<br><br>Sorry to be off topic. Have a great Thanks giving!
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 &quot;W&quot; (or &quot;M&quot;) to simulate the 5K potentiometer centered.
I've created a video of how to hack a servo on my site. Hopefully you find it useful.<br> <br> <a href="http://www.scottsbots.com/videos.php">http://www.scottsbots.com/videos.php</a>
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.<br> Just not to flood this site with the same questions over again, here is the link:&nbsp;<br> <br> <a href="http://www.instructables.com/id/HiTec-Servo-Hack/?comments=all#C0MB712GJ289SX1">http://www.instructables.com/id/HiTec-Servo-Hack/?comments=all#C0MB712GJ289SX1</a><br> <br> In brief, I'm looking for a servo that can be rotated more than 360 degrees, while maintaining it's accuracy.&nbsp;
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.<br> <br> Here is a guide I did a while back that has a little more information.<br> <br> <a href="http://www.azega.com/controlling-a-stepper-motor-with-an-arduino-part-2/ ">Controlling a stepper motor with an arduino</a><br>
Thanks! That's great. I'll have to study it in more detail though. Can I contact you if I have more questions? <br>How is the size and the prize of a stepper motor compared to a servo?
&nbsp;thanks, it worked great!
hi i need one clarification from u&nbsp; now i am converting servo motor into continuous&nbsp; running motor futaba s3003 but i seen some sites they are removing the pot and inserting a 2.2 resisters i need why they&nbsp; remove what is the function of pot in that circuit and tell me about the usage of 2.2 resestors also..<br /> <br /> <br /> <br /> <br />
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. <br><br>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?).<br><br>
Nice info. That's help us to learn about motor servo.<br><br>Regards,<br>Dave T.<br><a href="http://www.tokomikon.com">ATmega8535</a> | <a href="http://www.tokomikon.com">ATmega16</a> | <a href="http://www.tokomikon.com">ATmega32</a> | <a href="http://www.tokomikon.com">AVR USB ISP</a> | <a href="http://www.tokomikon.com">Motor Servo</a> Seller<br>
Thanks man! Worked like a charm. You got me worried about breaking the gear when I removed the plastic tab so I used a file.
thanks for your help mate all i did was just cut the other wires and put the same wirs back on to it
So easy and fast....<br /> Thank you so much!!!!
&nbsp;Thank you sooo much for this ible you made!!!!!!!!!! Its the&nbsp;answer&nbsp;to my problem! I am working on a robotic arm and I need it to be battery power and not those 1,2,3 ms pulses! &nbsp;Thanks again!
continuous rotation? is the rheostat in the servo can rotate 360 deg? i don't think soo..<br />
When what one really wants is just a motor with a gearbox, this modification is ok.<br/><br/>But you want a motor+gearbox+speed-control, then I prefer the modification below:<br/><br/><a rel="nofollow" href="http://www.kronosrobotics.com/an116/GAN116_3003.htm">http://www.kronosrobotics.com/an116/GAN116_3003.htm</a><br/><br/>It's easier to do: no soldering iron and you only open one side. You don't waste the electronics. And you get electronic speed control. There's this video here that shows a minimal modification (no calibration after the servo is closed) but it's in a language most of you won't understand; nevertheless, it may help to understand the modification:<br/><br/><a rel="nofollow" href="http://www.youtube.com/watch?v=VmLm1gl8glM">http://www.youtube.com/watch?v=VmLm1gl8glM</a><br/>
Can I ask why you are removing the control board? Cant you take off the top cover and just cut the arm? I actually removed all the gears and just used the output shafts to power my model boats many years back (small scale).

About This Instructable

320,049views

201favorites

License:

Bio: I am a French Canadian that loves robots and embedded electronics. I work on all kinds of cool projects, like a high-power electric push scooter ... More »
More by robomaniac:Arduino-Fart-O-Meter No pictures costume for Hong Kong Halloween Dead killer bee prank ( April fools ) 
Add instructable to:
Contest Group

Related