Instructables

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
 
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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.

Step 2: 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 )
I put a peace of tape so the gear box does not come appart when I remove the back cover.

Step 3: 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 )
Remove the back cover by removing four screws.

Step 4: 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 )
If you use a solder pump, it will be easy to desolder.

Step 5: 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 )
Be sure you have remove every solder before starting lifting.

When you are sure, take a flat screw driver to lift it.

Step 6: 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 )
Solder long wire to the motor.

Use the original servo wire. Remove the white wire.

Step 7: How to modify a servo motor for continuous rotation ( One motor walker robot )

This is the inside of the gear box.

Step 8: How to modify a servo motor for continuous rotation ( One motor walker robot )

After some thinking, I realise that you don't need to cut the tap for the one motor walker.
If you want to build the one motor walker, I suggest you try the to build the robot without cutting the tap.If you want to make a rolling robot by using servo motors for the locomotion then cut the tap.

To cut the tap please read carefully.

Warning!

I have already broken the entire gear by using a side cutter. I was sort of piss off!
I recommend you be carefull and use a hacksaw.

Take your time!

Put every thing back together and you have finish!
You can put some new grease it the gearbox if you want.
toywizard4 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.