Instructables
Picture of HiTec Servo Hack
This is a quick and easy walkthrough on how to modify a HiTec Servo and make it a normal dc motor with gears.

To see how you can control your motors with the Arduino visit this instructable:

www.guilhermemartins.net
 
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Step 1:

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1. Say hello to your servo, and say goodbye as well because what we are going to do here is irreversible.

We will hack essencial parts of the servo and it won�t be a servo anymore, it will be a powerfull dc motor with gears.

Step 2:

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2. This are the tools we need, I think I don't need to describe them :)

Step 3:

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3. Ok let's begin.

Start by removing the screw on the top.

Step 4:

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4. Remove the four little screws on the back of the case.

Step 5:

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5. Open the case.

Step 6:

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6. And remove the top carefully.

Step 7:

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7. We can see the gears inside the case. We only need to remove the first two gears, no need to remove the others.
Be careful enough and avoid contaminate the grease that surrounds the gears.

Step 8:

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8. Remove the black and white gears.

Step 9:

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9. Now it's time to remove the circuit on the bottom of the case, see the next foto.

Step 10:

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10. Use the soldering iron and gently remove the circuit.

Step 11:

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11. You can see now the dc motor.

Step 12:

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12. Cut the wires that connect the potenciometer to the circuit.

Step 13:

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13. Now remove the little screw inside the case.

Step 15:

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15. Parts we don't need anymore.. I wasn't carefull enough and broke the circuit.. no problem, we won't need it anymore, at least I don't know what I can do with it... :)

Step 16:

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16. Now grab two wires with +- 15 cm, depends on your needs.

Step 17:

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17. Grab your soldering iron and solder the wires to the motor pins. Note the red mark on the motor.

Step 19:

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19. Remove the white ring.

Step 20:

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20. Make an horizontal cut.

Step 21:

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21. Then make a vertical cut.

Step 22:

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22. The thingey is removed.

Step 23:

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23. Remove any imperfections you see.
ataylor99911 months ago
Is there anything else besides a soldering Iron that will work?
bertus52x113 years ago
I'm new to this (but learning) so maybe my question is a bit obvious:
When I hack the servo as described in your excellent Ible, will it become a continous spinning motor (when power is applied)?
Or in other words, can I still controll the angle that I want to turn it?

I'm looking for a servo that I can control accurately, but I want to turn it more than 360 degrees.
Hope you can help.

guibot (author)  bertus52x113 years ago
Unfortunately no, your servo will behave like a normal geared DC motor. If you need that specification you will need an encoder, there are many tutorials about DIY encoders. Good Luck ;)
Thanks! Could you recommend a good DIY tutorial on encoders, because I did a search myself and found it hard to select a good one.
guibot (author)  bertus52x113 years ago
depends on what kind of approaches you prefer, just to mention a few:

http://letsmakerobots.com/node/17597

http://letsmakerobots.com/node/12293

http://www.societyofrobots.com/sensors_encoder.shtml
Thanks! I'll look into it.
I'm thinking of making a robot (Arduino controlled) and it needs to ride over an exact pre-calculated distance (the wheels rotate more than 360 degrees).
if You want it to move Your given angle, or just spin --- use steppers (pretty slow, compared to DC, but precise) -- In Your case -- the best solution..
Otherwise use DC with optical encoder..
zetsway5 years ago
Excellent post. Thanks, I was able to follow it step by step and modify my servo. Thanks, and keep up the good work
MNskier5 years ago
You can use the servo board to make an electronic speed control. Make a note of the (+) solder pad before removing the motor from the servo board you can then use it to drive the gate of a power mosfet (such as the IRL 520N) to have a low power ESC for approximately $2. Be sure to put a 500-1k ohm resistor between the gate and motor output of the servo board. The PWM signal from an R/C receiver or microcontroller can now drive a small motor with variable speed.
guibot (author)  MNskier5 years ago
very interesting!!! it would be cool to see an instructable with this subjet :)
texabyte5 years ago
I wish I could do this in reverse. I have 50,000 dc motors and want to make them into servos.
where did you get that many motors?? Ebay...??
maybe like 30. I take lots of things apart
wow 50 thousand? I have half a million XP
ReCreate5 years ago
Sometimes the thing is on the thread of the gear,so if you remove it it still won't fully spin
travis7s5 years ago
Good write up, very clear pictures. If you haven't fried the board you can just replace the pot with a pair of 2.7k ohm resistors and you have a radio controlled gearmotor.
travis7s5 years ago
You can optionally make it a much faster gearmotor (with less torque) at this stage if you want. Remove the left black gear entirely, and glue the bottom white gear to the top black gear.
toelle5 years ago
So you basically turned a servo into a regular DC-motor? Why not just buy a DC motor with a gearbox in the first place?
Wouldn't it be smarter to turn it into a continuous rotation servo (which is even easier)? That way you would get speed control of the servo. I've done that, and my robot runs great with it =D
Ya but this is good if you fry the board inside a servo. Reduce! Reuse! Recycle!
cyrozap toelle5 years ago
Agreed.
guibot (author)  cyrozap5 years ago
The servo h-bridge can be slightly less of a driver than needed in certain applications. The servo circuit has a limit pulse drive of the motors. Using your own h-bridge (FET based) and electronics gets more of the power to the servo motor for better torque and speed.
Phylth5 years ago
Interesting, but why dismantle an otherwise good servo instead of picking up a basic DC motor from, say, Radioshack? Unless the servo's shot I wouldn't think this would be an economical way to get my hands on a new motor.
This servo has a added gear box, so not only getting a dc motor you get a good dc motor complete with gearbox :)
guibot (author)  Sparkington5 years ago
Yes that´s it, you get a geared dc motor, inside of a nice case with mounting holes, and with many servo horns
http://www.futaba-rc.com/parts/servo-horns.gif
Yep i have seen this hack to many to count but you have done a great i'bles 5*

Have Fun