Instructables

Waterproof your servo motors

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If you are using servo motors for any underwater activity, although these hitec waterproof servos are super nice, you don't have to spend 50 dollars per servo. Here's how to waterproof servos yourself in a few steps. I havent tested this at super low depths, nor have I done extensive tests for long periods of time. However, I have made little robot fish that are totally fine after many swim sessions using this method.

Currently, I'm making a swimming robotic snake like this one using this method. 

I've read that people have successfully tried and used the condom method (wrap your servo motor in a condom, basically) but my condom broke : ) when I tried it.
 
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Step 1: Materials

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Screwdriver
marine grease
Auto marine sealant (DAP works well but another silicon sealant will also work)
Servo motor
o-ring, like this one : EPDM O-Ring, AS568A Dash Number 007

Step 2: Seal the seams

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There are two seams that run around the servo motor body. One is about 1 cm from the top, and the other is right along the bottom, where the screws are. Using silicon marine sealant seal with a thick layer all around the seams. Make sure to also put silicon around the spot where the wires enter the motor, as well as a lot around the 4 screws on the bottom of the servo motor. 

(Note: In this photo, I am using a bathtub & tile silicon sealant but it adhered way worse than the silicon auto/marine sealant)

Step 3: Hang them to dry

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Let them dry for as long as the glue requires.

Step 4: Unscrew the servo horn

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Once your silicon has dried, unscrew the servo horn, (or the plastic round part that comes on the servo). 

Put it to the side. 

Step 5: Lube up the o-ring and slip it on

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I'm using SuperLube synthetic grease in the photos here but I prefer marine grease. But any dielectric grease will do. Make sure if you are using silicon o-rings, however, not to use a silicon lubricant. 

Lube up the o-ring and the servo motor shaft, and put the o-ring on. 
mPky1 year ago
Why is it wrong to use a silicone oring together with a silicone grease ?
mPky1 year ago
How does one know the size of ORing to buy for a given servo ? Do all standard servos require the same Oring ?
hellzlegend2 years ago
Awesome. Nice work!
Bookmarked for future projects.
if you try to Plasti Dip is the same but permanet