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Asked — Edited

Servo Makes Buzzing Sound When Under Load


I have a small arm on my robot and when it extends outward the servo makes a slight buzzing sound from the weight of the arm. Is this bad for the servo?


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No, Digital servos are very noisy under load. This is common and causes no problems or harm other then to your nerves. There are a few ways around this. You can use analog servos that run very quiet, add a servo helper to keep the load on the serve down (a simple spring works nice) or wrap sound proofing around the servo like Dynamat/ sound proofing wrap. I've used Dynamat and this works great.
It's possible that the servo is attempting a load that is heavier than it's designed for. Over time it may fail. Can you lessen the load or use a stronger designed servo ?
Well it's a pretty light light, a little plastic piece and another servo. Can a servo carry its own weight?
As @dschulpius has more experience with these servos than I do it appears that your servo is working as it should and it can support its own weight. Most pan and tilt cameras have a similar arrangement.
Well, Robot-Doc could be correct also. If your servo is overloaded it will fail.
Also, I'm no expert. ;) This is just what I have read in this and other forums. Just passing along learned info with a tad of personal experience behind it. :)

I did add a helper spring to my High Power Servo. It's lifting about 15 lbs and it stopped buzzing.
Thanks Dave!....Helper spring or bungee cord ! ..and you can measure the torque with a SCALE...fish or DIY.:)
I'd go with analog servos for shoulder joints.
Near all servos are loud... It's how they work - and you'll never really be able to stop it. Unless you wrap it in some sound dampening material.

Servos are loud because of their design. A servo is a little motor. And the little motor has gears. The gears add torque to the motor's output. If you turn the motor a few rotations, the output shaft of the servo will turn a tiny little bit. This allows the servo to move heavier objects with precision. The servo circuit knows what position the servo is in by a little potentiometer. When the output shaft moves, the potentiometer does also. The EZ-B sends a signal to the servo and tells it what position to hold the potentiometer in. When you apply load to the shaft, the potentiometer notices and sends a pulse to the motor. The motor moves to attempt and hold the position. The motor will move back and forth rapidly to hold the position.

And voila, your buzzing noise:)
Out of the mouth of our Guru.
If you have room in your robot, get some Dynamat off of eBay and give it a try.
@feroze if you can't do dynamat then I would look into high torque analog servos. In areas where I simply didn't have extra room I found analog were quiet in comparison. Here's a video of two that I had to modify for continous rotation for gearboxes and also a video comparing analog vs digital.

Here's a video comparing accuracy but you can use this as a reference of what difference analog vs digital makes.

Here are two analog servos close up and you can hear about how much noise they make ( not much)

I can understand your concern , my hitec 5995 ltg servos make a loud buzzing that would drive me nuts even under the lightest load so I found they would not be what I want for my robots shoulders. I went with a analog servo and a gearbox to multiply the torque. You can usually search YouTube by model to see how a servo performs and sounds. Digital will always buzz at least a little and is part of how they work but a analog in some cases can make much less noise. Its all preference.