Advice on "quiet" servo

[electr0n]

I'm working on my first talking skull for Halloween and everything is going well. I haven't worked with servos before and was suprised how noisy they are - or at least the one I'm using is. It's a Futaba S3004, I just got it from a local RC hobby store - there's no particular reason I decided on that servo except that I could get it locally.

I haven't actually mounted the servo in the skull yet (so it's basically moving unloaded) but I can hear it several feet away with the audio output at a "conversational" level. I would like to be able to hear nothing (or as little as possible) from a few feet away if this is possible. For all of the servos I have seen they don't seem to list how noisy they are. I know that that would be hard to standardize and admittely for RC applications it doesn't matter. ;-)

I know that how noisy a servo is certainly is a subjective thing, but I wanted to see if there are any recommendations for a quiet and reliable servo to drive a skull jaw. Ultimately I can turn the volume up on the speakers from the audio driver, but I thought it would be a good time to get some advice on what servos people are using and recommending.

BTW it looks like the Futaba S3004 I'm using has 44 oz-in of torque at 4.8V just for reference.

[TERBObob]

Not really sure what volum you are referring to , when you say
"conversational" level ,
but , if you can hear it over the volume at a couple of feet away , one of two things is wrong .

1) the servo is faulty
2) the volume is VERY low

I have just built 3 ( quantity ) 3 axis skulls , each with 2 axis eyes and used Hitec HS 311 servos for all movements except the eyes ( they were micro servos -HS 55 ) purchased from :
http://www.servocity.com/

But , I have used NUMEROUS Futaba servos in my planes and boats without really noticing any extra loudness . I also went and dug up a 3004 and tried it , and didn't notice any loudness coming from it . You might want to bring it back to the LHS and check it against another for noise .
And as far as a "quieter" servo ? You might check iout the digital servos , BUT ... make sure your sitting down when you look at the prices .

[djulien]

I know that how noisy a servo is certainly is a subjective thing, but I wanted to see if there are any recommendations for a quiet and reliable servo to drive a skull jaw. Ultimately I can turn the volume up on the speakers from the audio driver, but I thought it would be a good time to get some advice on what servos people are using and recommending.

An additional approach might be to put some distance between the skull and the servo with a longer pull-rod, so the servo could be hidden or mounted somewhere where the noise is baffled, rather than inside the skull.

don

[kostyun]

I also used the Futaba S3004's myself - one thing I noticed - was the old servo's I had (10 years old) were a lot noisier than the new ones I purchased.

[electr0n]

Thanks for the replies. I should've mentioned that the noise increases with the speed it is being driven, which I assume is normal for servos. In other words when I program my PIC to do a slow sweep (taking several seconds to go from one end of travel to the other) there is very little noise (just kind of a low hum). But when I use the servo for an eyelid function (with an open/close travel in less than .5 second) or manually driven via DMX (from an audio source) or using Scary Terry's audio circuit it gets noisy.

I thought someone would catch me on the conversational level thing. What I meant was that I intend to put this either in my front yard or in my garage as a greeter for the kids. He'll tell jokes - I don't want it to be too scary as we have lots of little kids around. But I don't want to have to turn the volume way up to cover the sound of the servos moving, although I know that would solve the issue.

It's possible that I have a bad servo although it works fine otherwise. I'll probably pick up a Hitec to compare it against, I've heard good things about them. At this point the Futaba is the only servo I've got so it's hard to know what is a "normal" noise level. I also could take a look at somehow acoustically insulating the servo. Also the servo is only temporarily mounted and I don't have any rubber grommets so the vibration could be conducting through what's holding it. That could be part of my problem. I'm glad to know that other people don't seem to have a problem with the noise so that helps me with my troubleshooting.

[51fordf2]

The servos we use in our planes are notoriously noisy. The digitals can be less noisy, but they also have a "whine", part of the digital technology, and it can be aggravating, as well. And, the faster they are moving, the more torque they are generating, thus, more noise. You are right, the mounting can help quite a bit. You can also cut a foam block, that can fit around it, and that will help quiet them down a bit. All the servos have a 3 or 4 gear train, and that's where the noise comes from, plus, add the whine from the digital circuitry, and the digitals can be louder over all. Most of the cheaper ones have nylon gears, and the more expensive ones are metal.

The big thing is, the servos are used for moving flight surfaces in flight, where the noise doesn't matter, so there are no requirements to be quiet. So, NO one makes a "quiet" servo. Other than padding and mounting, or going through a bunch of servos, there's no way to get a quiet one.

I have actually saved a plane stuck in the trees, because of the noise - we lost it, had NO idea where it had come down, but by working the control surfaces, we finally heard the servos, and found the plane...

Been flying RC planes for 25 years...ain't heard a "quiet" one yet! Again, you can pad it quite well, and there's really no need to worry about heat build-up - the case is sealed anyway, so there's not much need for heat dissipation.

Good luck!

R

[Aurbo99]

Most R/C Servos are mechanically noisy, its the design.

What I would suggest is you modify your skulls to accept control horn and use "nyrods" thereby placing your servo farther away from the skull.

I did this a few years back with a Bucky, I had the servo in a project box 3 feet down near the base of the fence post, I had soft foam from am old pillow cut and fitted into the project box to reduce the servo noise. then wrapped the box in more foam, almost no noise could be heard from the servo at that point.


R/C flying for 32 years and counting..

[TERBObob]

Well , its nice to see other avid flyers , but , not sure what to think here about that loud of noise . if , as described , THATS loud !
I mean , I have them in a bucky and in Boris and also in Lindberg skulls and the thing I was worried about , was the clunking noise I first made when I was adjusting the trim on the servo whilst the jaw was bottoming out on the up trip towards the skull . Too far off , and the jaw seemed to be too far away . Too close , and the teeth hit and literally clunked when it did .
But , as far as servo noise over powering the audio I had for it ? nope .
Might want to ask Frank also . I know he has done a couple of 3 or 2 axis skulls
or go here , and ask him ( Dr. Morbius - Bob Dane )) about noise level ( he builds the 3 axis skulls to sell , complete ) .
www.hauntforum.com
he also has a website that he sells them on also, you can contact him from there also . http://www.noisesintheattic.com/skulltek.html
heres his YAHOO email if you prefer : bobdane01@yahoo.com
I know he'll be glad to help you . Hes a really nice guy .

[electr0n]

I have actually saved a plane stuck in the trees, because of the noise - we lost it, had NO idea where it had come down, but by working the control surfaces, we finally heard the servos, and found the plane...


Now that's funny! Thanks for the tips. I'll keep playing with it and use some shock and sound absorbing material. I'm sure it will be fine. When I get everything mounted and running I'll link to a video so maybe you can see (well hear) what I'm talking about.

[51fordf2]

Off topic, but something has occurred to me. Here we are talking about servos, and it's apparent, that a few of us have been flying for a while. Of course, we're all interested in blinky-lights, but I went to electrOn's site, and he has a page on Papillons. Now, WE have a papillon. I've also noticed a LOT of my other hobbies, mentioned time and again...

Is it something about our character, that makes us so similar, in different ways?

And while we're on servos. I just ran out and looked. I have several 3004's - I don't use them in anything, but probably got them in trades or something...man, they ARE noisy as heck!! They are just about the cheapest servos you can buy, and probably one reason they ARE so noisy. Most of mine are usually fairly expensive, because I fly 1/4 scale, or larger, but they are all a lot quieter. Just thought I'd mention it.

R

[electr0n]

Well I lied a bit when I said I had no experience with servos I had an RC plane when I was 13 which was - many years ago. ;) So I suppose I am an RC'er from way back as well.

Papillons are technically my wife's hobby but I love them too. She says they are like potato chips - you can't have just one. :D I guess we all do have stuff in common...

[51fordf2]

She says they are like potato chips - you can't have just one. :D

I can!! But then, we also have a bloodhound, and two other dogs. Nine birds. Two box turtles. Two cats. So, only one Pap...but, they are all rescue animals...the disadvantage of having a great big house!! :)

Papillons are 3 foot tall dogs, in a 1 foot tall body...our "Gizmo" only has one eye, and a limp (no "Lucky" jokes, please!), but he's great!

R