# Advice needed: Sound dampening a motor in a model rocketship **URL:** \ **Category:** Factual Questions\ **Created:** [September 21, 2020, 8:45pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180 "2020-09-21T20:45:28Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [September 21, 2020, 8:45pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/1 "2020-09-21T20:45:28Z")
My latest model project is a classic-style rocketship with a rotating ring for artificial gravity. The ring is driven by a little 9V motor and gearbox. The last time I used one of these motor/gearbox units was in a Mechanical Mole, and when the motor’s running it’s quite a noisy little devil. Small wonder, since the plastic hull acts as a dandy soundbox. So I need advice on reducing the motor noise. The motor is/will be mounted solidly to a bulkhead inside the hull. The hull is about the size of a coke can. I’m thinking of gluing some kind of sound absorbent/deadener to the inside of the hull. I have 0.030" lead sheet, cotton batting, egg cartons, and celluclay (a papier-mache material) available. Which of these materials would be best to reduce sound? A picture. The motor drives the blue central gear, which rotates the rubber-band-wrapped drum beneath it. [![](https://live.staticflickr.com/65535/50364807628_ac2f06b7e1_4k.jpg) ](https://live.staticflickr.com/65535/50364807628_ac2f06b7e1_4k.jpg) ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [September 21, 2020, 9:09pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/2 "2020-09-21T21:09:38Z")
If you can mount it with grommets (or otherwise separating whatever part of the motor touches the structure with some rubber), that could quiet it down a bit. How much of the noise is from the gears vs the actual motor? If it’s from the motor, maybe investing in something built to be quieter. I assume you don’t want to make the unnecessary leap to a stepper motor, but with the correct drivers, those can be just about silent. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [September 21, 2020, 9:25pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/3 "2020-09-21T21:25:47Z")
Gear drives like that need lubricant to cut down on noise. White grease works well if it’s not a problem on the components or leaking out. Sometimes just shafts turning in tight plastic holes make a lot of noise and need lubing or the addition of an o-ring. Don’t know if it will work for you here but a stepper motor will produce a lot less noise since you won’t need those reduction gears. ---
**Author:** ![Vesicant](https://avatars.discourse-cdn.com/v4/letter/v/43a26b/32.png) [@Vesicant](https://boards.straightdope.com/u/Vesicant)\ **Post date:** [September 21, 2020, 10:17pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/4 "2020-09-21T22:17:17Z")
Blu Tack, QuietPutty, Vibra Block, acoustic caulk? Acoustic foam is probably going to be too thick. ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [September 22, 2020, 12:28am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/5 "2020-09-22T00:28:17Z")
I think an integrated gear motor would be quieter. How fast do you want to rotate? If 1 RPM then a motor for a clock with a second hand would be very quiet. ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [September 22, 2020, 12:40am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/6 "2020-09-22T00:40:32Z")
It would require some rejigging but bevel cut teflon gears would be self lubricating and I imagine quite a bit quieter. Maybe a sheet of Dynamat or automotive sound deadener lining the nose cone and bottom of the motor. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [September 22, 2020, 1:04am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/7 "2020-09-22T01:04:11Z")
If you need very little torque, a small stepper motor driven by a “silent step stick” in “stealthchop” mode will be almost silent and very smooth. ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [September 22, 2020, 5:13am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/8 "2020-09-22T05:13:26Z")
> [@swampspruce](#): > > It would require some rejigging but bevel cut teflon gears would be self lubricating and I imagine quite a bit quieter. Maybe a sheet of Dynamat or automotive sound deadener lining the nose cone and bottom of the motor. The blue gears are polyethylene, I think, and seem to be pretty quiet. The gear in the gearmotor are steel, and I think I’ll give 'em a hefty coating of grease. I have some dynamat lying around somewhere. Have to do some experimenting! ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [September 22, 2020, 5:38am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/9 "2020-09-22T05:38:14Z")
> [@beowulff](#): > > If you need very little torque, a small stepper motor driven by a “silent step stick” in “stealthchop” mode That would be my advice; the only problem is that you need both a driver and a controller (Arduino, etc.). At least I’m not aware of any that simply run when you apply a voltage, the way a standard brushed DC motor does. If you want to get really fancy, the ultrasonic/piezo motors in SLR camera lenses are also silent. I’m sure the parts could be salvaged on eBay, but driving them would be even more difficult than the stepper. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [September 22, 2020, 7:03pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/10 "2020-09-22T19:03:53Z")
No EVA foam on hand? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [September 22, 2020, 7:19pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/11 "2020-09-22T19:19:57Z")
You can feed the driver pulses from a 555 or similar circuit. It’s a bit more involved than just applying DC to a motor, but very flexible. Here is the driver board: [https://ebay.us/PmPE6g](https://ebay.us/PmPE6g) BTW, I used this to modify a solar tracker that was originally AC powered to run from a battery (I had a nice geared stepper motor handy). The final design was smooth as silk - no motor noise or vibration at all, just like a clock should be. ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [September 22, 2020, 11:00pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/12 "2020-09-22T23:00:59Z")
IMO, your reference to a sounding board is the key point. I don’t think sound absorptive material inside the model will have much effect, because firmly mounting the motor and gears to the model is going to transmit a lot of sound directly into the body. You need, as much as possible, to isolate the motor and gears from the model with rubber or some other vibration-absorbing material. If you can do that, absorptive material inside may help deaden the remaining sound being transmitted through the air, which I think would be a small percentage of the total. Or get a quieter motor, as others suggest. ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [September 23, 2020, 12:18am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/13 "2020-09-23T00:18:22Z")
How often do you really need the gravity to be turned on? Let the ship’s complement float around most of the time; they knew what they signed up for when they accepted their berths (the crew) and bought their tickets (the passengers). P.S. Looking forward to your pix of the final project; those are always a marvel to behold! ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [September 23, 2020, 5:07am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/14 "2020-09-23T05:07:13Z")
[quote=“kaylasdad99, post:13, topic:921180, full:true”] How often do you really need the gravity to be turned on? Let the ship’s complement float around most of the time; they knew what they signed up for when they accepted their berths (the crew) and bought their tickets (the passengers).[/quote] On the real ship, the ring section would be rotating for the entire trip; I think there’s enough evidence that prolonged weightlessness has serious health implications, and long-duration spacefllight really really needs artificial gravity of some sort. On the model, it only needs to rotate for perhaps an hour or two at a time, for model shows. That’ll be limited by the 9V battery I plan to use to power it. > [@kaylasdad99](#): > > P.S. Looking forward to your pix of the final project; those are always a marvel to behold! Thanks! Today I kinda taped the whole thing together for a sanity check: [https://live.staticflickr.com/65535/50372789181\_0eed88cb6c\_4k.jpg](https://live.staticflickr.com/65535/50372789181_0eed88cb6c_4k.jpg) [![](https://live.staticflickr.com/65535/50372950772_d236c54940_4k.jpg) ](https://live.staticflickr.com/65535/50372950772_d236c54940_4k.jpg) ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [September 23, 2020, 8:58pm UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/15 "2020-09-23T20:58:26Z")
This morning I did some experimenting, using a sound meter app on my phone. Lining the hull in the vicinity of the motor with 0.030 lead sheet gave me a decibel or two drop. But I had concerns about adding so much weight to a model that’s going to be cantilevered way out there on its stand. So this afternoon I messed around with some 1/8" cotton batting **Mrs R** gave me. Two layers inside the hull reduced the sound by 4 dB, with virtually no weight increase. So cotton batting it is. I told **Mrs R** that if the sound really got to bothering me, I’d just add a sound card to the base and drown out the motor with some “Hey, we’re going off to Outer Space!” music. 😉 ---
**Author:** ![Rocketeer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocketeer/32/4437_2.png) [@Rocketeer](https://boards.straightdope.com/u/Rocketeer)\ **Post date:** [October 8, 2020, 5:20am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/16 "2020-10-08T05:20:35Z")
Board member **Beowulff** was kind enough to send me a lovely little gearmotor which is quite a bit quieter than my original one, so I’ve just finished reworking the motor mount to take it. I still plan to add the cotton batting, just to quiet things even more. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [October 8, 2020, 8:04am UTC](https://boards.straightdope.com/t/advice-needed-sound-dampening-a-motor-in-a-model-rocketship/921180/17 "2020-10-08T08:04:41Z")
Record players - for vinyl records - were quiet. By design. They used quiet motors. either by direct drive (33 rpm, which is probably about what you want), or by a drive belt (which allowed the motor go a bit faster than the platter). They typically cost only a bit more than a ‘cheap’ electric motor. Called “record player motor” or “turntable motor”.