# Small slow speed motors?



## SpaceCrawler (Mar 22, 2010)

I'm looking to add some motion to a project (I want only a rocking motion, imagine someone at a ship's wheel turning it slowly back and forth). I'm looking for a motor that might work for this purpose. I've seen a few geared motors like from Tamiya, but the gears seem to be plastic and I'm not sure how durable they'd be in the long run. Plus they obviously run in circles rather than rock back and forth, but I suppose there are ways to make that work. Any tips appreciated.

Sean


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## Rotwang (May 25, 2011)

Hey SC, the Tamiya Planetary Gearbox motor I have works ok, but is very noisy. You might want to Google how windshield wiper motion works. It would be applicable to what you are trying to do.


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## djnick66 (May 2, 2008)

plastic gears will be fine unless you plan on running this thing for say 10,000 hours. For hobby use plastic can be better than metal as the plastic can have some give if things aren't perfectly aligned or have torque or rub, etc. People learn this the hard way in RC cars when they replace the plastic gears with metal then lock it up and burn out the motors or the metal rubbing on metal destroys the gears.

Most motors run in one direction only unless there is some sort of interruptor circuit or electronic signal to reverse it (like a servo motor).

in general running a standard electric motor back and forth causes more wear on the brushes than running it in one direction only, too.


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## SpaceCrawler (Mar 22, 2010)

I think I can make a normal motor work, but it needs to be slow speed. That's the trick. Most motors I've found aren't slow speed.

Sean


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## djnick66 (May 2, 2008)

Usually for slow speed you would use a reduction gear box. Robbe RC used to make some small ones for use on some of their scale model ships to make things like radars rotate slowly. http://www.robbe.de/


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## spawndude (Nov 28, 2007)

I remember the old Linberg kits that included the parts to make an electric motor.

Never did get one to work.


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## Antsnest (Jul 26, 2011)

You could reproduce a slow rocking motion with either a servo, or stepper motor - unfortunately both would require some computerised control to drive them in the required way. Could be achieved with an Arduino micro controller and motor shield though. Servo would probably be best because it will give you a high torque output for a very small physical size.

Ant


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## TAY666 (Jan 8, 2000)

You can use a regular motor to get a rocking motion, without changing the direction of the motor at all.

All you need is a hole on the outer edge of one of the gears.
Then a linkage attached to that hole and leading to whatever you want to rock.
As the gear spins, the linkage will move back-and-forth.


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## SpaceCrawler (Mar 22, 2010)

TAY666 said:


> You can use a regular motor to get a rocking motion, without changing the direction of the motor at all.
> 
> All you need is a hole on the outer edge of one of the gears.
> Then a linkage attached to that hole and leading to whatever you want to rock.
> As the gear spins, the linkage will move back-and-forth.


Yeah, I already planned to do that. The main problem at this point was speed and a confined space that wouldn't really make it easy to have multiple gears stepping down the speed. In any case, I found these motors, but not sure what the speed would be like:
http://store.schoolorders.com/navigation/detail.asp?MySessionID=20-581998185&id=WGMotor

http://store.schoolorders.com/navigation/detail.asp?MySessionID=20-581998185&id=GEARBX-2

Any ideas?

Sean


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## djnick66 (May 2, 2008)

SpaceCrawler said:


> Yeah, I already planned to do that. The main problem at this point was speed and a confined space that wouldn't really make it easy to have multiple gears stepping down the speed. In any case, I found these motors, but not sure what the speed would be like:
> http://store.schoolorders.com/navigation/detail.asp?MySessionID=20-581998185&id=WGMotor
> 
> http://store.schoolorders.com/navigation/detail.asp?MySessionID=20-581998185&id=GEARBX-2
> ...


well the one tells you right in the description its almost 10,000 RPM which is fast


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## SpaceCrawler (Mar 22, 2010)

djnick66 said:


> well the one tells you right in the description its almost 10,000 RPM which is fast


Yeah, but it offers other info about gear ratios that I am not familiar with and I thought might indicate a possibility to lower speed- maybe someone with more mechanical knowledge can offer advice:



> A unique gear box system constructed around a motor. The gear box is easily assembled and can create a range of *gear ratios from 4:1 to 256:1*. Simultaneous drives can be achieved from each end of the gear box. The motor is 3-6 Volt, 9600 RPM.


Sean


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## djnick66 (May 2, 2008)

If they mean one turn of the motor shaft equals four turns of the drive shaft thats nearly 40,000 rpm. If its the other way around, its about 2500


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## hal9001 (May 28, 2008)

There is a tiny motor on eBay that will fit on a dime, but there again, it runs at 13,000 RPM!

http://www.ebay.com/itm/280873972656?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649


HAL9001-


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## SteveR (Aug 7, 2005)

Looking for gears and stuff?

http://www.scientificsonline.com/project-components/gears.html
http://www.gizmoszone.com/shopping/agora.cgi?page=plastic_gear.htm
http://www.hobbyengineering.com/SectionM.html

And here's some info on slowing DC motors:
http://electronics.stackexchange.com/questions/1154/very-slow-electric-motor


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