Choice of motors, please advise

[jmjudg01]

I know you all probably hate this sort of general question, but I'm kind of on a tight schedule so it can't hurt to ask. I am working on creating a prototype for a project which will require a rotating circular stand for an adult person to stand on which will then be capable of rotating at low speed (thinking 1-2 rpm) and stop for a brief period (3-4 seconds) at regular intervals during that rotation. for sake of argument stand probably 50lbs or so and person max 250 or so. I have no background in engineering (Surgical resident doing research) so I am a little lost on the choice of motors. choice of drive system (gearing, vs a belt system vs. direct drive) is open. Cost is an issue, but willing to invest 500 or so in a motor alone (more if absolutely necessary). Planning to drive the system with an arduino uno microcontroller board (been having a blast learning to program it) + whatever arduino shield or alternative controller is necessary with an outside power source obviously. My first inclination would be a stepper motor, but most of the ones I have found online look too small (and very expensive for small ones even). I could use help on type and size/power capabilities.

Sorry to ask such a general question that sounds like a cop-out. I am totally willing to learn this stuff on my own, actually enjoy it, but our funding for the project is going to dry up at the end of december so I really don't have the time to learn a whole lot about it until after the fact. Also, if you think this fits better in mech engineering, please feel free to move it.

Thanks.

 

[vk6kro]

I would be looking at antenna rotators. These rotate at about 1 RPM and good ones have plenty of torque.

For the platform, I haven't verified this, but how would one of the rotating food platforms you see in Chinese restaurants go? We call that a "lazy Susan". Our Ikea sells them.

You can get good rotators for prices within your budget, but here is something different:
http://www.crazysales.com.au/dual-power-outdoor-hdtv-digital-aerial-rotating-uhf-vhf-fm-2003-antenna_p8121.html?utm_source=newsletter&utm_medium=cdemail&utm_campaign=CSNEWS_2010-12-12_CD
Throw away the antenna and keep the rotator.

 

[vk6kro]

Another choice of motor would be replacement rotisserie motors for domestic ovens.

These do about 15 RPM, so you might be able to use a belt or chain drive for one of these to drive a turntable.

 

[sparkey]

a rotisserie motor would work nicely in my opinion. the slightly higher RPM allows you to add a direct drive gearbox to it to reduce RMP and increase torque at the same time.

 

[jmjudg01]

Those are two good suggestions I hadn't thought of. Thanks!

 

[Fish4Fun]

Ebay frequently has high gear ratio industrial speed reducers for < $100, (50:1 to 250:1). Any one or combination of these with a servo motor, DC motor, AC Gear motor etc would do fine and provide a long service life. The motor itself, for 1RPM to 10RPM, would not require much output power, but remember 10RPM is only one revolution every 6 seconds, that is really VERY SLOW if you are expecting to maintain an audience's attention.

(been having a blast learning to program it)

uControllers are REALLY FUN in general. The things you can do with them are amazing! Frequently the biggest chore is overcoming the mental process of "slowing them down" to do things in "our time". EG, if it's only task is to do something four times a second, and the clock is running @ 16mHz, you need to create a delay routine to "eat up" 15 * 16 * 10^6 cycles, and this seems so "wasteful" of processing time! :-)

Have FUN and I hope your project turns out to be fabulous!

Fish

 

[vk6kro]

The motor itself, for 1RPM to 10RPM, would not require much output power, but remember 10RPM is only one revolution every 6 seconds, that is really VERY SLOW if you are expecting to maintain an audience's attention.
Fish

This is going to be used to rotate a platform with a person standing on it.

Even at about 3 RPM people would get dizzy and disoriented. You would probably need some sort of safety rail so they could avoid falling and get off the platform safely.

 

[jmjudg01]

Thanks for all of the replies. These are certainly all good ideas and have given me some good direction in looking for parts.