How do i choose the correct motor?

[bobgaggle]

I just posted a thread about building a 22' diameter revolving turntable. If possible, i would like to power the thing with an electric motor. After doing some research on this site in previous threads, i still have no idea how much horsepower, torque etc. i would need to spin the revolve. Another question thats bugging me:
If i have a motor that puts out 2000 rpms (that seems to be average) how do i use that massive amount of rotation to spin the small tire that drives my turntable? do i need a gears/belts/pulleys to reduce the rpms to a number that i can use? If i put it directly on the revolve without gear reduction, will the weight of the revolve make the motor burn out?

I was reading up on some worm gear set ups. If i hook up the motor drive to the worm, the worm to the gear, then the gear to the tire, would this be the simplest way to power this revolve? I know worm gears greatly reduce rpms, but do they steal torque as well?

Can anyone help me?

[avkid]

RPM and torque are two different things.

http://en.wikipedia.org/wiki/Torque
http://en.wikipedia.org/wiki/RPM

You can have a huge amount of rpm's but if you don't have enough torque you'll just burn up the motor.

[icewolf08]

For the last revolve we used, which was not quite as big as yours, we drove it with two 5hp motors connected to 20:1 gear reducers which were then connected to the drive wheels. We used a friction drive. I don't even pretend to know all the math involved to make the system work (that is why I am not a TD). I know that we had plenty of power to creep the revolve along with a heavy and changing load, and we topped out at a fairly high number of degrees per second.

The other thing you need to think about is how you are going to control your motors. Ideally you would want to have a motion control system, but it can be done with limit switches or just by sight and a toggle switch.

You also have lots of choices in motors, AC vs. DC being the biggest. DC motors will require a power inverter. The more sophisticated inverters will allow 0-10v control signal input, which can be useful. Some inverters allow you to set accel/decel so that you could use a toggle switch and not jump right to full speed.

There are lots of options, it is hard to know what would work best for your situation and budget. If you want, you could contact Creative Conners Inc. They are a company that produces automation gear, and they offer consulting on projects requiring automation. You can also rent gear from them, or buy it.

[Van]

Read Icewolfs post! Good advice there, and this was a really good question to post. Check out www.grainger.com and do a search for "Gear motors" or "Reduction Gears". Check out the connors site as well. there is no reason you can't build thecontrol stuff your self if you have a good working knowledge of the electronics, an electrical supply necessary.