Before putting alot of money into it, stay with your garage door opener with its AC motor. Use a 2:1 transformer to change the input voltage to 60 volts. That will slow it down but reduce the torque.

I think he will surely burn that motor out if he did that. For one thing, it will never pull itself out of the start winding. An Induction motor's speed is governed by the line freq not the line voltage. Reducing the line voltage only invites a stall.

 

I think he might have meant that there was a 22:1 gear reduction in the motor, followed by a 2" sprocket driving the linear chain...

Ha, I think you're absolutely correct. A 22:1 sprocket would be quite large indeed!

 

There are more ways than one to change the speed of induction motors. One is to change the frequency, another is to reduce the input voltage. The control of fans, for example, is usually by voltage reduction. But not all loads lend themselves to this type of control. That's why experimentation is necessary. It could be the cheapest way of getting this job done and that makes it worth the effort of finding out, I think.

 

There are more ways than one to change the speed of induction motors. One is to change the frequency, another is to reduce the input voltage. The control of fans, for example, is usually by voltage reduction. But not all loads lend themselves to this type of control. That's why experimentation is necessary. It could be the cheapest way of getting this job done and that makes it worth the effort of finding out, I think.

Ceiling fans and portable vari speed fans do not employ a Capacitor Start Motor. The OP stated that it's a 1/3 HP Cap Start Motor. Cap Start Motors don't lend themselves to Voltage or Freq control because of the start winding. If you manage to reduce the speed by freq control you risk dropping back into the start winding when the RPM drop.

Call your local Electric Motor/Pump sales and repair shop and ask them what they think. As for me, there is absolutely no doubt in my military mind. Quote: Sgt. Harraway

 

You're right, Cdrive, I either didn't read the OP very well or I forgot about the capacitor. Thanks for setting me straight.

 

You're right, Cdrive, I either didn't read the OP very well or I forgot about the capacitor. Thanks for setting me straight.

No problem, PRS, we all miss things... Me too!