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-   -   How to make a shop fan variable speed (http://www.diychatroom.com/f18/how-make-shop-fan-variable-speed-147934/)

lynndm 06-22-2012 07:08 PM

How to make a shop fan variable speed
 
I have a 48" industrial shop fan that I need to slow down. It has a single speed 1/2 hp AC motor and I need to know what kind of motor I can put on it that will enable me to run the fan at half the RPM it now runs, and ideally, several slower speeds without giving up the capability of running it at full speed when needed.

joecaption 06-22-2012 07:19 PM

http://www.rockler.com/product.cfm?p...0&site=ROCKLER

zappa 06-22-2012 08:23 PM

The best way to do this is to buy a 2 or 3 speed direct replacement motor and use a selector switch to control the speeds.

dmxtothemax 06-22-2012 09:28 PM

Electronic speed controls are readily available,
Purchase one suitable for your existing motor,
Easy as !

lynndm 06-23-2012 04:06 AM

Quote:

Originally Posted by zappa (Post 949314)
The best way to do this is to buy a 2 or 3 speed direct replacement motor and use a selector switch to control the speeds.

Any suggestion on where to buy such a motor? I have looked and come up empty.

zappa 06-23-2012 06:01 AM

Quote:

Originally Posted by lynndm (Post 949457)
Any suggestion on where to buy such a motor? I have looked and come up empty.

Well, I don't know your location or country but Grainger is the place to start here in the U.S. If you don't want to buy from there at least you will have a model number so you can search for other places to buy it.

Others have mentioned electronic variable speed but I don't think you will be happy with the performance on such a large fan. You will get it set to a speed that you want and then conditions will change causing the motor to speed up or slow down.

I switched out a single speed motor for a 3 speed on my 36" whole house fan years back and I mostly use low or medium speed.

zappa 06-23-2012 07:01 AM

It has been a long time ago but I think I picked a similar motor in one of these links. My original motor mounted with a belly bracket attached to rubber rings on the front and rear of the motor so I simply swapped the motor out using the original mounting hardware. The long shafts can easily be cut if you are using belt drive but I can't remember if the motor I bought had a long shaft.

http://www.grainger.com/Grainger/DAY...er-Motor-4M100

http://www.grainger.com/Grainger/AO-...&cm_vc=IDPRRZ1



If you look in the belt drive or evaporator cooler catagory there are a number of 2 speed motors.

http://www.grainger.com/Grainger/hva...log/N-9xz?bc=y

tarnall 12-12-2012 10:57 AM

I have seen there are two different kind of motors, brushless (induction) and brush type. Each I think requites different type of speed controller - one being a VFD type.
Any ideas here??

tarnall 12-12-2012 11:02 AM

I believe most routers are a bush type motor and this speed control might work fine, but the 1/2 horse, washing machine, type motors are induction type motors, with this device work on these to slow them down? I have a drill press and a band saw with these type of single speed, 1750 RPM, that I would love to control the speed. VFD??? variable infrequence drive - do these come in small motor applications?

BigJim 12-12-2012 11:08 AM

If using one of the speed controls, it would be a good idea to check to see if the control will handle the amps the motor is pulling.


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