Before I spend the money....

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3/16th's

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Apr 19, 2000
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A while back I was sponging some free information about the differences between variable and non-variable speed motors from an electrician friend of mine. During the course of the conversation he said I should try hooking the speed controller from a ceiling fan to my grinder motor. He told me that unlike a dimmer switch to a light-bulb, a ceiling-fan switch changes the frequency of the AC running to the motor which in turn varies the speed. Has anybody out there tried this or has my buddy been testing live circuits with his tongue again?(insert smiley here)

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President of Knifemakers Anonymous - "The sickness can be cured!" Call 1-800-cutfingers
 
As I recall when I was in the Navy, we had devices called synchros. The machinists that are familiar with CNC machines probably know what I am referring to. I believe some of the older Fanuc or Morisaki machines made use of these.
We were able to substitute a 60 Hz synchro for a 400 Hz device in a pinch but not vice versa. The 400 Hz synchros were much smaller and had smaller conductors (wiring diameter). They would burn up at the lower frequency. If, in fact, the frequency is lowered, then you run a very good chance of burning up the motor.
I am sorry to say that if it worked, then everyone would be doing it.
At this point, there is not really an inexpensive way to have a viable variable speed other than with an SCR or phase controller. About the cheapest way you could hope for would be to use different size pulleys on a constant speed motor but change out is a pain.

C Wilkins
 
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