My single-speed bench grinder is too fast for some work I need to do. Can I install a standard lighting dimmer (household) on the power cord to use as a regulator? Or, will I possibly damage the motor? Is there a better solution? Any ideas/experience would be most appreciated!
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Dimmer won’t last long! you can purchase a motor speed control at an electrical supplier that is rated for the voltage and amperage of your motor. if you are good with wiring, it can easily be mounted in a box with a male cord on one end and a female cord on the other end. that way it can still be used at full speed when needed by not using the speed control box.
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For a cheeper solution you might look for an old sewing machine pedale or a variable control pedal for a scroll saw.
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If the motor is a brush type you can slow it down by reducing the voltage available to it. But most likely its an induction motor. An induction motors speed is determined by the frequency of the AC line. Induction motors need a frequency modulator to reduce speed. Some dimmers use a triac chopper circuit that breaks up the frequency of the AC line voltage. If you do use one it needs to be able to handle the load of the grinder motor. They tend to work on both motor types but may burn out if the load gets too high. The only problem is that when the speed is reduced, so is the power of the motor. If the dimmer reduces voltage it will still work on a brush motor but it won’t have any effect except reducing the power(and likely overheating) of an induction motor and the dimmer. Dimmers are designed to work on low amperage incandescent lighting. Motors have a larger load than lighting. But grinder motors aren’t usually very large motors so it may work still but the dimmer may not last very long. Don’t put anything flammable near it.