On Wed, 19 Jan 2005 16:56:19 +0000, Andy Dingley
wrote:

On Wed, 19 Jan 2005 07:55:10 -0800, mac davis
wrote:

Can the router be damaged by the reduction from the dimmer switch?

How many possible variations of dimmer and router are you concerned
about ? 8-(

There's a problem in running any motor at low speeds, in that the heat
dumped into the motor for a given torque will rise. If you throttle
the motor back, and a high load slows it even further, then you have a
risk of overheating.

There's also the waveform issue. Simple dimmers work by phase control.
Their output wavefom becomes "spiky", which means there's an added
high-frequency component. Electric motor windings don't care for this,
and again there's more heating going on.

So you can run a motor with a dimmer, but you need to de-rate it for
useful power and to watch the temperature of the windings.


With a drill, the use of a speed control might be for low-power
low-speed uses like a polishing mop. It works well enough.

For a router though, such an additional speed control is typically
used with an underpowered high-speed router swinging a large
speed-limited cutter. This still needs a fair amount of torque and
thus power, and the power may already be marginal for a small router.
This is less successful.

Thanks, Andy...
I don't have a need to change speeds, but now I know that I wouldn't
try a dimmer switch if I did want to..

What made me ask the question was something that came up recently in
an RV forum, about checking the voltage and amperage at RV
parks/hookups...
Someone said that appliances, especially refrigerators, could be
damaged by "power drops" more than power spikes..


mac

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