So, looking at realistic HP ratings (not shop vac sensationalized
values), my table saw is a 230 volt, 3hp motor. My router is a 120v
3hp motor. TS spins about 3 to 4 000 RPM, router can go up to 22K. I
still find it difficult to comprehend that the two motors are rated the
same. (And I trust Porter Cable!).
Does the output speed make the router rate as high as the TS?
Obviously it is not turning as heavy a cutter as the TS.
Marc

Jim wrote:
"boorite" wrote in message
oups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.

Me too. Perhaps you should understand more about horsepower ratings.

The purveyors of this stuff rate motorins things like the Shop Vac as the
product of the maximum amperage times the maximum voltage. And, they don't
worry about such niceties as temperature rise.

However, motors for machinery such as table saws are rated at the average
power (which is 1/2 of what the above calculations show) and for an
intermittent load. This load results in a temperature rise of 60F above
ambient temperature. Thus, machinery motors are conservatively rated
whereas those other are wildly optimisticall rated.

Jim