# Tablesaw HP

I'd be wondering if that is a 3hp induction motor or a universal motor.
HUGE difference between the two. I laugh anytime I see a shop vac being sold as a 7 1/2 hp machine. Then cry when someone believes it.
Mike
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says...

With a 16ga 120V line cord. ;-)
IME, if it's got a belt it's an induction motor, if not it's a universal. If it's *NOISY* it's a universal motor.
--
Keith

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krw wrote:

There are some exceptions to this; bench grinder, horizontal mortising/boring machine, hollow chisel mortiser, dust collector...
> If it's *NOISY* it's a universal motor.
This one is pretty much guaranteed. Wailing like a banshee means universal.
Chris
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On Sun, 7 Sep 2008 10:03:15 -0500, "The Davenport's"

Not really. Power is still Amps X Voltage (with phase angle considered for AC) regardless of whether it's a universal or induction motor.
The difference is in the marketing department of the manufacturer's sales organization. They like to claim as much power as they can get away with for their shop-vac. So, most of that hype comes from using the amperage drawn by the motor with the rotor locked - the absolute maximum the motor will draw. That amperage multiplied by the supply voltage gives a pseudo wattage value that can be converted to Horsepower at the rate of 746 watts per HP.
Now that's the power consumed (or in marketing terms, "Developed") by the motor under conditions in which it is actually producing no power at all. Mechanical Power = Torque X rotational velocity (with the proper units). So with rotation = 0, Power = 0.
That marketing approach to power ratings seems to be most often found in small universal motor applications, but I've also seen applications using induction motors emblazoned with such things a "7 HP Developed" and in much smaller lettering "3 HP Running".
But, it's all marketing hype, not something intrinsic to universal vs induction motors.
Tom Veatch Wichita, KS USA
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Tom Veatch wrote:

Sounds like the same approach used for cheap audio systems, especially the ones you attach to computers. You know, the ones that say 200W and are fed from a wall-wart the size of a matchbox.
--
Stuart Winsor

For Barn dances and folk evenings in the Coventry and Warwickshire area
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Stuart wrote:

And Monster Cable and K&N Air Filters.
All work miracles!
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says...

Sorta, except the audiophools are even more creative. They take the open circuit voltage times the short circuit current and give it a technical term lie "music power". If they are really creative they'll call it "RMS music power" or some other nonsensical term. It would be like measuring the rotor torque close to stall times the unloaded RPM.
--
Keith

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And they probably "measure" it playing a pure tone at the resonance frequency of the speaker.
Puckdropper
--

To email me directly, send a message to puckdropper (at) fastmail.fm
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<puckdropper(at)yahoo(dot)com> says...

Nope. That would give a number that makes at least some sense.
--
Keith

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On Sat, 6 Sep 2008 16:14:05 -0700 (PDT), DejaVoodoo

Keep in mind that you may need 5 HP+ when a DC and air filters are running. A motor can be replaced in a table saw--I'd suspect a belt drive type is easier to swap. In my opinion, table saw power is less important than a large flat cast-iron table, a quality precision fence, and a sharp blade. If your 1.75 HP is not constantly bogging down I doubt you need 3 HP.
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In article <de26a03d-45ec-4a41-8158-
says...

It doesn't "smooth out" the power but as others have mentioned, it will give you somewhat more power (and keep the motor cooler) because there is less drop in the wires (all assuming the same sized wiring).

It *can*, but likely won't. 1HP ~= 750W, assuming 100% efficiency. A 120V 30A circuit might be able to supply a 3HP motor, but it would be a waste of copper (#10 wire required). A 220V 20A circuit is almost always simpler and cheaper, all around.

Don't worry. Be happy.

It likely can be replaced, but since you're happy with the saw now there is little chance the "upgrade" would be worth the expense.

A bit of difference there! ;-)

For most, I think you're right on the money.
--
Keith

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