Wood lathe Motor Amps.

[Clarence Martin]

Looked at the Grizzly Mini Lathes. One has 1/2 HP and the other is 3/4 HP. The 1/2 HP draws 6 Amps , and the 3/4 HP draws 5.3 Amps. How is it that the smaller motor draws less Amps than the bigger motor ?

[Dave Cullen]

Is the 3/4 hp current for 240 V and the 1/2 hp for 120?

[Mike Henderson]

A HP is about 750 watts. 3/4 of a HP is about 560 Watts. A half HP is about 375 Watts. The rest of the amps going into to a motor is either power factor issues or efficiency issues. If the motor has a poor power factor, some of the current going through the motor is not doing any work. One reason better motors use a run capacitor is to improve the power factor. Cheaper motors generally do not had a run capacitor and thus have worse power factors.

Mike

[The part of the current that is due to power factor issues is not charged to you. Your electric meter is a watt meter and only registers real power.]

[Wade Lippman]

Horsepower doesn't mean anything; it is just what the manufacturer chooses to put on the tool. Witness HF 2hp DCs or 3hp routers.
In most cases power is proportionate to the current. Yes, some expensive motors are more efficient, but you won't find them on Grizzly lathes.

A general rule of thumb is 1200w is one horsepower, regardless of what the manufacturer says. No, I can't explain why my Grizzly 3hp cyclone is 22a and my 3hp SS is 13a (240v).

But to answer your question, there is probably a typo; 6a could be 1/2hp, but 5.3 is way too low for 3/4hp. Ask Grizzly and let us know what they say.

[David L Morse]

It looks like you are comparing the two variable speed mini lathes. These are most likely DC motors with SCR speed controls. Because of the way these controllers work the current waveform is very "spiky", that is it has lots of harmonics. This makes for a very bad power factor and a RMS current that's much higher than what you would expect for the output power. In addition, the two lathes are similar enough that I find it odd for Grizzly to have both in their lineup. It reminds me of the 690/1023 situation with two products that seem to compete with one another. So it's quite possible that, like the 690/1023, the two are made by different manufacturers and if that's the case I wouldn't expect much consistency between the specs. It could also just be a typo. I think Grizzly mostly depends upon the manufacturers for specs so you might be the first person to actually compare them.