Jim
Your figures are right. KW x 1.33 = HP (close enough for estimation purposes anyway).
This is the same thing I was saying up above about constant horsepower versus constant torque. Its also one of those places where peak horsepower ratings are demonstrated to be less than honest, and, when combined with a non-geared headstock, can lead to a machine running out of power pretty quick at low speeds.
If you look at the max available torque on your Haas and do some simple multiplying and dividing, you'll immediately know how much horsepower you have at any given speed thats equal to or greater than the rpm where the max torque occurs. Below that rpm, the available torque will be somehing less than the max amount, so the available HP will be even less.
Lets say your lathe has 20hp, 4000rpm max speed, and a non-geared headstock. For simplicity, assume the drive will develop max torque at 200 rpm and remain constant from there to max speed. Because HP is a product of speed and torque, the available HP varies linearly with speed. Translated, that says if you've got 20hp at 4000rpm, you'll have 10hp at 2000rpm, 5hp at 1000rpm, and 2.5hp at 500rpm.
To demonstrate the effect of a multispeed headstock and its effect on available power, I'll use my LC30 because I know the speed ranges without looking them up. It has 4 ranges which top out at 200, 550, 1100, and 3000rpm. Its got a 22kw (30hp) spindle motor, so a casual glance would say its got 1.5 times the power of the direct drive 20hp lathe up above. But, in the 550 range it develops full torque at about 200 rpm. The torque then remains constant and horsepower increases with speed until the speed reaches 550rpm. So, at 500rpm it should develop about 90% of max hp, or 27hp. What looked like a difference of 50% at first glance turns out to be not even close. One lathe has 2.5hp at 500rpm and the other has 27hp, so the difference is 1100% instead of 50%. Since the rpm is the same in both cases, the torque has to be 11 times as much. So, when the Haas loadmeter hits 100%, the LC30's loadmeter will be around 10%.
Peak readings come into play in the following manner. IIRC, I've seen numbers that say a 20hp Haas spindle is good for about 12hp on a continuous duty basis. The LC30's 30hp is a continuous rating. Lathes get into cuts where continuous hp is important much more often than mills do. Once again, the first glance comparison was deceptive. Instead of having 50% more hp, the 30hp lathe has 2 1/2 times as much continuous hp when both are running in high gear at 1 to 1 drive ratios thru the headstock.
Obviously, to state that my LC30 has more power than a SL-10 would rate a major Well Duhhhh, but I used its numbers since they're already in my head. As can easily be seen, the comparative numbers are deceptive on their face.
Personally, I think there should be some requirement that all lathes be rated according to standard machine tool duty ratings. Those ratings would list the continuous horsepower and the horsepower which can be utilized for 30 minutes out of each hour. Its fine with me if someone wants to believe a Craftsman shop-vac really has 6.5 horsepower, but those sorts of numbers games have no place in machine tools where the buyer expects to be able to remove metal and produce parts based on realistic power ratings.
Sorry for the long winded explanation, but its a subject that rates something more than a couple half-assed one liners that really don't help anyone understand the subject
