Volume of a solid bounded by a cylindrical surface is: V= ((4/3 x pi) x (radius cubed)) = 14.1 cubic inches for a radius of 1.3inches.
According to Machinery's Handbook, and if all elements such as sharpness, optimum rate of feed, efficiency of power transmission, etc are taken into account:
The "K" factor (specific power consumption) of plain carbon steel is given as
0.63 HP required to remove material at the rate of 1 cubic inch per minute. Therefore, it would take 22.4 minutes to remove 3 inches of material with 1 HP turning a 3" face mill. And that is if everything else is optimum. Thus it would take at least 22.4 minutes to remove the 14.1 cu. inches. Not likely, because of lost motion re. repeated passes.
A more reasonable diameter to cut on a 1 HP mill might be 1 inch. That works out to 48 seconds; but again would take longer because of lost motion between passes.
PS: Someone please check me on this because I'm pretty loopy right now because of Vicodin taken for a broken ankle, in a cast.
I have a MVI vertical mill with the original low-speed 1 HP motor driven from a VFD, with an R8 spindle.
My first question is how large a diameter is reasonable. I've heard that such machines can spin a 3" face mill with no problem. Would that that be for steel, or only for aluminum? What sizes have people used?
My second question is what make and model of face mill to get. Again, what kinds have people used, and how well did the face mills work?