Curtiss

I use mine to cut a lot of aluminum and hardwoods, etc. I think the 4HP spindle is a solid choice for me. If you are doing light cutting on light materials, it would likely be overkill. I also often use bits that are 1/2" or larger diameter- and shaped bits that take a lot of energy to drive into the material. Speed (forward speed) is always controlled by me and I derived my cutting speeds from suggestions from more knowledgeable people and my own trial and error. This, combined with rotation speeds are governed by chip load calculation ( or by direct measure of the thickness of the chips. Which I have done a number of times). You can also tell if a router or spindle is struggling by the sound it makes. if it SOUNDS like it is struggling, IT IS. Change forward speed or depth of plunge or rotational speed (or all three).....