Machine Shop Math - How to calculate spindle speed

[@37yearsofanythingisenough39]

Try 4 as a constant times the cutting speed divided by the diameter. (4X50 /dia) Much easier to remember. Taught it that way to my students for decades. This assumes HSS tool. Carbide is triple.

[@geremypelleran8487]

N=3.83xSFM/Dia is much more simplified.

[@nobraino]

An easier method for metric calculation is Cutting Speed x 318, then divide by diameter.

[@omegalasermexico]

what about the feed formula?

[@Jathxnn]

Marc Spector?