Only if you're going like a bat out of hell! Contrary to popular belief, putting a decent edge on a rotary mower blade will make a HUGE difference to the performance of the mower. For a start, it will CUT the grass, rather than break it off/rip it out, and second if will HALVE the amount of power needed to drive the blade.
Just be sure the blade is balanced after you grind the cutting edge (TOP SURFACE ONLY), or - better - replace it.
phil_saunders(a)bigfoot.com
Phil Saunders, May 2012
