A Saturday in July around Massapoag Pond sounds like small engines — a whole town cutting at once, and somewhere behind all of it a bench where the blades got sharpened. Ed's Lawnmower Service works both ends of that, mowing, trimming and keeping lawns up across Tyngsborough with equipment held in the shape that makes a clean cut instead of a torn one. Grass shows the difference within a day; a lawn taken down with a keen edge stands greener and holds better through the August heat. When the year turns cold the deck comes off and a plow goes on, and the same attention goes into a driveway cleared corner to corner before the coffee is finished.