Machine tool sales are offering another sign of a manufacturing economy on the mend, although growth has been somewhat uneven and less than certain. Sales of machines that factories use to make everything from automobiles to appliances were up nearly 32% the first six months of 2004, a report released this week says. "We are doing pretty well right now, but what's scary is the majority of our work is for one customer," said Howie Taylor, an executive with Key Products Co., a machine-tool company in Milwaukee. Taylor has been in the toolmaking industry more than 30 years, and most...