American Machinist magazine and website serves manufacturing plants in industries primarily engaged in the production of durable goods and other metal products. Find numerous Calculators, a forum, the latest editions of the magazine and more.
http://www.americanmachinist.com

Modern Machine Shop online magazine is focused on all aspects of metalworking technology - Providing the new product technologies; process solutions; videos and more calculators and tools.
http://www.mmsonline.com/

The online extension of Production Machining magazine and the most comprehensive Web site available for high volume precision machining professionals.
http://www.productionmachining.com/