Portland Bolt & Manufacturing Company, Bolt Depot, Imperial Supplies, Engineers Handbook and Federal Screw Products provide torque charts as of 2016. CNCexpo.com, Allied Systems Company, XRF Reduced Friction Chassis Parts, Engineers Edge and Repair Engineering also provide torque charts.
Torque calculation estimate charts often vary by company and are provided only as general specification guides. Most charts list several torque characteristics, such as bolt size, threads per inch, steel grades and torque value estimates. Many variables affect torque tensions estimates, such as individual joints, surface texture, lubrication and human error. Proper torque can only be properly applied through trial and error under typical conditions.