Jam nuts can be adequately tightened by squeezing two wrenches in one hand. Using two hands and arms to tighten jam nuts risks nearly welding them to the bolt’s thread.

Removing broken bolts can be one of the most challenging workshop tasks, especially when standard extractors fail. This video ...

This article was originally published with the title “The Sellers Standard System of Screw Threads, Nuts, and Bolt Heads” in SA Supplements Vol. 17 No. 443supp (June 1884), p. 7072 doi:10.1038 ...