Common hacksaw blades are available with 14, 18, 24, and 32 teeth per inch. For metal that is in the vicinity of 1/16-inch thick and thicker, use a blade with 14 to 18 teeth per inch.

Such a hammer developed to cut hot metal is called, appropriately, a hot cut. To cut cold metal, it’s called a cold cut. Remove the handle from a cold cut, and you've got a cold chisel.

This article was originally published with the title “Knife Made from a Hacksaw Blade” in Scientific American Magazine Vol. 105 No. 23 (December 1911), p. 497 doi:10.1038 ...

Fiberglass boxes can be busted out with a hammer and a chisel or sturdy screwdriver. Its best to cut the nails on plastic boxes with a hacksaw.