A method of making twisted boring ;ools has been patented by Mr. Charles Robin, of Chester, Conn. It consists in swaging a blank with a plane md a concave side and then twisting the same to form a )it, with a deep spiral groove on one side and II shallow piral groove on the opposite side, making a bit which requires but little grinding.
This article was originally published with the title "Mechanical Inventions" in Scientific American 52, 25, 393 (June 1885)
doi:10.1038/scientificamerican06201885-393a
