The gimlet bit is an extremely previous design. The bit is similar type as that Employed in the gimlet, a self-contained tool for monotonous little holes in wood by hand. Because about 1850, gimlets have had a variety of cutter designs, but some are still made with the first Variation. https://drillbitmanufacturer94938.blogocial.com/not-known-factual-statements-about-drill-bit-supplier-70051152