All over the nineteenth century, the most commonly applied kinds of screw head (that may be, push kinds) had been straightforward inside-wrenching straight slots and external-wrenching squares and hexagons. These had been straightforward to machine and served most applications adequately. Rybczynski describes a flurry of patents for option drive varieties https://stainless-steel-banding-s63592.blog-a-story.com/10706029/not-known-facts-about-woodscrews