Screwdrivers
These ones are counted over the most frequently used tools in wood working. The main use, as it may sound obvious, is introducing and extracting screws. These ones have different kinds of head, and this is what the shape of the screwdriver depends on.
For example, there are screwdrivers that work with slot head screws (the most typical) and there are also others that suit the cross Philip-like head. This extremely useful handtool also has a variety which reduces the amount of effort you need for the job, without need to use the power tools. I am talking about the ratch drill, a tool that works by pressing the grip onto the screw. You do not need to twist your hand niether for introducing nor for extracting. In order to pull out the screw you just change the pawl or ratchet from the screwdriver. This wil shift as well the sense of the turn, letting the screw out at the minimal effort.
History
We can search screwdriver-s origins in the fifteenth century and although it seems that Leonardo DaVinci used a device that could be considered its predecessor. It emerged in the carpentry workshop where the nails were made to a slot in the head to rotate around and ensure its grip once inside the timber. Following this technique was developed what is now known as screw. 
Between 1860 and 1890 there was a deluge of patents for magnetic screwdrivers, utensils to grab the screw and mantain subject, all slots that did not pass through the screw head, double slits, and a variety of plain square, triangular and hexagonal. The latter seemed the most promising. Replace the slot for a screwdriver to adjust the cap perfectly allowed, preventing slip by it. The difficulty lay in the manufacturing process. The screw heads are mechanically punched into a cold steel spike, but if a cap is pierced deep enough so that he could fit the screwdriver was almost inevitable that the screw would be more weak or deformed head.
The solution to the traveling salesman found a Canadian 27 years, Peter L. Robertson, a preacher of a company in Philadelphia fabicante tool, which displays your sample in the corners of the streets or at fairs in the villages. He spent his free time tinkering with mechanical inventions in his workshop. He invented and promoted the "key-Robertson brace for the twentieth century, a multiple instrument that could be used as a drill, wrench, screwdriver and riveter.
Know the parts of the screwdriver, the types or put to good use is essential for small DIY jobs at home are safe and successful.
The parts of the screwdriver
In this simple tool can distinguish three distinct parts, each with its own characteristics.
The handle: this is the part for holding the tool and over which he has the strength to make it work. It may be of different materials, most notably wood, plastic resins and PVC. The most important thing to consider when choosing is that fits comfortably in your hand, the grip appropriate, non-slip and insulating material having an electrical current.
The body, also known as a wedge or rod is a metal bar that varies in thickness and length depending on the type of screwdriver.
The head: perhaps the most important part, is inserted into the screw to turn it. The different types depend on the lag screw to be used, varying the thickness and edge length and shape.
