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Screwdrivers, earlier known as turnscrews, have been around since at least the fifteenth century. At first, screwdrivers were very scarce because screws were so expensive to manufacture. But the beginning of the nineteenth century saw the arrival of machine-manufactured screws. As the per-piece cost of screws came down, their use increased, and with that, the need for more screwdrivers.
Until the 1840s, screws had a flat or blunt tip, which necessitated drilling a lead hole first in order to start the screw. Early screws had their heads slotted by hammering a knife-edge into a red-hot screw head.
The screwdriver was flat and the tip was ground or beveled on both sides almost to a point to fit the V-- slot. When the first machine-made screws came out, their heads were slotted with a saw.
Finally, machinery was developed to make the screws with a gimlet point. Then the price of the screws came down and the practicality of their use improved, especially with the use of butt hinges.
With advances in screw manufacturing, more screwdrivers began to appear. Up until the 1850s, screwdrivers had a flat blade with a turned handle that was flat on two sides. These common flat blade screwdrivers were made into two patterns-the London pattern and the Scotch pattern-that evolved over time (Figure 1). The London pattern had a semi-circular dip on the sides, about halfway down the blade. The Scotch pattern was a straight, tapered blade.
It wasn't until 1870 that Stanley entered into the screwdriver business. Up until then, there were only fifteen United States screwdriver patents. The earliest...