Screws for wood

The mechanical principle of the screw can be found back in history, and the first screws for wood were used for clocks, in the sixteenth century. The mechanism consist of a round nail with a threaded shaft and a slot in the head, made for an easier removal. The first screws were handmade, but this is no longer manufactured –which would be a really unaffordable enterprise.

The industrial screws appeared in the eighteenth century. In the year 1840 the modern pointed screws –with a blunt end- were first made in Birmingham, thus starting a new age in what refers to wood working. An interesting subject is to deduce the age of a furniture by taking a look to its fittings and joineries. Building styles have varied along the decades, which can be observed at the minimal details, and screws here are fundamental.

Parts of a screw

The head can hold the screw or impart a swirling motion with the help of appropriate useful, the neck is the part of the cylinder that has run out of thread (in some part of the neck screw that is closest to the head can take other forms, the most common and ribbed square) and the thread is the part that has carved the groove.

Moreover, each element of the thread has its own name, is called a thread fillet or the overhang of the groove bottom or root to the bottom and the most prominent ridge.
Right or left thread
Types of threads

According to rub the groove (or, figuratively, will roll the plane) in one way or another thread we called right (with the fillet rolled in the sense of clockwise) or left thread (rolled in the opposite direction).

Types of screws

Hexagonal screws

They are the most frequent. According to the shape of the tip of the ear, are used as mounting screws, pressure or fixing. They can be totally or partially threaded. They are screws having head with a hole or a slot which fits any type of screwdriver: Straight slots are useful for manual screwdrivers.

The holes in hexagonal cross and automatic screwdrivers are useful because they allow the self-centering of the screwdriver.

Allen screws

They are countersunk screws with cylindrical or conical head, using a special key, called the Allen key that fits into a hexagonal hole in the head. Stainless steel screws are the most common, but there are also copper screws which are no t used for wood but for heavy load machines.

Special screws

They are used for special functions such as:

Locking screws, which are mounted with a flange on the end and play the role of screw.

They are used to hold rings on shells to be moved by lifting and transport elements such as overhead cranes.

Screws with eyelet, which allows joints to build elements. These are thumbscrews that can be tightened by hand.

Philips screw story

Philips claimed that his cap was "particularly suitable for a strong grip with a suitable screwdriver, so that one does not tend to get out of the hole." Instead, he could not think starting your own business, but granted licenses to use its patent to other manufacturers of screws.

The biggest companies have turned their backs, "the manufacture and sale of these items not promising enough commercial success" was the typical response. But Philips did not give up. A few years later, a new president of the American Screw Company, which was and remains one of the largest manufacturers and had prospered with Sloan's patent screw-tipped, agreed on an industrial develop new screw. In his patent, Philips insisted that this was particularly suitable to be introduced with an automatic machine, which then was mainly related to the automobile assembly lines.

The American Screw Company persuaded General Motors to test the new screw that was used in the Cadillac 1936. The test proved so effective that after two years all car companies, except one, had chosen cruciform screws, and in 1939 most manufacturers produce screws which was then called "Philips screws.

Philips screw had many of the major advantages of Robertson, more of which could be replaced with a normal screwdriver if necessary: "We believe that our workers saving between thirty and sixty percent of the time using Philips screws," wrote a boatbuilder satisfied and gliders. "Our men claim they can improve their productivity by 75%," said a manufacturer of outdoor furniture. Philips screws and screwdriver -family were now everywhere. The First World War had blocked Robertson, the second, however, raised the Philips screw the industry standard range. In the mid-sixties when patent rights expire Philips more than 160 licenses in the United States and 80 other countries.