Thursday, November 14, 2013

Self Tapping Screws And Other Magical Devices

By Bonnie Contreras


Another name for self tapping screws is self drilling screws. The clue is in the name. They drill the hole in the metal for you so you do not have to drill what is called a pilot hole first. This is useful when you want to mount things like computer monitors onto metal shelving because you do not have to fiddle around matching up holes, you just drill the screw through everything and you only have to do it once.

These gadgets are really clever. You get the job done without needing extra pairs of hands or starting any arguments. They are also used to mount security cameras and in dental and other types of surgery. Dental implants are a type of linear actuator.

The heads of these remarkably useful devices are in the Phillips or crosshead configuration. This gives the drill bit a little more leverage when drilling it through two or three layers of metal. Plain ones are also available. It just goes to show how important it is to have the right tool for the job and how a subtle change to form can make a huge difference in function.

Most conventional screws are right-handed and need to be tightened in the clockwise direction. To loosen, turn the screwdriver counterclockwise. A convenient mneumonic is, "lefty-loosey, righty-tighty." The same principle applies to adjusting a radiator or opening or closing a jar of jam or pickles.

There are a wide variety of screw types. The distance between threads along the shaft, for example, is called the pitch. The metal from which they are made is also a factor; this can be steel, zinc, copper, nickel, brass or chromium. They can have flat or round heads and one or two grooves in the head. The ones with two grooves that are at right angles to each other are called Phillips head or cross head screws.

Henry F. Phillips bought the design from a guy named John P. Thompson, tinkered with it then patented it. One of his early customers for the new technology were the makers of the Cadillac, General Motors. Phillips, in ailing health, sold the patent to Ford Motor Company in 1945 for a whopping $5 million, a lot of money now and a whole lotta money then.

When a screw is likely to face strong counterclockwise torque, which would loosen a right-handed screw, a left-handed screw is the correct choice. For instance, the left side of a bicycle has a left-handed thread. Anything with helical threads can legitimately be called a screw. The propeller of a ship is an example, as is an Archimedes' screw water pump.

It is really fun to watch self tapping screws in action. You can get quite a lot of work done in very little time, a satisfying prospect. Juggling two or more pieces of material together and trying to get the screw to hold can be tricky and exasperating. In many ways, simple devices are better than more complicated ones. There are a number of varieties of screw. They have different diameters and different distances between individual threads. They are manufactured from several different types of metal, including copper, nickel, chromium, brass, zinc and steel. Another important difference is in the construction of the screw's head, whether it is flat, round, plain or Phillips headed.




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