Are There too Many Types of Screw Drivers?
The answer is surely yes!
Why do we have to relearn the benefit of standardization over and over again. We had to learn it with railroad gauges, lightbulb sockets, VCRs, connectors for computer accessories and countless other products. (There are currently over 20,000 standards so why not add the screw driver among others.) Until then, disruptions and inefficiencies in market transactions and everyday life will continue.
I purchased a package of screw drivers some time ago because they were a traffic bargain. For better known brands, one screw driver along was the same price as the package of 13. However, as you probably guessed, for half the screw drivers I will never encounter a screw on which to use them. Some of them I did not even know the name of. On further research I discovered there are more than 30 different types of screw heads and their corresponding drivers or bits. (This does not include sizes.) Some I grant you are variations on a theme and are not included. I will draw attention to seven categories of screw heads: slotted screws, star or cross screws, the square screw, the hex screw, security screws, triangle screws and the torque screws.
Lets look at each in turn.
The Slotted Screw:
This is the earliest screw invented and I am baffled as to why it is still in use. Slotted screw drivers have the least torque and slip more easily and damage heads quickly. Admittedly, slotted screw drivers are handy for prying and even chiseling in a pinch. While the screw itself was likely invented about 400 BCE by Archytas, the big innovation came in 1770 when Jesse Ramsden invented the screw cutting lathe which allowed mass production of screws with precise sizes. This first screw and screwdriver were slotted and changed the world forever. No new ones seem to have appeared until the 20th century.
Star or Cross Screws
The Phillips
This is probably the most widely used screw but in my mind it is difficult to match screw to driver and often results in slipping. It was invented in 1933 by John Thompson but named after the industrialist Henry Phillips who had it adapted for the automobile industry. The Fearson, invented by Fearson of England is very similar but with a more pointed “V”. There is also the JIS (Japanese Industrial Standard) screw which is the most popular in Japanese manufactured products. If some of your Phillips drivers don’t fit what appear to be Phillips screws, there probably not.
The Pozidiv
Closely related to these is the Pozidriv screw which is just a more elaborate version of the star or cross screw . The Pozidriv was patented by GKN Screws and Fasteners in 1962. It was specifically designed to allow more torque to be applied and greater engagement than Phillips drivers. As a result, the Pozidriv is less likely to cam out (slip). It is not clear how popular they are.
The Square Screw
Canadian P. L. Robertson invented this type of screw in 1908. While Canadian steel makers rejected the screw, Ford Motor Company took to it immediately and made it their standard because of its efficiency of use. However, Robertson refused to sell them a license which probably limited its sales and broader acceptance. At present, I invariably choose Robertson screws over the Phillips.
You know precisely which driver to use (often colour coded) and screws stick in the driver head while you manipulate them into place.
The hybrid Phillips screw
Phillips, to their credit, manufactures the hybrid screw which combines the Phillips star with the Robertson square.
The Hex
This appears to be a slight variation of the Robertson and was invented a year or two later by William Allen after whom the Allen key is named. Ikea products have made significant use of this product, among other companies.
Security Screws
The rather interesting looking Clutch Head or Bow Tie Screw was designed for security and cannot be removed once installed. Others in this category include the Spanner screw (snake-eyes or pig-nose) and requires a special wrench-like screwdriver to install or remove.
Three other types in this category are inspired by the triangle: the tri-wing, the triangle and the try-point. They are used and have been used in the computer and aerospace industries.
Torque Screws
The Torq-Set&Reg Screw
This is a screw principally used in the aerospace industry, including satellites, space craft and aircraft. With its high torque in both directions, it can be removed even when corroded.
The Torx
It would seem to me that if one were to standardize to a highly flexible and slip resistant screw, the torx might be the answer. It comes in 24 sizes which may be a benefit and a drawback but I suspect a few size would suit most uses. If it indeed provides the greatest torque and can hold a screw in the driver as in the case of the Robertson, then why not standardize on this type for all but security and aerospace screws and remove the enormous frustration of never seeming to have the correct screw driver for the job at hand. If we can be smart enough to invent such a wide variety of screws, why can’t we be intelligent enough to choose the best one and set a standard. Unfortunately, one would still have to keep the other drivers around for removing old screws for replacement or repair but let’s start now.
My mantra
If you agree, I’m serious, if you don’t, I’m not.
