I recently noticed that there are almost no slotted screw heads on the new device. I think the only thing worth noting is that it took so long. Although slotted heads have been around for a long time, better systems are common and have been around for at least a century.
The reason slotted heads (technically called drives) are so common may be because they are so easy to make. A hacksaw is sufficient for this job, and there are other ways to achieve the goal. The only advantage for users that I know of is that you can easily clean the slotted drive and possibly use on-site emergency supplies (such as a butter knife and quarter) to turn the screws. I heard some people claim that the screwdriver can pry open the lid of the paint can is also a function, but this is the function of the tool, not the screwdriver.
However, the disadvantages are significant. It is difficult to apply a large amount of torque to a slotted screw driver without pulling it out or breaking the head from the screw. Screwdrivers are also not self-centering, so applying off-axis force is common and can cause problems.
A bit of history
About 2000 years ago, threaded wood for olive presses and the like began to appear. In the 15th century, metal screws appeared, but because they were handmade, they were not very regular and only popular in limited applications. Job and William Wyatt applied for a patent for a screw machine in 1760, but it would take ten years before a viable model appeared.
In 1770, the British Jesse Ramsden (Jesse Ramsden) invented the first viable threading lathe, which he used to make micrometers and other scientific instruments. He is also a mathematician, and you may know him from his contribution to optics. Around 1800, Henry Maudslay invented a large threaded lathe, and American mechanic David Wilkinson also invented a similar lathe. Lathes allowed the production of interchangeable parts, which was the key to the industrial revolution, in which people like Eli Whitney were able to mass-produce items such as guns that were previously unique.
Before Maudslay’s invention, lathes were usually operated with foot pedals, and the operator only had to fix the tool on the workpiece. This is not enough to cut the thread, so the screw is made by hand using a chisel and file. Maudslay’s lathes have replaceable gears, allowing the use of threads with different pitches. Wilkerson’s machine is larger, but not easy to configure. Even so, the government used about 200 lathes like Wilkerson’s and awarded him $10,000 for his invention-which is about a quarter of $100,000 today.
The head has always been a simple slot. In 1744, you can get a flat blade that fits a carpenter’s stand, a bit like today’s drill requires a drive bit. However, by 1800, hand-held screwdrivers had become commonplace.
Cutting threads with a lathe is only one way to form threads. Although it is precise, it is also expensive and weakens the metal. Cold rolling was economical and did not remove any metal, but William Keane’s first attempt in 1836 failed because cast iron molds were not up to the task. In 1867, Harvey J. Harwood also tried cold rolling, but the actual thread forming using this method had to wait until Hayward Harvey and Charles Rogers in the early 1880s. Nevertheless, some special bolts are still being cut, the video below shows modern operations, and the second video shows a more common modern process.
The irony is that although assembly lines are possible with standard threads, they are also the cause of dissatisfaction with slotted drives. The inventor wants to do better. In 1908, Canadian Peter Robertson invented a lag screw driver with a slight taper in the driver and hole. There have been other attempts to produce similar drives, but they are difficult to manufacture and have not become popular. Robertson’s invention facilitated cheap manufacturing using molds.
This has several advantages. First of all, the drive is self-centering. Secondly, even at high torque levels, the driver will not slip out. More than 700 Robertson screws were used in the Canadian Model T Ford.
Ford and Phillips
Ford found that Robertson Drive saved a few dollars in the production cost of each vehicle, but was cautious about a single supplier. However, Robertson had a bad experience in obtaining a license in England, and he was unwilling to reach another license agreement.
In the 1930s, Henry Philips introduced the Phillips drive for screws based on the work of John Thompson. Compared to slotted drives, this is also self-centered and more suitable for automated methods. However, as you may have already experienced, too much torque may protrude from the head. The company claims that this is a function to prevent excessive tightening. General Motors used the Philips drive in the Cadillac in 1936, and its popularity was guaranteed.
Robertson Drive screws account for almost all screws sold in Canada, and almost none have been used elsewhere. Although most people think that the Robertson drive is better, business decisions make it a small player.
There are a surprising number Drive type There, many of them have no questions about the head of Phillips. Hex drives from William Allen are used in many applications. Pozidriv is not common outside of Japan. However, slot drives survived, and Phillips is almost everywhere in most parts of the world.
This surprised us. An old saying is that if you build a better mousetrap, the world will pave the way for you. But this does not seem to be true. It’s more like if you made a better mousetrap, successfully marketed it, built a great distribution network, and defended your intellectual property… well, you get the idea.
I focus on drive technology, but the thread itself is a fascinating design, and our own Dan Maloney put it in a few years ago. If you want to learn more about other types of bolts and their attractiveness, the interesting video below has a lot of good information. It still does not answer the question of why we have not seen more use of “better” drives. what do you think?
If you want to try your own bolts, maybe you need a small lathe. Or maybe you just want some advice on getting the perfect screwdriver.