The following is excerpted from “The Workshop Book,” by Scott Landis. First published in 1991, it remains the most complete book about every woodworker’s favorite place: the workshop.
“The Workshop Book” is a richly illustrated guided tour of some of the world’s most inspiring workshops — from garage to basement shops, from mobile to purpose-built shops.
The author traveled all over North America to discover the workshops featured in this book. The result is an intriguing and illuminating look at multiple successful approaches to shop layout.
Without threaded wood or metal screws, the modern woodworking vise wouldn’t exist. Richard Starr, a woodworking teacher and writer in Vermont, has long been fascinated by wooden threads. Here he examines their history and how they’re made.
The first person to make a screw probably did it by hand the way the Eskimos did. Historical photographs suggest the Eskimo’s technique: holding a piece of antler, bone or wood in one hand, they’d twist it past a knife grasped in the other. With the blade at an angle to the shaft, the knife would scribe a helical mark (a spiral) on the material, resulting usually in a left-hand thread because most people are right-handed (try it!). Then, whittling toward the incision, they produced a buttress-shaped thread that could hold a spear tip to its shaft.
That this isolated aboriginal society had threads is a glitch in the history of technology, since most researchers believe every screw on earth had direct ancestors in ancient Greece. Though helices appear in nature and in decorative arts worldwide, we know of no practical application of the shape until the first century B.C. in the land of Plato and Aristotle. The pyramid building Egyptians never thought of it; Chinese machinery did without screws until the 17th century. So if the Eskimos did come up with the idea on their own, they share the pride of invention with a rather sophisticated culture.
By the first century A.D., screws of wood and metal were common in Hellenistic technology. A press for flattening cloth has survived at Herculaneum (covered by Mount Vesuvius’s eruption in 79 A.D. ), its wooden screw in fine condition. At the surgeon’s house in neighboring Pompeii were found dilating instruments (specula) operated by metal screws, as are modern ones. A twin-screw press appears in a wall painting in that doomed city.
How were screws manufactured in antiquity? Fortunately, we had a reporter on the scene: Hero of Alexandria, who lived during the first century A.D. He created several tools of fundamental value, including a basic surveying instrument, but he is best remembered for his simple steam turbine, which was only a toy. An early engineer who wrote broadly about the mechanical technology of his time, Hero described the evolutionary improvement of screw presses used to produce olive oil. Machines identical to the ones he knew survived into the 19th century. He also explained how screws were made in both wood and metal.
Until quite recently, historically speaking, large wooden screws, up to 12 in. or more in diameter, were cut the way Hero described. After laying out a helix on the surface of the cylinder (he used a metal template) you would saw a notch along the mark to the depth of the threads. Then you’d chisel the V shape into the sawkerf. I’ve tried this; it’s easy.
Making the nut was a problem. The earliest method was to use a bare hole with one or more dowels intruding into it to engage the threads. This worked, but lacked strength. Another method was to carve the nut in two halves, then fasten the halves together. This was stronger than the dowel method, but its strength was limited by the integrity of the fastenings, which might have been glue, rivets or bindings of some sort. Besides, fitting the female thread to the male was incredibly tedious. Despite these shortcomings, the practice survives today, as shown in the photo [below].
Finally, Hero described (and possibly invented) a mechanical tap that etched a thread in a hole, working a little like a modern machine lathe. This gadget, shown in the drawing below, remained in use for almost 2,000 years until hydraulic presses made the wooden machinery obsolete.
In Hero’s time, if you needed a small-diameter metal screw, you’d probably cut it with a file and use the dowel-in-the hole method for the nut. It was also possible to cast a nut around an accurately filed screw. The worm drive, where a male screw engages a gear rather than a nut, is said to have been developed by Archimedes in the third century B.C.
Blacksmiths had a technique where inside and outside threads were made at the same time. First the smith would forge a ribbon of iron, square in section, and fold it back on itself, then he would wrap the doubled strip around a metal rod. Sliding the rod out, he’d separate the pair of helices, then solder one to the rod, the other inside a hole. Large screws for presses or vises were made this way and jewelers could use the method on tiny work.
Threading taps for metal and wood, similar to the design common today, were described by da Vinci in the 16th century and probably were in use much earlier. Usually these amounted to notches filed on the corners of a square rod, very simple to make but capable of cutting a decent thread.
Dies, the female-threaded devices designed to cut male screws, are probably as old as the metal-cutting tap needed to make one. Screw boxes, the wood-cutting equivalents of the die, used a V-gouge cutter positioned against a nut. I imagine this tool to be very old, although I doubt they existed in antiquity or Hero would have described them. Da Vinci sketched a tool that may or may not be a screw box; if it is, it’s the earliest representation I’ve been able to find. The 18th-century screw box and tap are almost identical to those available today. Several devices are now available that use a router to cut screws in wood very neatly.
After Hero’s wood-threading tap it was probably twelve or fourteen hundred years before people resumed the search for new methods of cutting screws quickly and accurately. Most methods were adaptions of the lathe, a tool that had been in worldwide use for thousands of years. The challenge of threading and, later, of turning screw-like ornamental shapes, stretched mankind’s ingenuity and eventually evolved into the machine-tool industry upon which our modern technology is based. As woodworkers we owe a nod to the early inventors who made possible our labor-saving machinery. And when we cut a screw in wood for a child’s toy or a workbench vise we are a lot closer to our roots than we may think.
8 thoughts on “A History of Threaded Screws”
Very good article, nice way to start my day. Thanks.
I understand this is an older text, but the condescending and dismissive discussion of Inuit culture and technical innovation (as well as the mis-naming) is quite disappointing. Rather than taking the opportunity to expand our conventional narratives of invention, the author seems desperate to reinforce a ‘great cultures’ myth of history. Obviously, this book isn’t supposed to be an exhaustive study of threaded screws; however, to encourage further learning about (and value for) a piece of cultural history that is not well known would hardly overburden the text. For example, Landis doesn’t even offer us an approximate not-earlier-than date for the Inuit bone threading. Nor does he offer even the slightest detail as to how Inuit people remember this innovation. I would be pretty surprised if at least one elder somewhere in Nunavut doesn’t have some recollection of their grandparents telling a story about a spear maker sometime making a threaded spear. Did no one ask about this?
It is frustrating how many history-using woodworking books fail entirely to be aware of the underlying assumptions and value-judgements they are unquestioningly using. If we want our own knowledge and practice to grow, we need to start asking different questions, and taking much more sceptical views of our received history.
The lady doth… methinks.
It is frustrating to read such off-handed comments from commenters who fail entirely to be aware of the underlying assumptions and value-judgements they are unquestioningly using. If you want your own knowledge and practice to grow, start asking different questions. Probably starting with “Is this book something I would consider to be good source material from the early 1990’s on the Inuit.”
Then I suggest you research the 1990’s. I’m sure you can find someone’s grandmother, or someone who remembers what it was like back then, to find the kind of direct testimony you describe. Or, you could start by locking up your smart phone, and also stay completely off of the internet, while you try to research anything.
Landis would have had to find someone, who knew someone who lived in Alaska. And then, he’d have to amass hundreds of dollars (In 1991 dollars) in long-distance calls, In the hopes that he’d find someone, who not only happened to be home when he called, but also happened to know someone’s grandma in Ninavut, to ask them about screws.
You know, to make sure that the footnote to the tangent about hand-carved screws, in the subsection on vises, in the chapter on workholding, would be scholarly enough for the sensibilities of early 90’s woodworkers.
The Workshop Book along with his Workbench Book are both early favs of mine and still in the top 10
Yeah, I’ll second Dixon here. I enjoyed Landis’ book and found much of it helpful, but the passages in question- even viewed generously, in the context of an older work, with the presumption of good faith on the part of the author- aren’t great. “Eskimo” is a contested name for the indigenous people of the North, and one that many people perceive as a racial slur or pejorative. Yeah, 1991 is 30 years ago, but “inuit” or the more specific “alaskan native” has been the standard since the 70s. Landis is about 15-20 years out of date, even by the standards of his own time. It would be better to avoid racist language. Better still would be actually referring to the relevant indigenous nations by the name they actually use for themselves, instead of relying on catchalls.
And also, the technology thing: All of us sitting here messing about with bits of wood on the North American continent owe an immense debt of knowledge and technique to the indigenous people of the continent. They developed specialized tools, technologies, and understandings of local materials that met their needs in a way no different from any other civilization. All of this has deeply informed subsequent material cultures and practices on this continent as carried on by settlers. Indigenous societies, technologies, and comprehensions of the material world were no less “sophisticated” than that of the Greeks, Egyptians, or Chinese. To suggest otherwise is racist.
I don’t have a problem with publishing or quoting Landis’ work, but I think the right thing to do would be for LAP to acknowledge the language and issues in question alongside the publication. LAP has struck me as a bright spot in the woodworking community when it comes to thoughtful behavior around correcting things like racism and misogyny, so it’s a bit disappointing to see this continue to be published without that thoughtfulness being present. Revising, updating, and critically engaging with past works will offer up a more robust practice and theory of woodworking that is available and meaningful to more people than will either enshrining them as written or shunting them aside entirely.
The simple answer for how the Eskimo/Inuit came up with the screw-thread, is that a narwhale tusk was used as a spear shaft at some point, or maybe other purposes, and an eskimo/Inuit realized the spiral taper on the narwhale tusk could tighten into holes or sockets.
Then, when using other materials, for the same purpose as whatever the narwhale tusk had been used for, one or more of the natives copied the spiral groove from the narwhale tusk, but at a more perpendicular angle, either because a more perpendicular angle was easier to carve, or because it seemed to work better.
What do use to lubricant the threads, for wood to wood contact ?
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