Screw Threads in the 17th century

[99Panhard]

A good friend of mine is working on a book on Swords of the English Civil War (1642-1651) and we would like to include a chapter on the metallurgy and construction techniques used at the time. As far as we know, this is a subject that has never been examined closely regarding sword making. One of the distinctive English hilts utilized a threaded end to the tang of the blade that was secured by a nut on top of the pommel. This feature allowed the sword to be "tightened" easily. Sword blade tangs were usually peened in place and easily came loose, requiring hammering to tighten them. (I'll post some pictures in a day or two - they are in the office).

My question is this... do any of our tool collector members have or know of period illustrations of the tools that would have been used to make internal and external threads at the time? Or, can someone steer me in the direction of a contemporary work I might be able to locate. This is going to be a scholarly work so it is critical that we get our facts straight. Most of our museum curator friends have art history backgrounds and the technology aspect is virtually unknown to them. It would be fantastic to get photos of the real tools if any exist but I'd be very happy to get any period illustration. I am presuming that threads were actually swaged rather than cut. That is certainly what the originals look like. I'd also guess that the same techniques probably continued to at least the early 18th century but the closer we come to the actual dates of the war, the better it will be.

[sfriedberg]

I'd also like to hear what the solid research turns up. If I had to guess, I'd guess tang threads were hand filed, hand chiseled or (primitive) die cut cold, or twisted hot. Probably not lathe chased (even with hand chasers on spring pole lathes).

Edit: Actually, forge hot work is probably more likely than cold work. Much easier to use a open die/swage/fuller than to chisel/file out a thread.

Presumably your friend has access to some representative tangs for a detailed examination. The tool marks should be fairly informative as to the process used.

[bryan_machine]

When you say "tightened easily" - that would be true *now* when one could resort to a pliars or a wrench. Part of the question is collateral technology - in the *17th century* what did they tighten the nut *with*? (A wrench? A pliars? Some other contrivance?) What fraction of armorers had these tools?

And in addition to the thread form (and how they made it) a key question is "how did they make the nut?" Internal threads are more difficult than external.

[99Panhard]

I'll post some pictures... probably Monday as I don't have copies at home. We have at least two swords of this pattern and have taken one of them apart and photographed it. The "nut" is actually a tube about an an 1 1/2" long with a blind threaded hole and a round knob on top that is drilled through horizontally. The sword was tightened by inserting a rod or pin in the hole and twisting. Its surprisingly modern considering the pattern of sword dates from approximately 1625-35. Close examination of the threaded parts suggest to me that they were formed by forcing the relatively soft iron of the tang into a threaded hole in a hardened plate. Probably the original threaded "screw" was filed, hardened and forced into a screw plate. "Screw Plates" are commonly listed in armorers inventories well into the mid 19th century. The plate was then hardened and use to make the male thread on the end of the tang and the hardened "screw" to make the female thread in the nut. But, I'm applying what I know of 18th century practices to the subject and I'd like to confirm if those go back to the 17th century. While sword blades have a relatively hard surface, the tang is always very soft.

As to how common this was, our current thinking is that only one English sword blade maker (he was an immigrant German from Solingen working at Hounslow, near London) used this system but that he was quite prolific. We have pictures of half a dozen of his products, including one where the nut was lost and the blade has been peened to hold it in place. In the general run of things it was not common at all but this is what makes it distinctively English.

[doug8cat]

I don't mean to hijack the thread however this all sounds very interesting, I have a 20 + year back ground in medicine and now have been working as a machinist. My love of the history of medicine, science and technology has grown over the years, and I know have a nice little collection of mostly antique medical instruments and a growing one of machine tools. Some of craftsmanship of early medical instruments is truly remarkable and find it interesting that the two subjects of machining and medicine are linked (how did they get the two parts of hemostat together when designing the prototype?
I would be interested in answere to the sword question and baybe somone knows of some text book that relate the two.

[camscan]

Have you tried re-enactment societies, museums or army museums ?

[Gordon B. Clarke]

Just a bit newer than you're looking for but the search has to start smewhere and part of the "trick" will be to use the right key words for an internet search.

history of screw threads

I must admit that I've never thought about it but as mentioned in one post an external thread would have been easier to make than an internal. Perhaps a "nut" (with a hole in it) and forged around the external screw thread?

It also gets me wondering when screw threads were used for fastening/tightening things rather than riveting.

Screw - eNotes.com

Screw - Wikipedia, the free encyclopedia


Gordon

[DMF_TomB]

try books by John J. Holtzapffel . I first came across on ornamental lathes. You will see by his books that by 1850 things were advanced for instrument makers, clock makers, telescope makers. some of the advanced stuff of 1650 was taken from wood working tools and scientific work.
.
try google books and look for older books. some stuff back then was consider trade secrets. without patent law protection and many trades people not knowing how to read or write all that much if at all you probably will not see much written down other that by Scientist or Monks. Printing presses often used screws and some information might be found there.
.
When you think about it building a printing press or making eyeglasses and spyglass telescopes and clock making or even a water pump were extremely difficult in 1650. Just making a file for filing metal often required a hammer and chisel to cut the file teeth one at a time.

[gwilson]

I spent 39 years working in Colonial Williamsburg. Retired as Master Toolmaker. I can't recall how many times I've made screws for antique mechanical devices. They usually were originally made with screw plates and taps,or were chased freehand with threading combs on simple lathes. There was a French lathe that had a travelling spindle that could travel forwards about 3/4" to make short threads against a stationary cutting tool. It was not the common way of doing it,and was very expensive.

Wrought iron threads were best squeezed into the metal rather than cut,as the iron had layers in it that would fall apart. Old screw plates have 2 or 3 holes for each size thread. You started with the largest hole,then used the smaller ones to complete a thread by squeezing it progressively. I made the screw plates that some of the other historic trade shops used in the museum.

The only screws that they made by filing were wood screws where real precision was not essential.

[Joe in NH]

Just making a file for filing metal often required a hammer and chisel to cut the file teeth one at a time.

Actually, until the late 19th century and well into the 20th century, that is EXACTLY how it was done.

Specialized trade. Special chisels and hammers with angled heads (angling towards the user IIRC.)

A good file maker could cut 20 teeth a minute and the entire file might take 10 minutes.

Hand cut files are still held in esteem. Something about the minute irregularities between teeth that make a hand cut file more resistant to vibration and cut smoother. Covered in some detail at "Treatise on Files and Rasps" by Nicholson File Co. ca. 1878.

http://www.amazon.com/Treatise-Files...Nicholson+File

Currently not available but maybe at AbeBooks Official Site - New & Used Books, New & Used Textbooks, Rare & Out of Print Books.

Also descriptive on this in "Modern Machine Shop Practice" by Joshua Rose.

Joe

[JST]

Saw a video link on another forum that showed the entire process of hand-making rasps in a French factory. Went looking but could not find the link...... maybe someone else can.

As for screw threads, I would think that by the English civil war, threads were fairly common in certain types of equipment... not modern ones, not standard ones, not necessarily "good" ones, but....

[gwilson]

I was offered an Elizabethan sword that had at least 3 screws on its hilt. I noticed they were numbered. On old gun locks,often the screws are punched with different #'s of punch marks corresponding to punch marks where they went. But that was to make sure the screw slots stayed timed. On the old sword,I think it was more likely to make sure the screws were the correct diameter,and possibly length. The screws all looked to be the same diameter,but possibly were slightly different. I didn't buy the sword.

In regards to my post above,I also have seen simple U shaped devices with a split top that had a threaded half-hole on each side. You put the thing into a vise,and screwed your bolt to be down through the threads,tightening the vise and repeating until the thread diameter was correct for your nut. This was a crude device probably made for blacksmiths. It did only 1 thread size(TPI).

In looking under magnification at early threads,they varied from shallow "V" threads,to deeper "V" threads,to what looked like light bulb threads(knuckle threads) in small screws,with very hemispherical crests and roots. Some quite deep,too,although most of the museum people were convinced that early threads were shallow. I doubt they ever made a study of it,however. I had to,since I made many replacement threaded parts for mechanical antiques,and wanted them to be very authentic,sometimes threading into original holes. Many would have just re tapped the holes,but I wanted to preserve them for posterity,which is the correct thing to do.

[Bruce Nelson]

i would agree with Gordon on this. Once the external thread was made by filing, or chiseling; a internal matching thread could be made by fitting an oversize hole in a mating part over the completed external thread, and swaging the red hot nut threads into the external threads. After the nut cools, it is then unscrewed. I also have a theory of how pyramids were built.

Lord Byron

[dinosaur]

The link below will take you to thread cutting lathes of the 1400-1500's

On ye art and mysterie of turning

[sfriedberg]

The link below will take you to thread cutting lathes of the 1400-1500's

On ye art and mysterie of turning

I'm willing to be proven incorrect, but I think it highly unlikely that a sword tang was threaded on a lathe in the mid-1600's.

[bryan_machine]

@gwilson - how does one make a screw plate? (There seems to be a bit of chicken and egg problem, but I'm likely missing something...)

[S_W_Bausch]

I have a hard time believing "didn't exist at that time".

The larger any population, the more likely a critical mass of highly intelligent, very clever craftsman. Ancient China had technologies much sooner than other cultures.

The gifted sometimes take their talents for granted, and there is little motivation for others to acknowledge those gifts.

Since metal can be recycled, and metals can corrode, it's easy to understand why early metal tools don't survive.

[99Panhard]

I'm certain it wasn't threaded with a lathe. When I post the pictures I believe it will be clear that the threads were formed as gwilson has suggested. The challenge is to identify the tools used and try to find a surviving example to photograph or a period illustration. I don't want to use a modern replica for the obvious reason that no matter how well researched it is, it will always be open to question. If space permits (and I doubt it will) we've even considered illustrating the process... for that a replica would be in order as long as we have a period illustration to go with it.

bryan machine... I had the same thought. Presumably the first screw had to be very carefully filed ... or perhaps turned or cut in some manner that I'm not familiar with. They would have had small pieces of fairly good steel available and they throughly understood hardening and tempering. Remember, they were also making steel springs for gun locks in the early 16th century. The "master" screw would then have been hardened and used to make the screw plate which, in turn, could be hardened and used to make more screws. While the tang screw is fairly large - about 1/4" or maybe a #12, there are much smaller screws used to hold the branches of the guard to the pommel. Those are around #8 or #10 in size.

[Vince]

You want this book -

"One Good Turn, A Natural History of the Screwdriver and the Screw" by Witold Rybczynski

Amazon.com: One Good Turn: A Natural History of the Screwdriver and the Screw: Witold Rybczynski: Books

Vince

[L Vanice]

You want this book -

"One Good Turn, A Natural History of the Screwdriver and the Screw" by Witold Rybczynski

Amazon.com: One Good Turn: A Natural History of the Screwdriver and the Screw: Witold Rybczynski: Books

Vince

I bought that book at the American Precision Museum gift shop many years ago. I don't think it was as infomative as I had hoped. After I read it, I loaned it the fastener engineer at work. He must have liked it, since he never gave it back.

Somewhere in my stored library, I have De Re Metalica translated by our only engineer U. S. President, Herbert Hoover, reprinted by Dover. It was written in the 1500's and has great pictures. I do not recall if threads were mentioned. I also have a book called A Theater of Machines from the 1500's with more great pictures. I read it 50 years ago, but I recall seeing pictures of some beautiful adjustable wrenches with screw threads. If I could find them, I would look for info on how to make threads in them.

Larry