Making 18thc style screws for wood

[James Wilson Everett]

GUYS,

I have several scans of both the wood screw swage tool along with several screws made from the tool. I just sent them to a Mr. C. White who wrote a great article on 18th C. furniture wood screws. If you would like to see the scans I can send them, though I don't know how to do ity using this thread forum. I can send them by email, regular mail, or whatever. If you ever come through W. Pa. let me know and we can meet.

Jim Everett

[george wilson]

Can you scan them on a scanner/printer and get them into the computer that way? I'm no computer guy,but have done that a lot. We'd love to see these tools. What proof do you have that they are truly 18th.C.? I know Jay Gaynor would like very much to see them,as would I,and I'm sure,others here.

[James Wilson Everett]

Guys,

Here is a scan of an 18th c wood screw swage tool that makes 7 different sized screws. The threads swaged are clearly wood screw threads, not machine screws. The tool is 8 inches long.

Jim Everett

[James Wilson Everett]

Guys,

Here is a tapered blank for a #12 wood screw before swage, and the finished screw. The rod is puddled wrought iron put into service c 1860-1880 and recovered near Oil City PA. I turn the tapered blank on the wrought iron rod using a lathe, although a purist may use only a file. Next I close the swage tool on the rod, tighten the swage screw and rotate to tool. As the thread is formed the swage screw is tightened, there is no cutting or chips produced. The tool operates a lot like a modern tubing cutter. I install the screw in the wood before cutting it from the rod to give a good purchase for the installation torque. After installation I cut the screw from the rod and finish the head and cut the screw slot.

Jim Everett

[James Wilson Everett]

Guys,

Here are 2 screws made from the 18th c swage tool. The larger is about a #12 and is made from the largest size hole in the swage tool. I was shy to complete the swage process as the effort seemed high and I feared damage to this very rare tool. You can see that the thread is not fully formed. When completed the two edges of each thread would come together leaving only the tell-tale line at the crest of the thread form. This line is very often seen on original screws. When I need such large screws, like for a rifle butt plate, I use a tool that I modified from a much more common 19th c machine screw swage split die tool. I simply made a set of replacement split dies in the wood screw thread form. The smaller screw is about a #8 and is used for the rear of the trigger guard. Even smaller screws are a little more interesting, and frustrating to make using wrought iron, I have better results using modern leaded steel rod for the smaller screws.

Jim Everett

[george wilson]

Certainly an interesting tool.How can you prove it is 18th.C.,though? Also, it mashes the threads together,and may leave the tell tale little groove at the crest of the thread. I have not seen this on any 18th.C. screws that I have examined,but I may be forgetting what I saw as I haven't actively studied 18th.C. screws like I did when I was in my 18th.C. shop,trying to use 18th.C. tools only. Still,I can't infer that this was a mainstream type of tool for making wood screws. It is an adaptation on a way to make metal screws,and a clever one. As tall and large as wood screw threads are,compared to the much smaller threads of metal screws, I must wonder how long it would take to wear out the thread formers in this tool? Squeezing metal that much has to be hard on them. As you mentioned,you were afraid to use the tool too hard for fear of damaging it. The same would have applied when the tool was new.

[George Neill]

That's a very interesting tool, but I have not seen any eighteenth-century screws formed like that in my 35 years of working with eighteenth-century English furniture – maybe it was used by Americans. It looks to be well made; are there any markings or a name on it?

[James Wilson Everett]

Guys,

Thanks for your interest in the wood screw swage, I will try to answer your questions one at a time.

1. It is difficult to date any unmarked tool, especially when one is nearly unique. But I feel sure that the screw swage was in use prior to the mass production of wood screws and probably before the availability of machine/lathe cut screws. The only markings on the tool are the engraved numbers 1-7 for the different swage positions.

2. Check the good reference link at D. Keller's response of 07-05-11. This links to a great research article by C. White, Observations on the Development of Wood Screws in North America. Look closely at the screws shown on page 10 and 11, both from the late 18thc early 19thc. The screws clearly show the swage line at the crest of the thread. The screw on page 10 is really incompletely formed as the two sides of the swage do not quite meet to form a line, very simliar to the screw shown in one of my scans.

3. I have made about 100 wood screws using both the original tool and my 19thc swage with new dies. I have not noticed any wear on the dies, although they do require cleaning with a brush, I use a .22 caliber bore brush, to get the junk out of the swage crest areas.

4. Lathe cut threads will tend to be very rough in the thread valley since the lathe cutting tool is cutting 90 degrees opposed to the wrought iron grain in the rod. Any time I have done lathe cutting on wrought iron rod there is a definite roughness to the cut surface, when using leaded steel rod the cut surface is much smoother. When using the swage tool the thread valley is nicely smooth and somewhat polished while the thread crest tends to be sharp and rough, likely to cut your fingers.

Jim Everett

[George Neill]

Jim, I'm afraid I don't see what you see. The images on pages 10 and 11 look like any other rough-turned taper shank lathe-turned screws I have seen – which is how the supporting text describes them too. The text even mentions the burrs on the threads caused by the cutting process.

Like you, I have seen rough surfaces on lathe-turned wrought iron, but conversely, I have seen a significant number of rust-free eighteenth-century screw threads with smoothly turned surfaces.

[Jim Koepke]

Jim, I'm afraid I don't see what you see. The images on pages 10 and 11 look like any other rough-turned taper shank lathe-turned screws I have seen – which is how the supporting text describes them too. The text even mentions the burrs on the threads caused by the cutting process.

I am not the Jim referred to in George's post. I do see similar markings to the screws formed by using the swage tool.

Here is an image from page 10. There does appear to be separation at some of the peaks of the threads.

It might be clearer in an enlarged image.

Picture 3.jpg

I do not see any mention of burs left by cutting on page 10 or 11.

I am wondering how unique the swage tool may actually be. Having an ability to make screws faster than another cabinet shop may have been an advantage the maker of such a device might not want to share.

Once a less expensive way to make screws appeared, having such a tool would not be an advantage.

[James Wilson Everett]

Guys,

I am really pleased at the great responses to the screw swage, I think that this is an obscure corner of information that really needs to be resurrected and thoroughly explored. This is a scan of the 19thc machine screw swage tool that I modifed to make the larger wood screw threads. Remember that in an earlier post I am shy of damaging the older tool due to the high force required to swage the larger threads. On this tool I removed a pair of the machine tool split dies and replaced them with a pair that I made for the wood screw threads. You can see the diffferent split dies on the scan. The material is 1095 carbon, hardened and tempered to dark straw. I machined a large female wood screw thread using a boring bar on a lathe, then split the die into the two halves. I polished the thread valley, that is the smallest diameter of the split dies, to give the rounded thread valley like the original screws. I close the split die on the tapered wrought iron pin and rotate the tool while keeping it level and allowing it to move parallel to the pin centerline. It takes several passes with several tightenings to swage the threads. It only takes a minute to do this. Make your own and try it.

Jim Everett

[george wilson]

I see the lines you mention in your screw. They had similar die holders in the 18th.C. for metal. I don't see why someone couldn't convert one for wood screws like you did(but back then).

About cutting threads in wrought iron,they can be cut smoothly if you do them right. Also,I have used very old wrought iron samples,and more recent samples taken from structures like bridges. There is a BIG difference in the quality of the wrought iron. Real old wrought iron from gun parts files and turns much more nicely than the structural wrought iron. The structural stuff is gummy,and pins up the files badly.

We used samples of different wrought irons over the years a Williamsburg. It definitely isn't all the same. Since wrought iron was the prominent forgeable metal that they had at that time,they had a lot of different varieties available to them. Several different grades were imported from Sweden alone,with significant differences in cost. English wrought iron wasn't so good because of the sulfur content in it,which rendered it "hot short" for forge work. Since they knew little about chemistry until about 1830,they did not know how to improve the domestic product. Spanish iron was thought to be better due to the AIR in Spain!

Poor grades of wrought iron are better swaged into threads than cut,because the excessive amount of inclusions in it causes the threads to fall off. We made screw plates for the gunsmith shop that swaged the threads on. Perviously,they wasted a lot of labor FILING out screw blanks for metal screws,and then trying to cut the threads with more modern types of dies. The threads just would fall off sometimes.

The wrought iron they have to use in the museum are from old bridges,etc.,and just not good grades of the metal.

[John Toigo]

You might look here: http://www.blacksmithbolt.com/gpage14.html They have an interesting assortment.

[David Keller NC]

You might look here: http://www.blacksmithbolt.com/gpage14.html They have an interesting assortment.

John - Thanks greatly for that link. I've been resorting to cheap 'n crappy slot-head zinc-plated wood screws from the Home Despot for my projects and stripping the zinc off with citric acid. But these screws are really soft and gummy, and are not available in many sizes. And I refuse to put philips, torx, or square-drive screws in an 18th century repro. I'll give these guys a call.

[James Wilson Everett]

Guys,

Here is the 19th c machine screw swage tool that was modified by replacing a pair of split dies with a new set to make wood screw threads. remember in an earlier post that I am shy to use the older tool to make the largest threads because of the risk of damage. The new dies were machined from 1095, hardened and tempered to dark straw. I cut female wood screw threads in a block using a lathe boring bar sharpened to a point. Next I cut the block in half to make the split dies. I polished & rounded the die threads to give the rounded valley thread profile of 18th c wood screws. The tap I use to tap hard wood, like sugar maple before installing the wood screw. Try this yourselves.

Jim Everett