How would the old timers chase the thread on a wood screw?
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    Post How would the old timers chase the thread on a wood screw?

    How would the old timers chase the thread on a wood screw thread? That is, the thread on a screw to hold into wood, NOT a "wooden" screw !

    I'm asking how this would be done on a non-screwcutting lathe such as a bench lathe or a Fox lathe. (Hope I used that term correctly; I think it means a brass-turner's lathe)

    What did the tool look like, and how was it held and manipulated? The screw needs to have a taper......

    Thanks - JRR

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    The wood screws in 19th century US-made military guns do not have tapered points. Apparently they were made to go into pilot holes. The threads had sharp crests with semi-circular roots. They were made on special purpose machines. The stocks for those guns were shaped on Blanchard lathes and there were secondary machines to rout and drill for mounting the metal parts. The American Precision Museum has examples of these machines.

    Early 19th century civilian guns often have wood screws with hand-filed threads. Somewhere around 1850 factory-made modern-type wood screws with points became available and can be found in furniture, clocks and guns of the time.

    I no longer have things with wood screws that date much before 1850. But I removed one of the screws that holds a drawer lock in a hand-built curly maple Empire style chest of drawers that may have been made before 1850. The screw was a flat head with v-threads probably cut with a screw plate. There was no taper and no point. The slot was probably hand filed.

    Larry

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    John:

    My guess would be that if it were a matter of a few pieces, the thread for a woodscrew would be chased freehand. Before screw cutting lathes were commonplace, "turners" chased screwthreads using a single point tool on a rest like a wood-turning rest. The work was laid out with the helix on it's circumference beforehand, if large enough in diameter. The turner then took a scribing cut with a single point tool, following the layout line. If smaller diameter, I suspect they simply marked the work off with circumferential lines on the pitch of the thread. Once the turner had taken a few light cuts, they could then "adjust" the screw thread by eye with a few more passes of the single point tool. They might then use a multiple point thread chasing tool which was also held on the wood-turning tool rest.

    With wood screw threads, if the work were first turned to the starting taper and shank diameter. Freehand turning off a wood turning type tool rest made it relatively easy to turn the work to a taper for the starting section and however long a straight threaded section was required. I suspect the turner simply used a single point tool ground to the thread form for a wood screw. A wood screw thread is simply not so critical as a machine thread, so a little error in pitch or helix angle was not going to hurt anything. Possibly, the turner touched up the lead thread with a knife edge file while the work was in the lathe, then blended the lead thread or point with the work turning, also using the file.

    Joe Michaels

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    A "Multi point" thread chaser would make quick work of producing screw threads on any bench lathe. (think of a single flute of a threading tap used as the cutting tool. Or an acorn die.)

    The two volume set, "Modern Machine Shop Practice" by Rose, in my collection shows the technique and single point methods also. That reference was published in 1914! Were you thinking older than that?

    CalG

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    Guys,

    Prior to the last quarter of the 18th century, wood screws were swaged, not cut or filed. A tapered pin was filed or forged from wrought iron and a hand swage tool was used to form the threads. The swage process only took about a minute and the threads were very smooth and rounded at the valley and sharp and rough at the peak. If you wish to view the swage tool and the resulting screws go to Making 18thc style screws for wood. Here is posted scans of the original tool and screws.

    Jim Everett

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    The pics are not visible.

    You have to register before you can see them.

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    Default Screw Swage Tool Scans

    Guys,

    Here are scans of an 18th century wood screw swage tool. The tool is 8 inches long and only marked with numbers 1 - 7 for the differing sizes. The wood screws were swaged from this tool using 19th century puddled wrought iron. A tapered pin is turned (or filed for the purist) from the wrought iron. The tool is closed over the pin, tightened and rotated to swage the threads. The tool operates a lot like a tubing cutter except it travels along the tapered shaft as the tool is rotated.

    Jim Everett

    tool-aa.jpg

    screw5.jpg

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    Thanks to all who replied!

    Perhaps I am easily impressed, but I've always been amazed at what a determined person can do with a hand file and cold chisel.

    I have a question for James Everett:

    Does that swaging tool have a maker's name stamped on it?

    Do any 18th century sources, such as catalogs or Diederot [mid 18th century] or something like that, show similar tools ??? {I have the Dover reprint of Diederot, which is not the whole "Cyclopedia", just the parts that Dover thought are the most useful.) I'm NOT challenging the statement that this is an 18th century tool ! I'm just trying to fit it into my feeble understanding of 18th century technology and craftsmanship.

    John Ruth

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    Default Swage Tool

    Unfortunately there is no maker's name on the swage tool, only the numbers 1 through 7. I assume that such a tool was manufactured by a tool maker, and not by a local blacksmith as it requires hardened taps of the seven wood screw thread forms to make the tool. It is most probably from the mid 18th century as mass produced wood screws were available in the last quarter of the 18th century making such a tool unnecessary.

    The tool really does produce wood screws that are identical in all respects as originals. Even to the tiny line or split at the thread crest resulting from the swage process. I have made a working tool using a much more common 19th century machine screw split die swage by replacing a pair of dies with some I made to form the larger wood screws. As you can see in the scan of the largest screw the thread is not completely formed as the split at the thread crest is more open. The force to swage the largest screw using the original tool is high and I feared damage to the tool, so I stopped short of completing the screw. With my "modified" 19th century tool I can make a finished thread on the larger screw without damage to the tool.

    Let me know if you wish to see more scans of screws or of the 19th c. tool.

    Jim Everett

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    The screw on the left is a #5-20 standard American cut wood screw.

    The screw on the right is a #5 import from Asia, however the pitch is 18 TPI. A pitch of 18 is more consistent with a #6.

    The thread shape looks to be Acme.

    ...MC
    Attached Thumbnails Attached Thumbnails outofspec.jpg  

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    Quote Originally Posted by SouthBendModel34 View Post

    What did the tool look like, and how was it held and manipulated? The screw needs to have a taper......

    Thanks - JRR
    As stated elsewhere, those threads were not "cut", ... the were cold formed, in a process quite similar to modern day "thread rolling".

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    I often find these "c" chips among the box of screws indicating single point cut thread.
    Attached Thumbnails Attached Thumbnails cut-thread-c-chip-005.jpg  

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    Default Old Catalog Scan

    Here is a scan of a screw swage tool taken from a catalog of tools for clock makers, John Wyke of Liverpool, England. The catalog dates from the third quarter of the 18th century. As can be seen, the tool is very similar to the swage tool original shown in an earlier scan. The Wyke tool uses a hinge to align the two tool halves together whereas the original tool is of one piece. Both tools are used in the same manner to form a tapered thread by swaging. The Wyke catalog does not state the screw sizes or thread form of the tool, but it is assumed that it is for making tapered threads - wood screw threads.

    Thanks for your interest and comments - keep it up!

    Jim Everett
    Attached Thumbnails Attached Thumbnails wyketool2.jpg  

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    Thanks AGAIN to all of you for your efforts !!!

    Jim, that is really and truly interesting that you were able to find an 18th-century catalog with essentially the same tool. I had not noticed the one-piece construction of your tool until you pointed it out. You are wise to treat it gently.

    MachinistChest, your observations of asian import screws are also interesting to all. It seems like the idea is to make 'em as cheaply as can possibly be, without regard to whether they screw into the wood very well. Isn't a wood screw supposed to cut wood fibers to make its own thread? Sharp threads were always considered a necessary feature.

    And, certainly, the coarser pitch isn't going to be welcomed in hardwoods.

    JRR

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    Quote Originally Posted by SouthBendModel34 View Post
    MachinistChest, your observations of asian import screws are also interesting to all. It seems like the idea is to make 'em as cheaply as can possibly be, without regard to whether they screw into the wood very well. Isn't a wood screw supposed to cut wood fibers to make its own thread? Sharp threads were always considered a necessary feature.

    And, certainly, the coarser pitch isn't going to be welcomed in hardwoods.

    JRR
    Uh...wood screws I believe, hold because they part the long fibers, not cut them. The threads wedge apart the long fibers of the wood and the crest of the threads lies between the fibers. No doubt that some crushing of the fibers in the pilot hole occurs as well. They don't cut threads into the wood the way a tap cuts threads into steel. The only time the fibers are cut to any great degree is when a fool drives a wood screw into end grain and expects it to hold. Then it's serving more of a wedging function, held in place in the wood, like a common nail.

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    Default Screw Installation Force

    Guys,

    Talking about installing wood screws, you should try installing an 18th century design wood screw! The force to install these things is very much more than that required to install a modern one (either USA or Chinese). If you look closely at the scans of the 18th century screws you will see that they were made with a taper along the entire screw shank. As you install a modern wood screw only the first thread is doing the cutting (or wedging or forming) of the wood fibers, the subsequent threads merely follow the path of the first. With the 18th century screw each subsequent thread is slightly larger in diameter than the previous. In this case all of the screw threads are doing the cutting (or whatever term is appropriate) and the force is really high. When I make an 18th century screw, the thread is swaged onto the end of a long rod. The rod is 19th century puddled wrought iron, circa 1860-1880 from Oil City Pa. I then install the screw in the wood while still on the rod giving a good purchase for installation torque. After installation I cut the screw from the rod, form the head and cut the screw slot. You would really be surprised how difficult it is the get the screw slot on center!

    I also have in my collection two original 18th century wood screw taps used to tap the hole in the wood, something very useful way back then, but unknown today. See the scan below.

    The John Wyke tool catalog has been published and is a wonderful resource for tool collectors, it is out of print, but perhaps you could find a used copy.

    Jim
    Attached Thumbnails Attached Thumbnails scan0003.jpg  

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    Somewhat on this thread:

    I caught a portion of "How It's Made" which went through the making of auger bits. The plant where the bits were made used a surprising amount of manually done steps to make the bits. The bits began as round stock, heated and drawn out under some kind of open-die light power or pneumatic hammers. A drop forge die swaged the conical point. After a number of steps including heat treating, the threads were put on the point. Surprisingly, this was done on a form grinding wheel with the operator holding the bit freehand and turning it manually. It took a few hand-twists of the bit against the wheel and the threads were ground into the tip. I was surprised at how this was done, as I had always seen the cutting of the threads on a conical auger bit point as a tricky thing to do.

    The plant making the bits appeared to be doing it on a production basis, which also surprised me given the amount of hand work.

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    Thanks Joe Michaels!

    That is definitely interesting. I guess I had thought it would be a hands off process. For those that want to see at least part of the episode of making an auger bit, see it here:

    < How It's Made: Augers : Video : Science Channel >


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    Default Reference Cited

    Guys,

    You know that essentially all published works on antique tools deal only with wood working tools, never on antique metal working tools. Unfortunately this is an area of historical research that is virtually unknown. One great exception is the John Wyke tool catalog, originally from the third quarter of the 18th century. This reference is:

    A Catalogue of Tools for Watch and Clock Makers by John Wyke of Liverpool, Published for the Henry Francis du Pont Winterthur Museum by the University Press of Virginia, Charlottesville. 1978 ISBN 0-8139-0751-9

    Of course this is out of print but you may be able to obtain a copy by Amazon or EBay, or maybe the Winterthur Museum may still have a copy.

    This book shows hundreds of metal working tools & jigs from the period that were used for many trades other than clock making. A really great reference for anyone interested in old tooling.

    Jim

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    I tried searching for the John Wyke catalogue mentioned by James Everett to see if it was available on archive.org with no result.
    I also searched for wood screw
    Internet Archive Search: Wood Screws
    Not an answer to S.B.34’s original question but in the case of this mass production machine from 1837 shown in the link below the threads are cut with a tool bit .
    IMPROVEMENT IN MACHINES FOR CUTTING THE THREADS OF WOOD-SCREWS - United States Patent 154 : Free Download & Streaming : Internet Archive
    Regards,
    Jim


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