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Machine Screw threads - How Old?

Gazz

Stainless
Joined
Sep 7, 2004
Location
NH
A friend was working on a 1866 Allin Conversion rifle (these are the muzzle loading rifles converted to breech loading immediately after the Civil War) the other day and found that an 8-32 machine screw was a perfect fit for the breech block release latch. He was a bit surprised as he thought that something that old would have used a standard that was no longer available, especially since it was a firearm. So my question is, how long have the screw threads that are so common today been around? I have seen some old tap and die sets or screwplates and there are threads listed in them that are not so readily available today. I know that most used today are SAE standardized but how long has that been so? Thanks for your responses and input!
 
....sellers made an outstanding contribution , but others had their 'proprietary thrd.....armstrong w/ an absurd 3/8 xFIFTEEN grub screw on their # 1 holder .... i also had to cut a 5/8 X13 square thrd & a 1/2 X12 when i put my Reed 1895 14 in lathe to use.....
the military did have standardization , but i have repaired many sporting firearms of the 19th century & found all kinds of odd ball thrds....i think the standardization may have been a long time coming exclusive of the military , where it was of paramount importance...
many strange things ...i have a tool holder marked stanley & something i cant remember now , that takes a 9/32 square BIT used tangentially verticle ..much like the current commercial one xcept in the manner of retaining it ....STAMPED 1866 !!!!!!!
i thot that only forged tools were in use at that time ( shank is abt a #1 )..?????/comments pls?
best wishes
docn8as
 
Standardised "military " Thread systems:

Springfield armoury ( est. 1795) used the French metric system for the manufacture of the M1795 Springfield Flintlock Musket, as it was a derivation of the M1766- Charleville Musket of the Revolutionary War, as Modified by the French Committee of Public Safety, St. Denis Armory, in 1791-92, to use a metric system of threads, based on the earlier french system of "numbered Gun Threads" used by the Factories of Charleville, St. Etienne, etc.

One of the first actions of the Public Safety was to enforce the use of the metric system , and the unification of Gunmaking throughout France, to simplify Gun manufacture for the new Republic. BY 1810, they had a centrally controlled system of QA throughout all the Imperial manufactories, with reasonable interchangeability of most parts from all sources, and a "guide book" for Inspectors on how to carry out these QA inspections of Contractor's work ( M.Dale, M.re Imp. de Liege, 1810, republished by Liege Metropolitan Arms Museum, 1980s).

The Springfield Armory thread system was rendered into "inches" ( Thousandths of an inch)...and this was used by Prof. Sellars of Philadelphia to construct his Unified System Threads, presented to a conference of Engineers during the American Civil War..( all inch dimensions and pitches, but with the metric 60 degree thread form).

The "Springfield metric" system was used up until the adoption the the Krag rifle in 1892, which was designed and made according to the Sellars Thread scheme. ( Thread diameters, Pitches, sizes.)...so one will find some of the M1873/884 45/70 guns will use some truly metric screws, in exchange for the Springfield ones.

Given the sequential commonality of all the US Thread systems in Gunmaking for Military use, it is no great surprise that some Modern screws will interchange with the more "ancient" ones.

Regards,
Doc AV
AV Ballistics Film Ordnance Services,
Brisbane
Australia.
 
Hi Doc(#1),

My experience is like yours.

You mention Reed 1/2 x 12. I was cleaning up and sorting my nuts, bolts, taps and dies into bins on/off over past month or so. I got a drawer with 1/2 x12,13,14 nuts, bolts, taps and dies. Guess what? There are nuts that only work with certain bolts and other jam tight and some combination so loose as to be worthless together. The 1/2 12 really bad and even 1/2 13 occasionally all over the map. Some maybe Reed and some Putman and some xyz degree vee or whatever Mr Big builder though would make him the microsoft of the early machine tool era.

I suppose a lot of guys talked standards, but I am sure it was a long time before you got everybody to follow. I know about stubborn too, any pos metric taps I found all got thrown in a big coffee can. Ka clank.

The thing about early days builders made their own taps and their own nuts and bolts. As these items became relatively cheap off the shelf, the old ways had to die.
 
Springfield Armory......there's some kind of a legend about the breechplug threads of the Springfield Rifle (One of the Muzzleloaders, dunno which model) being "slightly off" from being an integer threads per inch pitch, and this caused grief to contractors trying to supply either whole rifles or parts during the US Civil War (I think)

Supposedly, contractor's sample pieces were being rejected as not to gauge, again I cannot recall if this was whole rifles or parts. The Armory officials supposedly weren't too helpful. The legend says somebody UNOFFICIALLY "borrowed" the official thread gauge set long enough to make true copies.

Anybody know anything about this half-remembered legend?

I'm NOT making this up. I know I read it somewhere, as opposed to having heard it related verbally.

The whole story makes sense now that DocAV has stated that the Springfield Armory was originally a Metric house.

John Ruth
 
one more springfield legend ...read this in pseudo gunsmithing book , written by a NON gunsmith , abt 65 yrs ago ....seems like one lot of springfield rifles( 30.06)were more accurate than normal ..seems the sine bar rifling machine had "slipped" ...twist was now one in eleven & a half instead of spec one in ten
so what did the army do? , you guessed right ...they had the armory reset back to one in ten ......credence is enhanced by the fact that earlier bench rest shooters found better 30 caliber accuracy w/ a one in twelve twist .......but it still may be apocryphal.....over the years i found lots of incorrect info , repeated in print as well as word of mouth abt subjects that i was increasingly knowledgeable ....scares me badly how much wrong printed , media ,& email info i digest abt subjects i have little or no knowledge of ....

best wishes
docn8as
 
I know this is an old post, but I’ve got a related question.

I’m trying to replace a grip screw on an early model of 1905 bayonet (1909 dated SA). I bought a catch lever assembly for the later models (1942+), and quickly discovered that the it is too large to thread into the escutcheon.

The screw that came out of the bayo has a shaft dia of .1515”. At the end of threads (at shaft), it measures .1505”. It appears to taper to .1470” at the thread start, but that could be due to oxidation, use, and age. The bayo has been blued (came in the bright from the factory), so it has been reworked at some point. If I understand correctly, likely before 1917 (most were parkerized when returned to the arsenal).

The later model screw measures .1585” at the shaft and .1550” at the thread OD.

At 32 tpi, it’s a coarse thread, but seems to fall between a #6 and a #8.

Can anyone shed light on this? I’m finding it incredibly difficult to find a replacement grip screw for early versions.

Thanks in advance.
 
I know this is an old post, but I’ve got a related question.

I’m trying to replace a grip screw on an early model of 1905 bayonet (1909 dated SA). I bought a catch lever assembly for the later models (1942+), and quickly discovered that the it is too large to thread into the escutcheon.

The screw that came out of the bayo has a shaft dia of .1515”. At the end of threads (at shaft), it measures .1505”. It appears to taper to .1470” at the thread start, but that could be due to oxidation, use, and age. The bayo has been blued (came in the bright from the factory), so it has been reworked at some point. If I understand correctly, likely before 1917 (most were parkerized when returned to the arsenal).

The later model screw measures .1585” at the shaft and .1550” at the thread OD.

At 32 tpi, it’s a coarse thread, but seems to fall between a #6 and a #8.

Can anyone shed light on this? I’m finding it incredibly difficult to find a replacement grip screw for early versions.

Thanks in advance.

Please start a new topic over in the GUN Forum, not here. Asking about this. You will get much more help and direct answer over there than here. Ken
 
I know this is an old post, but I’ve got a related question.

I’m trying to replace a grip screw on an early model of 1905 bayonet (1909 dated SA). I bought a catch lever assembly for the later models (1942+), and quickly discovered that the it is too large to thread into the escutcheon.

The screw that came out of the bayo has a shaft dia of .1515”. At the end of threads (at shaft), it measures .1505”. It appears to taper to .1470” at the thread start, but that could be due to oxidation, use, and age. The bayo has been blued (came in the bright from the factory), so it has been reworked at some point. If I understand correctly, likely before 1917 (most were parkerized when returned to the arsenal).

The later model screw measures .1585” at the shaft and .1550” at the thread OD.

At 32 tpi, it’s a coarse thread, but seems to fall between a #6 and a #8.

Can anyone shed light on this? I’m finding it incredibly difficult to find a replacement grip screw for early versions.

Thanks in advance.

You are correct. A 7-32 is between a 6-32 and an 8-32. Here are the ASME machine screw tables from the 1914 2nd edition of American Machinists' Handbook. Note that 7-36 was the standard and 7-32 was a special. Victor has the tap, but not the die. A replacement screw can be lathe cut.

Larry

DSC01059 (2).jpg DSC01060 (2).jpg DSC00554.jpg
 
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