Guys,
Here is another old patent for boring of gun barrels, the patent is dated 1814, number 2064, but the inventor claims that he has been using the design beginning in 1799. The document is signed by James Monroe.
Lest we think that the old timers were unsophisticated, this patent includes a boring bit with a replaceable pilot guide, replaceable square cutter bits, a stepped boring bit, and a hollow bore reamer. This stuff is almost state of the art machining today! None of these tools was used to bore a barrel from a solid rod, they all were used to follow an existing hole. So the barrel blank was either previously forged as a tube, or drilled and forged to length. Also the patent includes a rack that is geared to the cutter so the bit advances through the barrel bore at a definite fixed rate as the bit is turned. The patent states that the bit rotates at about 1 rev/sec, rather slow to be sure.
The actual document is really difficult to read, so I have only included one of its pages as an example. The text is my best effort in reading the old script.
To all to whom these Presents shall cover, greeting
I certify that the annexed are two copies of the petition specification on both of invention, drawings and reference to workings of an improvement in boring Musket, Pistol & Rifle Barrels, by an auger, either the spiral groove or twisted same auger for which Daniel Pettibone obtained a patent the 12th Day of February 1814.
To the honorable James Monroe Esq. Secretary of State of the United States of America. The petition of Daniel Pettibone now of Philadelphia edge-tool maker humbly showeth. The he did invent construct and apply to use in the year 1799 a new and useful improvement in the manner of boring musket, pistol, or rifle barrels by means of peculiar constructed auger or bitts called the spiral groove or twisted screw auger or bit (side specification). A model of the auger and a partial description of his improvement were filed or deposited in the Office of State (where in this city) in the months of January and August in the year above mentioned.
Your petitioner is therefore desirous of obtaining an exclusion proper in his said invention and humbly prays that Daniel Pettibone duly executed according to law may be granted basis for his said invention as in duty bound will ever pray, your most obedient.
Daniel Pettibone
Philadelphia
31 March 1812
Specification. To all persons to whom these presents shall come Daniel Pettibone edge tool maker sends greeting. Be it known that I Daniel Pettibone did invent and apply to me in the year 1799 a new improvement in the manner of boring musket, pistol, or rifle barrels by an auger (called the spiral groove or twisted screw auger). The invention of the spiral groove or twisted screw auger for the purpose of boring musket, pistol, or rifle barrels consists in the manner of making it; or in the particular form or construction of the same; as also the mode of application.
First These augers I make of the best cast or other good stub welded to a handle or shank of good iron or steel. Then they are forged, hammered & twisted in a similar manner to the common or screw auger, used by carpenters for boring wood, excepting the plate is left thicker before it is twisted. The differences in the form of this improved auger forms the common screw auger and for boring wood are that the points or cutters are next to the shank; and that the auger is less twisted for boring iron than for boring wood. The shank of the auger is long enough to put through the barrel and fasten to the socket of the machine that moves or turns the auger. The auger revolves about once per second and the points or cutters are pressed against the iron that is to be bored from the inside of the barrel: By the force application of one or more endless screws that revolve in a rack or cogs attached to the carriage on which the barrels are fastened. These endless screws revolve very slowly so as to give time for the augers to cut all that is required. My further improvement is the placing of the barrels perpendicularly. The improved auger can be well applied if the barrels are placed horizontally. The size of the shank of the augers are about one eight of an inch less than the screw or cutters.
I consider it of much consequence to file or make the points of the cutters flat in the front so as to give chips a proper direction into the grooves. I make use of several different sizes to bore a barrel: the shank of the second auger for about four or five inches from the cutters is just as large as the cutters of the first and the shank of the third the same size as the cutters of the second, xc. xc. xc.
Secondly For convenience of repairs I put a piece of cast or other good steel about one eight of an inch square through the shank ext to the twisted part to form points or cutters.
Thirdly I have also made augers by forging and turning very smoothly in a latter a bolt or pin of good steel six or seven inches long It was then welded to a shank at one end And with in one or two inches of the other I put through a piece of steel to form points or cutters. This piece of steel is secured in its place by a small screw entering the end or side of the bolt or pin. and from the points or cutters. spiral grooves are cut to the end.
Fourth In some instances I cause the barrel to revolve instead of the auger for the purpose of boring more straight and true. I frequently repair the points or cutters of the twisted augers with a steel punch or set, by heating the auger to a red heat and temper it again.
Fifth - I sometimes make these bolts and or pins hollow in form the cutters or points to the end. So that the chips may pass off internally; instead of passing off in the spiral grooves on the outside. I also make bolts/pins, or hollow cylinders that screw together some what like the joints of a common flute or clarinet that when screwed together the cutters or points are fastened I its place chips or fareings pass off internally or externally as circumstances may require.
The advantages of the five articles.
Article Firstly The screw auger is more easily made & kept in repair than any other; and will bore the straightest without injury to the barrel; and of an excellent size alliber.
Art. Secondly By putting movable cutters to the screw auger or to the other kind, they will last a long time, as only the cutters will need repairing.
Art. Thirdly The placing the barrels perpendicular to be bored is a great improvement as it will save much room in a building or factory. and one man can tend ten to twelve augers at once. Also the chips will drop out conveniently.
Art. Fourthly the endless screw rack of cogs is a matter of consequence to give a regular pressure against the cutters.
Art. Fifthly The making of hollow augers for the purpose of passing the chips internally is very convenient. But there is none as the simplicity of the twisted screw and so easily made by a common workman & tools.
Signed Daniel Pettibone