AN IMPROVED VARIABLE BORING BIT
Year: 1858

page_text: LETTERS PATENT to William Tucker, of the State of Rhode Island, of the
United States of America, for the Invention of "AN IMPROVED VARIABLE
BORING BIT."
Sealed the 5th November 1858, and dated the 7th September 1858.
COMPLETE SPECIFICATION filed by the said William Tucker at the
Office of the Commissioners of Patents, with his Petition and Declara-
tion, on the 7th September 1858, pursuant to the 9th Section of the
Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, BE IT
KNOWN, that I, WILLIAM TUCKER, of the State of Rhode Island, of the
United States of America, have invented "AN IMPROVED VARIABLE BORING BIT;"
and I do hereby declare that the nature of the said Invention and the manner
in which it is to be performed, or in other words, its construction and mode of
operation are fully described and ascertained in and by the following Specifica-
tion and the accompanying Drawings, of which Figure 1 is a side view of it;
Figure 2, a longitudinal section; Figure 3, an end view; Figure 4, a side
view of the shank divested of the main cutter and its clamp nut.
In these. Drawings, A exhibits the shank of the bit as constructed with two
male screws a, b, one of which has its threads pitched or inclined in opposite
directions to those of the other, one being a right threaded and the other a left
threaded screw. One screw (viz. a) is arranged in front of the other (b), and
carries at its outer end a cutting edge or cutter c, and a tapering centering
point or screw center d. This latter does not have its axis arranged in line
with the common axis of the two screws a, b, and the shank A, but has it
disposed eccentrically or aside of parallel thereto, and at a distance therefrom.

page_text: A clamp nut e screws on the male screw b, and against a cutter f, which is
screwed on the screw a. This cutter f, formed as shown in the Drawings, is
furnished with a cutting edge g, which, when brought end to end with the
cutter c, may form therewith one cutting edge. It also has a small lip or
creasing cutter h, standing from it at right angles. The cutter f should be so
constructed that while the bit is in use there will be room for the shavings
made by the said cutter f to pass by it and across the clamping nut.
.
With a bit or tool so made the distance of the axis of the conical or screw
center & from the cutting lip h, may be varied by simply turning the cutter f
around on the screw a, as by so doing the said center point or screw may be
moved either toward or away from the lip h within certain limits. At what-
ever distance it may be placed within such limits, it may be secured by screwing
the clamp nut e forward against the cutter f. From the above, it will be seen
how the bit may be adapted to bore holes of various diameters.
Instead of two screws a, b, on the shank A, and having the threads of one
pitched in reverse directions to those of the other, or, in other words, so that
one shall be a right and the other a left screw, there may be cut on the shank
A but one screw for the reception of the cutter f and the clamp nut, but in
this case there would be great liability of displacement of the nut by the action
of the cutter during the process of boring with the instrument. The use of
two screws a, b, arranged, constructed, and applied to the nut e and cutter f,
as described, causes the nut to be sure to maintain the cutter in place on the
shank when the nut and cutter are in contact.
I am aware that it is not new to make a center bit with a tapering or screw
center made adjustable in such manner with respect to the extreme outer edge
of its cutter as to enable the center bit to be capable of boring holes of different
diameters. Therefore, I do not claim such in the abstract, but what I do
claim is the combination of a tapering center point or screw center d, and an
auxillary cutter c arranged on the shank A, as described, with a main cutter f
applied to the shank A, so as to be capable of being revolved thereon, and fixed 5
in position thereon by means substantially as specified.
In testimony whereof, I have hereunto set my signature and seal, the
Sixth day of August, One thousand eight hundred and fifty-eight.
WILLIAM TUCKER. (L.s.)