Improvement in countersinks
US 117237 A
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Description (OCR text may contain errors)
UNITED STATES PATEW SEWALL L. ABBOTT, OF DEERING, MAINE.
IMPROVEMENT IN COUNTERSINKS.
Specication forming part of Letters Patent No. 117,237, dated July 25, 1871.
'o all whom it may concern:
Be it known that I, SEWALL L. ABBOTT, of Deering, in the county of Cumberland and State of Maine, have invented a new and useful Iniproved Countersink; and I hereby declare the following to be a full, clear, and exact description of the saine, reference being had to the accompanying drawing forming part of this speciica-tion, in which- Figure 1 shows a back side view of the countersink. Fig. 2 shows a side or edge view. Fig. 3 shows a section of the lower part of the tool, designated at a, to illustrate the form of the curve.
Same letters show like parts.
The general purpose of Iny invention is to show Van improved form of tool for cutting' depressions for the reception of screw-heads, &c.
The part b of the shank shows that end of the cutting-tool made square which is designed to enter and be fastened into the socket of a bit or other tool for giving rotation to the countersink, so as to enable it to cut such a hole or depression as may be desired. c shows the stock, which may be round or rectangular. The portion of the tool upon which the cutting-edges are made and from which the point is formed is best seen in Fig. 3. This would form an oval if the curve Were completed. The portion upon which the This is produced by cutting or :filing down the edges inja taper form, as illustrated. The inner edge e is the cutting-edge, or the one that rims out the hole made for the reception of the screw-head. The taper back from the point d enables the tool to cut recesses of various sizes, as may be desired, and to further this object the gaugefmarks f are cut and applied to the back or convex part of that portion of the tool seen in section in Fig. 3. With this the user has only to determine the diameter of the desired recess he Wishes to cut, and to ascertain which gauge or mark exhibits such diameter, and then to apply the tool till the gauge of the requisite diameter is on a level with the surface of the wood. The tapering cutting-edges e are also, as will be observed, slightly concave or curved inwardly. This enables the tool to perform its work without breaking out the bers of the wood in the hole, and thus it makes a smooth surface or cut.
Vhat 1 claim as my invention, and desire to secure by Letters Patent, is-
The countersink, constructed as herein described, that is, having the oval-shaped cutting portion, seen in section in Fig. 3, the tapering point, the inner cutting-edge c, the point d, and the gauges f, as herein set forth.
Portland, April S, 1871.
SEVVALL L. ABBOTT.
WILLIAM HENRY CLIFFORD, GEORGE E. BIRD.