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Publication numberUS77819 A
Publication typeGrant
Publication dateMay 12, 1868
Publication numberUS 77819 A, US 77819A, US-A-77819, US77819 A, US77819A
InventorsCharles Krbbs
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Charles krbbs
US 77819 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

@uiten tats-s @anni @ffice Lenen Patent No. 77, s19,'dafa'May 12,1868.


'dite tlgrhnle afinar tu in time' etir's @anni imi: mutiitg grd nf the same.


Be it known that I, CHARLES KREBS, of West Springield,'in the county of Hampden, and Commonwealthof Massachusetts, have invented a n ew and useful Improved Countersink; and I do hereby declare that the following is a. full, clear, and exact description thereof, reference being had to the accompanying drawings,

making a part of this specification, and to the letters of reference marked thereon, in which.-

v Figure 1 is a. side view of a countersink with my improvement, having two lips or cutting-edges.

Figure 2 is a view of said'confntersinbblank, showing its shape before the lips are turned. ,Figure 'isianother side view of said countersink-blank. i Figure 4 is a perspective view of said countersink. i v

Figure 5 is a view of a countersinlc-blank, having one liplora singlecutting-edge, before said lip isV turned, and i Figure 6 is a perspective view of said countersink after the lip is turned.

The nature of my invention consists in the construetion'ofV a countersiuk, to be used in wood, whereby the same shall have a thinner and moreA perfect cutting-edge than can possibly be made as at present constructed.A

As they are new made, the lower or conical portion of the countersink is forged or swaged out solid, and a small channel is then cut, lextending from the apexto the base of the cone, leaving one 4side or edge of said channel in suchv form as that-it may be sharpened butit vis wellknown to wood-workmen that the best countersinks, when constructed as above described, are very imperfect in their oper'atio'n, and do not smoothly and neatly countersink a hole made in wood, but merely grind awaythe'wood in the upper purtof the hole,'leaving it very rough andjagged in appearance, and the channel behind the edge cannot be made suiiciently'large to,

permit the wood, which is cut or ground outof the'woodeusubstanco being worked, to be forced-out of thetool.A

By my invention, I am enabled toproduce a countersinkwhich admitsof being slrarpenedwith an oil i stone to avery sharp cutting-edge, and whieh, ins'tead of merely grinding away. `the wood, neatly and smoothly outs it away, and much quicker, too, than can be'done with the ordinary cuntersink, and, there being suiiicient space behind the edge, and between the stem andv lips, a' free passage of the s'hnvings out o f theqtoolis provided, and itis not liable to get choked or clogged, as is the case with the ordinary countersink.

To enable others skilled in the art to make and use my invention, I will proceed to describe its construe# tion and application to use. l I

A piece of suitable metal is forged out, having a circular blade, B, of a proper thickness, and the stem A, and a portion of said bladev B, equal to about one-sixth of the whole, is then cut out, leaving -the space a', extending frolnthe points s' s', inthe circumference, to the points s s. A small slot,.e, is then cut, extending from the points s s to about the centre of the blade B.` The edges, n u, are then brought to an approximate degree of sharpness, and the whole blade is `then heated suiiiciently, and the lips a a are then turned back A towards the stem A, and areeasily formed into a. conical shape, as shown vin iig. 1, the slot e in iig. 2 serving to furnish sufficient space in turning to`produce al sharp and perfect point, s, in Aiig. 1. This -produces a coun tersink, having two lips, a a,.a.nd two cutting-edges, n n. y

I make' a countersink having one lip, c, and one cutting-edge, n', as follows: The dat blade B and stem A, both constituting a. blank, are forged as before described, and a portion equal to about one-quarter of the blade,

extending from the point i in the stem A to the point t in4 the periphery of the blade B, is removed'or cutout,

leaving the space 6 as shown in iig. 5, that which is to be the cutting-edge, it', extending from the point t to the point t. From the point t the blade is eut to about its centre, und from thence to thepoint t" o u the stem,

leaving the small triangularspace a near the centre,- which space-o furnishes suiicient turning-space, in turning back the lip e, to form a perfect point, o', as shown in iig. b. The edge n is then brought to asucient approxii mate degree of sharpness, and the blade B is then heated sufficiently, andthe lip c is turned back towards tli'e stem A, and at the same time is somewhat twisted around the base of the stem A, or around its junction' with the blade B, which operation gives the4 blade B its conical form, as shown in iig. '6. The cone, or conical portion, is then tempered suicient'ly,'the edge sharpened, and the tool is then ready for use. The end, C, of the stem A is then tapered in a rectangular form for insertion into a common bit-stock for use.

' It is not actually necessary,'in forminga blank having two lips, that exactly one-sixth of theblade shall be cut out or removed, as, if a little more or less were removed, the countersink might operate teler-ably wel] but I find by experiment that if about that proportion be removed,a better countersinl is produced. The same may be remarked -in regard to the blank for a eountersink having one lip, as it might operate toleably well if either a little more' or a little les's than'one-quarter of the 'blade were cutout, but I prefer to remove about that vportion, asa better tool isv the result.

In manufacturing in quanti-ties, these blanks may be forged or swaged out' at one blow of a drop or swage', and'proper tools may be construoteand used in the remaining: operations of bringing them to a finished 'countersnlgso that they an be as oheaply made as those now in use', and they will last much longer, as there is moro'avalable materialto wear away. I Y

' IaniV aware that a device has been heretofore used as a eountersink, as in Letters Patent granted to W. G. A. Bonwill,l dated October-'10, 1865, and numbered 50,328, and also thedevice now commonly used, but'I d sclaim any and every partof said deviee's, irrespective of my'arrangeinent and construction.

Having thus described my invention, `Wbat'I clairn as new, anddesire to secure by Letters Patent, is-

Av countersink, having one or more bent lips, when'fconstructed substantially as here'indeseribed -andset forth. i f



' T. A. Gnarls,


Referenced by
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US5556399 *Feb 14, 1995Sep 17, 1996Huebner; Randall J.Bone-harvesting drill apparatus and method for its use
US20050036594 *Sep 10, 2004Feb 17, 2005Intervoice Limited PartnershipSystem and method for measuring interactive voice response application efficiency
Cooperative ClassificationB23B31/113