US3515187A

US3515187A - Pencil lead pointer

Info

Publication number: US3515187A
Application number: US674271A
Authority: US
Inventors: Robert Scofield Condon
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-10-10
Filing date: 1967-10-10
Publication date: 1970-06-02
Anticipated expiration: 1987-06-02

Description

June 2, 1970 R. s. CONDON 3,515,187

PENCIL LEAD POINTER Filed Oct. 10. 1967 INVENTOR. ROBERT S CONDON United States Patent 3,515,187 PENCIL LEAD POINTER Robert Scofield Condon, 112 Cindy Lane, Berlin, Conn. 06037 Filed Oct. 10, 1967, Ser. No. 674,271 Int. Cl. B43] 23/08 US. Cl. 145-33 2 Claims ABSTRACT OF THE DISCLOSURE A pencil pointer having a blade support secured inside a hollow housing. A hole in the support axially aligned with an orifice in the housing opens into a downwardly extending recess providing a flat surface for the hard carbide blade which has a cutting corner curved at one end for tangential contact with the lead. Cap screws acting as dowels in oposed V-shaped slots in the blade secure the blade to holder and an adjusting screw regulates the position of the blade. Two interengaged brushes clean the point when withdrawn.

BACKGROUND OF THE INVENTION This invention relates to pencil lead pointers and more particularly to the type haping pencil pointing means secured within a holow housing for pointing the lead of a pencil inserted through a guide orifice and rotated.

Heretofore pencil lead pointers have been either comparatively expensive motor-driven devices or, where inexpensively made, the blade has been of the knife type which quickly becomes dull. Furthermore the conical point produced by such sharpeners is easily broken and must be cleaned of graphite dust before using. Users of such devices found it necessary after sharpening to round over the weak tip of the conical point on a piece of paper and then to wipe the point clean before using.

SUMMARY OF THE INVENTION It is proposed, accordingly, to provide an economically constructed pencil sharpener having a blade of hard and lasting material so disposed as to cut the excess lead or graphite oif the tip, allowing the resulting dust to drop from the cutting portion free of the pencil, and at the same time to burnish the cut portion to smoothness. Wiping means are provided at the point of entry of the pencil into the device to free the shaped point of dust upon withdrawal. The blade is so shaped as to give a conical but sharp rounded tip to the point and provision is made for the precise adjustment of the blade position.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective side view of a sharpener according to the invention;

FIG. 2 is an enlarged end view of the blade and blade support as viewed from the right in FIG. 1;

FIG. 3 is a bottom plan view of the top portion of the sharpener showing a pencil being pointed, a portion of the blade support being broken away;

FIG. 4 is a view similar to FIG. 3 with the pencil being withdrawn;

FIG. 5 is an enlarged fragmentary sectional view of the blade and pencil lead on the line 55 of FIG. 3; and

FIGS. 6 and 7 are greatly enlarged diagrammatic end elevational and plan views, respectively, of the blade and associated parts showing the means for precisely positioning the blade.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing the lead pointer or sharpener 10 is shown as having a box-like plastic housing 11 inside the top of which a blade holder 12 is secured to one wall by the screws 13 Housing 11 is made of plastic, having a top half portion 11a and a bottom half portion 11b, the top being of clear plastic and the bottom of opaque material, to conceal the removed dust. Top and bottom are separably secured together by hinges 14 and clasp portions 15. An entrance orifice 16 in the side of the top opposite holder 12 serves as a pencil guide.

The blade holder 12 has a central axially extending tapered hole 17 axially aligned 'with orifice 16 to serve as a lead guide and whose outer end is funnel-shaped, as shown. The holder has a recess 18 extending down away from the lead guide, here quadrant shaped, and to one side of the recess, which has a flat portion 18a, the blade 20 is secured by means of screws 21. At the inner end of the flat portion 18a, the recess side is undercut at 18b to provide for the curved end 20a of the blade and to allow loose graphite cut from the lead tip to fall downward into the dust receptacle formed by the housing bottom 11b.

In an appropriate hole extending from the recess 18 through the holder 12 an adjusting screw 22 is provided bearing against blade 20 between screws 21 and the blade side edge 20b which extends approximately along the lead guide 17. The blade corner edge 23 between side edge 20b and the fiat side 20c, opposite the side 20d which is secured against the flat portion 180: of the recess side, is the cutting edge of the blade, as will. appear.

A pencil 25, when it is inserted through orifice 16 with its graphite lead 26 in the lead guide hole 17, as shown in FIG. 3, is rotated clockwise, as indicated by the arrow. As the lead meets the corner edge 23 a layer of graphite is cut from the lead and falls down through recess 18. At the same time the edge side 20b, tangent to the shaped point burnishes the cut surface smooth.

A sharp pointed pin 27 is provided in another hole 28 through the blade support, the pin having a slide fit therein so it may be easily Withdrawn for clearing any broken point tips from the lead guide 17.

Two opposed fine-hair brushes 30 are secured to the inside of top 11a of the housing, as shown, at the orifice 16. The intermeshing hair-ends of the brushes are easily penetrated by the pencil lead 26 when the pencil is inserted and the hairs brush away any graphite dust remaining on the lead when the pencil is withdrawn, at the same time closing orifice 16, as shown in FIG. 4. Screws 31, which may be of the self-tapping type, secure the metal ferrules 30 of brushes 30 to housing 11. The brushes, being intermeshed, are self-cleaning.

It will be understood that the abrasive clay in graphite pencil leads would soon dull an ordinary knife-edge blade so the edge side 20b of blade 20 is formed to meet the fiat side 200 at a degree angle and the blade 20 is made of almost diamond-hard tungsten carbide. This material after sintering is too hard to be easily ground or machined by ordinary tools and, furthermore, may warp and shrink up to 20% upon sintering. Ordinary screwholes or slots for the cap screws 21 cannot be provided since it is impossible to control screw hole size after sintering and the material is too hard to ream by ordinary means.

A novel means for securing blade 20 to the holder 12 is illustrated in FIGS. 6 and 7. The blade 20 has V-shaped slots 32 at either end, formed before sintering. In order to precisely locate the blade while the holes for screws 21 are drilled, a mandrel M shaped like the tapered pencil point desired is inserted in the hole 17 and the mandrel blade are clamped in place. As shown in FIGS. 6 and 7, the mandrel M is flatted along its top where it contacts the cutting corner 23 of the blade to allow the blade 20 to protrude the proper distance into the lead guide hole 17. The shape of mandrel M before flattening is indicated by the broken line M' in FIG. 7.

When drilling the tap drill holes for screws 21, a bushing 33 (FIGS. 6 and 7) is used around the drill. Bushing 33 has an outside diameter equal to the screw thread diameter of screw 21 and an inside diameter equal to the tap drill size. When the screws 21 are assembled they contact the sides of their V-slots 32 tangentially at 34 and 35 and blade is dowelled accurately in place.

Before screws 21 are tightened, the adjusting screw 22 is adjusted to bring the side 20c precisely radial of the lead guide hole 17 so that side 20c is aligned with the center of lead 26 as shown in FIG. 5. This ensures that the edge side 20b is tangential to the shaped lead to give it the proper burnishing action.

In operation, a pencil 25, shown as a draftsmans mechanical pencil, is inserted in the pencil guide orifice 16. If the housing top 11a is grasped between thumb and forefinger on either side of the sharpener at the base of brushes 30, the device is self centering. The lead 26 enters the funnel-like mouth of the lead guide 17 nad continues until a portion of the lead meets the cutting edge 23 of the blade. When the pencil is rotated clockwise, exerting about the same pressure as used in drawing, lead is cut from the point, first at the high spots and then all along the point, until the pencil turns freely indicating the point is shaped.

The curved end 200 of the blade gives a similar shaping to the edge 23 so that the shaped point is truly conical along the point in contact with the straight portion of blade side 20b and then rounded to a strong pointed tip, the apex of the tip being conical but with a greater apex angle, as illustrated by the shape of mandrel M in FIG. 7 and the point 26 in FIG. 3.

When the pencil is withdrawn the parted hairs of brushes 30 wipe the lead point free of the dust from sharpening. Housing 10 is about 1% X 1%" X 2" in size and can be easily opened for emptying of dust.

It will be apparent that the sharpener 10 provides economically a pocket size device which, in one operation, points and correctly shapes the pencil lead and wipes the shaped point ready for use.

As will be apparent to those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

What is claimed is:

1. In a pencil lead pointer of the type having a hollow housing, the housing having a pencil orifice therein, a blade holder secured within the housing and having a tapered lead guide hole at least partially therethrough axially aligned with the pencil guide, the improvement comprising: the holder having a blade recess extending along the lead guide, one side of the recess having a substantially flat portion extending away from the lead guide; a generally rectangular sintered carbide blade having two fiat sides joined by two narrow edge sides, the blade being positioned with one of its fiat sides against the flat side of the recess and the other fiat blade side forming with its adjacent edge side a cutting corner extending into the lead guide therealong; the blade having a V-shaped slot at each end, and a pair of securing cap screws securing the blade against the recess fiat portion, the screw portions of the cap screws being in dowelled relation to the sides of the V-shaped slots.

2. In a pencil lead pointer of the type having a hollow housing, the housing having a pencil orifice therein, a blade holder secured within the housing and having a tapered lead guide hole at least partially therethrough axially aligned with the pencil guide, the improvement comprising: the holder having a blade recess extending along the lead guide, one side of the recess having a substantially flat portion extending away from the lead guide; a generally rectangular sintered carbide blade having two flat sides joined by two narrow edge sides; cap screws securing the blade with one of its fiat sides against the flat side of the recess and the other fiat blade side forming with its adjacent edge side a cutting corner extending into the lead guide therealong; the blade holder having an adjusting screw normal to the recess flat portion between the securing screws and the lead guide and adapted to bear against the blade for precisely adjusting the blade cutting corner with its adjacent fiat side radial of the lead guide, whereby the end of the lead of a pencil turned in the pointer is cut to the desired shape by the adjacent flat side and burnished by the adjacent edge side.

References Cited UNITED STATES PATENTS 454,356 6/1891 Horton et al. 118121 2,169,908 8/1939 Wells 3.31 3,090,358 5/1963 Condon 14428.72 3,387,314 6/1968 Shirk 15-210.2

FOREIGN PATENTS 10,496 1914 Great Britain. 712,982 8/1954 Great Britain.

LESTER M. SWINGLE, Primary Examiner 0 R. V. PARKER, JR., Assistant Examiner