US2830378A - Center-punching tool - Google Patents

Description

April 15, 1958 D. E. GlvAN CENTER-PUNCHING TooL Filed May 2o, 1954 El rlo m n J a W Q 1 A 0 J M .J g 9 a ,M 1 M M v w z/vm 1, W J O I. A Hwmi 1 |,I E 8 )f7 7 2u u 2 1 2 y 2 Q 3 3 J J qu f a W l @la 5 F M mkg- E M2\\1 UM/W/N TV7 a.; 2 8 6 a IM a E d P l1. Um. 5 l man a.. W a? 1 02 5a/ J 6 Ja 2 2a J 6 United States Patent O CENTER-PUNCHING TOOL David E. Givan, Anderson, Ind.

Application May 20, 1954, Serial No. 431,121

1 Claim. (Cl. 33-189) In machine shops and the like, it is frequently necessary to accurately center-punch plates, blocks and the like for the performance of drilling or other operations. For example, if the center for an opening is to be, say, one inch from an end edge of a plate and two inches from a longitudinal edge of said plate, the customary procedure is: (l) measure one inch from the end edge and make a scriber mark on the plate parallel with said end edge; (2) measure two inches from the longitudinal edge of the plate and make a second scriber mark parallel with said longitudinal edge and intersecting the rst scriber mark; (3) locate the point of a center-punch accurately on the point at which the two scriber marks intersect; and (4) strike the center punch with a hammer.

The above explained procedure possesses six possibilities of slight error: (l) in making the iirst measurement; (2) in making the first scriber mark; (3) in making the second measurement; (4) in making the second scriber mark; (5) in exactly placing the center-punch point on the point at which the two scriber marks intersect; and (6) in steadily holding the center-punch perpendicular to the plate while it is being struck with the hammer. On some work, one or more inaccuracies thus acquired are unimportant, but on precision jobs they cannot be tolerated and result in waste of materials and' labor and in delays which are often serious.

The present invention is designed to provide a novel tool embodying a center-punch, and two measuring scales for accurately locating the punch point in predetermined spaced relation with respect to two right-angularly related edges of a plate or the like. Thus, the machinist is only required to initially set the tool accurately, hold it properly on the work, and strike the punch with a hammer.

The two measuring scales cross each other in rightangular relation and the center-punch is slidably mounted on one of these scales, and further objects of the invention are:

To provide novel means for mounting the center-punch and normally holding it yieldably in a retracted shielded position in which there is no possibility of its point being accidentally damaged;

To provide for positioning the center-punch perpendicular to the work;

To provide a novel detachable connection between the center-punchmounting means and the scale which carries it, permitting more compact packaging of the tool for marketing;

To provide a novel clamp adjustably connecting the two scales in such manner that at least one of said scales may be detached, whereby said scales may be packaged compactly, side-by-side; and

To provide an extremely simple construction which may be profitably marketed at a reasonable price, yet will give excellent service for years.

In the accompanying drawing:

Fig. l is an enlarged plan view showing the tool set for locating the punch mark in accordance with the example given above;

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Figs. 2, 3, and 5 are sectional views on the correspondingly numbered lines of Fig. l; and

Fig. 4 is a detail sectional View on line 4-4 of Fig. 3.

The drawing discloses the preferred form of construction and while that construction will be rather specifically described, it is to be understood that variations may be made therein without departing from the spirit and scope of the invention as claimed.

Two measuring scales 6 and 7 of any desired length cross each other in right-angular relation, and a clamp 8 adjustably and detachably connects said scales. The minus end of the scale 6 has a lateral linger 9, the inner edge 10 of which is at a right angle to the length of said scale 6. The minus end of the scale 7 is provided with a mounting post 11 in which a center-punch 12 is slidably mounted with its axis perpendicular to the plane of said scale 7. This center-punch is normally held in a retracted position by means of a spring 13 and is provided with a head 14 to be struck with a hammer to drive the point 15 into the Work.

The graduations 6a and 7a of the two scales 6 and 7 respectively, may be in any standard units of measurement and fractions thereof. The graduations 7a of scale 7 denote distances from the punch point 15 to the front edge 16 of the clamp 8, which edge lis at a right angle to the longitudinal edges of said scale 7. The graduations 6a of scale 6 denote distances from the inner edge 10 of the linger 9 to a line L at a right angle to said scale 6, which line L intersects the punch point 15. The graduations 6a are cooperable with the left edge 17 of the clamp 8 in setting the scale 6; and in setting the scale 7, the graduations 7a cooperate with the front edge of said clamp 8. The line L does not of course exist on the actual tool but is applied to the drawing for purposes of description.

The clamp 8 includes a body 18 having a shallow groove 19 for the scale 7 and a similar groove 20 for the scale 6, the groove 19 being in the top of said body and the groove 20 in the bottom thereof. A clamping bolt 21 extends through the body and has a head 22 received in a recess 23 in said body, said head having a T-slot 24 slidably receiving the scale 6. The other end of the bolt 21 has a clamping nut 25 which overlaps the scale 7. When this nut 25 is tightened, the two scales 6 and 7 are tightly clamped to the body 18, and when said nut is loosened, scale adjustments are permitted as required.

The post 11 is detachably mounted on one end of the scale 7. To accomplish this, the scale 7 is formed with an integral dovetail head 26 and the lower end of the post 11 has a dovetail groove 27 receiving said head. A screw 28 normally holds the parts 7 and 11 in fixed assembled relation but when removed, allows disconnection thereof.

The post 11 has a bore of two diameters, the larger being shown at 29 in Fig. 3 and the smaller at 30. At the juncture of the two diameters there is a shoulder 31 upon which the spring 13 is seated. The punch 12 extends centrally through the large-diameter portion 29 of the bore and is slidably received in the small-diameter portion 30. This punch is provided with a collar 32 which abuts the upper end of the spring 13, and a sleeve 33 is threaded into the upper end of the bore 29 and abuts the upper end of said collar 32. The spring 13 is placed under compression as the sleeve 33 is threaded into place and said spring acts to normally hold the punch in a retracted position in which its point 15 is shielded against accidental damage. This point descends through an opening 30' in the headed end 26 of the scale 7 when the punch is operated.

To enable better understanding of the manner of operating the tool, a work-piece W has been shown in broken lines in Fig. 1, with the tool placed upon it. The elongated front edge 16 of the clamp 8 rests against a longitudinal edge E of the work-piece W, and the edge of the finger 9 rests against an end edge E' of said workpiece. The tool is shown as set to locate the punch point two inches in from the edge E, and one inch in from the edge E. It will thus be seen that after setting the tool for the required measurements, the machinist is only required to 'place and hold it upon the work-piece and strike the punch head 14 with a hammer, the result being accurate location of the indentation made in the work-piece, whether a mere mark be desired, or a depression suiciently deep to center a drill.

At the factory, the tool may be packaged with the scales 6 and 7 disconnected from the clamp 8 and with the post 11 disconnected from the scale 7. This not only saves on assembly cost but allows more compact packaging, and simple directions will enable the purchaser to complete the assembly.

From the foregoing, `it will be seen that a novel and advantageous tool has been disclosed for the desired purpose. However, while preferences have been shown andV described, attention is again invited to the possibility of making variations within the scope of the invention as claimed.

I claim:

A tool for center-punching a work-piece having two right-angularly related edges, comprising two scales in crossed right-angular relation, a clamp slidably connecting said scales and effective to hold them in adjusted positions, an abutment on the minus free end of one of said scales, and a center-punch mounted on the minus free end of the other of said scales, said abutment being adapted to abut one of said edges of the work-piece, said clamp having an edge to abut the other of said edges of the work-piece, said clamp edge being disposed at a right angle to the length of said other of said scales, said scales having graduations cooperable with said slidable clamp in setting said center-punch predetermined distances from said edges of the work-piece, said other of said scales being provided with a post at its minus free end in which said center-punch is slidably mounted, the punch being perpendicular to the scale plane, and a spring in said post for normally holding said center-punch in a retracted position, said post being detachably mounted on the minus free end of said other scale, said clamp including a body having shallow grooves in its opposite outer faces receiving the two scales respectively, and a bolt extending through said body, said bolt having a head which holds one of said scales in one of said grooves, said bolt having a nut which holds the other of said scales in the other of said grooves.

References Cited in the le of this patent UNITED STATES PATENTS 497,071 Gardiner May 9, 1893 1,183,977 Hoeiie May 23, 1916 1,330,069 Fischacher Feb. 10, 1920 1,545,424 Heimrich July 7, 1925 1,630,414 Baier May 31, 1927 1,976,841 Durkee Oct. 16, 1934 2,054,503 Iambura Sept. 15, 1936 2,197,505 Mosher Apr. 16, 1940 2,497,733 Kebour Feb. 14, 1950 FOREIGN PATENTS 152,215 Germany June 6, 1904 81,091 Austria Aug. 25, 1920 170,513 Switzerland Oct. l, 1934

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