Oct. 1, 1946. - c. LIEBLEIN 2,408,565 DETACHABLE‘ SCREW CUTTING DISK AND TOOL SHAILIK I Filed June 7, 1944 'rw v I . Fig.5 _ . ’ $291.4 , F213/0 INVENTO Y'C/z'aim Lieb/ei'n ' ATTORNEY 2,408,565 Patented Oct. 1, 1946 UNITED STATES PATENT OFFICE 2,408,565 DETACHABLE SCREW-CUTTING DISK AND TOOL SHANK Chaim Lieblein, Brooklyn, N. Y. Application June 7, 1944, Serial No. 539,068 1 Claim. (01. 10-141) 1 2 This invention relates to an improved screw The end stud 1 is considerably smaller than tap and one of its objects is to lower the cost the head 6, and the surface of the forward end of producing taps for forming screw threads in of the head is disposed at right angles to the large diameter tubes and holes. axis of the shank, and thus provides a thrust It is at present the common practice to form shoulder or bearing surface 8. screw thread cutting taps upon a solid piece The cutting disk 9 is formed with a central open of tool steel, so as to provide the necessary ing 9a, which has a form corresponding, to that thread cutting teeth and a shank for holding and of the stud 1, and is positioned on the stud 1 operating the tool. When the threads are broken and against the thrust or hearing shoulder 8. or otherwise rendered useless the whole tool must 10 The forward end of this disc is formed with a be rejected, or subjected to a complete regrinding circular recess 9a which snugly receives the or retooling operation. Screw taps of this type washer l0, and this washer is formed with a coun are not adapted for use in forming screw threads tersunk opening Illa which receives the screw ll. in large diameter tubes and holes. having a countersunk head Ila, and this screw is My improved screw tap tool consists of a disk 15 threaded in the stud ‘I, so as to secure the disk 9 of hardened and ground steel suitable for this on the stud 1 and against the shoulder 8. purpose, and a shank having a square stud which The disk 9 is formed with a plurality of rows snugly ?ts in a square hole formed in the tool of screw thread cutting teeth 12, and in the con disk and a screw and washer set for holding the struction shown there are four rows of such disk on the square stud, so that it may be re teeth, the rows being equally spaced from each moved and replaced with a new disk, or one of other. The disk is relieved at l3, in advance of smaller size, or for a different screw thread. the leading or cutting edges of the teeth so that Another object of the invention is to provide an e?icient cutting action will result, and the for a screw tap, which includes a screw thread cut ward or cutter side of the teeth l2 are disposed ting disk, which can be' arranged in multiples or 25 in a slight pitch to aid in effective thread cutting. gangs upon a squared shaft, ‘so that the screw The cutting disks are formed from circular threads may be cut or formed, as by milling or blanks M of .tool steel, each having a square cen grinding the whole group or gang at one time. ter hole Ma.‘ These blanks are mounted on the With the above and other objects in view the square shank or mandrel l5, clamped against invention comprises certain new and useful con 30 each other, and then the screw threads are out structions, combinations and arrangements of upon all of the disks at one time. The disks are parts, clearly described in the following speci?ca tion, and fully illustrated in the drawing, in which: . then subjected to the usual ?nishing operations, when they are ready for use. I have found that my improved method of Fig. 1 is a side elevation of the combined tool. 35 manufacture materially reduces the cost of form Fig. 2 is an end view showing the disk, hold ing the screw tapping disks, and that it is more ing washer and its connecting screw. economical to replace a disk having broken teeth, Fig. 3 is a detail plan view of the washer. . than it would be to purchase a large screw thread Fig. 4 is a detail sectional view thereof. tap'of-corresponding size and capacity. 40 Fig. 5 is a detail side view of a holding screw. Having described my invention I claim as new: Fig. 6 is a central vertical sectional view show A thread cutting tool, comprising a shank ing the combined tool. having a polygonal stud on one end thereof and Fig. 7 is a plan view of the disk removed from I a shoulder at the inner end of said stud, said the holding shank. stud being disposed centrally of the shank, a disk 45 having a central opening which receives the Fig. 8 is an end view of the tool shank; Fig. 9 is a side view of a gang of blank disks polygonal stud and disposed against said shoul arranged for milling the teeth on all disks in one der, said disk having a plurality of radial lands operation. ' > Fig. 10 is a plan view of one of the blank disks. provided with screw‘ cutting teeth, and also formed with a recess concentric with said central opening, a washer disposed in said recess and engaging the outer end of the stud, and a screw Referring to the accompanying. drawing il so lustrating the practical construction of the in vention, 5 designates a shank of tool steel, which extending through the washer and threaded into is provided with an integral head 6 and an end the stud 'for retaining the disk on the stud be stud ‘I, centered axially thereon, and formed with tween said washer and said shoulder. a plurality of parallel sides, resulting from the 55 milling of the stock from round to square or CHAIM LIEBLEIN. other polygonal form.