US2124093A - Grinding machine - Google Patents

Grinding machine Download PDF

Info

Publication number
US2124093A
US2124093A US29940A US2994035A US2124093A US 2124093 A US2124093 A US 2124093A US 29940 A US29940 A US 29940A US 2994035 A US2994035 A US 2994035A US 2124093 A US2124093 A US 2124093A
Authority
US
United States
Prior art keywords
drill
grinding
cam
quill
bearing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US29940A
Inventor
Frank O Wells
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
CARROLL E ADAMS
Original Assignee
CARROLL E ADAMS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by CARROLL E ADAMS filed Critical CARROLL E ADAMS
Priority to US29940A priority Critical patent/US2124093A/en
Application granted granted Critical
Publication of US2124093A publication Critical patent/US2124093A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B3/00Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
    • B24B3/24Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of drills
    • B24B3/26Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of drills of the point of twist drills
    • B24B3/32Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of drills of the point of twist drills for thinning the point
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B3/00Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
    • B24B3/18Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of taps or reamers

Description

July 19, 1938. (1 WELLS 2,124,093
GRINDINGMACHINE. Y
Filed July 5, 1955 5 Sheets-Sheet 1 IN VENTOR,
ATTORNEY.
July 19, was. Q W LL 2,124,093
GRINDING MACHINE Filed July 5, 1955 5 Sheets-Sheet 2 INVENTOI;
i l I 97 61244; 40?
ATTORNEY.
y 19, 1938. F. o. wEL'Ls' 2,124,093
FRINDING MACHINE I INVENTOR,
ATTORNEY.
July 19, 19 38. V Q. W LL 2,124,093
GRINDING MACHINE Filed July 5, 1935 5 Sheets-Sheet 4 INVENTOR, 1 10M d fil ATTORNEY.
July 19,1938. F. o. WELLS 2,124,093
' GRINDING MACHINE Filed July 5, 1955 5 Sheets-Sheet S 1N VEN TOR,
my j 0. Welel's;
I J .93 BY ATTORNEY.
Patented Julyl9, 1938 UNITED STAT S PAT- Eur oFFic-E.
, GRINDING MACHINE I v Frank 0. Wells, Greenfield, Mass, assignor to I Carroll E. Adams, Pawtucket, R. I.
Application July 5, 1935, Serial No. 29340 8 Claims.
My invention relates to improvements in grind? ing machines, andmore particularly to that type of grinding machine intended for use in the sharpening of drills and taps.
An object of my invention is to provide a sharpening machine, combined in a single structure for sharpening drills and taps, that is semiautomatic in its action, which will quickly and efiiciently sharpen a drill or tap, and which may be set to accurately grind the cutting edges and v the lip clearances of a drill point to the proper angles, and the land faces and flutes of a tap to the proper angles of clearance and hook.
A further object of my invention is to provide means on my machine for grinding corners at the intersections of the faces of the drill point and the sides of the flutes. At the present time, it is customary to grind drills with a sharp corner or edge at these intersections. It has been found by exhaustive experiments that the life and cf.- ficiency of a drill may be multipled many times by rounding or removing these corners or intersections and therefore materially save the cost of purchasing a new drill.
These and other objects and advantages of my invention will appear in the accompanying drawings, the specification, and the appended claims.
Broadly, my invention comprises a base member, a motor mounted on the base member, aplurality of grinding wheels secured to and actuated by the motor, chuck and quill means for holding a drill or tap to be ground, adjustable bearing members pivotally secured to the base member in'which the quill is slidably secured,.cam means on the quill for controlling the movements of the drill or tap against the grinding wheels, means for locating a drill or tap in the quill in proper relation to the cams, and means for dressing the grinding Wheels for the purpose of maintaining their faces in a true and sharp condition.
A preferred embodiment of my invention is illustrated in the accompanying drawings, in
which:
Fig. 1 is a side elevational view of the complete grinding machine, showing the drill locator, motor, grinding wheels, the two pivoted posts, the
' pivoted housing with quill assembled therein in the right hand post position for grinding the point of a drill, and the housing in the left hand post ready to receive the quill for the purpose of grinding rounded corners of a drill on its edges, or removing them by grinding on a chamfer.
Fig. 2 is an end elevational View of Fig. 1 of the grinding machine illustrating the method of pivoti ng theposts for the purpose of feeding the work to the grinding wheels.
Fig. 3 is a longitudinal sectional view of a drill and chuck assembled in the quill.
Fig. 4 is a cross sectionalvie'w on the line 4-4 of Fig. 3. v
Fig. 5 is a cross sectional view-on the line 5-5 of Fig. 3 illustrating the cam for feeding the drill point across the face of the grinding wheel.
Fig. 6 is a side elevational view of the drill point locator with the quill assembled therein.
Fig. '7 is a plan view of the pivoted housing in which the quill is supported while the drill point is being sharpened.
Fig. 8 is a. detailed elevational view of the housing and quill shown in Fig. 7,.in the same position as that shown in Fig. 1.
Fig. 9 is a side elevational View of'the housing shown in Fig. 7, looking in the direction of the view on the line as that shown in Fig. 1.
Figs. 13 and 13 'are plan views of the point of a drill which has been sharpened on this machine. I
Figs. 14' and 14 are side elevational views of the point of the drill shown in Fig. 13 and Fig. 13A. 1
Fig. 15 is a partial side elevational view corresponding to Fig. 1 showing the pivoted-housing in the right hand post with quill assembled therein and adjusted in position for grinding a tap and the tap rest secured in the left hand post by means of which the flutes of the tap are ground.
Fig. 16 is a side elevational view of the tap rest shown in Fig. 15.
. Fig. 17 is a diagrammatic transverse sectional view of a tap illustrating the results obtained by the use of the grinding machine.
Fig. 18 is an elevational view of the adjustable dressing tool used to dress the grinding wheel to the proper shape for rounding the corners of a drill point.
Fig. 19 is a. plan view of the dressing tool shown in Fig. 18, and
' Fig. 20 is plan View of the dressing tool used for facing the grinding wheel ce-operating with motor 2 to which are secured in the usual manner the grinding wheels 3 and 4, the drill point cator 5, the details of which are shown in Fig-:3
in section, and the post 5 which supports the' wheel guard A shaft 3 is secured in the base member I, and the posts 3 and II are pivotally secured on this shaft by means of the bearings The extent of swing of the posts 8 and II on the shaft 8 is controlled by the adjusting screws l2 and. i3. The post i3 is formed with the socket l4, in which the shanks of the drill housing turn; also the tap rest, or, the wheel dresser, may be secured by the wing set screw l5.
In describing the drawings, the methods and attachments used in the process of sharpening the point of a drill'will be first described, then the methods and attachments used in the process of sharpening a tap, and finally the devices used for dressing the grinding wheels.
Figs. 3, 4, 5, and 6 illustrate the means for holdinga drill in the quill and for locating the lips of the drill in proper relation to the cams on the quill and quill housing. The drill i5 is slipped into the spring chuck I! having spring fingers and held lightly in place by a slight turn on the tightening knob II. The chuck I1 is formed with the tapered and split end portion I3, which engages the tapered surface 28 of the quill 2|, and the tapered and split end portion 22 which is engaged by the tapered surface 23 of the threaded tightening shaft 24 to which the knob I3 is secured. The chuck I1 is formed with the alternately spaced slots 25 and 25, and the ends of the chuck. II are also formed with slots 21 and 28. This construction permits the fingers of the chuck to be gripped and compressed at each end simultaneously, which results in a firm, double grip on the shank of the drill. The tightening shaft 24 is adjustable in the quill 2| by means of the threads 29, and, by unplug the knob l8, the spring ends of the chuck are compressed or expanded to grip or to free the drill. The quill 2| has secured thereto, by
means of the 'set screw at the end opposite the drill point, the cam member 30, formed with oppositely located lobes or cars 3| and having secured in the body 32 the cam or locating pin 33.
While the drill is still lightly held in the chuck, the quill 2| is placed in the bearing portion 24 of the locator 5, and is revolved until the lips of the drill point are engaged in the locator button 35, (see Fig. 6), which is retained in-the bearing portion 35 of the locator 5 with the set screw 35. With the drill point held by the button 35, the quill is pushed forward until the cam 38 impinges against the pin 31, then revolved until pin 33 is brought into engagement with the pin 31. The knob I8 is then turned until the drill I5 is tightly grippe in the chuck IT. This procedure locates the drill in the quill with the of the drill point in the proper relation to cam 30. I
After the drill has been properly set in the quill, the'quill 2|, with the drill l5 gripped therein, is removed from the locator 5 and placed in the pivoted bearing or housing 4||, illustrated in! Figs. '7, 8, 9, and 10. The bearing is pivotally secured on the post 5 by means of the arm 4|, pivot bearing 42, and pivot shaft 43. The
The base member I has mounted thereon the axis or center line of the pivot shaft 43 inter.-
' sects with the axis or center line of the radius to which the cutting edges of the drill point will be ground. The adjusting screw 44, impinging against the lug 45 formedon the 'post 3, may be set to bring the axis of the housing 48 to any desired. angle relative to the face of the grinding wheel 4. For grinding the cutting edges of the drill points, this angle is usually 59 degrees, but may be varied if desired. The adjusting screw 44 has a threaded connection in the arm 4| of the quill housing 48, and as the screw 44 is threaded into the arm 4|, it impinges against the lug 45 and forces this arm and quill bearing 45 to swing around the pivot shaft", as illustrated by the arrow 45 in Fig. 10. The post 3 is also formed with the extending arm 41, to which is secured the cam-enga ing rod 43 by means of the clamp 43, stud 53, and screw 43. The stop lug 5|, formed on the pivot bearing 42, co-operates with the adjusting screw 44 to hold the bearing 45 with its axis parallel to the face of the grinding wheel 4 when the wheel is being dressed. In this position, the stop lug 5| is in contact with the post 3, and prevents further movement of the bearing 43. This operation will be more fully explained later. The cam munber 52 is secured to the bearing 43 by the set screw 53, and' is properly aligned with the bearing 48 and the drill |5 by means of the indicator marks DD", on cam and bearing as a reference mark 52' for positioning a drill, see Fig. 9. The cam member 52 is formed with the cam face 54, on which the pin 33 of the double cam 35 rides. In operation, the quill 2| is pushed into the bearing 43 until the pin 33 engages the cam face 54, the quill 2| is then revolved in a clockwise direction by turning the knob l3, and the combined movements of the drill point I5 caused by.the action of the arms 3| of cam 38 against the rod 48, and, the pin 33 against the cam 52 will cause the drill point l5 to be ground with the correct angle of cutting lips and the jcorrect eccentric relief or lip clearance.
and 20 on the top face of the clamp 49, shown.
in Fig. 7, assist in the proper location of the rod 48. 1
- The housing 45, carrying the quill 2i and drill I5, is fed toward the grinding wheel 4 by the adjusting screw l2, shown in Figs. 1 and 2, and as the grinding wheel is worn down, the loss in diameter is also compensatedby swinging the post 9 inward by the adjusting screw I2.
After the drill point l5 has been ground to the properangle and relief against the grinding wheel 4, the quill 2| is removed from the bearing 43 and inserted in. the bearing 55, illustrated in Figs. 11
, and 12. The bearing member 55 is formed with the standard 55' and slide 51-. The slide portion 51 is slidably secured in the slide bearing 58, and
its position relative to the slide bearing 58 is regulated by the adjusting screw 58. Once properly set, the slide 51 is secured by the set screw 58. The slide bearing 58 is formed with the shank portion 6|, which is removably-secured in the socket |4 formed in the pan II, by the set screw 55. The angle of the axis of the bearing 55 with the face of the wheel 9 may be adjusted by turning the shank ti in the socket is and adjusting the slide 57 with the screw 59. The cam 62 is secured to the bearing 55 by means of the set screw $3. The purpose of the cam is to feed the drill point toward the grinding wheel, in order to form a relieved rounded, or chamfered corner on the drill point it. The cam 62 is formed with the cam face 66, on which the pin 33 rides. The quill 28 is inserted in the bearing 55, until the pin 33 is engaged against the .cam face 64, then the quill fl is revolved by turning the knoblt; The grinding wheel 3 is formed with the concaveshaped face 55, and as the drill point it is fed forward and backward against and away from the face 55, a relieved rounded corner is formed at the intersection of the faces of the drill point and the sides of the flutes. If the wheel 3 has a flat face, a chamfered corner is formed, as indicated at it, in Figs. 13 and 14 The result of the operations above described is to sharpen the drill it with both cutting edges 66 exactly alike as to length and having the same angle with the axis of the drill, as indicated at 67 and 68 in Fig. 14. The angle of lip clearance, or contour of the relief surfaces 59 and Ill back of the cutting edges is the same for both cutting edges. The drill has been shaped with the rounded comers ii and 12 or, chamfered corners ltflld", both exactly alike. Thus the sharpened drill point has been shaped to be correct according to thebest practice in every respect, and in addition, the rounded corners H and F2 or, chamfered corners i6", it increase the emciency and life of the drill many times.
If it is desired to thin the web of the drill point 36, as indicated at E3 and 16 in Fig. 13, this may be accomplished by the use of the tap rest, indicated in Figs. 15 and 16 in cooperation with the grinding wheel 3'.
Figs. 15, 16, and 17 showthe manner in which at by bringing the indicator marks T T- into registration on cam and housing, shown in Fig. 15. The housing id is set at the proper angle with the grinding wheel 6 corresponding to the taper of the tap end Tl by the adjusting screw 6%, the quill 2i inserted in the housing d0 until the pin 33' engages the face til of the cam '89, and the quill 2i turned in a clockwise direction by the knob I8.
The tap is moved in and out across the face of the wheel ti by the cam face 80, thus causing a correct relief, indicated at 89 in Fig. 1'7, to be ground on the tapered faces of the lands id. The cam face til is cut with a plurality of high points 32 equal in number to the number of lands on the tap to be ground. The housing 40 is fed toward the grinding wheel d'by the feed screw it, in the same manner'as that employed fordrills.
' When sharpening taps, the flutes 83 should be are-ground to provide plenty of chip room and the correct hook or rake for free cutting. For this operation, the tap it is held on the V-shaped tap rest i1 3, and fed to the narrow formed grinding wheel 3' by the feed screw it. The tap rest dd is formed with the round shank 85, which is adjustably secured in "the secket M of the post it by the set' screw id. The angle of the tap rest, relative to the wheel 3', may be adjusted by turning the shank 85 in the socket M to provide the correct hook.
Figs. 18 and 19 illustrate the dressing device used for dressing the formed wheel which grinds the roundedcorners on the drill point. A similar device is used for dressing the formed wheel used in grinding the flutes of taps. The diamond-- pointed dressing tool 85 is secured in the swinging support member d'i which is formed with the handle 86 and shaft 8d. The shaft portion 89 is .pivotally supported in the bearing portion 90 of ber 92 and the pivot-supporting member M,
respectively.
The straight faces of the wheels 3 and 6 are dressed with the tool'illustrated in Fig. 20. The diamond pointed dressing tool 95 is secured in the-reduced end. portion 91 of the shaft 98. The shaft 98 is formed with the same diameter as the quill 2i, and has formed at the end opposite the diamond point 96 the knurled knob. 99. In operation, the shaft 98 is substituted in the housing Iii for the quill 2 I. The housing 40 is swung around on its pivot 43 in the bearing 42 by the adjusting s'crew at until the curved stop lug 5i engages the post 9. In this position, the axis forth across the face of the wheel a. The face work which they are designed to accomplish.
It will be observed, with reference to Figs. 13 and 14 that the corner portion, indicated at it, is chamfered, instead of being formed curving or rounded, as in Figs. 13 and i4, at El and i2.
What I claim is:
1. In a grinding machine, a. grinding element, means for operating the same, a. pivotally supported post, a pivotally supported .housing member on said post, means for rotatably supporting a tool to be ground. as a drill, in the housing member, means when the tool is, rotated in the housing member for moving the tool across the grinding element and for simultaneously of wheel 3 may be dressed straight in the same forming the relief on the tool point, said means tion with a grinding element, a movably mounted post, a tool-receiving housing pivotally mounted on said post, an adjustable arm on the post, a tool chuck rotatably mounted in the housing, a cam on the chuck engaging the arm for, moving the tool to be ground across the face of the grinding element for imparting a relief surface. to the tool, a second cam on the housing and a member on said first cam engaging said second cam for controlling longitudinal movement of said chuck.
3. In combination in a grinding machine, a base member, grinding elements on the base member, means for operating the grinding means, a shaft in said base member, posts pivotally supported on said shaft, members for supporting tools to be ground pivotally supported on said posts, means for positioning the toolsupporting members in angular relation to said grinding elements, means for moving the posts toward and away from the grinding elements, and cam' means for imparting a relief. for the cutting edges of the tools when the tools are rotated-in engagement with said grinding elements.
4. In a drill grinding machine, a grinding element having a concave face, a post, a housing pivotally supported on saidpost, a table slidably supported in said housing, means for adjustably positioning said table relative to the axis of said post, a bearing sleeve on said table, a quill for holding a drill slidably and rotatably supported in said sleeve, a cam on said sleeve, a stud on said quill and in engagement with said cam for imparting longitudinal movementto said drill when said drill is. rotated, whereby the shoal-- ders of the drill point will be chamfered with a relief angle identical. with the relief angle on the face of the drill point.
5. As a constituent mechanism of a machin holder operating a screw for actuating saidmeans. t
6. A drill sharpening mechanism comprising a grinding wheel, a support movably mounted adjacent thereto having a cylindrical bearing opening therein, a separable drill holder having means unitary therewith for clamping the drill centrally therein in a flxed'position and having a forwardly extending cylindrical shank free of radial projections adjacent the forward end thereof and constructed and-arranged to fit said bearing and be entered thereinto from the rear side, cam elements on the holder adjacent the rear.en d thereof, a cam element on the support and a cam element adjacent thereto for cooper-. ,ating respectively with said elements on the holder for controlling axial and swinging movements of the drill during the grinding operation.
7. A drill sharpening mechanism comprising a grinding wheel, a support movably mounted adjacent thereto having a cylindrical bearing openholder, and'means at the rear of the holder for applying rotative movement to the same.
8. A drill sharpening mechanism comprising a grinding wheel, a support movably mounted adjacent thereto having a cylindrical bearing opening therein, a separable drill holder having means unitary therewith-for clamping the drill centrally therein in a fixed position and having a. forwardly extending cylindrical shank free of radial projections adjacent the forward end thereof and constructed and arranged to fit said bearing and be entered thereinto from the rear side, a cam element projecting in a transverse plane at the rear of the holder, a cooperating element adjacent the support cooperating therewith, cooperating cam elements on the forward face of said first mentioned cam element and the rear face of the holder, and means at the rear of the holder for applying rotative movement to the same comprisinga wheel handle effective to operate the drill clamping means. I FRANK O. WELLS.
US29940A 1935-07-05 1935-07-05 Grinding machine Expired - Lifetime US2124093A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US29940A US2124093A (en) 1935-07-05 1935-07-05 Grinding machine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US29940A US2124093A (en) 1935-07-05 1935-07-05 Grinding machine

Publications (1)

Publication Number Publication Date
US2124093A true US2124093A (en) 1938-07-19

Family

ID=21851688

Family Applications (1)

Application Number Title Priority Date Filing Date
US29940A Expired - Lifetime US2124093A (en) 1935-07-05 1935-07-05 Grinding machine

Country Status (1)

Country Link
US (1) US2124093A (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2477135A (en) * 1945-10-22 1949-07-26 Barber Colman Co Cutter sharpening machine
US2593847A (en) * 1947-11-26 1952-04-22 Clark John Wesley Toolholder
US2672714A (en) * 1950-11-07 1954-03-23 Garnet A Wilson Grinding machine
US2805522A (en) * 1954-11-15 1957-09-10 Theodore S Dayton Apparatus for sharpening wood bits
US2827741A (en) * 1953-09-29 1958-03-25 Robert K Thomas Drill grinding machine
US3126679A (en) * 1964-03-31 Device for point thinning of drills
DE1960814A1 (en) * 1968-12-04 1970-06-25 Omark Winslow Co Device for grinding a convexly curved drill bit on a twist drill
US4001975A (en) * 1975-07-09 1977-01-11 Darex Corporation Twist drill sharpener and aligning fixture
US4543857A (en) * 1983-12-09 1985-10-01 Urban Engineering Co., Inc. Surgical instrument and method of making same
US4742648A (en) * 1983-04-30 1988-05-10 Thomas Ketteringham Drill sharpening tool
US6244938B1 (en) 1999-07-16 2001-06-12 Lisle Corporation Drill grinder

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3126679A (en) * 1964-03-31 Device for point thinning of drills
US2477135A (en) * 1945-10-22 1949-07-26 Barber Colman Co Cutter sharpening machine
US2593847A (en) * 1947-11-26 1952-04-22 Clark John Wesley Toolholder
US2672714A (en) * 1950-11-07 1954-03-23 Garnet A Wilson Grinding machine
US2827741A (en) * 1953-09-29 1958-03-25 Robert K Thomas Drill grinding machine
US2805522A (en) * 1954-11-15 1957-09-10 Theodore S Dayton Apparatus for sharpening wood bits
DE1960814A1 (en) * 1968-12-04 1970-06-25 Omark Winslow Co Device for grinding a convexly curved drill bit on a twist drill
US4001975A (en) * 1975-07-09 1977-01-11 Darex Corporation Twist drill sharpener and aligning fixture
US4742648A (en) * 1983-04-30 1988-05-10 Thomas Ketteringham Drill sharpening tool
US4543857A (en) * 1983-12-09 1985-10-01 Urban Engineering Co., Inc. Surgical instrument and method of making same
US6244938B1 (en) 1999-07-16 2001-06-12 Lisle Corporation Drill grinder

Similar Documents

Publication Publication Date Title
US2124093A (en) Grinding machine
US2109308A (en) Drill grinder
US3040631A (en) Portable power-operated cutting tools
US1994975A (en) Drill grinder
US2328549A (en) Method of grinding twist drills and machine for same
US2672714A (en) Grinding machine
US2209228A (en) Tap chamfering machine
US4483104A (en) Drill bit sharpener
US2958167A (en) Grinder fixture
US3200540A (en) Device for grinding compound-convex surfaces
US2068915A (en) Drill grinding appliance
US1803429A (en) Lens-tool-surfacing machine
US1363194A (en) A corpora
US1710647A (en) Machine for grinding twist drills
US2512888A (en) Apparatus for grinding drills
US2725690A (en) Cutter grinding mandrel with tooth rest
US2372794A (en) Machine for grinding twist drills
US2984949A (en) Apparatus for sharpening wood bits
US2780894A (en) Twist drill sharpening attachment for tool grinder
US1873612A (en) Grinding device
US2596916A (en) Drill grinder
US2232563A (en) Machine for pointing drills
US3197924A (en) Twist drill sharpener
US3380200A (en) Drill grinding machine
US2827741A (en) Drill grinding machine