US1933581A

US1933581A - Grinding apparatus

Info

Publication number: US1933581A
Application number: US635396A
Authority: US
Inventors: Lewis J Bazzoni
Original assignee: United Shoe Machinery Corp
Current assignee: United Shoe Machinery Corp
Priority date: 1932-09-29
Filing date: 1932-09-29
Publication date: 1933-11-07
Anticipated expiration: 1950-11-07

Description

L. J. BAZZONI Nov. 7, 1933.

GRINDING APPARATUS Filed Sept. 29, 1932 4 Sheets-Sheet 1 1933- L. J. BAZZONI GRINDING APPARATUS Filed Sept; 29, 1932 4 Sheets-Sheet 2 Nov. 7; 1933. J. BAZZQNI GRINDING APPARATUS Filed Sept. 29, 1932 4 Sheets-Sheet 3 4 Sheets-Sheet 4 m, m w W Nov. 7, 1933. J. BAZZONI GRINDING APPARATUS Filed Sept. 29, 1932 Patented Nov. 7, 1933 GRINDING APPARATUS Lewis J. Bazzcni, Swampscott, Mass., assignor to United Shoe Machinery Corporation, Pater son, N. 3., a corporation of New Jersey Application. September 29, 1932 Serial No. 635,396 7 i 21 Claims.

This invention relates to abrading machines and is herein illustrated as embodied in a machine for shar ening'the cutting edges of rotary toothed cutters of the type illustrated and described in my copending application Serial No. 635,395, filed September 29, 1932, which cutters are especially designed for use in rounding the breast edges of wood heels and are used ina type of machine known as a wood heel spooling machine. C-ne of the essential characteristics of a cutter of the type referred to is that the cutting edges, although straight, are arranged to produce a convex surface on a Work-piece. To obtain this result, the cutting edges are skewed so that one end of each edge is circumferentially ahead of the other end. With the teeth arranged in this manner, the cutting edges of all the teeth, when the cutter is revolving, generate or describe the same hyperboloid of revolution.

It is necessary, in a cutter of this type, as in practically all types of rotary peripherical cutters, to provide a cutting clearance by backing on the outer faces of the teeth, and it is desirable that the cutting clearance be substantially uniform at all points along the length of the cut-' ting edges notwithstanding the straightness oi the cutting edges and the circumferential skewing thereof. These conditions in cutters create a grinding problem to the solution of which the.

present invention is directed.

It is to be understood, therefore, that an object of the present invention is to devise a method, and provide an abrading machine, by which the teeth of cutters having characteristics such as those defined above may be readily sharpened grinding their outer surfaces in such a way as to provide substantially uniform cutting clearance at all points along their lengths.

It is another object of the invention to provide a machine for grinding the teeth of both righthand and left-hand cutters of the above type in a manner that will insure straight cutting edges and uniform cutting clearance, which machine conveniently be altered by a simple adjustment to grind right-hand and left-hand cutters set forth, the invention provides for relatively feeding a cutter anda grinding wheel with a compound motion, one component of which is angular motion about an axis that touches and crosses the periphery of the grinding wheel, and the other component of which is a rectilinear 6 motion lengthwise of that axis. As the new face is formed on the cutter by the grinding wheel, it develops that the cutting edge coincides with the aforesaid axis of compound motion. When these principles are utilized in grinding skewtoothed cutters the eliect of the angular motion about the axis is to counteract the circumferential skew of the cutting edge, to the end that each tooth oi the cutter will have uniform cutting clearance at all points along its length.

Preferably, and as herein illustrated, theapparatus for presenting a cutter'to the grinding wheel comprises a carrier in which the cutter is secured, the carrier being arranged to execute both components of the compound motion defined above. Moreover, through the medium of suitable means, the component of angular motion of the carrier is caused to impart to the carrier its component of rectilinear motion or motion of translation lengthwise of the aforesaid axis, whereby the cutter is caused to traverse the grinding wheel at a certain rate constrained to. bear a predetermined ratio to the number of degrees of the component of angular motion.

Another feature of the invention consists in means'for regulating the ratio of the components of motion given to the cutter-carrier, to the end that the length of the axial movement of translation may be varied for any given angle through which the carrier is swrmg. As herein illustrated, this movement of translation is producedby a stationary cam relatively to which the cutter-carrier swings, provision being made for regulatingthe pitch or steepness of this cam with a resultant increase or decrease in the length of the movement of translation with respect to the angle of swing. I

Another feature of the invention consists in an adjustable holder for mounting the cutter in the carrier, the holder being adjustable relatively to the carrier from one position of adjustment to another which is oppositely but symmetrically related thereto so that both right-hand and lefthand cutters may be ground with equal facility and accuracy, to the end that mated cutters, whether for a spooling machine or for any other purpose, may be truly matched, one with the other, when sharpened. 7

Still another feature of the invention consists in an improved combination of gaging devices by wheel shown in Fig. 5

The invention further consists in the features of construction and in the combination and arrangements of parts hereinafter described and claimed, the advantages of which will be apparent to those skilled in the art from the following description of the preferred embodiment of the invention illustrated in the accompanying drawings, in which,

Fig. 1 is a plan View of the complete grinding machine, showing a left-hand cutter in position for starting the grinding operation,

Fig. 2 is a front elevation of the machine with the parts in the same position as in Fig. 1,

Fig. 3 is a front elevation of a portion of the mechanism of Fig. 2, with the cutter and its carrier swung to the position where the grinding operation is being completed,

Fig. 4 is an end elevation partly in s ction, at right angles to the axisv of thegrinding wheelshowing the mounting of the abradin'g wheel with its motor drive and the mechanism whereby the abrading wheel is adjusted to and from the work,

Fig. 5 isa front elevation of, a portion of the machine showing the gage used in determining the proper. adjusted position of the abrading wheel, V v

Fig: 6 is an end view of the gage and abrading with the gage shown in section,

Fig. 7 is a detail view showing-the arrangement whereby the cutter may be accurately positioned about its own axis, ona stub shaft, for grinding,

"Fig. 8 is a plan view-partly in section, of an indexing device by which any cutter, whether right-hand or left-hand, may be adjusted in ac cordance with the angle of skew of its. teeth.

Fig; 9 is a view from right to left of Fig. l and partly in section, showing the mounting for the cutter-holder, wherebythe cutter may be adjusted vertically into proper position to be ground and also representing the adjustments that insure coincidence of the sharpened cutting edge of a left-hand cutter with the axis about which and along which the cutter moves while being ground. This view also shows, in dash lines, the position that certain parts assume at the completion of the grinding operation, I

Fig. 10 is a view from front to rear of Fignl and showing a right-hand cutter mounted on its holder in position to be ground and with the grinding wheel shifted angularly from grinding a left hand cutter to a position to permit the grinding of said right-hand cutter.

Fig. 11 is an enlarged view of a portion of Fig.9, showing the gage for determining the initial adjustment of the cutter, a tooth of a lefthand cutter being shown in section at the beginning of the grinding operation and in dash lines at the completion thereof.

In the drawings, 20 indicates the abrading or grinding wheel. This is mounted on one end of a shaft 22 located in a bearing member 24. On the opposite end of the shaft .22 is a pulley 26 by which the shaft is driven, by means of a driving belt 28, from a pulley 30 located on one end of the shaft of an electric motor 32. The motor is bolted to a base 34 which is clamped to an adjustable bracket 36 by means of. a bolt 38.

The bracket 36 is urged to swing around a pivot shaft 40 by means of a spring 42, the tension of which may be adjusted by a nut 4% on a stud 45. The position into which the bracket will I swing as it is urged by the spring 42 in a counterclockwise direction (Fig. 4), is determined by an adjustable stop-screw 46, the end of which contacts with an abutment 48. This abutment extends from a lug 49 on another base plate 50. the lug serving as a bearing for the pivot shaft 40. It will thus be seen that the grinding wheel is held yieldingly against the work by the spring 42 and may be raised and lowered with respect to the work by the adjustable stop screw 46.

The base plate 50 is provided with a groove which engages a tongue 52 which is integral with, and on the upper side of, a plate 54. This tongue-and-groove connection is at right angles to the grinding wheel shaft 22 and relative movement of the base plate 50 and the plate 54 in this groove provides an adjustment in a horizontal plane of the grinding wheel toward and from the work. The plate 54 is provided its under side, with a segmental rib 56 which can slide in a corresponding groove 53. By means of the segmental rib and' groove, the motor and grinding wheel may be positioned at any suitable angle in a horizontal plane. By test, two suitable and symmetrically related positions of the grindin wheel have been found. in one of which all righthand cutters may be ground and in the other of which all left-hand cutters may be ground. To readily determine these two positions when changing the machine to grind pairs of mate. .-d cutters, two

stop screws

59, 59 are provided. against which one end or the other of the p ate 54 may be positioned. In order to clamp the

plates

50 and 54 together, and to clam the latter in the segmental groove 58. after the rinding wheel has been positioned in the desired loca- 115 tion. a nut 60 and check nut 62 are tightened upon'a stud 64.. the body of which passes through a segmental slot 66, concentric with the groove 58. and is threaded into a head member 57 which bridges the under side of the slot 66.

It will thus-be seen that the grinding wheel is universally adjustable relatively to the cutter not only to produce the desired angle of cutting clearance but also to avoid contact with the tooth. next behind that being operated upon. and at the same time to locate the operating portion of the grinding wheel exactly on an as will be explain d later.

The machine is provided with a base 30 which is supported by legs 82. This base carries the segmental groove 58 and slot 66 referred to above and is provided also with two

integral standards

84 and 86 in which are mounted, respectively,

coaxial bushings

88 and 90. the axis of which is the axis X-X referred to above. In these bushings there are mounted, respectively,

hollow trunnions

92 and 94 which are, accordingly. coaxial. From the inner ends of the trurr one 92 and 94' is suspended a cradle 96 for ca1. .1251, the cutter to be ground. The cradle is provid d with split hubs in which the trunnions are clamped by

bolts

98, 98. The trunnions can turn and slide in the bushings and, accordingly, the cradle 96 may be given an angular motion about the axis XX and a motion of translation along said axis. 7

As heretofore stated, the cutter and the grinding wheel should be positioned, relatively to each other, so that they may be given a relative compound motion. One component of this motion should be angular about an axis that touches and crosses the periphery of the grinding wheel and the other component should be a rectilinear motion lengthwise of that axis. Under these conditions, the cutting edge, as it is formed, will coincide with this axis of compound motion. Preferably, and conveniently, the cutter is the member that is movable about and along such an axis and therefore the cutting edge of the cutter that is in the process of being ground should lie in an axis which meets these conditions. By mounting the cutter in the cradle 96 so that its cutting edge will lie in the axis XX of the cradle, these conditions will be fulfilled. Accordingly, in order that a cutter to be ground may be correctly adjusted relatively to the cradle 96, so that its cutting edge will be thus positioned, the following mounting for the cutter in the cradle is provided.

The cradle 96 has a split bearing 104 in which is mounted a cylindrical post 99 the axis of which is at right angles to, and intersects, the axis X-X. The post 99 is provided with a screw thread and a knurled nut 100 by which it may be raised and lowered, the nut being mortised into a slot 102 in the cradle 96. The split bearing 104 is provided with a clamping screw 106 having a handle 108 by which the post 99 may be secured in any position of rotary and axial adjustment. The post 99 carries at its upper end an index plate 116 which will be described later and which is integral therewith. Extending above the index plate 116, and also integral with the post 99, is a standard 113 which carries a stub-shaft 120 the axis of which intersects and lies at right angles to the post 99. The cutter to be ground is mounted on this stub-shaft. The stub-shaft 120 is provided with a collar 122 which is shrunk upon it (see Fig. '7). Also mounted on the stub shaft 129, is a loose member 124 having a tongue-andgroove connection with the collar 122 so that it may rotate therewith. This member 124 has a stop lug 126 against which the front face 142 of a tooth of the cutter to be ground may be held manually during the grinding operation, to locate that tooth angularly. Prior to the grinding, however, the cutter C and the stub-shaft 120 are rotated together in the standard 118, with the front face of a tooth of the cutter held against the stop lug 126, until the edge to be ground is properly located by a gage hereinafter described, and then the stub shaft is locked in position by the thumb screw 128. Thereafter, the stop 126 serves to establish the angular position of the cutter for each grinding as the teeth of the cutter are brought successively against it by manipulation of the cutter.

In order to provide for grinding both righthand and left-hand cutters of different angles of skew and to position each so that each cutting edge in process of being ground will coincide with the axis XX, various adjustments are provided.

With regard to different angles of skew of both right-hand and left-hand cutters the post 99, with its index plate 116, can be rotated about its axis to bring the stub-shaft 120 into proper position for any cutter. There are two different and definite angular positions, equidistant from a mid-position, into which the post 99 should be rotated for grinding cutters of a given angle of skew, one position for a right-hand cutter and the other for a corresponding left-hand cutter. In order that an operator may conveniently rotate the post 99 into proper position to grind any cutter, the index plate 116 is provided with two series of notches, symmetrically arranged about a center notch 0; these notches corresponding to the above definite angular positions into which the post 99 may be rotated in order to accommodate any cutter which may be ground on the machine. For the further convenience of the operator, these notches are marked with numerals which correspond to the effective radii of the cutting profiles of the cutters in lfiths of an inch, corresponding to the marking on the cutters to be ground. The post 99 is indexed by positioning the beveled end of a locking block 130 in the designated notch in the index plate 116, after which the locking block 130 is secured in position by a thumb screw 131 to lock the post 99 in the proper angular position.

In order to indicate the exact location of the axis X-X, and thereby properly locate a cutter relatively thereto, a gage rod 132 i provided. This gage rod telescopically mounted in the hollow trunnion 9d and is provided at one end with a handle 134 for sliding it to the left (Figs. 1 and 2) into operative position and to the right out of such position. At its opposite end it is pro-- vided with a straight edge 149 (see Figs. 9 and 11) that coincides with the axis X-X, this edge being formed by the intersection of two angularly related fiat faces 136 and 138. When the cutter C and the stop 126 have been interengaged the cutter is rotated manually to bring the front face 142 of one of its teeth into complete contact with the vertical gaging surface 138 (see Fig. 11), after which the'stub shaft is locked in position by means of the thumb screw 128. The cutter is then adjusted vertically by raising or lowering the post 99 by means of the thumb nut 19o iuitil its dull edge is slightly above the top gaging surface 136 so that the new cutting edge that is to be formed by grinding will later coincide with said surface 136. Now, when the cradle is swung about its axis XX the new cutting edge will coincide with the axis 'X--X, provided the operating surface 144 of the grinding wheel is positioned to grind on said axis, as described below.

The edge 140 may 'alsobe used to locate the operating face 144 of the grinding wheel 20 on the axis X--X, but to save this edge from abrasion I prefer to use another gage rod 146 which is telescopically mounted in the trunnion 92. This gage rod may be slid into operative position by moving it to the right 1, 2 and 5) far enough so that the longitudinal center line of the flat suriace 148 on its inner end be used to position the operating face 144 of wheel on the axis X-X, with which axs said longitudinalv center line coincides. In order that the gaging surface 148 may always be located angularly in operative position with the gaging surface tangential to the grinding wheel, when the wheel is brought to the proper position on the axis the outer end of the gage rod is pro" vlded With an arm150v which has a locating pin 152 near its outer end, which pin is arranged to enter a hole 154 drilled in the base of the machine when the gage rod is rotated into proper gaging position. With the gage surface 148 thus definitely located, the grinding wheel may be adjusted, by the means hereinbeiore referred to, so that it is tangential to the surface 148 at said longitudinal center line. In this manner the grinding wheel is accurately located so that, after the gages are withdrawn into inoperative position (or removed from the machine), and the grinding wheel started, it will grind a cutter so Qri that its finished ground edge will lie in the axis X-X.

To prevent dust from the grinding operation from being deposited in the boresof the

trunnions

92, 94, and on the

gage rods

132 and 146, the inner ends of the trunnions are provided with spring-operated dust covers 156 which close the ends of the trunnions automatically when the gage rods are Withdrawn to inoperative positions.

In order to grind the whole length of each tooth, it is necessary to give the cutter a component of motion parallel to the axis XX. As heretofore stated, the cradle 96 and the

trunnions

92 and 94 not only swing about the axis XX but they also slide lengthwise of this axis. In order to produce this sliding movement of the cradle and to regulate its amplitude, the following mechanism is provided.

The cradle 96 is provided with an off-set arm 16!) at the end of which is mounted a cam-rol1 162 by means of a stud and nut in the usual manner. This cam-roll is arranged to travel in an arcuate cam-slot 164 out in an adjustable cam member 166. This cam member is provided with a stud 168 which passes through extending bracket 170 formed integrally with the base 80 of the machine. The cam member 166 and the bracket 170 are so arranged that the cam member may turn about the stud 168 as an axis. To hold the cam member in position in the bracket and permit such turning, an adjusting nut 172 and a check nut 1'74 are threaded on the lower end of the stud 168. In order to position the cam member for grinding any given cutter, and to lock it in adjusted position, a hand lever 1'76 is provided. (See Fig. 2.) This hand lever is connected by a bolt 178 to a lug 180 extending from the rear end of the cam member 166. The hand lever 176 is provided wi h two sets of graduated

notches

182 and 184 symmetrically arranged about a center notch 186. The hand. lever passes through a slot in a plate 188 extending below the base 80 and mounted thereon by means of bolts 190. Under one of these bolts is mounted a spring 192 which engages the hand lever 1'76 to press it downwardly. By lifting the hand lever, against the pressure of the spring, it may be moved either to the right or left to position the cam member 166 as desired. When in adjusted position, the spring 192 will force one of the

several notches

182 or 184 into engagement with the plate 188 at the lower end of the slot in this plate, thus locking the cam member 166 in adjusted position. The cam member 166 is located at right angles to the axis X-X when the mid slot 186 is in engagement with the plate 188. The two groups of

slots

182 and 184 are graduated in degrees and when any one these slots is in engagement with the plate 188, the cam member is displaced, either to the right or left, the number of degrees indicated by the graduation.

It will be seen that, when the cam is adjusted with the plate 188 in engagement with the extreme notches (marked the cradle 96 will be moved by the cam slot 164 and cam roll 162 to give the cradle the maximum amount of movement of translation along the axis X-X as the cradle is being swung about such axis. This movement is required for cutters having the maximum length of teeth. Shorter cutters are ground by setting ei her the 16 or 12% notches in the plate 188 according to the requirements of the cutter, as noted by previous experience with individual cutters.

a downwardly Fig. 2 shows a left-hand cutter (so called in accordance with the terminology adopted by manufacturers of milling cutters) in the machine in position to be ground. In this cutter the large end is toward the front and the small end is toward the rear. The machine is shown in this figure positioned to start the grinding at the rear end of the tooth. As the cradle is swung to the rear, by means of the handle 108, the desired movement of translation to the left, to bring finally the front or large end of the cutter into grinding contact with the wheel, is given to the cradle 96 by the cam roll 162 and the cam slot 164 (the plate 188 being. in engagement with one of the series of notches 184). When the grind ing operation on that tooth is completed, the parts assume the position shown in Fig. 3. The position that the cradle 96 assumes at thecompletion of the swing of the cutter about the cutting edge of the tooth being ground is also indicated in dash lines in Fig. Qand similarly, Fig. 11 shows, but on an enlarged scale, the corre sponding positions of the tooth, relatively to the grinding wheel, both at the beginning and at the end of the swing; the beginning being shown in cross section and the end in dash lines.

When grinding a right-hand cutter, the plate 188 is correspondingly in engagement with one of the series of notches 182. A right-hand cutter is shown on the stub shaft 120, with the index plate 116 and locking block 180, in front elevation in Fig. 10, the locking block being in a notch that is symmetrically and oppositely disposed (from the center notch c) from that used for the corresponding left--l1and cutter. In this view, the motor 32 and the grinding wheel 2 have been swung into a position opposite to, but symmetrically related to, the position shown in Fig. 1, so that the opposite end of the plate 54 is in contact with the stop screw 59 at the left of Fi 1.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:-

1. The method of forming a straight cutting edge with a uniform cutting clearance on each of the teeth of a rotary cutter havin skewed peripheral teeth, which consists in impartinggrinding movement to a grinding device arranged to operate on the outer face of a tooth, and relatively moving th cutter and grinding device with a combined motion of rotation about, and of translation along, an axis coinciding with the cutting edge being formed.

. 2. The method of forming a straight cutting edge with a uniform cutting clearance on skewed peripheral tooth of a roary cutter, which consists in operating a grinding device in contact with the outer surface of the tooth and relatively moving the cutter and the grinding device with a combined motion having components of rotation about, and of translation along, an axis coinciding with the cutting edge being formed, the components of which motion are in constant ratio according to the angle of skew of the tooth.

3. A grinding machine comprising a grinding wheel and a work-holder arranged to have con ponents of relative movement angularly about, and at the same time lengthwise of, an axis that crosses and touches the periphery of the grinding wheel, and means arranged to constrain such relative movement so that a predetermined ratio of its components will be maintained.

4. A grinding machine comprising a grinding wheel, a work-carrier provided with means for 5. A grinding machine comprising a grinding wheel and a work-holder arranged to have a component of relative angular movement about, and a component of relative movement lengthwise of, an axis that crosses and touches the periphery of the grinding wheel, and adjustable means arranged to constrain such relative movements and to regulate the ratio of components;

6. A grinding machine comprising a grinding wheel, a carrier provided wi h work-holding means, the carrier being arranged to have a component of angular movement about, and a component of movement lengthwise of, an axis that crosses the periphery of said. grinding Wheel, and adjustable means arranged to constrain the movements of said carrier and to regulate the ratio of said components.

7. A grinding machine comprising a grinding wheel, a carrier provided with work-holding means, the carrier being arranged to have a component of angular movement about, and a component of movement lengthwise of, an axis that crosses the periphery of said grinding wheel,

and means arranged to constrain the movements of said carrier so that a predetermined ratio of its components will be maintained, said constraining means being adjustable to reverse the direction of one of said components relatively to the other component.

8. A grinding machine comprising a wheel having a peripheral grinding face, a work-holder having a stub shaft for the central bore of a rotary toothed cutter to be ground, said work holder being adjustable along a path at rightangles to the axis of said stub shaft, and said work-holder and the grinding wheel being arranged to have a component of relative angular mot-ion about, and a component of relative motion lengthwise of, an axis that crosses and touches said peripheral grinding face, and means arranged to constrain such components of relative motion in accordance with a predetermined ratio.

9. A grinding machine comprising a wheel having a peripheral grinding face, a work-holder having a stub shaft for the central bore of a rotary toothed cutter to be ground, said workholder being adjustable angularly about an axis at right-angles to the axis of said stub shaft, and said work-holder and the grinding wheel being arranged to have a component of relative angular motion about, and a component of relative motion lengthwise of, an axis that crosses and touches said peripheral grinding face, and means arranged to constrain such components of relative motion in accordance with a predetermined ratio.

10. A grinding machine comprising a wheel having a peripheral grinding face, a work-holder having a stub shaft for the central bore of a rotary toothed cutter to be ground, said workholder being adjustable angularly about and lengthwise of an axis at right-angles to the axis of said stub shaft, and said work-holder and the grinding wheel being arranged to have a component of relative angular motion about, and a component of relative motion lengthwise of, an

axis that crosses and touches said peripheral grinding face, and means arranged to constrain such components of relative motion in accordance with a predetermined ratio.

ll. Agrinding machine comprising a grinding wheel and a worl -carrier arranged to have a component of relative angular movement about, and a component of relative movement lengthwise of, an axis that crosses and touches the periphery of'the grinding wheel, a work-holder secured to said work-carrier with provision for angular adjustment about another axis at rightangles to, and intersecting, the first said axis, indexing means arranged to determine two alternative positions of angular adjustment of said worinholder about said other axis oppositely and symmetrically related to said work-carrier, means to adjust said work-holder toward and from the first said axis, and means arranged to constrain relative movement of said workcarrier and said grinding wheel so that a predetermined ratio of said components will be maintained.

12. A grinding machine comprising a grinding wheel and work-carrier arranged to have a component of relative angular movement about, and a component of relative movement lengthwise of, an axis that crosses and touches the pe- 1 riphery of the grinding wheel, said work-carrier being provided with a stub shaft for the central H bore 'of a work-piece such as a rotary toothed cutter, and with provision for adjusting said stub shaft toward and from said axis, means arranged to be engaged by each of the teeth of the cutter successively to locate them uniformly in operative position, and means arranged to constrain relative movement of said work-carrier and said grinding wheel so that a predetermined ratio of said components will be maintained.

13. A grinding machine comprising a pair of fixed coaxial bearings spaced apart, a movable cradle arranged between said bearings and provided with trunnions journaled in them, means carried by said cradle for supporting a rotary toothed cutter so that the front face of a skewed peripheral tooth thereof will lie parallel and coincide with said axis, a grinding wheel the periphery of which is arranged to grind such tooth on said axis, and means arranged to constrain movement of said cradle to include a component of angular movement about, and a com ponent of movement lengthwise of, said axis 14. A grinding machine comprising a cradle arranged to oscillate about, and move lengthwise of, a fixed axis, a grinding wheel the periphery of which is arranged to touch said axis, means car ried by said cradle for supporting a work-piece in positionto be ground adjacent to said axis by the periphery of said wheel, and a gage having an edge coinciding with said axis to locate a face of the work-piece in a position to intersect said axis and to indicate how far the stock to be ground projects beyond said axis.

15. A grinding machine comprising work-can rying means arranged to oscillate about, and move lengthwise of, a fixed axis, a grinding wheel and an adjustable support therefor by which the operating surface of the wheel may be adjusted to touch said axis, and a retractable gage against which the operating surface of said wheel may be adjusted to locate said surface in position to touch said axis.

16. A grinding machine comprising a bearing, acarrier provided with a hollow trunnion journaled in said bearing, work-holding means carried by said carrier and adjustable relatively thereto toward and from the axis of said trunnion, a gage member telescopically mounted in said trunnion and provided with a work-engaging edge that coincides with said axis, and a grinding wheel arranged to operate on a work-piece mounted on said work-holding means, the operating surface of said wheel being arranged to touch said axis.

17. A grinding machine comprising a bearing a carrier provided with a hollow trunnion journaled in said bearing, work-holding means carried by said carrier and arranged to support a workpiece so that the portion to be ground will lie in contiguous relation to the axis of said trunnion, a grinding wheel and an adjustable support it erefor by which the operating surface of the wheel may be adjusted to touch said axis, and a gage against which the operating surface may be adjusted to locate it in position to touch said axis, said gage being telescopically mounted in said trunnion to be movable along said axis to and from its position of use.

18. A grinding machil e comprising a pair of coaxial bearings spaced apart, a cradle arranged between said bearings and provided with hollow trunnions journaled in them, means carried by said cradle for supporting a work-piece between said trunnions, said means being adjustable relatively to said cradle toward and from the axis of said trunnions, a grinding wheel and an adjustable support therefor by which the operating surface of th wheel may be adjusted toward and from said axis, and two gages telescopically mounted in said trunnions respectively, one to indicate a desired relation of the work-piece to said axis and the other to indicate a desired relation of the grinding wheel to said axis.

19. A grinding machine comprising a cradle arranged to swing about an axis, worksholding means carried by said cradle and adjustable relatively thereto toward and from said axis, a grinding Wheel and an adjustable support therefor by which the operating surface of the wheel may be adjusted to touch said axis, and a gage having a work-engaging edge that coincides with said axis, said gage being movable along said axis to carry said edge to and from the grinding locality.

20. A grinding machine comprising a workcarrier arranged to oscillate about an axis and move lengthwise thereof, a grinding wheel the operating surface of which touches said axis, and a stationary cam. arranged to cooperate with an element of said work-carrier to constrain the movements of the latter to include two components, one of angular motion about said axis and the other of motion lengthwise of said axis.

21. A grinding machine comprising a workcarrier arranged to oscillate about an axis'and move lengthwise thereof, a grinding wheel the operating surface of which touches said axis, and a stationary cam arranged to cooperate with an element of said work-carrier to constrain the moveinents of the latter to include two com- LEWIS J. BAZZONI.

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