USRE18246E - edgar - Google Patents

Description

J. EDGAR ART OFjRINDING HOBS 5 Sheets-Sheet 1 Nov. 10, 1931.

Original Filed June 22, 1925 KNVII Y J. EDGAR Ncw. 10, 1931, V ART OF GRINIJING HOBS Re. 18,246- 5 sheets-sheet :3

Original Filed June 22, 1925 J. EDGAR ART OF GRINDING HOBS' 5 Sheets-Sheet 4 Nov. 10; 1931.

Original Filed June 22, 1925' 7 FIG.

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J. EDGAR ART OF GRINDING HOBS Nov. 10, 1931. Re. 18,246

Original Filed June 22. 1925 5 Sheets-Sheet 5 avwenioz Jbhm) Edge/1,

Reiuued Nov. 10, 1931 I Re. 18,246

PATENT OFFICE JOHN EDGAR, OI ROCKFORD, ILLINOIS, ASSIGNOB TO Banana-comm 001mm, ROCKFORD, ILLINOIS,A OORPQRATION OF ILLINOIS ART 0] GBINDIHG HOBS Original application fled lane 28, 1818, Serial llo. 106,888. Divided and this application flied I ene 2!, '1885; Serial No. 38,846. Original Ho. 1,617,198,4ated February 15, 1927; Application for relune flied.

April 20, 1931. Serial 1T0. 581,852.

This invention relates to the manufacture of hobs used in generating spur and spiral gear wheels. After the partially-completed hobs have been hardened, it is necessary to grind the teeth of the hobs to give them correct form and dimensions.

In application Serial No. 106,339, filed June 28, 1916 on which Patent No. 1,561,064

was granted on November 10, 1925, I have disclosed a machine by means of which the teeth of a hob may be quickly and accurately ground to form and size, and the venous ste of the process utilized in thus grinding the hob. The present application is a division of application Serial No. 106,339, and claims said process.

A hob has one or more spiral series of relieved cuttin teeth, the cutting faces of the teeth being efined by gashes which may be either straight (i. e., parallel with the axis of the hob) or spiral. In order that the hob shall have relatlvely long life, the circumferential length of the teeth is made as great as possible, which means that the gashes are relatively narrow-much narrower, proportionately, than in the case of a tap, for instance. Because of the length of the teeth, there is considerable diiference between the height of a tooth at its front end and its height at its rear end, which fact necessitates a relatively long relieving stroke and an abrupt return stroke. Moreover, because of the narrowness of the gashes it is impracticable to grind the two opposite sides of a tooth space at the same time. Before finishing one such tooth space the grinding wheel would engage the next tooth space.

In order to avoid rotating the grinding element at an objectionably high speed and to prevent excessive wear on the grinding element, it is desirable to use an abrasive wheel of relatively large diameter; and in order to obtain clearance between the wheel and each succeeding tooth, it is desirable to mount the wheel so that its periphery may be employed in grinding.

The machine herein disclosed is specially adapted to fulfill the requirements peculiar to the grinding of hobs, straight-gashed as well as spiral-gashed, and to produce accurate work at a relatively fast rate and with a minimum of interruption for dressing the grinding element.

In the accompanying drawings,

Figure 1 is a top plan view of one form of hob grinding machine which may be employed in carrying out my improved process.

Fig. 1' is a fragmental sectional view of the tailstock ofthe machine.

Fig. 1 illustrates the position of the grindin wheel with relation to the hob.

Fig. 2 is a sectional view of the connection between the hob slide and the feed screw for moving said slide, the view being taken in the plane of dotted line 22 of Fig. 5.

Fig. 3 is a fragmental side elevation of the machine.

Fig 4 is a section taken in the plane of dotted line 4 of Fig. 1.

Fig. 5 is a section taken in the plane of dotted line 5 of Fig. 1.

Fig. 5 is a view of a clamp for the wheelcarrying head.

Fig. 6 is a section on dotted line 6 of Fig 1.

ig. ,7 is a horizontal central sectional view of the hob-supporting means.

Fig. 8 is a view looking from the lefthand end of Fig. 3.

Fi 9 is a sectional view of the means for rotating the hob.

Fig. 10 is a view of the means for indexing a plural-thread hob.

Fig. 11 is a section on dotted line 11 of Fig. 4.

ig. Fig. 4.

Fig.

Fig. 4.

ig. 14 is a section on dotted line 14 of Fi 1. Fig. Fig. 5.

Referring to the top plan view entitled Fig. 1: A indicates a hob and B a grinding wheel. In operation, the grinding wheel B is rotated at high speed. The hob A is slowly rotated in the opposite direction and is also given a movement of translation past the grinding wheel, the rotation and movement 12 is a section on dotted line 120i 13 is a section on dotted line 13 of 15 is a section on dotted line 15 of of translation of the hob being so proportioned to each other that one side of the thread (or more accuratel speaking, the spiral series of relieved teet 1) of the hob is presented to the grinding wheel. After the hob has been fed past the grinding wheel, the hob is returned to initia position and adjusted with relation to the grinding wheel so that the latter shall be able to remove more material. The hob is then rotated and fed past the grinding wheel as before. These operations are re eated until one side of the thread of the ob has been completely ground. The head that carries the rinding wheel is then reversed so as to p ace the grinding wheel in position to ind the other side of the thread of the ho The hob is then fed past the grindin wheel the desired number of times until the ast mentioned side of the thread has been properly ground.

A slide 1, upon which the hob is supported, is mounted upon two guides 2 and 3 (Fig. 5) formed upon the bed of the machine. pon theslide 1 is a headstock 4 and a tailstoc 5, the latter being adjustable toward and away from the headstock upon a guide 6. The tailstock is secured to the slide 1 in adjusted position by means of a bolt 7 (Fi 1) extendi through thetailstock, the ead of said b0 1 'ng a T-slot 8 in the slide. A spindl: 3 and 7) is rotatably supongitudinal movement in said headstock by means of a flange 10 and a collar 11. The spindle 9 is made tubular to permit of inserting and removing the support or arbor 12 that carries the hob. The arbor 12 has a tapered portion adapted to be driven into a correspondingly-tapered socket inthe end of the spindle 9. The s indle being tubular, as shown in Figs. 7 an 9, a rod may be inserted into the other end of the spindle for the purpose of driving out the arbor 12 when necessary. The hob is secured upon the arbor between an annular shoulder 13 and a nut 14,

and is further held against rotation with relation' to the arbor by means of a key 15. The end of the arbor opposite to the tapered end is provided with a center 16 arranged to be rotatably supported by a sleeve 17 carried by the tailstock 5. Said sleeve is held against rotation by means of a key 18 and is arranged to be moved into and out of operative relation to the center 16 by means of a. screw 19 having an operating hand wheel 20. Clamp members 17" (Fig. 1) and a screw 17 provide means for securely locking the sleeve 17 against movement.

The means for rotating the spindle 9 comprises a sleeve 21 (Fig. 9) rotatably mounted in bearings 22 and 23 in the supporting framework of the machine. The spindle 9 is slidable longitudinally of the sleeve 21, but is caused to rotate with the sleeve by means of a spline 24 (Fig. 9) connected to the 9 (Fi 1 me in the iluismck 4 and is held against sleeve and lying Wltlllll a keywayw 25 in the s indle. By means to be later described, the s eeve'21 is adjustably connected to a gear wheel 26 that meshes with a pinion 27 (Fi 1) fixed on the drive shaft 28. On said shaft is secured a stepped pulley 29. Said pulley is driven from a reversible countershaft (not shown) or other suitable source of power.

The means for feeding the slide 1 comprises a feed screw 30 (Figs. 4 and 5) sup- )orted in a bearing 31 in the machine frame. igid with the slide 1 are two downwardly extending lugs 32 (Figs. 2 and 5). A bearing 33 lies between these In S and has flanges 34 to cause the lugs and bearing to travel together. Rotatablv mounted in the bearing 33 is a. nut 35, sai endwise movement with relation to the hearing 33 by means of a shoulder 36 and a nut 37. The nut is threaded upon a nut 38 on the feed screw 30. The nut 38 is prevented from rotating with relation to the bearing 33 by means of an arm 39 which is rigid with said nut, said arm having an opening through which a pin 40 is slidable (see Fig. 4), said pin bein fixed in-the bearing 33 and extending on 'tudinally of the feed screw 30. When the eed screw 30 is rotated, the nut 38 will be caused to move longitudinally of said feed screw, the nut 38 carrying with it the nut 35, the bearing 33 and the lugs 32, and thus imparting movement to the slide 1.

- In ordert with relation to the nut 38 I rovide a shaft 41 rotatably supported in t e slide 1 and having upon its lower end spiral gear teeth 42 meshing with similar teeth 43 formed upon the nut 35. The upper endof the shaft 41 is uared to receive a crank. Fixed to thesha 41 is a micrometer dial 44 arranged to coact with a zero mark on the adjacent portion of the slide. After the wheel B has made a cut and the slide 1 has been returned, the slide may be adjusted by means of the shaft 41 to permit the grinding wheel B to make another cut on the same side of the thread of the hob.

The feed screw 30 is arranged to be -rotated by power means for advancing the hob with relation to the grinding wheel and is also arranged to be rotated by manually actu ated means for the purpose of returning the slide 1 to initial position. Said manually actuated means comprises a shaft 45 (Figs. 1, 3 and 4), said shaft being connected to the feed screw 30 by means of spiral gears 46 and the outer end of said shaft being squared to receive a crank.

The power means for rotating the feed screw 30 comprises a clutch shaft 47 (Fig. 4) alined with and supporting one end of the feed screw 30 and having a clutch face 48 arranged to be engaged by a clutch member 49 which is slidable longitudinally of the feed screw 30. The feed screw 30 and the at the slide l shall be adjustable nut being held against clutch member are caused to rotate together by means of a key Fig. '11). The clutch member 49 is arrang to be slid longitudinally of the feed screw 30 by means of a fork 5'1 engaging said clutch member and fixed upon a rock shaft 52. Upon the outer end of the rock shaft 52 is fixed a hand crank 53 (Fig. 3). After the clutch member 49 has been disengaged from the clutch shaft 47, the shaft- 45 may be rotated to adjust the slide 1 to place the hob in apfproximately operative relation to the grin ing wheel. Fixed to the clutch shaft 47 is a change-gear 54 (Figs. 4 and 8) meshing with a changegear 55 the latter gear is rigid with a changegear that meshes with a change-gear 56; the change-gear 56 is rigid with a gear 57 that meshes with a ear 58 which is rigid. with the ear 26; the latter, it will be remembered, meshes with a pinion 27 on the drive shaft 28.

A hob may have one or a plurality of threads. After one thread of a multiplethread hob has been ground, it is necessary to turn the hob to bring another thread into position to be ground. For this purpose the spindle 9 is adjustably connected to the gear wheel 26. Rigid with the sleeve 21 is a flange or disk 59. A ring 60 is adjustably secured to the disk 59 by means of bolts 61 extending through the disk 59 and, having heads that lie within circular undercut slots 62 in the ring 60. The ring 60 is adjustably secured to the gear wheel 26 by similar clamp bolts 63.- For setting the ring 60 with relation to the gear wheel 26 there is provided a spring-pressed index pin 64 carried by the gear wheel 26 and arranged to enter anyone of a number of openings in the ring 60. Vhen one thread of a double-thread hob has been ground, the clamp bolts 63 are loosened, the index pin 64 drawn back and the ring 60 turned through one-half of a revolution, thus bringing an opening 65 into register with the index pin 64. which latter is then permitted to spring into said opening. In the case of a triple-thread hob the operator would turn the ring 60 with relation to the gear wheel 26 through one-third of a revolution, thus bringing an opening 65 into register with the index pin 64. For thus turning the ring 60, a bar (not shown) would be inserted in openings 21 (Fig. 9) in a collar on the sleeve 21. Any desired number or arrangement of openings 65 may be provided to take care of hobs having various numbers of threads. In order that the spindle 9 may be adjusted for hobs having a number of threads not provided for by the spacing of the openings 65,, the disk 59 and the ring 60 are adj ustably connected together as hereinbefore stated. A graduated ring 66 is rotatablv mounted upon the periphery of the disk 59 and is secured thereto in adjusted position by means of a clamp bolt 67. On the ring 60 is a vernier 68. Normally the zero 'line on the ring 66 is opposite the zero line of the vernier 68. After one thread of a hob I having such special number of threads has been ground, the hob is turned to bring the next thread into position to be acted upon by the wheel B by loosening the clamp bolt 61 and turning the disk 59 with reference to the vernier 68 through an arc of the neces flange 59 and the ring 60 affords means for conveniently setting the hob with relation to the relieving cam 71 so that as the hob rotates the grinding wheel shall be moved outwardly in time to begin operation on each succeeding tooth.

The grinding wheel B is carried by a slide.

69 (Figs. 1 and .5) which is reciprocable at right angles to the direction of movement of the slide 1. As shown in Fig. 5, the teeth of the hob A are relieved with a uniform clearance. As a tooth revolves past the wheel B, the slide 69 is moved toward the slide 1 to maintain the wheel in proper relation to the tooth. As soon as the tooth has passed the wheel the slide 69 is given a nick outward movement to place the wheel B in position to grind the next succeeding tooth. The means for thus reciprocating the slide 69 comprises a shaft 70 (Figs. 1, 3 and 5) carrying a cam 71 arranged to operate against a block 72 upon the slide 69. As shown in Fig. 14 the shaft 70 is made in two sections connected by the one-way clutch 73 shown in Fig. 13. in order that the cam 71 shall not interfere with reverse movement of the rest of the machine. when it is desirable to turn the drive shaft 28 backward in adjusting the relation of the hob to the grinding wheel. The shaft 70 is driven from the drive shaft 28 tl'rrough change gears 74, 75 and 76 (Fig. 8)..

The slide 69 is moved away from the hob by means of a coiled compression spring 77 (Fig. 5) which bears at one end against a stationary post 7 8 and is adjustably connected at its other end to a lug 79 on the slide 69. A rod 80 fixed to the post 78 and extending freely through the lug 79 carries a nut 81 which may be turned up against the lug 79 for the purpose of forcing the slide 69 away from the cam 71, when another cam is to be substituted.

Upon the slide 69 is mounted a slide 82 for movement parallel with the direction of movement of the slide 69. When the machine is running the slide 82 is stationary with relation to the slide 69, but means is provided whereby the slide 82 may be moved toward and away from the hub when the machine is being adjusted. Referring to Fig. 5: A bar 83 is fixed to a lug 84 on theslide 69. On the bar 83 is slidably and rotatably mounted an adjusting screw 85 having holes 85 to 5 receive an implement for turning the screw.

The screw is slidably and rotatably supported in a guide 86 on the slide 69. A coiled compression sprin 87 surrounding the bar 83 bears at one en against the lug 84 and at its other end against a portion of the screw 85. The s ring 87 is restrained by a hand lever 88 1g. 1) which is pivoted to the outer end of the bar 83, said hand lever havin a cam rtion 89- that bears against a was er whicli in turn lies in contact with the screw 1 85. A detent 88 yieldingly locks the handle 7 frame 93 (Fi'g.'15.) provided with trunnions 94 which are mounted for oscillation in a bearing 95 on the slide 82 and in' a bushing 96 carried by a portion 97 of the slide 82. It will be observed that the bearing 95 and portion 97 of the slide together constitute a tool post in which the tool-carrying frame 93 is pivoted upon an axis a (Figs. 1" and 15) intersecting the axis 6 of the hob at a right angle. When grindin the hob the point of intersection c of the pitch line (I and the line of contact of the hob and the grinding wheel is in the axis a of the trunnions 94. The frame 93 is arranged to be held against swinging movement by means of a screw 98 engaging a threaded opening 99 in said frame and adapted to extend through either of two diametrically opposite curved slots 100 in the slide portion 97. When dressing a grinding ,wheel that is to be used in grinding the into either one of two openin teeth of a spirall gashed hob, the frame 93 should be secure in the horizontal plane of the spindle 9, and for this purpose I provide a positioning pin 101 adapted to be inserted 102 provided at diametrically opposite points in the portion 97 The pin 101 is adapted to enter a hole 103 in the frame 93. The pin 101 is used only in setting the frame 93 preparatory to dressing the grinding wheel, and at other times is withdrawn from the openings 102 and 103.

For setting the frame 93 at an angle corresponding to the angle of the thread of the hob, I provide a protractor ring 104 (Figs. 1, 5 and 15) rotatably mounted upon the bushing 96 and arranged to be clamped to the portion 97 by means of bolts 105 extendin through t e portion 97 and having hea s while the aw 113 is arranged lying in an annular T-slot 106 in the'protractor ring. At diametrically op osite points on the protractor ring are formed notches 107 to receive a spring-pressed detent pin 108 carried by the frame 93. For withdrawing the pin 108 from engagement with a notch 107, there is provided a pinion 109 arranged to engage rack teeth formed on the pin 108. The upper end of the pinion 109 is adapted to be engaged by a key 110.

The protractor ring 104 is provided with graduations as shown in Fig. 1, and the portion 97 is provided with a cooperating zero mark.

The inding wheel spindle is carried by a power ead 111 which is mounted in a clam on the frame 93. The construction of the clamp will be apparent from Fig. 5. The jaw 112 of the clamp'is relatively stationary, to be drawn toward the aw 112 by means of a bolt 114 and nut 115 so as to clamp the head 111 rigidly to theframe 93. The clamp jaw 113 is loosely secured to the frame 93 by means of two screws 116 (Fig. 15). After the nut 115 has been loosened, the head 111 ma he slid back and forth with relation to the ame 93 by operating nuts 117 on a screw stud 118 fixed to the frame 93, said nuts lying at opposite sides of a lug1119 on the head 111.

The grinding w eel B is removably secured in any usual or suitable wayl to a spindle 120 (Fig. 15 the axis of whic intersects the axis of the ame 93. Said 8 indie has a tapered rtion which lies wit in a corresponding y-ta red bushing 111, the spind e being ur forward against said bushing by means 0 a coiled spring 122. Fixed to the spindle 120 is a r wheel 123 that meshed with a gearwhee 124 on a shaft 125 arranged parallel to the spindle and carried by the head 111. Rigid with the shaft 125 is a bevel gear wheel 126 that meshes with crown gear teeth formed upon one side of a flanged driving pulley 127, said pulley being rotatably mounted upon a stud 128 fixed to the head 111. The pulley 127 receives a belt 129 extending from a counter-shaft or other suitable source of power.

While the sequence of operations in making the several adjustments may be varied, the operation of grinding a single-thread hob may be described, in general as follows: The handle 88 (Fig. 1) is operated to allow the "spring 87 (Fig. 5) to move the slide 82 outwar The frame 93 is adjusted, with the aid of the protractor ring 104, to the proper inclination with reference to the angle of the thread of the hob (see Fig. 3), the frame 93 being secured in adjusted position by means of the screw 98. The tailstock 5 is slid away from the headstock 4. The arbor 12 is inserted into-the tapered end of the spindle 9. The hob is placed on said arbor and secured thereto by means of the nut 14. The tailstock 121 in the-head is slid u to place the end of the sleeve 17' st e center 16. The nut on the bolt? is tightened up to clamp the tailstock m place. The hand knob 20 is turned to rose the sleeve 17 against the center 16 an' the sleeve is locked in adjusted position by means of the clamp 17. The .clutch 49 being in the thrown-out position, the shaft 45 is rotated manually until the side of the forward end of the thread is near the workin portion of the grinding wheel B, after whic the clutch 49 is thrown in. The handle 88 is then turned to advance the wheel B toward the hob The flange 59 is then adjusted with rclationto the ring 60 until the hob is in proper relatlon to the cam 71. The machine is then in operation, whereby'the wheel B is rapldly rotated, the slide 1 slowly advanced, and the s indle 9 slowly rotated. By means of the shaft 41 the operator accelerates the feed movement of the slide '1 until the grinding wheel is making a proper cut. After the hob has been fed past the grinding wheel B the machine is stopped, said wheel is withdrawn by operating t e handle 88, and the slide 1 is returned to initial position by reversing the drive for the pulley 29. After the slide has been returned to initial position, the machine is stopped, the wheel B is returned to working position by means of the hand-lever 88, and the machine again set in operation to feed the hob past the grinding wheel. The operator turns the shaft 41 so as to advance the slide 1 sufiiciently to enable the wheel B to make a second cut of proper depth.

After one side of the thread has been completely ground, the machine is stopped, the clutch 49 thrown out, the wheel B retracted by means of the lever 88, the slide 1 returned by means of the shaft 45, and the clutch 49 thrown in. The screw 98 (Fig. 15) is withdrawn; the detent pin 108 is removed from the notch 107 with which it is in engagement; the frame 93 is swung through an arc of 180 degrees until the detent pin 108 springs into the other notch 107; the screw 98 is inserted into the other slot 100 and into the hole 99 and tightened to secure the frame 93 rigidly in place. The belt 129 is then removed from the pulley 127 and twisted and replaced. The wheel B is then moved forward into grinding position. The slide 1 is then adjusted to move the hob longitudinally, a distance aproximately one half the circular pitch of the hob so as to bring the unground side of the thread into approximate position to be ground. The machine is started up and the shaft 41 is turned until the wheel is making a proper cut. After the second side of the thread has been made smooth, the operator employs at intervals a suitable gage in order to ascertain when the hob has been completely ground. The form of gage herein shown comprises a gage member 130 (Figs. 1 and 5) mounted for sliding movement toward ban and away 'from the hob in a carrier 131, said carrier slidable lon 'tudinally of the hob on a guide bar-132. he bar 132 is removably and stationarily upon two supported posts 133 on the slide 1. e ga gis, of course, done when the machine isi le.

In grinding a multiple-thread hob the spindle9 is indexed or turned with relation to the gear wheel'26 after each thread has been completely ground. A suitable gage (not shown) would be applied by the operator to determine; when the grinding of a thread has been completed.

Suitable modifications are made in the change-gear train 54, 55, 56 in accordance Kigh changes in the number of threads of the As shown, the machine is arranged to grind a ri ht-hand hob. To operate upon a leftshown) would be provided in t 0 gear train 54, 55, 56 so as to reverse the direction of feed movement of the slide 1.

Changes in the gear train 74, 7 5 and76 are made as required by the number of flutes or gashes in the hob to be ound, and when changing from a hob having straight flutes to one having spiral flutes or vice versa. Variations in the amount of relief of the teeth of the hobs operated upon are taken care of by changes in the shape of the cam 71.

A decrease in the diameter of the wheel B, due to wear and dressing, is adjusted for by advancin the slide 82 with relation to the slide 69 y turning the screw 85, and by ritzracting the head 111 by adjusting the nuts 1 As hereinbefore stated, the grinding wheel should be so positioned with relation to the hob that there shall be clearance between the wheel and the approaching hob tooth. This result has been attained by mounting the grinding wheel spindle in a manner which, for the sake of clearness, may be described by sayin that the spindle is at an oblique angle to t e hob axis when the spindle is in the horizontal plane of the hob axis. In the present instance, said angle is about 25. Because of this oblique mounting, it will be understood that the periphery of the wheel curves away from the approaching tooth and thus permits of grinding a relatively long surface on the side of each tooth, whereby I am enabled to produce a ground relieved hob which can be resharpened a relatively large. number of times without change of form or dimensions.

I claim as my invention:

1. The method of grindin a hob having a spiral series of relieved teet which includes the steps of positioning a grinding wheel with its axis of rotation in a plane normal to the hob helixyrotating the wheel and the hob and effecting relative reciprocation between the wheel and the hob to effect the hob an additional chan e gear (not grinding of one sideof each of said relieved teeth; reversing the position of the wheel to a cause the latter to assume a' position 180 re moved from the first position, the axis on which such reversal occurs'bein perpendic- I ular to the axis of the hob an parallel to r the plane of reciprocation; said axis of reversal intersecting the line of contact between-the grinding wheel and the hob at the 10 pitchlineof the hob moving the hob axiall a proximately one alf the circular pitc o the hob to bring the other side ofthe spiral series of teeth into position to be ground; and rotating the wheel and the hob and efiectin relative reciprocation between the wheel an the hob to efiect-the grinding of theother side of each of said relieved teeth.

2. The method of grindin a hob having a s iral series of relieved tee which includes .10 t e steps of positioning a grinding wheel with its axis of rotation in a plane normal to the hob helix and at an oblique angle to the hob axis, rotating the wheel and the hob and efiecting relative reciprocation between the wheel and the hob to efi'ect the grinding of one side of each of said relieveduteeth by a. certain surface of the wheel, changing the position of the wheel so that it occu ies a position about 180 removed from the rst position, efiectin relative adjustment between the hob and t e wheel axially of the hob to. place said surface of the wheel and the other side of the spiral series of teeth in o rative relation to each other, and rotating t e wheel and the hob and efiecting relative reciprocation between the wheel and the hob to efiect the grinding of the other side of each of said relieved teeth.

In testimony whereof, I have hereunto af 40 fixed my signature.

JOHN EDGAR.

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