US1667064A

US1667064A - Grinding machine

Info

Publication number: US1667064A
Application number: US70517A
Authority: US
Inventors: Yerkey Henry
Original assignee: Individual
Current assignee: Individual
Priority date: 1925-11-21
Filing date: 1925-11-21
Publication date: 1928-04-24
Anticipated expiration: 1945-04-24

Description

April 24, 1928. 1,667,064

H. YERKEY GRINDING' MACHINE Filed NOV- 21. 1925 7 Sheets-Sheet' 1 attenta? Aprl 24, 192s.

` H. YERKEY GRINDING- MACHINE Filed NO'V.

2l, 1925 7 Sheets-*Sheet 2 atto/mutt April 24, 192s. 1,667,064

H. YERKEY v GRINDING MACHINE Filed Nov. 21, 1925 7 Sheets-Sheet 3 f6 M a H. YERKEY GRINDING MACHINE Filed Nov. 21.. 1925 7 Sheets-Sheet 4 @5 Z7 45 :o 3f az 1 40 4/ 271@ im L 5 :a 27` I; "3 u Jy .76 6 3/34 o o i, a 206 44 s n zw zu '7 z 55 J ,L 204 a' n',

zo: a3 J7 as M J ,a 5 b 7 y fi, 20m [o] 455 20? 8 2W fgf 4 4My 474 Y f 5 4oz l'. m40 241' 46 A i" l L 1w j?" Afa, 7 07 W ff if) il 46 ZJ l mwwto mrylrhy April24, 192.8.

' H. YERKEY GRINDING MACHINE Filed NOV- 21. 1.925

gnomo@ Gary )iwi-zy 7 Sheets-Sheet 5 April 24,1928. .1,661,064

H. YERKEY QRINDING MACHINE Filed Nov. 21. 1925 v sheets-sheet 7 f respective grinding elements.

Patented Apr. l24, 1928.

' u Nirauffs T nENRYp-YEBKEY, .or VIOLA, ILLINoIsQ GRINDING. MACHINE.

Applicationniea November 21', 192s. Vaerial No.7 ,5 17.

This invention i'elatesjto. a grinding maf" chine primarily adapted foi-..u'se in sharlviening the blades of lawn mower i'eels andtlieir associated ledger bars.

One object is to provide a inachinefotthis character inr which the reel and-ledger bars are sharpened so Vas to align and-coact tothe l.;

maximum extentA when reassembled into the mower. l Y

A prime aim, is toprovide a machiner wherein the reel will be kshifted automati-`V cally so that its blades will be successively sharpened' without the intervention of an` opeiator. l i Another object-'is to produce. a machine having a grinding head equipped f with grinding elements special to a reel and ledger bar in combination with a carriage and op:

erating means common vto said reel and ledger bar, vadapted to selectively carry and position themin operative relation tov their A- third ob'ect is to devise a machine of this character having a column mounting;

the grinding elements and a. means slidably and rotatablyassociated with the column'to u D r view of the right-hand partsof Fig.` 8;

Fig. 14 is a `-detailperspective view illuscarry and position the work.

A further aim, is to so the reel or ledgar bar in operative position.

A fifth object is to produce Va machineof the present character wherein thev reel is subject to turn in a clockwise direction to keep its blades in engagement with the grind-l ing element and tofcoact with escapemeut means whereby the reel may shift for grinding of its blades successively in combination',

- specification proceeds, the invention resides in the many combinations and arrangements of parts and in the details of construction described and claimed. An operative embodiment is illust-rated in the accompanying drawings, wherein y Fig. 1 is a viewvof the machine infront elevation showing a' lawn mower-reel in posi- 7 of inotor M,.so that the motormay drive said lower line shaft 15. DirectlyA above and yparallel to the line shaft 15, is an upper line tion for sharpening; y A. Fig. 2 is a view ot the machine' in side .elevation in the condition of-Fig. 1;

'eniiig position ,l

form the Aworksupporting means that it may secure eitherv Fig. 3 is a planyiewiof the-machine inthe condition of Fig. 1; Y

broken away, having vadedger bar in sharpl Fg. 5 is an enlarged- .icentral verticalsection,v through the iniachinc taken on vthe line ii-e5 yof Fig; f'

.--, Fig. v6 is af fragmentary isideIelevationl'l showing the tool headand rest and escapement-means .for the reel-to bey sharpened;

Fig 7 is a sectionallview "taken onfthe line Fig. i8 is a, viewl primarily -inplai1v, .butv vpartly in section vand broken away, ,il`li1strat Y ingY thelfwork carriage and its loperating Fig. 10 is a detail longitudinal v'sectional view takenon the line'lOl-l() of Fig. 8;

Fig-$11 .is ya sectionalvv view takenv on the line11-11of Fig.8; i

Fig. 12 is a detaiisectionai View. akenfoa the line 12-12 of Fig. 3;

Fig.- 13` is a jfragmentary *inverted plan ltratingthe conneetionbetween the reversing vbar and associated'fleve'r;

' Fig. lois a perspective view of the escapement stop m'echanisinforgthe.reel ;y and Fig. 16 is a plan view of lthe saidescapementfstop mechanism for. the-reel.'y f I generally designat'esa- 'supporting stand f or base. 'Stand 9V is composed, for instance, oi

two. castings 1702 ofthe fo'rm'shown in Fig; 2,

each vhaving two/'legs 11 joined b v a bridge -lZadjacent the bottom. The castings 10 are v connected -togetherfbyfdetachable; bars or vbraces as at 13. Said castings' 10 are surmounted by a plate l4'bolted .oiuother'wise' which a belt `17 is trained and lwhich also passes over a pulley 18 onthe main shaft 19 55. Fig. 4 is a plan view ofthe machine, partly 'roy ' Referring. specificallytn tliedi'aivlings, 9 Y

shaft 20 which is journaled in the castings .1() and held against displacement by thrust collars 20a.

pulleys

21 and 22 respectively keyed there- The shafts and 2O have to, which are traversed by a belt 23 so that the upper line shaft may be driven from the lower line shaft 15.',

A hollow column or standard 24 rests on the plate 14 and has an outwardly extending base flange 25 through which bolts 26 pass in order to detachably fasten it to the plate.

A toolhead or grinding'head supported at the top` of the column 24 is generally indicated at27. y 1

The tooZ-or gni/lading heeft.k y

Referring to said tool head 27 (see Fig.

`5), two sleeve bearingsor the equivalent 28 are fitted into the` upper end of column 24 in transverse alignment and journa-led therein is a spindle 29. lSpindle 29 at one end, exteriorly of the column 24, has an outwardly extending flange 30, andan exteriorly `screv'v-t'hreaded stud 31 extends outwardly,

beyond the flange. A sharpening' tool such as an emery wheel 32 is slipped over the stud 31 and against the flange 30 and,y

@Another sharpening tool, such as an emery the tool or cutting edges of the helical blades ay of a reel such as is used in a lawn mower and shown-conventionally at A (Figs. 1 and wheel 35, is provided onY the outside of column 2li/opposite to einery Wheel 32 designed to `grind the .straight cutting edge b of a. ledger bar B so 'that `the same machine, by reason of the provision of

grinders

32 and 35 may sharpen the reel andledger bar of the same lawn mower.

As willlater appear more in detail, parts of the machine are laterally shiftable in the path of 90o according to the use of the machine in sharpening the reel A or ledger bar B, Aand in order to minimize adjustment of` the parts in view of this feature emery wheel 35-is of less diameter than emery wheel 32.

A mandrel 36 carries emery wheel 35 to which end it has a-flange 37, against which wheel 35 abuts,` and a screw stud 38 over which whee'l35 is slipped. A nut 39 is threaded to the stud 38 to clamp thewheel 35 in placer. Ma-ndrel 36 has a tapered portion 40 which removably and snugly lits a tapered recess 41 in one end of the spindle 29. Spindle 29 also has a longitudinal bore oc- 1 cupied by a removable bolt or rod 42 having a screw-threaded end 43 engaging a Vscrewthreade'd opening of the tapered portion 40.

-A knurled' manipulating knob 44 is formed plate 14.

rod 6 0 and bears against the outer surface of one of the castings 10. A 'conventionab on the bolt 42. By reason of the construction described, the mandrel 36 is efficiently fastened to be readily removable from the spindle 29 so that the emery wheel 35 may be removed or replaced.

Spindle 29 is adapted to be rotated so as to impart rotation to the grinding

wheels

32 and 35. To this end, a pulley 45 is applied to the spindle 29 and a drive belt 46 is trained thereover. Said drive belt 46 isvervtically disposed substantially centrally of Mounting for the work carriage.

A collar 51 surrounds and is vertically slidable or adjustable on the column 24. On the collar 51, through the' instrumentality of parts to be later described, the work to be ground by the wheels 32 and l35, namely reel A and ledger bar'B, are selectively supported and operated. At diametrically opposite positions, columnv 24 has vertically elongatedv slots 52 through which the ends of a vertically movable bracket 53 extends. l Braeket 53 projects outwardly beyond the column at opposite ends into an inner annular' groove 54 of the collar 51, in order to carry and support the latter. Entrance ofthe. ends of bracket 53 into groove'54 iseffected through the medium of diametrically opposite longitudinal entrance grooves 55 provided in the inner surface of collar 51.

' Said bracket 53 has "a cent-ral vertical opening 53"l (Fig. 5) provided with screwthreads in mesh with thefthreads of avertcally disposed adjusting screw rod 56 which is journaled ata plain portion thereof in an opening at the center of the plate 14. A thrust collar 57 is fastened to the screw rod 56 and rests on top of the plate 14 while a bevel gearwheel 58 is fastened to the screw rod 56 and disposed below the plate -14 with its upper edge in contact therewith. .Gear Wheel 58 meshes with a bevel gear wheel 59 carried by an operating shaft 60 journaled in one. of thecastings 10 and in a bearing lug 61 integral with andv depending from A thrust collar 62 is fastened to manipulating' crank 63 is fastened to the outer end of shaft or rod 60. Thus it will be seen that through the operation of crank 63, shaft 60 will be rotated to turn screw- IUI) lia)

through by means of kwhich the 86 and associated parts in the opposite dvi-K' rection until the iinger 149 strikes the other lug 142 andthereby changes the direction of y y ing spindle'173'is 'a coil Spring 180 which has one'termin'al 181detachably fastened to movement ot' the carriage to that first-inentioned. In thisv way the carriage and' work thereon have a reciprocatory vmotion"i relative to the grinding lwheels A32 andi andthe 'changing ot the direction otinove-KA ment is automatic. Y

Work .su'ppmti'n-g/ bm' and bmc-7cets.Y

Reverting to the crossfvit'eedj'late 75, itfv has a screw stud 151 thereon 'which passes through an opening 152 of a work-supporting bar 153 (Figs. 1,10 and A nut 151i vonstud Y1511'emovably clamps the bar, `153 in place. i

Said bar .153 alSoengages rest-s 155 integral with carriage 1.

adjusting screws' 157v adapted to bear against one side 4 secure it and thejwork in parallelism to the grindingsurface, since the` bar 153,'.while nut 155 is loose, may swing'fhorizontally on the axis'ofstud 151. 5

Two work-'supporting Each `bracket '158 consists rof an uprightpost 159i havino' 'a transverse .o "eninwuthereslidable on bar 153. '.Setscrews 160 carried bythe posts 159 bind'them in adjusted posi` tions on the bar. Integral with the posts 159 are `otlset bearing arms 161 and vertical screw rods ,162.. Plates 163 are 'slidably disposed on rods 162 and held in placeby vnuts 16er.l form two vpairs of bearings whichjournal the trunnions' otshattends c 'of the reel A while positioned in the machine. distal end portions of the

arms

161 and 165 are notched or otherwise shaped at 166 vto hold the trunnions a" against lateral dis? placement.

' `The reel turner.

AV supporting" an lopening 169 in. oneot the applicable in 12). The opposite posts 159 (Figs. land end portion 17() has a'collar 171 removably and rigidly fastened thereto. VA tube Kor casing '-172' is clamped stationary in -collar Rigid on spindle 173 is '@ehdgl I bearing for casing? In turn an end ring 176 is rigidly.

stepped at 175 to form al 172. fastened within and tothe casing by a screw 177, and journaled on spindle 173. Casing 172 is held 'against displacement from 156 integral with the cross feed plate'inount ot' thebar 153 to rigidity it and hole7 one or more offwhich` are `always pro-v bmkas 15s (Figs) 1 and 2) are adjustably mounted on bar 153. f

bracket is Y plates 1877 N Each; plate163 hasa lateralbearing arnr165. r1`he adjacent arms 161 and 165.`

The

rod "167 generally of Z-shape has one end p ortion168 removably outer Vendotsaid spindle andpinned thereto y at179'. f

Located within casing 172 Vand surround' J endring l74gand the other' terminal' 182i v detachably' secured to end ring 176. Theref` tore 'spindlef173 maybe turnedin casing 172 to windj'or tension spring 180, in orderfto turn and position the reel bladesfar* properly/,with respectto kgrinding wheel 32 yma manner to be laterfdetailed. f

Detacliablv fastened onthe inner-'end of' A' spindle 173v`by a set sc1ew f181 aftubularchuck 182. Said'chuck A receives in one so.v

end thereof, one of the trunnions cfof the reel A andthe latter is Coupled 'for' turning-r inovementwiththe spindle by 'aset screw orpin 183` passed removablythrough`- an it elongated slot 1840i' the chuck 'and'entering i an opening 185 :in the last-mentionedv trunnion c. Said opening v185-d0e's`rf1ot haveto be speciallydrilled since it malylbe a screw vided in the reel trunnions as necessary to f accoinm'odateffastening -of 'the parts which'Vv mount the lreel in a lawn mower.` 'VVithi/the yz spring 180. l Y y Reel grinder guard. f Integral with the column24 above bracket 102is a stepped lugz186'to which guard, disposed on opposite sides of. grinding wheel 32 are' secured by a bolt 188- passing through slots' 189 thereof; Saidy plates '187 'fhave'enlarged openings 190 `accoinniodatingv iiange 30 and 'nut 31. Also' fastened in place by vsaid 'bolt 188andtween the plates -187 isA Ea bracket 191. Bracket 191 has a slot 192'` accommodating said bolt 188 and the slots 189.and 192 are enlarged to permit adjustment of the plates y and brackets relative -to grinding-"wheel 35 as vbecomes advisable incidental to wear..r thereof. Said bracket 191v and plates 187 have Vstraight lower 'edges y193 indirect conmet wittfthe Steprofiug 18e :1t-194 (Fig. 7) f so that such parts cannot'turn on and are rigidly secured in place by the single boltk 188 A bolt or pin 195,'1na 'valsov pass` through `the bracket '191' and plates-187 to; supplement. the fastening of these parts to each other. f .Y y Reet escape/ment nchten-isla. t 'y Said bracket 191 has av forward upwardly. curved yend portion 196'which has apreer--- ably triangular' guide `and rest plate 197 for'the reelr blades a bolted to said portion'. 196 as 'at`1.98. The base of said triangularplate 197 is horizontal so as to have in4 clined 'or cam edges 197al and=197bk and the llo .` i 1e i are r 1. iates rc a J v c os, apex o1 tl 1l t te n 11 t l tivtlU l e vto the horizontal plane passing through the axis of spindle 29. Said plate 197 is preterably slightly inclined upwardly toward grinding wheel 32 and is Vrshaped or dished in horizontal section with the concavity tacing away from said grinding wheel 32.

A rod or shaft 199 removably passes 1 through plates 187 and end portion 196 and frames 204 and 205 have

plates

206 and 207 blades wot' the reel at cam edges 206?, 207"L and 208a respectively in connection with' the turning and lescapement of the latter incidental to grinding. v

-A wire spring 209 of appropriate shape passes through the bracket 191 and plates 187, abuts rod 199 and has its terminals entered in the

frames

202 and 203. An abutment rod'or member, 210 is carried by the said bracket 191 and plates 187 and is located between

frames

202 and 203 and the column 24. The spring 209 urges and maintains the frames 202-and 203 to and in upright position in contact with abutment 210, but permits said frames to be pushed by the blades a so that the

devices

202 and 203, particularly their

respective plates

206 and 208, will yield or move in a direction toward the column 24 as is necessary for automatic operation of the reel A'with respect to grinding wheel 32.

rAt this stage it is to be noted that the reel A is urged bythe reel turner, specifi-Y cally spring 180, to turn in a clockwise direction so that the blade ai being ground will rest on and be guided by the apex ot' plate 197 and will'automatically turn the reel to nlaintain that relationship notwithstanding` the helical outline of the blades. The feed of the blades into Contact with grinding wheel 32 is governed by the operation of the cross feed plate through manipulation of crank 81. Presuming the carriage 71 and accordingly the reel A to be moving to the left as in Figs. 1, 3, and 16. as the spring 180 tends to turn reel A clockwise the blade (t being' wound by wheel rests on the apex of plate 197 and slides thereover and oill of the same so that the adjacent end of said blade a moves along the edge The

plates

206, 207 and 208 areV integral with the adjacent post 159.

197" and due to the helical outline o'l such i.

blade, it moves said plate 206 outwardly toward the column 24 sothat said blade (L will turn below such plate 206. The spring 209 immediately restores the plate 206.toinor mal position and4 hence it is engaged by the succeeding blade i of the reel.

Thus,

when the said blade a moves otti ot theV apex parts previously describedv automatically operate to reverse the motion Vof the carriage and reel, thus moving same to the right with such succeeding blade in contact with theapexot plate 197 and near the end ofits movement cominginto engagement with the side or edge 207L of plate 207 displacing such plate similarly t0 plate 206 as previously described to effect the automatic -escapement and positioning of the next succeeding bladek and in combination with the movement-reversing mechanism ofV the carriage, automatically andl successively operate all. of the blades with respect to grinding wheel 32. It is to be noted that'the said succeeding blade in moving toward the grinding wheel 32, first engage edge 208a of plate 208 to displace the latter as is necessary to permit operation.

As previously hinted, collar 51 and bed plate 65, carriage 71, and associated parts are in positions varying o according to whether the reelA or ledger bar B is being ground, because grinding wheel V32Vis usedV for the reel and grinding wheel 35 works on the ledger bar as contrasted in Figs. 3 and 4.

To accommodate the mounting of ledger bar B, each plate 163 has an inward extenllt) loo

sion or lug 211 in which a vertical clampf ing screw 212 is threaded. Each screw 212 coacts with a pair of inverted screws 213 threaded in inward extensions or lugs 214 Asbest appears in Figs. 2 and 4, the'ledger bar B is engaged above and below by the

screws

212 and 213 respectively, being thus clamped in operative position and at thedesired angle for coaction with the grinding wheel `35 since the-screws 212 and 213 permit maximum adjustment. i

llo

Desired partsV of the machine may he .turned longitudinal edge portions slidably disposed inlongitaidinal grooves 217 of the rails or bars 66. Another cover plate 218 may be detachably srifrewcd at 219 tothe ring 97 and ,disposed about the ad j acent gears 113 lil motor M is driven from any-suitable source ygear 96.

24, collar 51, and lassociated parts do not m Yoperation turn about a vertical axis..

ofvelectric'current and its shaftv 19 drives pulleyy 18 which moves belt 17. so that .the F latter will rotate the lower line shatt 15 as it is trained overpulley 16. Said lower line shaft, through the medium of pulley..47 and belt 46 drives pulley 45, spindle 29 and-mandrel 36, thus imparting continuous rotation to the grinding

wheels

32 and 35. `Also fromthelower line shaft 15, belt Y23 is driven `rbythe pulley 16so as to drive pulley 22 and the upper line shaftf 20.-."Said'up`per line sha-tt 20,:through the inter-meshing gears 106 v and 104 rotates vthe countershaft 101 and gear Wheel 99 thereon which rotates the ring It will-be seen therefore that the column Said'collar 51 lis placed.atanydesired vertical adjustment to properly position the work and to this end, crank 63 mayfbe turned to rotate shaft 60 in either direction and 'thereby causegears 59 and 58 to rotate `screw'rod 56 in order to raise or lower the'bracket The movement of bracket-753 governs ,the

movement ot'the collar 51 and'vassociated parts since the same are supported by"v saidbracket 53. Ring gear 96 drives'gear Awheels 115 and 117 so as torotate shatt119, gear-

k wheels

120 and 123 and sh aft 122. Since

gear wheels

124 and 125 are` in mesh with gear wheel 126, the latter will.be'rotatedalternately in opposite'l directions Ithrough the meshing of theteeth ofthe clutch` sleeve 131- with those at 128 and'129. Accordingly, the

s rod 85 will be rotated and it moves the car- ,y rate the nut sections87 riage 71 longitudinally otI the bed frame 65. It a. reel A is being sharpened or ground, the parts are in the position shown in Figs. 1 and-3 and hence they reel Vwill be reciprocated relatively to the grinding wheel The reel may be movedv toward yand away trom the grinding wheelmanually through the' manipulation of crank 81 since it moves the cross feed plate 75 toward and away from the work due to t-he mounting to the screw 80. In order to stop mot-ion of the carriagey 71v without shutting off the motor14, crank 92'is operated so as to rock drum93 to sepa# dueto the coacti/on between the pins 90-and cam grooves94. As

gear wheel V99 is vertically slidable, it will automatically adapt itself to the different positions of adJustment of collar 51.

`The reel A, while recipri'icatingavitlnthe carriage 71,:is simultaneouslyurged by the,

spring180 to turn in a-"clockwise,direction i sothat. theblade'aybeingground will rest andbe guided :bythe apex of plate 197. and

will automatically'turn the lreel to maintain v; that 'relationship vnotvv'ithstanding ithe khelical outlinejottheblades., It the carriageI c v71 andaccordingly ythe reel-A'move to lthe lett, asinl Figs; 1, 3, and8, the blade a beingr ground by lwheel 35,:1rests on the apex of plate 197,slidesgthereover and Yoi'pof-,the f same so -thatthe adjacentend of said. blade a movesalongxthe edge 197f.;;.Th-is move-i! mentot the iscrew.=and carriage ensues :be-v lcause the` clutch sleeve :131isinmesh Vwithl Said movement of the the clutch Vface 128. blade alongtheedge197a,'due toi the helical outline of-the last mentioned-blade, moves said plate 20G-outwardly awayfrom-the col-5 umn :24 so thatsaidbladea will .turn below y such plate 206; :The spring 209 .immediately 1 restoresv the vplate 206y to Inormal; position when theendofl the blade .passes itfand".

hence it; isengagedby the 'succeeding blade ai of they reel.: Thus,v when.` the saidfbladeaniovesoif of the. apex of plate` 197 onto;

edge .197,

it vwill automatically-be `given y clockwise movement by spring 180 Such i of the succeeding blade a with the plate 206, at which state, finger 148 willabut the left rand stopl 146, thus shifting the reversing rod'144 to .the left, rocking lever 137 and moving yokes 139 and=132softhat the latter,

movement will be arrested yby vengagement .'95

through the medium of pins 133 will shift the clutch sleeve 131 into mesh With the clutch teeth'129. l Accordingly, gear Wheel'v 125 Vwill be driven byshat't 122 and' in turn will drive gear 126 and screw rod- 85 in the.v

opposite direction toithat in which they are moved by :gear 124, and vhence the carriafzge` and associated partsjdueto the cloaction'y ot nut 86 with screwrod 85, will move tothe right, with the said" succeedingblade win contact with the apex of plate 197. The latter bladefnear the" end vof its movement enga-ges with; the side or edge 207 a of plate 207 nearestzto the column 24, displacing such plate similarly to plate 206 as previously descrilgied, `to .effect .the automatic escape.

ment and positioning of the next succeeding blade operatively to the grindingwheel 82. The last-mentioned blade .during its movement toward grinding A\vlieel"32 engages edge 208 of plate 208 to displace the latter to permit ysuch engagement.

lVhena sickle bar B isgroundv instead of a. reel A. it is fastened: in the machine as suggested mentioned bed plate65, carriage 71, bar 153, ,and-asso! ciated parts are in a position v:at an angle of 90O to that which they assume when the reel A is being ground. This cont-rast'may well be seen from an inspectionl of Figs. 3 and l. Said parts may be manually engaged and swung from one position to the other and incidental thereto, the proper parts are arranged out of gear by demeshing temporarily the gear 104 and gear 106, through the elevation of the rod 111. The ledger bar is reciprocated by the carriage 71 in a direction transversely to the axis ot the grinding wheel 35. The ledger bar B is fastened in operative position for engagement of its cutting edge bwith the grinding wheel by means of the

screws

212 and 213. lVhile the ledger bar is being ground, the supporting rod 167, casing 172 and other parts constituting the reel turner are removed. f v

The grinding or sharpening of the reel and ledger bar may thus be effected in the same machine by means coacting with a tool head or grinding head which does not move about a vertical axis and the means and method of grinding insures sharpening of Y the edges of the reel and ledger bar alongi parallel lines so that they will be sure to coact to the maximum extent when replaced in the mower in their sharpened condition.

Various changes may be resorted to without departing from the spirit and scope ot the invention as defined by the appended claims.

I claim:

1 A machine of the class described having work-holding brackets, means to mount the brackets, bearing arms on the brackets engageable by the work, vertically adjustable clamp plates on the brackets complemental to said bearing arms, said plates having extensions, lugs on the brackets, said lugs and extensions projecting from said brackets in the same direction but in a diterent direction from the bearing arms, and coacting work-securing members carried by said extensions and lugs.

2. A machine for grinding an article having spiral blades such as a lawn mower reel comprising a tool head, a. rest for the reel, means to reciprocate the reel, means to urge turning movement of the reel in opposite directions as the reel reverses its reciprocatory travel, and escapement mechanism for the reel having stop devices operable by the blades, one tor each direction of reciprocatory movement thereof.

3. A'machine for grinding an article having spiral blades such as a lawn mower reel comprising a tool head, a rest for the reel, means to reciprocate the reel, means to urge turning movement of the reel. ein opposite directions as the reel reverses its reciprocatory travel, .and escapement mechanism for the reel having stop devices operable by the blades, one for each direction of reciprocatory movement thereof, means pivotally mounting said devices, an abut-ment means to normally position said devices, and a spring' means to urge the devices into engagement with the abutment means.

Ll. A device for turning an article suchas a lawn mower reel while being ground, com-V prising a spindle, a casing normally fixed I against rotation surrounding the spindle,

spring within the casing to urge turning movement of vthe'spindle connected to the latter and to the casing, and a chuck carried by the spindle and provided with a s lot, said chuck and slot being adapted for t-he coupling of a reel trunnion thereto.

6. A machine for grinding' an article havand its fastening ing spiral blades such as a lawn mower-reel,

comprising a. device for turning thereel in opposite direct-ions as the reel reverses itsv reciprocatory travel relatively to a tool, ra plate having a part along which each blade individually is vdesigned to travel, and esy capement stops engageable by each bladeas it moves otlfof said partl and' located-.one on each side of said part.

7. A machine for grinding an article hav-Y ing spiral blades such as a lawn mower reel, comprising a device for turning the reel inopposite directions yas the reel reverses its reciprocatory travel relatively to a tool, aY plate having a part along which each blade individually is designed to travel, and escapement stops engageable by each lblade as it moves off of said part and located one on each side of said part, and an auxiliary escapement stop engageable by the` blades and superposed on one of the first-mentioned stops.

8. A machine for grinding an article hav. ing spaced spiral blades such as a lawn mower reel, comprising a device for turning the reel in opposite directions as the reel reverses its reciprocatory travel relatively to a tool, a plate having cam edges leading to an apex along which each blade individually is adapted to travel, escapement stops located one on each side of said apex and engageable by each blade as it moves otfof said ape'x onto said edges, and an auxiliary escapement stop engageable by the blades and superposed on one of the first-mentioned stops.

HENRY YERKEY. i