US2779957A - Heel trimming machines - Google Patents

Description

Feb. 5, 1957 B. J. M. MURPHY ET AL 2,779,957

HEEL TRIMMING MACHINES 4 Sheets-Sheet 1 Filed May 25, 1955 llll illlllllllllllll [n 0812 fora Brian JMMurphy John Pope Feb. 5, 1957 B. J. M. MURPHY ET AL 2,

HEEL. TRIMMING MACHINES Filed May 25, 1955 4 Sheets-Sheet 2 'lnvcmors Bman JM/furphy John ,5 Pope Feb. 5, 1957 r B. J. M. MURPHY E AL 2,779,957

HEEL TRIMMING MACHINES Filed May 25, 1955 4 Sheets-Sheet 3 fig. 7 (9 E w J E f fix Fig. 8

5 John R Pope J96 36 r By 13% may Feb. 5, 1957 B. J. M. MURPHY ET AL 2,779,957

HEEL TRIMMING MACHINES Filed May 25, 1955 4 Sheets-Sheet 4 Inventory Brian JMMJrp/ y John RPope United States Patent HEEL 'IRIMMING MACHINES Brian Julian Maurice Murphy and .iohn Rose Pope, Leicester, England, assignors to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application May 23, 1955, Serial No. 510,426 Claims priority, application Great Britain June 29, 1954 Claims. (Cl. 12-88) This invention relates to machines for trimming portions of partially fabricated shoes and more particularly to a heel trimming machine of the type disclosed in United States Letters Patent No. 961,752, granted June 21, 1910, on an application filed in the name of J. N. Bnsell. The Bnsell machine is provided with a pair of curved cutter blades removably clamped in a cutter head. The blades are adjustable radially of the axis of rotation of the cutter head, along a pair of eccentric ribs which fit mating grooves in each of the blades, by an adjustable rotatable plate which engages the rear ends of the blades. This mechanism is generally satisfactory provided the blades are a well matched pair. Should, however, one blade be shorter than the other, for example through unequal sharpening, it will project from the head less than the other and will not do its fair share of the trimming. Furthermore, once the blades have been sharpened, even if done uniformly, it requires a time consuming trial and error adjustment of the totatable plate to locate their cutting edges at the same distance from the axis as they were before sharpening, which is important in precise shoemaking.

An object of this invention is to provide a heel trimming machine having a plurality of interchangeable cutting blades, the cutting edges of which are always rotatable in a single circular path.

Another object of this invention is to provide a heel trimming machine having easily removable cutting blades in a cutter head and convenient means for accurately positioning the cutting edges of each blade equidistant from the axis of rotation of the cutter head regardless of the lengths of the blades which vary according to the extent of sharpening of the individual blades or the angles at which the cutting faces are ground.

In accordance with these objects and as a feature of this invention the trimming machine herein illustrated is provided with a cutter head comprising a pair of ribbed clamping members between which cutting blades are removably secured, one of the clamping members housing a pair of diametrically opposed positioning stops, each stop being engageable with the cutting edge of one blade, the stops being operative when the machine is at rest and automatically retractable out of engagement with the cutting edges when the head is rotated. By positioning the blades in the cutter head by mechanism such as stops which control the location of their cutting edges rather than their rearward ends as in the prior machines, the cutting edges are equidistant from the axis of rotation and when rotated both cutting edges move in the same path and equally share the task of trimming a heel. Furthermore, with this mechanism, blades need no longer be of matched pairs and the angle of their cutting faces need not be exact. Also, one blade may be replaced without replacing its mate. Likewise, blades of varying width designed for use on different height heels may be inserted in the machine with their cutting edges rotatable equidistant from the axis of the cutter 2,7 79,957 "Patented Feb. 5, 1957 head in the same circular path as blades of any other size or width.

The above and other features of the invention, including novel details of construction and combinations of parts, will now be described with reference to the accompanying drawings and pointed out in the claims.

In the drawings,

Fig. l is a front elevation partly in section of the operating portionof one form of machine embodying the invention;

Fig. 2 is a plan view partly in section of the part of the machine shown in Fig. 1 with the cutting head assembly removed;

Fig. 3 is a detail view in elevation and partly in sec tion of a cutter blade positioning means having stop members against which the cutting edges of the blades are positioned, the stop members being in retracted position;

Fig. 4 is a view similar to Fig. 3 but with the stop members extended to a position in which the cutting edges may be placedagainst them;

Fig. 5 is a front elevation, partly in section, of the cutter blade positioning means showing the stop members in retracted positions;

Fig. 6 is a View similar to Fig. 5 but with the stop members extended to positions in which the cutting edges may be placed against them;

Figs. 7 and 8 are detail views in elevation and partly in section of the mechanism for advancing and retracting the stop members, Fig. 7 showing the mechanism in the position whereby the stops are retracted and Fig. 8 whereby the stops are advanced; and

Fig. 9 is a diagrammatic representation of the shape of a crease guide viewed from the right of the machine in the position shown in Figs. 1 and 2, but on an enlarged scale.

The heel trimming machine herein illustrated is generally similar in construction and method of operation to the machine disclosed in the aforementioned Bnsell Patent No. 961,752, and attention is directed to that patent for the description of parts not hereinafter described in detail.

The machine has a cutter head assembly 2 (Fig. I) mounted in front of a dust hood 3 on the left end of a driven cutter shaft 4, journaled in a frame 6. The cutter head comprises a ribbed hub member 8 fixed to the shaft 4 and a mushroom shaped ribbed member 10 fixed to a shaft 12 which passes through an axial bore in the cutter shaft 4. Threaded in the shaft 12 is a screw 14 which, when rotated in a clockwise direction, draws the ribbed member 10 toward the ribbed hub 8 to clamp a pair of cutter blades 16 therebetween, eccentric ribs 18 (Figs. 5 and 6) formed on the opposed faces of the members 8 and 10 engaging mating grooves formed in the blades 16 acting as guideways for the blades. The ribs 13 and the blades 16 are similar to the parts referred to as 10 and 12, respectively, in the above-mentioned patent to Busell, although the ribs may be formed on the blades and the mating recesses in the members 8 and It A keyway 20 formed in the shaft 12 engages a complementary key fixed in the cutter shaft 4 to prevent relative rotation of the ribbed members 8 and 10.

Surrounding part of the ribbed hub member 8 is a top lift rest 22 and adjacent the blades 16 is a work rest 24. The top lift rest and the work rest respectively are similar in construction to the top lift rest 22 and the work rest 42 described in the Bnsell patent. A crease guide or guard attachment 26 shrouds the mushroom-shaped member 10 and will be described in detail hereinafter.

The ribbed member 8, best seen in Figs. 3 to 8, is hollow and of composite construction, housing a pair of retractable stops 23. The stops are located diametrically opposite each other on either side of the cutter shaft 4 (Figs. 5 and 6). Each stop has a finger portion 39 that is arranged, when the cutter shaft is at rest, to protrude from the hub member 8 in position to be engaged by the cutting edge 32 of one of the blades 16. An operator places the cutting edge of each blade against its respective stop by moving the blade along the eccentric r-ib 18. The blades are then securely clamped by tightening the screw 14-. By this construction, when the machine is started, the cutting edges 32 of both blades are always rotated in a single path, the edges being located equidistant from the axis of rotation B of the cutter shaft regardless of any difference in initial length of the blades or how much one of them has been ground, contrary to the machine of the Busell patent which requires perfectly matched blades at all times. It will be obvious that if more than two blades are used an additional stop for each blade would be provided and the stops spaced at equal angles around the cutter head.

Furthermore, when other size blades are inserted having, for example, different widths, their cutting edges will be rotated in the same single path equidistant from the axis B.

The retractable stops 28 are automatically withdrawn, by means new to be described, within the ribbed hub member 8 and clear of the cutting edges of the blades, when the cutter head is rotated. Each retractable stop 28 lies in a longitudinal slot 34 (Figs. 5 and 6) formed in a cylindrical stud 3:6, and is pivoted on a pin 38 fixed in the stud. The left-hand portions (Figs. 3 and 4) of the studs 36 slide in bores 40 formed in the hub member 8 parallel to the axis B of the cutter shaft 4, and the righthand ends of the studs are fixed in a ring 42, which lies within the hub member 8. A portion of the ring 4-2 embraces the cutter shaft 4 (Figs. 7 and 8) and slides lengthwise of it, being kept from rotation relative to the cutter shaft by the studs 36 engaging the bores 40.

The ring 42 is urged to the left (Fig. 4) by a pair of compression springs 44 housed in longitudinal bores 46 formed in the studs 36 and, v 1 1 1655ed between the studs and a face 48 on the hub member 5. Movement of the ring 42 to the left, under the action of the springs 44, is limited by the engagement of a conical concave face 5t) formed on the ring with a plurality of balls 52 which engage a circumferential groove 54 (Figs. 7 and 8) formed in the cutter shaft 4 and a concave Conical face 56 formed on the hub member 8. This plurality of balls 52 is divided into two egual groups by the studs 36, each group occupying an equal portion of an annular cavity 58 (bounded by the cutter shaft 4, the hub member 8, and the ring 42).

Spring-biased plungers 6*?) (Figs. 3 and 4) housed the studs 36 engage abutments 62 formed on each of the retractable stops 28, and tend to pivot the stops about the pins 38 in a direction to move the finger portions 34 away from the axis B of the cutter shaft. Pivotal movement of each retractable stop 28 under the action of its spring plunger 60 is limited by the engagement of the stop with a cam face 64 (Fig. 3) formed on the ribbed member 8.

Thus, when the cutter head is at rest and the balls 52 are in the positions shown in Figs. 6 and 8, the finger portions of the retractable stops 28 are held to the left, and outwardly away from the axis B of the cutter shaft, by the compression springs 44 and the spring-biased plungers 60 respectively, so that they protrude from the hub member 8, see Figs. 4 and 6. As they so protrude, the cutting edges 32 of the blades 16 may be moved by the operator into engagement with them before the blades are clamped between the ribbed members 8 and 10 of the cutter head 2 by the screw 14.

When the cutter shaft is rotated, the balls 52 are urged outward under the, action of centrifugal force, and at a speed well below the normal running speed of the cutter head the balls move outward, away from the circumferential groove 54 formed in the cutter shaft from the positions in Fig. 8 into the positions shown in Fig. 7. As the balls move outward they force the conical faces 50 and 56 apart, moving the ring 42 to the right and thus withdrawing the retractable stops 28 within the hub member 8. As the ring 42 moves to the right against the resistance of the springs 44 the cam faces 64 formed on the hub member 8 cam the finger portions 3% of the retractable stops inward toward the axis B of the cutter shaft against the resistance of the spring-biased plungers 60. Thus, before the cutter head reaches its cutting speed the retractable stops are automatically withdrawn clear of the cutting edges 32.

Cooperating with the top lift rest 22 and the work rest 24 to support and guide a shoe as its heel is presented to the cutting head is the crease guide 26 which shrouds the mushroom-shaped member 19 (Fig. 1). The crease guide is in the form of a dished plate having a stud 70 fixed to its convex surface, the center of which stud lies on an axis C. The work engaging portion of the periphery of the crease guide is in the form of an involute and will be more fully described hereinafter. The stud 70 is supported in a bore in the enlarged right-hand end of a slide 72, and is restrained from axial movement by a pin 74 (Fig. l) fixed in the slide and engaging a groove 76 (Fig. 2) formed in the stud and extending part way around its periphery. In order to adjust the work engaging portion of the crease guide relative to the cutting blades 16 as will be explained in more detail hereinafter, the creases guide is rotated on its axis C relative to the slide 72 but this movement is limited by the pin 74 engaging the cnd of the groove 76. A clamp screw 78 threaded in the slide engages the stud to enable an operator to lock the crease guide in a desired angular position. Graduations 73 marked on the crease guide assist the operator in selecting the angular position.

The main portion of the slide 72 which is cylindrical and coaxial with the stud 70 is axially adjustable in a carrier 80, in a manner hereinafter to be described. A key 82 (Fig. l) fixed in the carrier engages a complementary ,keyway formed in the slide and thus prevents rotation of the slide relative to the carrier. The slide is adjusted axially in the carrier by an adjusting screw 84', threaded in the left-hand end of the slide, the screw having a knurled knob 86 and a flange 68 which engages a plate 94 fixed to the carrier. A spring 92 compressed between the knurled knob 86 and the plate tends to prevent backlash developing in this mechanism and to prevent inadvertent rotation of the adjusting screw 34. Graduations (not shown) corresponding to different width cutter blades are marked on the slide to assist the operator in adjusting the crease guide to a desired position so that it just shrouds the ribbed member 16, as will be more fully explained hereinafter.

The carrier 80 is pivoted on a vertical stud 9.4 fixed in the forward end of a link 96 the rearward end of which is fixed by means of a clamp screw 98 to a vertical pin 100 journaled in bearings 102 and, 104 in the frame 6. Extending rearwardly from the carrier St) is a flange 106 having formed in it an arcuate slot 168. A link 110 is adjustably secured to the flange 106 by means of a clamp bolt 112 passing through the arcuate slot and having an enlarged head 114- engaging the lower surface of the flange. A wing nut 116 threaded on the bolt 112 enables the operator to clamp the link 110- in any position along the arcuate slot. Graduations 118 along the slot assist the operator in positioning the link ilt) for a purpose to be explained hereinafter. The rearward end of the link 110 is pivoted on an eccentric portion 129 of a bolt 122 adjustably mounted in the frame 6 and secured thereto. by means of a lock nut 123. The bolt 122 is in a position (see Fig. 2) forward and to the left of the pin 100.

The carrier 80, and consequently the crease guide 26,

is urged to the right, as seen in Figs. 1 and 2, by means of a tension spring 124 secured to the frame 6 and to an arm 126 fixed to the lower end of the pin 100. Movement of the crease guide to the right under the action of the spring 124 is limited by an adjustable stop screw 128 threaded in the link 96 and held in adjusted position by a lock nut 130. The forward end of the stop screw abuts a portion of the frame 6.

The work rest 24 is supported by a cylindrical split bar 132 having two branches 134 and 136 separated by a slot 138 which extends lengthwise of the split bar nearly to its rearward end. The split bar is supported in a horizontal bore 139 formed in the frame 6. The work rest 24 has a cylindrical stem 140 which is gripped between an arcuate seat 142 formed in the branch 134 and an eccentric pin 144 journaled in the branch 136, the eccentric pin having a handle 146.

The construction and arrangement of the parts are such that by turning the handle 146 the eccentric pin 144 binds the stem 14h forcing it against the seat 142. This single operation not only locks the stem 140 in position relative to the split bar 132 but, by forcing the branches 134 and 136 apart, also locks the split bar in the bore 139. Conversely, reverse movement of the handle 146 not only releases the stem 140 for sliding and rotating movement relative to the split bar 132 but also releases the split bar for sliding and rotating movement relative to the frame 6.

Referring to Fig. 1, the dotted outline of a shoe is shown in position to have its heel trimmed. The heel is supported on the work rest 24 with its top lift in engagement with the top lift rest 22. The crease guide 26 engages the shoe in the crease between the heel and the upper which is frequently called the rand crease. It will be noted that the distance from the top lift to the mud crease is greater at the rear of the heel than at the front or heel breast. Therefore, as the shoe isturned by the operator to present successive portions of the heel to the cutter, the crease guide must yield to the left as the rear of the heel approaches it and then must return to the right as the second side of the heel is trimmed, the crease guide at all times being in engagement with the rand crease. The amount of movement is relatively slight and just equal to the difference in the heel height from front to rear and varies, depending on the shoe size and style.

The arrangement of the links 96 and 110 supporting the carrier 86 and their associated mechanisms permit the crease guide to yield against the force of the spring 124, the positions of the various above-mentioned adjustable members determining the path of movement as now to be described. When the crease guide is in the position ready for use it shrouds the ribbed member the position of which, lengthwise of the cutter shaft 4, depends on the width of the cutters clamped in the cutter head. The cutters are selected to accommodate the height of a heel to be trimmed. In this position the axis C of the stud 70 lies substantially parallel to the axis B of the cutter shaft 4 and a little below it. The bolt 122 is rotated initially so that its eccentric portion 120 acting through the link iii) makes axes B and C parallel. The radius of the arcuate slot 108 is equal to the length between centers of the link 110; therefore any adjustment of the bolt 112 in the slot does not affect the parallelism of the axes.

Adjustment of the slide 72 in the carrier when the crease guide is in its starting position moves the crease guide lengthwise toward or away from the ribbed memher 10, the cutter size graduations on the slide 70 enabling the operator to set the crease guide in the appropriate position for the particular pair of cutters being used. The stop screw 128 is initially used to make the rough adjustment of the crease guide relative to the cutters and the knurled knob 86 to make the fine adjustment.

By adjusting the bolt 112 in the slot 108 the operator determines the path followed by the crease guide as it moves yieldingly away from the cutter head in accordance with the style of heel to be trimmed. The most suitable path to be followed for a particular style of heel is determined by trial and error, the slot graduations 118 assisting the operator to obtain a setting shown by experience to be correct. When the machine is used to trim a low heel the yielding movement of the crease guide is small and the setting of the bolt 112 relatively unimportant. V

The arrangement of the carrier 80, the links 96 and and their associated mechanisms which provide for this path of movement is well known and is not described in further detail.

Owing to the involute shape of its periphery, angular adjustment of the crease guide 26 about the axis C of the stud 70 varies the distance between the axis of the cutter head B and that forward shoe engaging portion of the periphery of the crease guide which engages the crease formed between the heel and the upper of the shoe. Therefore, angular adjustment of the crease guide 26 determines how close to the crease and the upper the cutters trim the heel.

Fig. 9 is a diagrammatic representation of the shape of the crease guide as seen from the right side of the machine in the position shown in Figs. 1 and 2 when the crease guide is in starting position shrouding the ribbed member 10. An intermediate portion A of the involute portion DAE of the periphery DAEFI of the crease guide 26 is shown turned into the shoe engaging position, this shoe engaging position being in front of and level with the cutter head axis B.

The involute portion DAE is generated by the end of a straight line rolling on a hypothetical circle I which has its center on the axis C of the stud 70 and passes through the axis B of the cutter shaft; thus, the radius of the circle I is equal to the distance between the axes B and C. It will be seen that the shoe engaging portion A of the crease guide lies approximately on the arc GH (shown as a dotted line) which is struck about the axis B of the cutter shaft. Because of this and the fact that the cutting edges 32 of any pair of blades 16 are always positioned equidistant from the axis B due to the use of the stops 28, the shoe will remain at a desired distance from the cutters should it engage the crease guide at a point somewhat above or below the axis B of the cutter shaft at any stage of the trimming operation even if the blades are changed before a heel is fully trimmed.

Since the crease guide is adjusted about the axis C and is required, in one position at least, to fit close to the ribbed member 10 (which rotates about the axis B) it is necessary to limit the involute portion DAE to about two-fifths of the periphery of the crease guide, and to limit angular movement of the crease guide (by means of the pin 74) to avoid contacting the ribbed member 10 in one position or another of the crease guide.

Arcuate portions DI and EF of the periphery of the crease guide blend smoothly with, and form continuations of, the involute portion DAE since they may engage the shoe, on occasion, should the operator cause the shoe to contact the crease guide at a point above or below the axis B of the cutter shaft, when the crease guide is set in an extreme angular position.

Thus for any working angular position of the crease guide, the shoe engaging portion of its periphery lies approximately along an arc struck about the axis B of the cutter head, thereby providing a working surface on which the shoe can be swung Without causing it to move appreciably, inwardly or outwardly, radially of the cutter head. Therefore, because the working portion of the crease guide is an involute rather than a series of stepped arcs, as in the prior machines, the shoe may be positioned with maximum accuracy at a desired distance from the axis of the cutter head and the path of the cutting blades. The operator may thus vary by any desired amount,

7 however small, the closeness with which thecutters, as they trim; theheel, approachthe-upper of the shoe:

The creasc i guide and its operating mechanism" formno part of the present invention but are claimed in a copendingdivisional= application Serial= No. 592,678, filed June 20, 19,56, in our names.

Having described our invention, what we claim as new and desire to secure by Letters Patent of' the United States is:

1. In a heel trimming machine, a rotatable cutter head mounting a. plurality of cutting blades adjustable radially of its axis. ofrotation, and positioning means carried at all times by saidicutterheadand engageable with the blades to locate all of said cutting edges at points equidistant from said, axis. of: rotation irrespective of the length of theblades or theangles of their cutting-faces.

2. true heel trirnming-machine; arotatable cutter head mountirr aplurality of cuttingbladesadjustable radially of its axis of rotation, and positioning means carried at all times by said cutter head and engageable with the cutting edges of each blade to locate all of'saidcutting edges at points equidistant from saidaxis of rotation.

3. in a heel trimming machine having a rotatable cutter head, mounting a plurality of cutting blades adjustable radially. of. its axis of rotation, positioning means carried by the cutter head and engageable with the cutting edges of each blade when the cutter; head is at rest to locate all of said, cutting edges at points equidistant from said axis of rotation irrespective of the length of the blades, and automatic retracting means operative to withdraw the positioning means from engagement wtih the cutting edges in response to rotation of the cutter head.

4. In a heel trimming machine having a rotatable cutter head mounting a plurality of cutting blades adjustable radially of itsaxis of rotation, positioning means carried by the cutter head and engageable with the cutting edges of each blade when the cutter head is at rest to locate all of said cutting edges at points equidistant from saidaxis of rotation irrespective of the length of the blades, and automatic retracting means operative by centrifugal force inresponse to rotation of thecutter head to withdraw the positioning means, from engagement with the cutting edges.

5. In a heel trimming machine having a rotatable cutter head mounting a plurality of curved cutting blades adjustable radially of its axis of rotation along symmetrical eccentric guideways on the cutter head, a plurality of positioning stops angularly spaced equally around the cutter head and" associated one with each blade, means operable when the cutter head is: at rest to locate each L stop in a position wherein it is engageable with the cutting edge of its associated bladeto-loeate all of the cutting edges at points equidistant from the axis of rotation of the cutter head irrespective of the length of the blades, and means operative in response-to rotation of the cutter head to withdraw said positioning stops from engagement with said cutting edges.

6. In a heel trimming machine having a rotatable cutter head mounting a plurality of curved cutting blades adjustable radially of its axis of rotation along symmetrical eccentric guideways on the cutter head, a plurality of positioning stops angularly'spaced-equally around the cutter head and associated one With-each blade, means operable when the cutter head is at" rest to locate each stop in a. position wherein it is engageable with the cutting edge of its associated blade to locate all of the cutting edges at.points.equidistantfrcm the axis of rotation of the cutter head irrespective ofthe length of the blades, and means operative by centrifugal force in response to rotation of the cutter head to withdraw said positioning stops from engagement withsaidcutting edges.

7. In a heel trimming machinehaying arotatablecutter head comprising a pair of, axially spaced clamping members, a p r i y Q 1 d.. uttr,,b ades nemovablymount ed between said-clamping members; and adjustable. radial:

1y of the cutter-head along; symmetrical guidew aysformed eccentrically to; its axis of rotation; a plurality of" positioning stops angularly spaced" equally around one of said clamping members and associated one with each blade, actuating means operable when the cutter head is at rest tol'ocate each stop in a position intersecting the path of adjustmentof its associated blade and engageable with its cutting edge whereby all of the cutting edges may beaccurately located at points equidistant from the axis of rotation of the cutter head irrespective of the length of the blades, and means operable in response to rotationof the cutter head to withdraw said positioning stops from engagement with said cutting edges.

8. In a heel tr-imming-machinehaving a rotatable cutter head' comprising a first clamping member mounted on a drive shaft, and a second clamping member spaced from and movable axially toward said first clamping member, a plurality of: curved" cutting blades removably mounted between. the clamping members and adjustable radially of the cutter-head along symmetrical guidew ays formed on the clamping members eccentrically to the axis of rotation of the cutter head, an annular ring movable axially within the first clamping member, a plurality of blade positioning members associated one with each blade and pivotally secured to the annular ring at points angularly spaced equally from each other, a finger portion on each positioning member engageable with the cutting edge of its associated blade, first resilient means for urging said annular ring and positioning members axially of the cutter head toward the blades, second resilient meansfor urging-the finger portions radially of the cutter head into the path of adjustment of the blades to limit their adjustment, whereby all of the cutting edges may be accurately located at points equidistant from the axis of rotation of the cutter head, and retracting means operable in response to rotation of the-cutter head to withdraw the fingerportions from engagement with the blades and retract the positioning members within the first clamping member.

9. In a heel trimming machine having a rotatable cutter head comprising a first clamping member mounted on a drive shaft, and a second clamping member spaced from and movable axially toward said first clamping member, a plurality of-- curved cutting blades removably mounted between the clamping members and adjustable radially of the cutter head along symmetrical guideways formed on theelamping member eccentrically to the axis of rotation ofthe cutter head, an annular ring movable axially withinthe. first clamping member, a plurality of blade positioning members associated one with each blade and pivotally secured to the annular ring at points angularly spaced'equally from each other, a finger portion on each positioning member engageable with the cutting edge of its associated blade, first resilient means for urging said annular ring and positioning members axially of the cutter head toward the blades, second resilient means for urging the: finger portions radially of the cutter head into the path of adjustment of the blades to limit their adjustment, whereby all of the cutting edges may be accurately located at points equidistant from the axis of rotation of thecutter head, and retracting means operable in response to. rotation of the cutter head to withdraw the finger portions from engagement with the blades and retract the positioning'memberswithin the first clamping member, said retracting means comprising a plurality of balls within the first clamping member and engageable with a, conical bearing surface formed on the annular ring, said balls being movable by means of centrifugal force to urge: said annular ring and positioning members in a direction opposite to the direction of force of said first resilient means, and: a cam face on the first clamping member cngageable with each finger portion to move said finger portion. radially inward asthe positioning members are retracted.

1-0.; Ina heel trimming machine, a rotatable cutter head mounting a plurality of cutting blades adjustable radially of its axis of rotation, and positioning means automatically efiective when the cutter head is at rest to engage the cutting edge of each blade to locate all of said cutting edges at points equidistant from the axis of rotation, said positioning means being inefiective when said cutter head is rotated.

References Cited in the file of this patent UNITED STATES PATENTS 406,582 Harrigan July 9, 1889 10 Glidden et a1. Sept. 12, 1893 Vose Oct. 1, 1895 Busell June 21, 1910 McDowell May 6, 1913 Noon Apr. 28, 1914 Mayo July 28, 1914 Harrold Sept. 21, 1915 Fowler Apr. 8, 1930 Taft Oct. 27, 1931 Ballatine Feb. 15, 1955

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