US3097555A

US3097555A - lindsley

Info

Publication number: US3097555A
Authority: US
Publication date: 1963-07-16
Anticipated expiration: 1980-07-16

Description

July 16, 1963 c. w. LINDSLEY 3,097,555

APPARATUS FOR NOTCHING VACUUM TUBE GRID LATERAL WIRE Filed May 2, 1960 2 Sheets-Sheet 1 INVENTOR.

Charles I. Lindsleq July 16, 1963 c. w. .LINDSLEY APPARATUS FOR NOTCHING VACUUM TUBE GRID LATERAL WIRE! Filed May 2, 1960 2 Sheets-Sheet 2 I INVENTOR. Charles 1U- Lindsleq United States Patent M 3,097,555 APPARATUS FOR NOTCHING VACUUM TUBE GRID LATERAL WlIlE Charles W. Lindsley, Cresskill, N.J., assignor to Radio Corporation of America, a corporation of Delaware Filed May 2, 1960, Ser. No. 26,130 13 Claims. (Cl. 836) This invention relates to improved apparatus for continuously winding vacuum tube grids, said apparatus having means for accurately severing the grid lateral wire at the proper point after each grid of a stick of grids has been wound, and particularly to improved means for notching the lateral wire prior to severance.

A continuous process of Winding a stick of grids comprises moving a pair of grid lateral supports or side rods, usually of relatively heavy gauge copper wire, uniformly in the direction of their lengths and at the same time rotating the side rods about an axis between them and parallel thereto. As the side rods are rotated and advanced, they are notched in a direction more or less perpendicular to their lengths and at uniform intervals. A lateral wire, usually of light gauge molybdenum, is fed laterally to the side rods in such manner that the lateral wire enters a notch in a side rod. The notch is peened over, holding the lateral wire in the side rod notch, causing the lateral wire to feed, and to enter the successive notches in the two side rods. In this way, a helix of lateral wire is wound on the side rods.

At the end of an individual grid, the notching and peening wheels are withdrawn from their operative position, but the side rods continue to be fed forward and to rotate. The lateral wire is severed just after the last notch in an individual grid is peened. The side rods continue to be advanced, and after they have been advanced far enough to produce sufiicient unnotched leg portions for an individual grid, the notching and peening means are returned to their operative position, and notching and peening of the side rods is resumed. The severed end or the grid lateral wire being fed enters the first notch of the next individual grid of the stick of grids, and it is peened therein and the process is repeated. After the winding is completed, the grids are sized by being stretched laterally to proper size over a mandrel and the individual grids are cut apart at the unpeened portions of the side rods.

In the present process of Winding grids in the manner noted above, the lateral wire is broken oil merely by holding or clamping it just after the lateral wire enters the last notch of the individual grid, while continuing to rotate the side rods. This action breaks the grid lateral wire. The lateral wire, in breaking, necks down in the vicinity of the break point whereby the end of the lateral wire of a grid is of smaller diameter than the remainder thereof. Since all of the notches of the side rods are the same size, the end of the lateral wire in the last notch of one grid and in the first notch of the next grid in a stick of grids, does not fill their respective notches. Therefore, the ends of the lateral wire may not be held firmly in their notches after the peening thereof, whereby in the sizing process, mentioned above, the ends of the lateral wire may pull out of their notches.

Furthermore, in breaking, the lateral wire does not always break at the same distance from the clamping or holding means. Therefore, different lengths of wire, or tails, extend laterally beyond the last notch of a grid. If the grid lateral wire breaks to tar from the grid side rods, the tail on a grid may be too long and it may be so long that the vacuum tube having that grid as an element thereof may be short-circuited by the tail touching another tube element. Also, if the grid lateral wire breaks off too close to the clamping means, the remaining grid lateral 3,097,555 Patented July 16, 1963 wire beyond the clamp will not reach to the grid side rods and will not be caught in the notch therein to start winding the next individual grid. In such case, the grid winding machine or lathe will cease winding grids until it is adjusted manually.

In order to make sure that the grid lateral wire will be severed at the proper point upon being held, the grid lateral wire is notched as it is being fed to be wound on the grid side rods. This notching takes place without substantial interference with the motion of the grid lateral wire. It takes place cyclically, once at the completion of each grid of a stick of grids, at a point in the grid lateral wire so that the grid lateral wire breaks, upon being held, just after being peened into a notch in a side: rod. In this manner, the tail, if any, on each grid of a stick of grids is short and the tails are uniform in length from. grid to grid. Also, the amount of grid lateral wire that extends from the clamping means towards the grid side rods, after the grid lateral wire has been broken, is long enough so that the grid lateral wire catches in the next notch in a grid side rod, to start the winding of the next grid of the stick of grids.

The notching of the grid lateral wire must be deep enough, considering the gauge of grid lateral wire and the material thereof, so that the grid lateral wire will break readily upon being held and yet this notch must not be so deep that ordinary stress due to winding the grid will break the grid lateral wire. Since the grid lateral wire may be a fraction of a thousandth of an inch in diameter, the grid lateral wire notching means must be very finely adjustable.

It is an object of my invention to provide grid winding apparatus having an improved means for notching a grid lateral wire, said means having accurate timing, quick notching responses and being capable of fine adjustment for controlling the depth of the cut.

In accordance with this invention, the moving grid lateral wire is periodically notched as the result of a bouncing blow by the chisel-shaped end of an elongated tool when the other end of said tool is struck by a moving part of a solenoid, upon periodic energization thereof. Further, in accordance with this invention, the depth of the notch is determined by a stop, attached to the tool, hitting a wedge, and the depth of the notch is adjusted by a micrometer means for moving the wedge in a direction so that different portions of the inclined surface of the wedge cooperates with the stop.

The invention may be best understood in connection with the drawing forming a part hereof in which:

FIG. 1 is a plan view of apparatus made according to this invention and showing the special relation of the notching means to the clamping means and to the grid Winding lathe;

FIG. 2 is a side elevation, partly broken away of the device embodying my invention;

FIG. 3 is a partial section, at a larger scale, of the device of my invention on the line 33 of FIG. 2;

FIG. 4 is a partial elevation partly in section of a clamping means and a grid winding lathe while Winding a grid;

FIG. 5 is a partial elevation partly in section of the clamping means and the grid winding lathe shortly after the grid lateral wire has been broken away; and,

FIG. 6 is a diagram showing the timing means for energizing the notching and clamping solenoids in accordance with this invention.

The grid lateral wire notching means of this invention and its relation to the clamping and winding apparatus is shown in FIGS. 1 and 2. The apparatus includes a base 8 on which is mounted a pair of lateral wire pressure pads 19 and 12, the lateral wire clamp '18 and on table 8 for cooperation with pressure pad 10 and is adjustable with respect thereto for adjusting the tension on the grid lateral wire which runs between them to the grid arbor.

The grid lateral wire 33 is wound in the usual way on

side rods

26 and 28 supported in the arbor 24 of the grid winding lathe thus providing the stick of grids 38- as well as the individual grids 32 of the stick of grids. 30. For convenience, the notching wheels 34 and the peening wheel 36 are not shown in FIG. 1. FIGS. 4 and are referred to for illustration of positions of these wheels with relation to the arbor and side rods. The several elements of the device are described separately below.

The arbor 24 of the grid winding lathe is provided with a pair of parallel longitudinal grooves diametrically arranged therein into which the grid side rods fit. This arbor is rotated in a clockwise direction by a motor (not shown).

Grid side rods

26 and 28 fit the grooves in the anbor 24 and are advanced together along the length thereof by suitable apparatus (not shown). As shown in FIG. 4, a notching wheel 34 is positioned to cut notches alternately and successively in

side rods

26 and 28 as they are rotated past the notching wheel 34 and a peening Wheel 36 is arranged to peen the most recently cut notch in the side rod after a lateral is laid in the notch. As shown in FIG. 5, the peening and notching wheels may be moved out of peening and notching position by means not shown. The grid winding lathe is conventional and no further illustration of the grid lathe and of the parts thereof is considered necessary.

The clamping means 18 comprising a stationary clamping jaw 38 (FIG. I) mounted on the end of table 8 and a rotatable clamping jaw 40 pivoted on table 8 by means of pivot 42 and cooperating with said stationary jaw 38. A metal strip 44 is secured to the upper face of clamping jaw 38 by means of a clamp 46 and extends across the upper face of clamp jaw 40 to hold the two clamp jaws 38 and 40 in the same plane. The clamp 46 is 'adjustably tightened against the top of the metal strip 44 by adjusting screw 48. The rotatable jaw 40 has a lever and 40 extending beyond the pivot point 42 for cooperation with lever 22. Lever 22 is mounted for rotation on base 8 by means of a pivot 52. One end of lever 22 is in contact with the lever end 48' of jaw 40 and the other end thereof is in contact with the shaft 54 of rotary solenoid 20 In accordance with this invention, a notcher 14, which will be described in detail below in connection with FIGS. 1, 2 and 3 is mounted on the base 8 between the pressure pads 10, 12 and clamp 18, and in line therewith so that the grid lateral wire 33 may be strung through these three elements in such a manner that the grid lateral wire 33 runs between the chisel end of the tool 56 and the anvil 78 of the notcher 14.

Referring to FIGS. 1, 2 and 3, the notcher comprises a tool 56 having a chisel end, already mentioned, means for slidably holding the tool, means for percussively driving it to its notching position, means for returning it to a position where it clears the grid lateral wire and means for controlling its depth of cut.

The means for slidably holding the chisel '56 comprises a frame 62 mounted on base 8 and having a forwardly projecting portion 64. A vertically extending hole, having

bearing

66, 66 therein is provided in the forwardly extended portion 64. The chisel is slidably mounted in bearing 66, 66. A stop means 68, shown in detail in FIG. 3, is secured to the chisel 56 to move with it. A compression spring 78 surrounds chisel 56 in the bore provided therefor and, bearing between the lower bearing 66 and the stop 68, urges the chisel upwardly until the fiat top surface 72 of the stop 68 contacts the upper bearing 66. An anvil 76 extends forwardly from frame 62 and carries a striker plate 78. As stated above, the grid lateral wire 33 is strung between the pressure pads 10, 12 and over the striker plate '78, and through the clamping. means 18 as shown in FIGS. 1 and 2.

The means for operating the chisel includes the rotary solenoid 16 mounted on frame 62 and the arm 82 of the rotary solenoid provided at its free end with a pin 98 extending laterally thereof and overlying the top of chisel 56. The lower portion of the arm 82 extends below the pin 98 and is prevented from turning beyond a predetermined point by contact of said lower portion of the arm 82 with the forwardly extending portion 64 of the frame 62 as better shown in FIG. 3. In this manner, upon energization of the solenoid 16, the arm 82 rotates clockwise until stopped by contact of the lower edge of the arm 82 on the forwardly projecting portion of the frame 64, and the pin 98 hits the chisel 56. The kinetic energy of the arm 82 is transferred to the chisel 56, driving it downwardly against the action of spring 70 to notch the moving grid wire 33.

The means for adjusting the depth of the notch produced by the notcher 14 comprises a wedge 60, and the micrometer 58 for moving the wedge in the direction of its length. The wedge 60 lies on a table portion 92 comprising part of the frame 62 and extends perpendicularly to and behind the chisel 5 6, in such manner that the sloped or lower surface 74 of the stop 68 overlies the upper surface of wedge 60 as better shown in FIG. 3.

The micrometer 58 is clamped to the frame 62 by a clamp 84. The thimble 88 of the micrometer 58 extends to the left of the clamp 84 and the moving spindle 86 of the micrometer extends to the right of the clamp, and into contact with the left end of the wedge 60. Spring means 94 and washer 9 6 are provided for pushing the wedge 60 towards the spindle 86 to keep it in contact therewith. Spring means 98 and plunger 101 are provided to press down on the top of the wedge 60 to keep it in contact with the table portion 92 of the frame 62. Therefore, upon rotation of the thimble 88, the spindle 86 is moved to the right or to the left to thereby slidingly move the wedge 60 along the direction of its length to adjust the spacing between the bottom surface 74 of the stop 68 and the top surface of the wedge 60, whereby the distance that the chisel is permitted to travel in a downward direction is adjusted.

FIG. 6 shows the timing means for energizing the notching solenoid 16 and the clamping solenoid 20*. A source of electricity 99 is connected to the solenoids 16 and 20 through switch means 100 and 102 respectively. The cam 104 closes switch 100 and a cam :106 closes switch 102. These cams are rotated at the same speed, as indicated by the dotted lines between them. These cams are rotated by the same motor (not shown) that rotates the arbor 24 but at a reduced speed so that the cams close their respective switches once upon completion of the winding of an individual grid of a stick of grids.

The operation of this device is as follows:

The lateral wire 33 is threaded between pressure pads 10 and 12 and between the striker plate 78 and the lower end of chisel 56. The lateral wire is further threaded between the jaws 38 and 40 of clamp 18 and to a point above the middle of arbor 24. The notching wheel 34 and peening wheel 36 are adjusted to notching and peening positions as shown in FIG. 4. The arbor 24 rotates clockwise, carrying

side rods

26 and 28 past the notching wheel 34, whereby notches are formed in these side rods. Since the side rods are evenly fed along the direction of their length, the notches are formed at even intervals and alternately in the side rods. As the first notch in a side rod arrives in an upper position in its rotation, the lateral wire catches in the first notch whereby it is peened into the notch by peening wheel 36. As the side rods continue to rotate and advance, a helix of lateral wire is wound on the side rods.

After a predetermined number of turns of the arbor 7A, cam 104 notates to the position, as shown in FIG. 6, where it closes switch 100, energizing rotary solenoid 16. The arm 82 of the rotary solenoid rotates clockwise, taking the position shown in FIG. 3, further rotation of the arm 82 being stopped by contact thereof with the portion 64 of the frame 62. By this rotation, the pin 98 on arm 82 strikes the top of chisel 56 transferring kinetic energy from the arm 82 to the chisel 56 and driving it down wardly until stopped by contact of the sloped lower surface 74 of stop 68 fastened to the chisel 56 with the upper surface of wedge 60. This downward motion of the chisel causes cutting of a notch in the moving grid lateral wire 33 and also compression of spring 70. The rebound of the chisel, aided by the action of spring 70, results in only momentary contact of the chisel with the moving grid wire, whereby the grid wire is not impeded in its motion.

In the meantime, the cams continue to rotate and cam 106 soon reaches the point where it closes switch 102. Closure of switch 102 energizes rotary solenoid 20. As the shaft 54, of rotary sonenoid 20 rotates, it also moves axially in a direction away from the solenoid 20 sufficiently far so as to cause rotation of lever 22 about its pivot and thereby rotates jaw 40 about its respective pivot, to clamp lateral wire 3-3, preventing further motion thereof. Since arbor 24 continues to rotate, lateral wire 33 is stretched and breaks at the notch therein. Upon proper timing of

cams

104 and 106, the notch in the lateral wire and therefore the break therein, will be just past the top of the arbor 24, as shown in FIG. 5 and just past the vertical axis 12 of the arbor 24, as shown, so that the lateral wire will overlie the notch when a side rod is positioned on the vertical axis. The notching and peening wheels are moved outwardly while the arbor continues to turn and the side rods continue to be fed longitudinally. Cams 104- and 106 continue to rotate, releasing switch 102 and deenergizing solenoid 20 thereby releasing clamp 18. As shown in FIG. 5, the end of the lateral wire 33 is in a proper position to be caught in a notch in a side rod when the notching and peening wheels are moved back to notching and peening position, and a cycle has been completed.

As explained above, the cyclic closing of the switch 100 causes energization of the solenoid 16 which in turn causes the cyclic notching of the grid lateral wire 33. The timing of the notching is by the closure of a cam operated switch and the notching and the timing of the notching is adjusted to take place at exactly the correct time to provide the desired length of the tails on the grids and to prov-ide the length of the grid lateral wire extending from the clamp towards the side rods necessary to start winding of the next grid.

As noted above, the depth of the notch is determined by the distance the chisel 56 moves before the sloped surface 74 of the stop 68 mounted on the chisel 56 hits the top of the wedge 60. This distance is adjustable by moving the wedge 60 laterally of the chisel upon rotation of the thimble 88. If a wedge 60 with a slightly sloped upper surface is provided, this adjustment can be made very fine, since a small lateral movement of the wedge would result in presenting only a slightly higher (or lower) surface portion thereof to the stop 68. Furthermore, while a micrometer means is provided for adjusting the depth of the notch, the notching action does not apply any force to the micrometer. The force required to stop the downward motion of the chisel is applied to the wedge 60 rather than to the micrometer, whereby the delicate micrometer 58 does not run the risk of damage.

As described in connection with the operation of rotary solenoid 20, the restricted axial motion of the shaft 54 thereof is used to operate the clamp 18. The restricted axial motion of the shaft of solenoid 16 may be used percussively to drive the chisel 56 to notching position 6 by mounting a solenoid 16 with the axis of its shaft in line with the axis of the chisel 56.

What is claimed is:

1. Apparatus for notching a moving wire without substantial interference with the motion thereof comprising a frame, a chisel having a notch producing end and mounted for sliding motion in said frame, means for causing motion of said chisel in a direction such that said notch producing end leads, a stop means mounted on said chisel, cooperative stop means mounted on said frame for stopping motion of said chisel in said direction and means mounted on said frame and resiliently engaged with said cooperative stop means for adjusting said cooperative stop means, a striker plate mounted at a point along the direction of motion of said chisel, means for moving said wire across a surface of said striker plate between said striker plate and said chisel and means for causing the motion of said chisel while said wire is moving.

2. The apparatus of claim 1 in which said cooperative stop means comprises a wedge and said adjusting means includes means for slidably moving said wedge in a direction transversely to the direction of motion of said chisel.

3. The apparatus of claim 2 in which said means for slidably moving said wedge comprises a micrometer screw means comprising a thimble, a barrel and a spindle, means for clamping said barrel to said frame and resilient means for urging said wedge against said thimble.

4. Adjustible means for notching a moving medium comprising a frame, an elongated chisel having a notch producing end and an opposite end and mounted for slidable movement in said frame in the direction of its length, resilient means for urging said chisel in the direction such that said opposite end leads, a stop fixed to said chisel, a wedge mounted on said frame and slidably in a direction perpendicular to the length of said chisel, said stop overlying said wedge, a micrometer having a spindle, a barrel and a thimble, means for clamping said barrel to said frame in such manner that said thimble contacts said wedge, resilient means for urging said wedge in a slidable direction thereof towards said spindle and means for moving said chisel in a direction such that said notch producing end leads.

5. The means of claim 4 in which the means for moving said chisel is a percussive means.

6. The apparatus of claim 5 in which said percussive means comprises a solenoid having a movable pant, said solenoid being mounted on said frame in such manner that upon energization of said solenoid, said movable part hits the said opposite end of said chisel.

7. Apparatus for winding individual grids on a grid stick to which a lateral wire is fed along a path to said grid stick and including a notching mechanism and a clamping mechanism between said notching mechanism and said grid stick, said notching mechanism including a supporting frame, an anvil mounted on said frame adjacent the path of said Wire, a notching tool slidably mounted in the frame on the opposite side of said path from said anvil, percussion means associated with said notching tool for driving said tool toward said anvil for notching said wire, resilient means connected to said tool which is put under compression when said tool is driven. to notching position whereby rapid return of said tool from notching position results, a stop means mounted on said notching tool, cooperative stop means mounted on said frame for stopping movement of said tool toward said anvil, and means mounted :on said frame and resiliently engaged with said cooperative stop means for adjusting said cooperative stop means.

8. Apparatus for winding individual grids in a grid stick to which a lateral wire is fed along a path to said grid stick and including a notching mechanism and a clamping mechanism between said notching mechanism and said grid stick, said notching mechanism including a supporting frame, an anvil mounted in said frame adjacent the path of said wire, a notching tool slidably mounted in the'frame on the opposite side of said path from said anvil, percussion means comprising a solenoid and associated with said notching tool for driving said tool toward said anvil for notching said wire and resilient means connected to said tool which is put under compression when said tool is driven to notching position whereby rapid return of said tool from notching position results, a stop member on said tool having a tapered surface, a stop having a tapered surface cooperating with the tapered surface of said stop member to determine the limit of movement of said tool and the depth of a notch in said wire, and means mounted on said frame and resiliently engaged with said slidable stop for adjusting said slidable stop, means for energizing said solenoid whereby said lateral wire is notched and means for causing clamping of said clamping means after said lateral wire is notched.

9. Apparatus for winding individual grids in a grid stick to which a lateral wire is fed along a path to said grid stick and including a notching mechanism and a clamping mechanism between said notching mechanism and said igrid stick, said notching mechanism including a supporting frame, an anvil mounted on said frame adjacent the path of said wire, a notching tool slidably mounted in the frame on the opposite side of said path from said anvil, percussion means associated with said notching tool for driving said tool toward said anvil for notching said wire and resilient means connected to said tool which is put under compression when said tool is driven to notching position whereby rapid return of said tool from notching position results, a stop member on said tool having a tapered surface, a slidable stop having a tapered surface cooperating with the tapered surface of said stop memher, and means mounted on said frame and resiliently engaged with said slidable stop for adjusting said stop to determine the limit of movement of said tool and the depth of a notch in said Wire, means for energizing said percussion means, whereby said lateral wire is notched and means for causing clamping of said clamping means after said lateral wire is notched.

10. Apparatus for winding individual grids in a grid stick to which a lateral wire is fed along a path to said grid stick and including a notching mechanism and a clamping mechanism between said notchin-g mechanism and said grid stick, said notching mechanism including a supporting frame, an anvil mounted in said frame adjacent the path of said wire, a notching tool slidably mounted in the frame on the opposite side of said path from said anvil, percussion means associated with said notching tool for driving said tool toward said anvil for notching said wire and resilient means connected to said tool which is put under compression when said tool is driven to notching position whereby rapid return of said tool from notching position results, a stop member on said tool having a tapered surface, a slidable stop having a tapered surface cooperating with the tapered surface of said stop member to determine the limit of movement of said tool and the depth of a notch in said wire, micrometer means mounted on said frame and resiliently engaged with said slidable stop for sliding said slidable stop with respect to said stop member, means for energizing said percussion means, whereby said lateral wire is notched and means for causing clamping of said clamping means after said lateral wire is notched.

' 11. Apparatus for notching a moving wire without substantial interference with the movement thereof comprising a frame, a chisel having a notch producing edge and slidably mounted in said frame, means for percussively moving said chisel in the direction such that said notch producing edge leads, resilient means for resisting motion of said chisel in said direction, a stop means mounted on i said chisel, cooperative stop means mounted on said frame for stopping motion of said chisel in said direction, and means mounted on said frame and resiliently engaged with said cooperative stop means for adjusting said lastnamed means, a striker plate mounted at a point along the direction of motion of said chisel, means for moving said wire across a surface of said striker plate between said striker plate and said chisel, and means for causing percussive motion of said chisel while said wire is moving.

12. Apparatus for notching a moving wire without substantial interference with the motion thereof comprising a frame, a chisel mounted in said frame for slidable motion therein and having a notch producing end, resilient means for resisting motion of said chisel in the direction in which said notch producing edge leads, a stop means mounted on said chisel, cooperative stop means mounted on said frame for stopping motion of said chisel in said direction, and means mounted on said frame and resiliently engaged with said cooperative stop means for adjusting said lastnamed means, a solenoid mounted on said frame and having a moving portion, said solenoid being so mounted that the moving portion hits the chisel upon energization of the solenoid to drive said chisel in said direction, a striker plate mounted at a point along the direction of motion of said chisel, means for moving said wire across a surface of said striker plate between said striker plate and said chisel, and means for energizing said solenoid while said wire is moving.

13. Apparatus for notching a moving wire Without substantial interference with the movement thereof comprising a frame, a chisel having a notch producing edge and slidably mounted in said frame, means for percussively moving said chisel in the direction such said notch pro ducing edge leads, resilient means for resisting motion of said chisel in said direction, a stop means mounted on said chisel, cooperative stop means mounted on said frame for stopping motion of said chisel in said direction, and means mounted on said frame and resiliently engaged with said cooperative stop means for adjusting said lastnamed means.

References Cited in the file of this patent UNITED STATES PATENTS 290,695 Lothrop Dec. 25, 1883 1,356,248 Wilcox Oct. 19, 1920* 1,414,939 Dougall May 2, 1922 1,667,184 Ballard Apr. 24, 1928 1,807,679 Winkley June 2, 1931 2,298,528 De Causse Oct. 13, 1942 2,509,956 Benoit May 30, 1950 2,867,824 OC-onner Jan. 13, 1959 2,968,983 Cousino Jan. 24, 1961 3,008,365 McNabb Nov. 14, 1961

Claims

1. APPARATUS FOR NOTCHING A MOVING WIRE WITHOUT SUBSTANTIAL INTERFERENCE WITH THE MOTION THEREOF COMPRISING A FRAME, A CHISEL HAVING A NOTCH PRODUCING END AND MOUNTED FOR SLIDING MOTION IN SAID FRAME, MEANS FOR CAUSING MOTION OF SAID CHISEL IN A DIRECTION SUCH THAT SAID NOTCH PRODUCING END LEADS, A STOP MEANS MOUNTED ON SAID CHISEL COOPERATIVE STOP MEANS MOUNTED ON SAID FRAME FOR STOPPING MOTION OF SAID CHISEL IN SAID DIRECTION AND MEANS