US2868090A - Attachment for internal keyway cutting and slotting - Google Patents

Description

Jan. 13, 1959 D. s. MCCULLOUGH ATTACHMENT FOR INTERNAL KEYWAY CUTTING AND SLOTTING Filed July 18, 1956 7 Sheets-Sheet 1 INVENTOR: DAVID S- MGCULLOQGH,

Lu-MW ATTORNEY I a X 1959 D. s. MCCULLOUGH 2,868,090

ATTACHMENT FOR INTERNAL KEYWAY CUTTING AND SLOTTING Filed July 18, 1956 7 Sheets-Sheet 2 INVENTOR: DAVID S. McCULLOUGH,

Y mmm ATTORNEY Jan. 13, 1959 D. s. m cuLLouel-l 2,868,090

ATTACHMENT FOR INTERNAL KEYWAY CUTTING AND SLOTTING Filed July 18. 1956 7 Sheets-Sheet 3 3 i /l? 35 i 43 1 34 .i

F I G 4, INVENTOR:

DAVID S. MCCULLOUGH,

ATTORNEY Jan.- 13, 1959 D. s. M CULLOUGH 8,

ATTACHMENT FOR INTERNAL KEYWAY CUTTING AND SLOTTING Fiied July 18, 1956 7 Sheets-Sheet 4 INVENTORZ DAVID s. McCULLOUGH,

BY WW ATTORNEY Jan. 13, 1959 D. s. MCCULLOUGH 2,363,090

ATTACHMENT FOR INTERNAL KEYWAY CUTTING AND SLOTTING Filed July 18, 1956' 7 Sheets-Sheet 5 INVENTOR: DAVID 8. M0 CULLOUGH,

ATTORNEY ATTACHMENT FOR INTERNAL KEYWAY CUTTING AND SLOTTING Filed July 18. 1956 Jan. 13, 1959 D. s. MCCULLOUGH 7 Sheets-Sheet 6 INVENTOR DAVID S. MeCULLUL/G/l (Lam d-M ATTORNEY Jan. 13, 1959 D. s. MCCULLOUGH 2,868,090

ATTACHMENT FOR INTERNAL KEYWAY CUTTING AND SLOTTING Filed July 18, 1956 7 Sheets-Sheet 7 INVENTOR DAVID S. McCULLOUGH mmuuw ATTORNEY shaping, slotting, and nibbling.

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ATTACHMENT FOR INTERNAL KEYWAY CUTTING AND SLOTTING Application July 18, 1956, Serial No.- 598,573

3 Claims. (CI. 90-39) This invention relates to means for using a reciprocating tool for such operations as internal keyway cutting, It is an object of this invention to provide an improvement over previously developed devices that offers greater flexibility of use for a wider range of work, avoids the necessity for heavy rigid frames by obtaining its rigidity through new design features, allows greater cuts in relation to its size and horsepower by providing an increased degree of rigidity between the tool and the work.

A second object of this invention is to provide a compact portable device which will add a wide variety of internal keyway cutting and shaping to work done on a lathe, while the work piece is still retained in the same position in the-lathe chuck in which its previous operations such as boring or turning were done.

A third object is to provide a practically universal portable shaper which can be readily carried to perform machining operations in place, including forming slots, developing flat surfaces in vertical and horizontal planes in a single set up, able to use either draw-shaping or pushshaping cutting strokes as may be desired and adaptable in its setup to increase accessibility.

Another object of this invention is to devise a tool capable of being mounted on such machine tools as milling machines and boring mills to convert their rotary spindle action to reciprocating tool use for precise shaping and slotting operations and with greater capacity than previously known devices.

Yet another object is to devise a tool unit for a lathe or similar work-turning machine tool that performs a combination of turning or boring and reciprocating tool action with only one handling and one set-up of the work piece, at the same time increasing the assurance of accurate relationship between circular surfaces and slotted surfaces. Other objects will appear as the specification proceeds.

While it is particularly adapted for use with the portable tool unit described in my Patent No. 2,497,735., its principles may be adapted for use with any source of power that provides spindle rotation drive of proper speeds and torque, and a means for feeding into a cut for use with the portable tool unit.

The device is particularly adapted for use on a lathe where, since its source of power is independent of the lathe spindle, the slotting operation can be immediately subsequent to the boring of a hub without a change in position of the work. However, it may be used similarly on other machine tools that are capable of boring a hole or hub, 01' it may be used for slotting operations on a machine table, work bench, or any place where the work and this device can be rigidly supported. For instance, when combined with a source of power and vertical feed, slotting can be done when the work is held in a vise in such a way that this device can be placed in position to cut.

This device, in the form illustrated, consists generally eat of a frame or housing supporting a rotatable crank with adjustable crank pin, which, cooperating with a rocker arm and ram, produces reciprocating strokes of varied lengths and high-cutting efficiency, and a tool bar adapted for a wide variety of types and sizes of cuts, which cuts may be in virtually any desired direction and angle.

As illustrated, when used on a lathe, it obtains its power from a source independent of the lathe spindle and is adjustable for use mounted on either the front or rear of the lathe carriage and able to make vertical or horizontal cuts in either direction on work, held in the lathe chuck or on the face plate, without changing the set-up in which the work was bored or turned.

As shown, the tool bar and tool holders, which can be'turned for any angle and installed to operate on either side of the device, equip it to become a completely universal shaper when combined with a source of power and a mounting that provides three directions of feeds in relation to each other.

in this environment the novel features relate the particular form and construction of these elements, their relationship to each other, and the method of holding cutting tools, both of itself and as related to the other elements.

in the accompanying drawings:

Figure, 1 shows a front elevation of the attachment.

Figure 1a is a partial view showing two positions of the rocker arm in producing a reciprocating stroke.

Figure 2 shows a side view of the tool unit, with parts of the attachment in section on the line 22 of Figure l, and mounted on a basic tool unit such as described in Patent No. 2,497,735, which supplies the rotating drive for the crank and vertical feed.

Figure -3 shows a side elevation of the attachment viewed from the same position as Figure 2.

Figure 4 shows apart of Figure 1, with a partial sectional view of the ram and tool bar with a different type tool held in the opposite end than in Figure 1.

Figure 5 shows a side elevational view of a tool head having means for relieving tool on the return stroke.

Figure 6 shows a plan view of the showing in Figure 5.

Figure 7 is a partial sectional view of the device of Figures 5 and 6.

Figure 8 shows a modification.

Figure 9 shows an enlarged view of the tool holder assembly shown in Figures 5, 6, and 7.

Figure 10 shows an exploded view of Figure 9.

Figure 11 shows the device mounted on a lathe in position to cut an internal keyway in the bore of a work piece.

Figure 12 shows the device ready for use as a portable shaper combined with a portable tool unit and a feed table as shown in my Patent No. 2,497,735.

As will be seen in Figures 1, 2, and 3, 1 is a frame which is attached to the face of the housing 2 of the basic tool unit. The frame 1 serves as a housing to surround and protect'such parts as crank 13, crank pin 9, sliding crank block 10, rocker arm 6 having a slot 24 providing guide surfaces for the crank block, and pivot 8, which together create the reciprocating motion which is applied to a smooth-bored ram 3 and through the ram 3 to a tool bar 22 held in the bore of the ram. As will be seen in Figures 1, 2, and 3, the ram 3 is, in effect, a clamp surrounding the tool bar 22. Clamping of the tool bar may be effected by any conventional means such as slot 16 and lock screws 25, as shown, or by a set screw. The ram is guided during its reciprocating movement and retained in a predetermined and precise path tangent to a circle surrounding the axis of the crank 13 by the male dovetail portion 17 of the ram 3, which slides in female dovetail slot 18 formed in ram-guiding slide 4.

The slide 4 provides an adjusted fit to the dovetail 17, by means of the gib 5, the gib retaining surface 5, and end adjusting screw '7; as the crank 13 is revolved, the crank pin 9 travels in a circle and the rocker arm 6, ram 3, and tool bar 22, move in a reciprocating fashion, while the angle of path of the ram 3 and tool bar 22 is determined by the position of the housing 1 to which is attached the dovetail ram guide means 4. If housing is turned in relation to base 23, the path of the tool bar will be at a corresponding angle, and therefore an angled cut or tapered keyway may be cut.

The housing frame 1, with its associated assembly so far described, comprises an attachment to be motivated by some motor-driven assembly or basic tool unit that may be characterized by that shown in my Patent No. 2,497,735, dated February 14, 1959. Figure 2 of the drawings of this specification shows the cutting and slotting attachment of this invention in an environment best illustrated by Figure 2 of that patent. Taken from that figure, are the base 20, the screw 32 and the handle 33; also motor 60 driving belt 61 around pulley 62 that drives worm 63 that in turn drives worm-gear 64 whose rotation rotates sleeve 65. Fitted into the sleeve 65 is a tapered shank of the drive spindle 66 that carries the crank 13 of this invention. In that patent, corresponding reference numerals are 100 equals 60 of this case; 119 equals 61 of this case; 118 equals 62 of this case; 46 equals 63 of this case; 68 equals 64 of this case; 67 equals 65 of this case; 90 equals 66 of this case; 21 equals 32 of this case; and 26' equals 33 of this case.

It will also be seen that the length of the reciprocating stroke of the ram 3 is determined by the position of the crank pin 9 and the radius of the circle it describes, as the crank 13 is rotated by drive spindle 66. The greater the radius of the circle of the path of crank pin 9, the longer will be the stroke of the ram 3.

The crank pin 9 carried by crank pin block may be moved adjustably along the crank in its slot 19 that is T-shaped in cross section, and locked in such adjusted position by pin bolt 14- and its nut 12. Pins 21 and 21 act as stops for preventing the crank pin block 10 from leaving the slot 19. Since the position of the crank pin 9 in relation to the axis of the crank is thus adjustable,

the length of the reciprocating stroke is thereby selectively controllable.

The tool bar 22 may be adjusted in its position by releasing the clamping action provided by the ram 3. This adjusting of position may consist of rotation of the bar around its own axis, so that a cutting tool or tool bit such as 35 may be moved to a new position such as shown at 35', or to any other position in a complete circle, or the change in position may be longitudinal by sliding the tool bar to bring the tool either nearer to or farther removed from the ram 3. Still another change in position is accomplished by removing the bar and reversing it end for end. Each of these kinds of position changes has a valuable use for the application of this type of tool, which will be explained later.

In Figure 1 the tool holder 34 consists of a small diameter bar combined with a tapered shank seated in a tapered socket 23 of the tool bar 22 with the threaded retention means 47, which co-operates with a draw bar 46 to keep the tool holder in position in the tool bar 22.

In Figure 4, the locking screw 53 holds the tool bit 52 in place. When this type iof tool is used, the tool bar is reversed to expose that end of the tool bar to the work that is adapted for holding this tool type.

When tools such as shown in Figure 4 are used, the ram may be locked in any desired position by means of the lock screw 48 which engages the ram guiding slide 4 when properly adjusted. With a tool bit ground for boring, the same device may be used when held in a stationary position for boring or turning the hub with the work turned in the manner usual on a lathe, the tool bar 22 now serving as a boring bar which has been adjusted in position and length as described above.

It can be seen that position of tool 52 in relation to ram 3 and to the ram guide 4 may be varied to conform to the depth of the bore of a work piece either by moving the tool bar longitudinally in the ram, or by moving the ram before locking in place.

It can be seen that the housing 1, together with the entire attachment described above may be moved in relation to the base 20 of the basic tool unit 2 by rotating the screw 32 by such means as the handle 33. The position and rate of change of position of the tool bar 22 is controlled by the handle 33.

The reciprocating cutting action of this tool attachment may be accomplished by pulling a tool across the work and shaving or planing ofi a chip in the same manner as is known for a draw shaper; or it may be accomplished by pushing the tool in a manner common to conventional shapers. The depth of cut is determined and controlled by moving the tool bar 22 in the direction in which the cut is being made. This travel may be vertical, either upward or downward by rotating the handle 33, and the screw 32; or it may be horizontal by moving either the base 20 or the work piece by means of a device such as a machine tool table or a portable feed table as shown in Figure 12.

When cutting a slot the width of the cutting tool, the tool bar 22 is turned so that the cutting tool such as 35 in Figure l, or 41 in Figures 5, 6, and 7 is in line with the direction of feed. However, in planing a flat surface wider than the cutting tool, the tool bar 22 is turned, as shown in Figure 12, so that the tool in a holder of a tool relieving type, such as illustrated is at an angle to the plane surface being formed and is fed sidewise in the direction of the angle so that the tool will be relieved from both the plane surface and the still-to-be-cut side on the return strokes, reducing the force needed on return strokes and wear on the tool.

The purpose of being able to rotate the tool bar 22 to obtain the many positions needed for the tool is now apparent.

Figures 5, 6, 7, 9, and 10 show an arrangement that may be used for supporting a tool or tool bit, in cutting position. In Figures 5, 6, 9, and 10, the cutter is in the preferable position for use in cutting internal keyways and slots where the work and the tool are mounted on alathe.

It will be seen that the cutting edge of the tool is toward the crank action of the device in position for a draw-shaper type of cut. This permits positioning the butt surface 70 against the work piece 71 as shown in Figure 11, removing any strain from the lathe cross slide 72 and providing greater mutual rigidity between the device and the work piece than would be the case if the cross slide would have to resist the separation force that would result from a push-shaper type of cut. Since my invention contemplates use of a source of power independent of the lathe spindle, the work piece 71 remains held in the lathe chuck 73 in which it was bored.

The tool in the upward position and fed upward, results in a downward thrust from the work, which assists in keeping the lathe carriage on which the basic tool unit is usually mounted, firmly on the ways of the lathe bed. This increases rigidity and, therefore, the rate of cut and degree of precision as compared to the condition that would exist with the cutter extending down which would tend to lift the device, as well 'as' the lathe carriage.

It can now be seen that the combination of draw cuts and cutting upward presents an improved condition for cutting keyways on a lathe resulting in greater rigidity, and therefore, the ability to take heavier and more precise cuts.

Figures 5 and 6 show a tool holder 40, a cutting tool or tool bit 41, a tool holder bracket 36 with free-ended 11135136 and 36", and-apivotrpin @7. It will be seen that with. such .an arrangement, the tool bit and holding assemblymay enter a hole or bore only slightly greater in diameter than the bracket.

Thetool head 44 is so positioned in the bracket 36 that its arc of pivot is limited by the surface 38. The corner 39 in contact with the surface 38 maintains the tool bit 41 upright incutting position on the cutting or pulling stroke. However, on the'ret-urn stroke the open area permits the tool head to pivot around 37, and so relieve the edge of the tool bit when returning to position to start a new cutting stroke. A relief cover plate is shown at 51 for protecting the space between the parts 44 and 40 from cuttings.

This arrangement provides the advantageof being able to extend the cutting tool into comparatively small bores, relieving the tool in approximately the plane in which the tool is cutting, and thereby reducing the power used on the return stroke and avoiding the dulling action to the cutting edge which results when no relieving action takes place, which is common to all shapers which have clapper box action outside of the bore in which a keyway is cut.

In Figure 8 the arrangement provides for cutting downward when the tool is used other than on a lathe.

In such cases, it is usual to bolt or clamp the base 20 of the basic tool unit firmly to a supporting surface to resist an upward thrust resulting from the resistance of the work to entry of the tool bit. The modified tool head 44' serves the same use as 44, to'support and position the cutting tool 42 during the pulling or cutting stroke and to provide a means to pivot the cutting tool or hit 4-2 to relieve the cutting edge on the returnstroke.

In Figure 5 the cutting :toolor bit 41, as shown, may be invertedand reversed, putting the cutting edge down and forward. This position provides for cutting with a pushing .shaper action when this is necessary, such as blind holes accessible only from the side next to the tool, or blind keyways, opening on the same side as is the tool. When the tool holder assembly ofFigure 5 is operated as a pusher shaper action, the feed for the cut is also reversed, feed now being downward for cutting action.

In either direction of cutting or feeding, the advantages of pivoting the tool within the hole, or bore of the work, are obtained.

Note, however, in Figure l, and particularly in Figure la that in producing the reciprocating strokes, that the crank pin d, and crank pin block travel approximately threequarters of the way around a circle to make astroke of ram 3 in one direction and only the remaining quarter of ,the circle to cause the return stroke. Because the pivot 8 for the rocker arm 6 is mounted on the housing outside of the circular path of the crank pin 9, the stroke made while the crank pin is on the side of the circle away from the pivot will always be slower than the stroke in the opposite direction, as the crank pin has a longer path to travel and the rate of crank rotation on any one revolution is constant.

It can be seen that the slower stroke has greater force and power. The resultant force on the ram and through it to the tool is also greater. The slower stroke is there fore used for the cutting stroke. It can be seen that by reversing the rotation of the crank 19, the direction {in which the ram and tool travel on the slow or cutting stroke is also reversed.

When a change is made from draw-cutting to pushcutting, the rotation of crank 19 is reversed, so that the direction of the slow, powerful stroke will again be in he directionof the cut made by cutter 41.

The arrangement of crank 19, crank pin 9, block 10, rocker arm 6, and ram 3 to move a tool bar and tool produces much greater cutting capacity from the same amount of power than do devices having pitman rod methods for producing reciprocating strokes, since in the 6 latter method the time for the cutt-ing-stroke isthe same as the time for the return stroke. It can be noted that having the ram travel perpendicular to a circle surrounding a crank axis results in thestrokes in either direction being of equal time andleverage, and permits no such relationship between cutting and return stroke as is otfered by my device.

Under optimum conditions, a device employing the principlesof my invention will develop a 60 percentmore powerful stroke than-can be obtained from the same source of power by adevice with a ram path perpendicular the circle of the crank pinpath.

Since the efiect of adeflecting force, such as the re sistance of the work to allow the tool to enter to make a cut, increases greatly as the distance from the point of support, it is important that cutting tools, such as 35 and 41 and 52 can be kept as close to the frame housing 1 as is consistent with thelength of cut required. Therefore, the tool bar 22 is adjusted axially in order to provide the most efiicient cutter position in relation to the stroke length.

The clamping action of the lock screws 25 in locking the tool bar 22 in the ram 3, permits positioning a cutter such as 41, -no further away from rigid support of the ram guide 4 than is needed to perform the cut.

It may be desirable to do the slotting with the work to the right of the attachment as shown inFigure 1. This would be the case when the unit is used mounted on the front of the carriage of a lathe with the work held in the lathechuck as shown in Figure 11.

If, however, it was preferred that the tool unit be mounted on the rear of the-lathe carriage in order to retain the lathe tool post in its usual position, then the work would be on the opposite sideof the tool unit. In such a case, the tool bar would be reversed end for end to providefor cutting on the alternate side.

In order to keep overhang, and, therefore, deflection at a minimum, ram-guide or slide 4 containing the dovetail surfaces 18 and gib-5, in which the ram 3 rides and slides, is so arranged that it may be detached from the housing, moved toward the opposite side, and mounted so that it extends in the opposite direction as is shown in Figure 1, by the dotted lines 4'.

This reversal is permitted by pairs of screws 26 and 27 between which is a dowel 28, and a duplicate arrangement 26, 27, and 28'.

By accomplishing this change of position of gib slide 4 with the end-for-end reversal of the tool bar 22 described above, and-reversal of the direction of rotation of the crank 13, a full reversal of cutting action from one side to the other is accomplished. This not only permits use of the tool unit on either the front or back of the lathe carriage to cut work held in the lathes chuck, but also gains added accessibility to work when mounted on a portable feed device as shown in Figure 12, in places other than on lathes, since the interference normally offered by source of power may be disposed where it offers the least interference or obstruction.

It can be seen the one end of the ram guide 4 is in the same plane as the side of the housing 1, while the opposite end of the guide 4 extends to provide for full travel of the ram 3. By positioning the device so that the end of the ram guide 4 is against the work and using a draw out to make a cut, great rigidity in relation to its weight and size is obtained; as in making a cut, the tool bar is in tension, and the reaction force of this pull is offset by an equal pushing force of the end of the ram guide against the work.

This balancing of a pushing force with a pulling force is available with the device, whether used on a lathe as in Figure ll, as a portable shaper independent of any fixed machine tool as in Figure 12; or as a slotting attachment driven by the spindle of a milling machine. In each such case, the device is positioned against the work piece, and the tool bar is adjusted axially to be in proper position to make the required cut.

By referring to Figure 12, it can be seen that this device can serve as a fully universal portable shaper. When combined with a source of power and vertical feed and mounted on a feed table providing longitudinal and cross feed in even a single set-up, slots or fiat surfaces may be cut vertically up or down, and horizontally in either direction, at either side of the assembly. The devices shown in Figure 12 are similar to those described in my Patent No. 2,497,735, and the adjustments or methods needed have previously been described in this application.

In Figure 12, the base 74 may be bolted or clamped to whatever support is convenient to the Work to be done. The lower carriage 76 is moved along the base by the lead screw 75. The upper carriage 77 may be similarly moved for cross feed over the carriage 76. The base 20 is attached to the upper carriage 76. The lead screw 32, operated by crank 33, will feed the housing 2 either up or down. The device, as indicated by the housing 1, ram 3, and tool head 44, moves with housing 2. The tool head and cutter 42, positioned at the angle as shown, are adapted for cutting a plane surface which may be as Wide as the total travel available along the base 74. By rotating the tool bar, as previously described, to bring the cutter into various positions, cuts in other directions may be made without moving any of the major assemblies of the set-up.

It may be seen in Figures 1 and 4 that the outer surface of the tool bar 22 is unbroken fro-m the position for the tool bit 35 to the opposite end. This permits the tool bar to be rotated freely when the clamp is released, and also provides a smooth, unbroken bearing surface no matter what axial position is chosen for the tool bar. There are, however, four longitudinal scribed lines which are used for referencing the position of the bar 22 and tool bits such as 35 and 41 and 52. These lines may be referenced from a line 43 in the ram 3, which is perpendicular with the face of the basic unit housing Thus, by this invention, there is provided a portable shaper or slotter attachment adapted as a device for cuting internal keyways and other slots in a wide range of sizes of bores because of the adjustability of: length of stroke; effective length of tool bar; and diameter of the tool bit support. Such an apparatus is of remarkably light weight by avoiding the necessity of bulky cast frames for rigidity, and yet capable of making heavy precision cuts. Also provided is a device of great flexibility and ccessibility to the work in its reversible features both as to machine setup and in direction of stroke.

As this invention may be embodied-in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is, therefore, illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within the mate; and bounds of the claims or that form their functional as well as conjointly co-operative equivalents, are, therefore, intended to be embraced by those claims.

I claim:

1. A portable tool unit for reciprocating a tool adapted to have a work piece positioned relative thereto, comprising a vertical supporting structure adapted to be mounted on a base by means of instrumentalities providing for the adjustment of said structure thereon in a horizontally longitudinal as well as a horizontally transverse direction with a supporting bracket vertically adjustable on said structure and feed means for effecting such adjustment, a frame mounted on said bracket to constitute an overhang, a rotatable crank operating in a vertical plane, a crank pin, a'rocker arm oscillatable by the crank pin to generate a reciprocating motion, a pivot mounted above the path of said crank on the frame on which the rocker arm turns, a horizontal guide structure connected to the frame and having guide means tangent to the bottom of a circle surrounding the axis of the crank, a ram movable along said guide means by the rocker arm, a reversible cutting tool positionable for push-cutting or draw-cutting, means for supporting the tool from the ram, and means for reversing rotation of the crank, whereby said cutting tool is employable for push-cutting as well as for drawcutting of longitudinal grooves in said work piece.

2. A tool unit for reciprocating a tool on a lathe having a source of power independent of the lathe spindle, a frame, a rotatable crank, a crank pin adjustable in position on the crank, a rocker arm for co-operating with the crank pin to generate a reciprocating motion, a pivot mounted on the frame on which the rocker arm turns, a guide surface tangent to a circle surrounding the axis of the crank, and a ram movable along the guide surface by the rocker arm, a tool bar carried by the ram, a cutting tool carried by the tool bar, and means for adjustably clamping the tool bar in the ram whereby the tool bar may be moved axially in respect to the ram, said tool bar being mounted in the ram adapted to be reversed end for end in its clamping means, so that different tool mountings may be provided at either end to absorb respective differently directed cutting pressures, the tool unit including means for reversing rotation of the crank, said cutting tool being reversible and thereby employable for push-cutting as well as for draw-cutting of longitudinal grooves in the work.

3. A tool unit adapted to have a work piece positioned relative thereto in the chuck of a lathe for reciprocating a tool comprising a vertical supporting structure adapted to be mounted on the carriage of the lathe by means of instrumentalities providing for the adjustment of such structure thereon in a horizontally longitudinal and a horizontally transverse direction, with a supporting bracket vertically adjustable on said structure and feed means for effecting such adjustment, a frame mounted on said bracket, a rotatable crank operating in a vertical plane, a crank pin thereon, a rocker arm oscillatable by the crank pin to generate a reciprocating motion, a pivot mounted on the frame on which the rocker arm turns, a horizontal guide structure connected to the frame and having guide means tangent to the bottom of a circle surrounding the axis of the crank, a ram movable along the guide means by the rocker arm, a tool bar carried by the ram longitudinally adjustable thereon, and a pivoted toolholder carried at the end of the tool bar, which tool-holder provides means for positioning the cutting edge of a tool on either side of the pivot axis, said vertical structure being movable with the carriage longitudinally of the lathe and providing bracing contact for said frame with said chuck whereby the mounting of said frame is rigidified incident to upwardly directed draw-cutting operation.

References Cited in the file of this patent UNITED STATES PATENTS 64,388 Webster Apr. 30, 1867 890,780 Lutter et a1 June 16, 1908 1,504,133 Mueller Aug. 5, 1924 1,661,509 Skinner Mar. 6, 1928 2,408,876 Pigott et al. Oct. 8, 1946 2,474,877 Wilson July 5, 1949 2,596,695 Keller May 13, 1952 2,604,020 Cook July 22, 1952 2,697,383 Klopp Dec. 21, 1954 FOREIGN PATENTS 252,589 Switzerland Oct. 1, 1948 263,169 Germany Aug. 2, 1913 1,029,245 France Mar. 4, 1953

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