GB2322317A - Oscillatory motion device for a drill press - Google Patents

Abstract

An oscillatory motion device 270 for a drill press 10 includes a power take-off with a pair of pulley 84,86 connected to one another by one belt 88 and to one of the pulley of the drill press by another belt. The driven power take-off pulley rotates a shaft 314 driving a worm gear 313. An eccentrically mounted arm (328 Fig 3) is rotated by the worm gear and converts rotary motion into a reciprocating linear motion. An actuator 276 of the device is movably mounted and has one end engaged with the quill 42 of the drill press and an opposing end coupled with the eccentric arm. Reciprocation of the arm causes linear movement of the actuator, quill, chuck and any tool (11 Fig 1) held in the chuck. A dust evacuator (Figs 4-9) can be mounted to the bottom of the table. A generally flatter, inlet or suction end of the evacuator is recessed to conform to the curvature of a central opening through the table.

Description

TITLE Oscillatory Motion Device for Drill Press BACKGROUND OF THE INVENTION Drill presses are most commonly used for drilling holes in materials. Drill presses can be used for other modes of material removal. A material removal tool other than a drill, for example a drum sander, can be rotated by the chuck of the drill. Only a relatively small portion of the tool may make contact with the workpiece. Deep horizontal grooves can be formed in the workpiece by particles of abrasive materials of the drum sander becoming disengaged. Also, parts of the drum sander always in contact with the workpiece fill very quickly. This requires the drum sander to be cleaned or repositioned or replaced.

These problems can be reduced by manually rocking the feed lever of the drill press so that the chuck and drum sander move up and down. Although manual rocking does reduce some of the above problems, it depends upon the dexterity of an operator to simultaneously move the workpiece and rock the feed lever.

A kit to modify a drill press to automatically provide an oscillating motion of the tool is disclosed in U.S. Patent 5,402,605. This kit includes a separate motor mounted on the drill press column. The motor drives an offset wheel which supports a connecting rod coupled with the wheel and a spoke of the drill press feed lever. Rotation of the offset wheel causes an oscillating motion of the connecting rod and a corresponding oscillating motion of the spoke and feed lever.

U.S. Patent 5,525,099 discloses an oscillation device which is mounted on the quill for vertical movement with the quill. The device is driven by the driven shaft supporting the chuck and eliminates the cost of an extra motor. The device is supported fully outside the head but close to the chuck. Because of its size, the device must be located on the side of the drill press head opposite the feed lever. Since the device rises and falls with the chuck, it is difficult to bring large work pieces of even modest height close a drum sander tool in the chuck.

BRIEF SUMMARY OF THE INVENTION In one aspect, the invention is, in a drill press including a motor having an output shaft, a quill supported for linear axial movement, a driven shaft having a central longitudinal axis and being supported for rotation within the quill and for linear axial movement with the quill, a chuck mounted on one end of the driven shaft and a first drive coupling between the output shaft and a remaining end of the driven shaft, an oscillatory motion device comprising: a rotating power take-off most directly coupled with and driven by one of the output shaft and the first drive coupling; an actuator member having a first end coupled with the quill and a second end, the actuator member being supported for linear movement with the quill; and a second drive coupling operatively located between the second end of the actuator member and the rotating power take-off.

In one aspect, the invention is, in a drill press, a device for imparting oscillatory motion to a shaft mounted for rotation within and for axial movement with an axially movable quill of a drill press, the device comprising a rigid frame; an input shaft rotatably supported on the frame; a lever movably mounted to the frame and having one end projecting sufficiently from the frame to engage an axially movable quill of a drill press; a drive coupling between the rotatably supported input shaft and the movably mounted lever; a pulley mounted for rotation on the input shaft; and a clutch mounted to selectively engage the pulley with the input shaft.

In another aspect, the invention is, in a drill press including a chuck to receive a tool and a table located beneath the chuck to support a work piece, the table having a central opening to receive the tool in the chuck, a dust evacuator attached to the bottom of the table, the dust evacuator being formed by a pair of mated semi-tubular shells, an inlet end of the evacuator being located beneath the table opening and generally rectangular in shape with a pair of arcuate cutouts having generally the same curvature as the table opening and an opposing outlet end more circular in shape to receive a circular vacuum hose.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS In the drawings, which are diagrammatic: Fig. 1 is a perspective view of a conventional multi-speed drill press with one oscillatory motion device of the present invention; Fig. 2 is a broken away side view of the oscillatory motion device and drill press of Fig. 1; Fig. 3 is a partially broken away top view of the oscillatory device of Fig. 2; Figs. 4 is a top view of a dust evacuator shell; Figs. 5, 6, and 7 are section views taken along lines 5-5, 6-6, and 7-7, respectively, in Fig. 4; Fig. 8 is a perspective exploded view of a pair of the dust evacuator shells of Figs. 4 through 7 mated together and mounted to the underside of a work table; Fig. 9 is a broken away side view of the table of Fig. 8 with mounted dust evacuator.

Fig. 10 is a perspective view of a multi-speed drill press with a second, fully internal, clutch equipped oscillatory motion device; Figs. 11 and 12 are simplified side and local top views, respectively, of the clutch equipped oscillatory motion device installed in the drill press of Fig. 10; Figs. 13 and 14 depict the clutch of Figs. 1112 in engaged and disengaged positions, respectively.

DETAILED DESCRIPTION OF THE INVENTION Referring to Fig. 1, a drill press 10 comprises a base 12, a column 14, an arm 16, a crank 18 to vary the height of the arm 16 on the column 14, a work table 20 movably supported on the column through arm 16 and a lever 19 for locking the table 20 to the column. Table 20 has a central circular opening 20A to receive a tool 11 such as a drum sander or an insert 21 with central opening sized to closely receive tool 11. A feed or pilot lever 22 with spokes 24 is provided for moving the chuck 30 and any tool supported in the chuck 30 up and down.

A "head" 25 is mounted on column 14. Head 25 includes a head casting 26, an upper housing 28 on the casting 26 and a removable cover 29 on the upper housing 28. Head casting 26 movably supports a quill assembly or simply "quill" 42. Upper housing 28 and removable cover 29 enclose a first or primary drive connection of the drill press 10, which is between a driven (or "spline") shaft 40 supporting the chuck 30 and the drive motor 34. Motor 34 is supported from the head casting 26 as shown or from column 14 (not shown). Motor 34 is on an opposing side of the column 14 from the driven shaft 40 and chuck 30.

In Fig. 2, the driven shaft 40 is received in one end of a pulley drive sleeve 44 (in phantom), which is supported for rotation in the head 25. Bearings and associated coupling and clamping components, which are conventional, are omitted. The pulley drive sleeve 44 is internally splined to drivingly couple with splines on the upper end of driven shaft 40. The splines of the drive sleeve 44 and driven shaft 40 remain engaged over the range of vertical, axial movement of the driven shaft 40 with quill 42.

The quill assembly includes a tubular member 43 which receives the driven shaft 40 and which supports the driven shaft for rotation on bearings (not depicted) in the tubular member 43 in a conventional manner. The driven shaft 40 and its attached chuck 30 are mounted for rotation within and for linear axial movement with the quill 42.

The chuck 30 is mounted on the lower end of the driven shaft 40 projecting from the quill tubular member 43. The quill assembly 42 also includes a rack 50 on the tubular member 43, which cooperates with a pinion 51 driven by the feed lever 22 (all in phantom in Fig. 2). The tubular member 43 is upwardly biased by a return spring 52 seated in a cup 54A fixed to member 43, and in a cup 54B attached to or part of the head casting 26. To lower the chuck 30, the feed lever 22 (Fig. 1) is rotated by any of its spokes 24 to rotate pinion 51 thereby forcing the tubular member 43 downward compressing the spring 52. Upon release of the spoke(s) 24, spring 52 expands and elevates the tubular member 43 back to its original, nominal position.

In Figs. 1 and 2, motor 34 has an output shaft 56, which is generally parallel to and laterally spaced apart from the driven shaft 40. Motor output shaft 56 enters the upper housing/cover 28/29, where it drives a first cone pulley 60 mounted on and coupled with shaft 56. In Fig. 2, a second cone pulley 62 is fixedly attached to the pulley drive sleeve 44 above the quill 42. A flexible coupling member in the form of a belt 64 (Figs. 1 and 2) is extended around the first and second cone pulleys 60 and 62, drivingly coupling the pulleys together. The cone pulleys 60, 62 and belt 64 collectively constitute the major components of the first or primary drive coupling 58 of drill press 10, which is provided between the output shaft 56 and the driven shaft 40.

Added to the basic components of drill press 10 is the oscillatory motion device of the present invention, which is indicated generally at 270 in Figs.

1-3, and a rotating power take-off, which is indicated generally at 272 in Figs. 2 and 3. Device 270 is coupled with quill 42 and cyclically reciprocates the quill 42 in an axial (vertical) direction, thereby oscillating chuck 30 up and down as the chuck rotates.

The rotating power take-off 272 can be driven by any of the coupled together output shaft 56, first drive coupling 58 or driven shaft 40 but preferably is most directly coupled with and driven from the motor output shaft 56 or the first drive coupling 58 for safety and convenience. It should further be recognized that other, known, alternative drive couplings may be used to take rotary power from the motor output shaft 56, the driven shaft 40 or the first drive coupling including but not limited to gears, other types of pulleys, cranks, rigid and/or flexible shafts, cables, chains and other conventional mechanical elements and even hydraulic couplings.

The rotating power take-off 272 includes a first take-off pulley 284 coupled with the second cone pulley 62 or the pulley drive sleeve 44, if accessible, for rotation in common with the second cone pulley, the pulley drive sleeve and the driven shaft, all on a common vertical axis 40A. The rotating power take-off 272 further comprises a flexible coupling member in the form of an endless flexible belt 88 extended between and around take-off pulleys 84 and 86, drivingly coupling the pulleys together. If desired, a step of the second cone pulley 62 might be used as the first take-off pulley or the second cone pulley might be supplied with an extra step in comparison to the first cone pulley just for that purpose.

Device 270 further preferably includes a mounting plate 273 and a chambered body 274 which forms a rigid frame of the device 270 on which movable components of the device are mounted. The second takeoff pulley 286 is fixedly mounted to one end of an input shaft 314. Shaft 314 forms one end of a second drive coupling indicated generally at 290, which converts the horizontal rotation of the second take-off pulley 286 into an oscillating up and down motion of an end 276A of an actuator member, which is preferably in the form of a link 276.

The second drive coupling 290 is preferably further provided by a first gear on shaft 314, preferably a worm 308, and a second gear, preferably a worm gear 310 engaged with the worm 308. Input shaft 314 is supported on ball bearings 302, 303 in the body 274. Worm gear 310 is mounted on a hollow worm gear shaft 311 and is supported in sleeve bearings 312, 313.

An eccentric is provided, in part, by a rotary member 324, which is fixed on shaft 326 passing through the hollow worm gear shaft 311. The rotary member 324 contacts and is frictionally coupled with the contacted end of the worm gear shaft 311 by means of a detent plate 316 and a coil spring 318 (in phantom). The coil spring surrounds a threaded projecting end of the shaft 326 and is compressed by means of a washer 320 and a pair of nuts 322. The compressed coil spring 318 pulls the rotary member 324 firmly against the worm gear shaft 311. The shaft 326 is supported by sleeve bearings 326a, 326b within the shaft 311.

Referring to Fig. 3, an arm 328 is mounted at an off-center location on the rotary member 324 to define an eccentric drive member which revolves around the axial center line 310A of rotary member 324. A pair of guide rods 304, 305 extend vertically through the body 274, perpendicular to and on opposite sides of the center line 310A of the shaft 326. Guide rods 304, 305 support link 276 for oscillating vertical motion.

The link 276 includes a pair of opposing sleeves 276A, 276B, a vertical arm 276C (Fig. 2) with an elongated horizontal slot 276D (Fig. 3), and a horizontal arm 276E (Fig. 2) generally perpendicular to the vertical arm 276C. The lower end of the horizontal arm 276E is provided with a clevis or fork 276F, which is received in a circumferential slot 242A provided around the exposed lower end of the tubular member 43 of quill 42. The arm 328 may be provided by a shoulder bolt, which is passed through the elongated horizontal slot 276D, thereby directly coupling link 276 with the rotary member 324. Horizontal slot 276D causes the rotational motion of worm gear 310, shaft 326 and rotary member 324 with eccentric drive member/bolt 328 to be converted into a linear up and down oscillatory motion of the link 276 on guide rods 304, 305 and of the engaged quill 42.

The mounting of the oscillatory motion device 270 to drill press 210 is best explained with respect to Fig. 3. Machine screws 280 are passed through bores in the mounting plate 273 and into the front end face of the head casting 26. Another set of machine screws 282 are extended in the opposite direction through mounting plate 273 on either side of the head casting 26, and into the vertical outer sidewalls of the body 274.

As can also best be seen in Fig. 3, the first drive pulley 84 is located along the longitudinal center line 27 of the head casting 26, which is also the longitudinal centerline of upper housing 28 and removable cover 29, the worm gear 310, shaft 311, and rotary member 324. The second take-off pulley 86 (phantom), input shaft 314 and worm 308 are located off the longitudinal center line 27. The second take-off pulley 86 partially overlaps the lowermost stage of the second cone pulley 62 to reduce the volume taken up by the device 270. The only moving part of the device 270 which is exposed is the bottom of link 276.

Referring now to another aspect of the invention, Figs. 4 through 7 depict in varying views, a generally semi-tubular shell 350. Shell 350 has a first, inlet or suction end 352 and a second, opposing, outlet or exhaust end 354. The inlet or suction end 352 is formed by a generally rectangular, U-shaped channel portion at 356 which transitions into a generally semicircular or slightly semi-conical shaped channel portion at 358. Mounting flanges 361-364 project outwardly from the lateral sidewalls of the U-shaped channel portion 356 with a pair of the flanges 361, 362 being located at the inlet end 352. Flanges 363, 364 at the end of the U-shaped channel portion 356 adjoin the generally semiconical shaped channel portion 358. The inlet end 352 is further provided with a semi-circular recess 366.

The semi-conical shaped channel portion 358 reduces in size as it extends away from the adjoining U-shaped channel portion 356 toward the outlet or exhaust end 354.

As seen in Figs. 8 and 9, a pair of the identical semi-tubular shells 350 are secured together with the open hollow interior of each shell 350 face-toface with that of the other to form a generally tubular dust evacuator 370 (Fig. 9). Evacuator 370 is mounted to the lower side 372 of work table 20 by machine screws 374 received in threaded bosses 376. An inlet or suction open end 372 of the evacuator is defined by adjoining first ends 352 of each shell 350. End 372 adjoins the opening 20A through the work table 320. Second ends 354 of the shells collectively define an outlet or exhaust end 384 of the evacuator 370. The base wall of each shell 350 bearing the recess 366 forms one of the sidewalls of the evacuator 370 proximal to and distal to the work table 320. Each recess 366 at least generally conforms to the curvature of the work table opening 320A adjoining the first end 382 of the evacuator so that the first end 382 can be located as closely as possible to any tool passing through opening 320A, without interference.

Preferably, the effective orifice of the joined together shells 350 at their inlet ends 352 is less than the effective orifice of joined together shells 350 at their outlet ends 354 to provide a Venturi effect at the inlet or suction end 382 of evacuator 370.

The circular open area at the outlet end 384 of evacuator 370 should be at least as great as the cross sectional open area at the inlet end 382. The outlet 384 end of evacuator 370 is exposed sufficiently from work table 320 to receive and mate with a comparably sized flexible vacuum hose. Preferably the second end 384 is slightly conical in shape and varies in diameter from just under to just over two inches (five centimeters) so as to wedge fit with a standard, twoinch (five centimeter) diameter flexible hose typically provided on shop vacuums in the United States. When coupled with a vacuum, evacuator 370 will suction dust and chips produced during sanding, rasping, filing or other material removing operations.

Fig. 10 depicts a conventional, multispeed drill press 10' which incorporates a second, fully internal, clutch equipped oscillatory motion device of the present invention. Apart from a slightly modified work table 20', drill press 10' has the same elements of drill press 10 of Fig. 1. Table 20' has a cutout or curved recess 20B along one outer side to receive tool 11. Cutout 20B can be positioned under tool 11 and chuck 30 by making arm 16 partially pivotable on column 14 or table 20B pivotable on arm 16. The curvature of recess 20B varies to accommodate tools of varying sizes.

Figs. 11 and 12 depict diagrammatically an second, clutch equipped oscillatory motion device 70 located fully within the drill press upper housing and cover 28, 29 of Fig. 10, which are omitted in Figs. 11 and 12 for clarity. Drive motor 34 with motor output shaft 56 supports a modified first, drive cone pulley 60'. A modified second, driven cone pulley 62' is attached to the pulley drive sleeve 44 above quill 42.

Pulleys 60' and 62' can be connected together by a single belt (not shown). Alternatively, an idler cone pulley 64' is provided longitudinally between the first and second, drive and driven cone pulleys 60', 62'. A first belt 66 is provided between selected steps of first cone pulley 60' and idler pulley 64'. A second belt 68 is provided between a remaining one of the steps of idler pulley 64 and a like step of second cone pulley 62'. In all, the four steps of each of the pulleys 60', 62' and 64' provide twelve possible belt and speed combinations between a fixed speed drive motor 34 and driven shaft 40.

A rotating power take-off 72 is again provided by a separate pulley 84 attached to the second cone pulley 62' (or the pulley drive sleeve 44) and a second take-off pulley 86 is provided as part of the second oscillatory motion device 70.

As can be seen from Figs. 11 and 12, device 70 is positioned laterally between drive and driven pulleys 60', 62' of the drill press 10' and within or between the legs 68A, 68B of the drive belt 68 encircling and driving the driven shaft 40 supporting the tool 11.

Second take-off pulley 86 is preferably provided as an integral part of the device 70. Device 70 further includes a rigid frame 74 pivotally supporting a lever 76. The first end 76A of the lever 76 is extended into a gap provided between the head casting 26 and the quill 42 and overlaps the top end 42A of the quill 42. Lever 76 is pivotally mounted to frame 74 by means of a pivot pin 78 so as to provide over a limited range, an at least generally oscillatory linear movement of the first end 76A.

The device 70 further includes a second drive coupling between the second take-off pulley 86 end of the power take-off 72 and the pivoting lever 76. A clutch assembly (or simply "clutch") is indicated generally at 150 between the second take-off pulley 86 and the input shaft 114 of the second drive coupling 90.

The pulley 86 and clutch 150 are all rotatably supported on the frame 74 by input shaft 114. The frame 74 includes a base 94 with a downwardly extending arm 96.

Arm 96 receives the pivot pin 78 and supports the lever 76. Frame 74 further includes an upper, inverted "U"shaped arm 102, which supports components of the second drive coupling 90. The second drive coupling 90 converts the rotary motion of the second take-off pulley 86 into an up-down oscillating motion of the end 76A of the lever 76.

The second drive coupling 90 is provided by a worm 108 and worm gear 110. Again, worm 108 and worm gear 110 provide a rate of oscillation which is significantly less than the rate of rotation of the driven shaft 40 and chuck 30. Preferably the ratio of the worm 108 and gear 110 is selected to provide a predetermined oscillating frequency of from about 10 to about 70 cycles per minute.

The second drive coupling 90 further preferably includes an arm 124 having a first end 124A eccentrically coupled with the worm gear 110 and a second end 124B rotatably coupled with the remaining end 76B of the lever 76. The eccentric attachment of arm 124 causes the arm to translate the purely circular, rotational motion of the worm gear 110 into a reciprocating, generally linear vertical motion at the end 76B of the lever 76. As the worm 108 and gear 110 rotate, arm 124 is forced down raising the first end 76A of the lever upward releasing the quill 42 and allowing it to be biased back to its original position by spring 52.

Referring to Figs. 13 and 14, the clutch 150 is preferably provided in part by take-off pulley 86 and by a pin 152, which is staked through shaft 114, a collar 154 and a spring 160 indicated diagrammatically in phantom, all positioned around the shaft 114 between the upper arm 102 of the frame and the collar 154.

Spring 160 biases collar 154 towards the second take-off pulley 86. Collar 154 has a diametric slot 156 facing pulley 86 and a downward tab 158. Take-off pulley 86 has a pair of diametrical downward tabs 86A and 86B, which are received in the slot 156 of collar 154 simultaneously with pin 152 for simultaneous engagement with the collar 154. Once the tabs 86A and 86B are engaged with the slot 156 as shown in Figs. 11, 13, the collar 154 is maintained in engagement with the tabs 86A and 86B by spring 160. In this way, the second take-off pulley 86 becomes fixedly coupled to the shaft 114 through the simultaneous engagement of the tabs 86A, 86B and the pin 152 with the collar 154.

To disconnect the device 70 from the rotating power take-off 72, collar 154 is depressed and rotated sufficiently to engage the tab 158 with a portion of the arm 102 of the frame 74 and the pin 152 with notches 162, which are offset at right angles to the slot 156 on the upper side of the collar 154. Engagement between pin 152 and notches 162 is maintained by spring 160.

The notches 162 are sized to receive only the pin 152 and not the pulley tabs 86A, 86B. If need be, the input shaft 114 can be held stationary by inserting a screwdriver into a slot 120 provided in the top of the shaft 114. In the disengaged position of the clutch assembly 150 indicated in Fig. 14, take-off pulley 86 is allowed to freely rotate on the end of shaft 114. Tab 158 assists in maintaining that shaft 114 stationary through the collar 154 and pin 152 by contacting arm 102.

It will be appreciated by those skilled in the art that changes and modifications may be made to the above-described embodiments without departing from the inventive concept thereof. It is understood, therefore, that the present invention is not limited to particular embodiments disclosed, but is intended to include all modifications and changes that are within the scope and spirit of the invention as defined by the appended claims.

Claims (12)

1. In a drill press including a motor having an output shaft, a quill supported for linear axial movement, a driven shaft having a central longitudinal axis and being supported for rotation within the quill and for linear axial movement with the quill, a chuck mounted on one end of the driven shaft and a first drive coupling between the output shaft and a remaining end of the driven shaft, an oscillatory motion device comprising: a rotating power take-off most directly coupled with and driven by one of the output shaft and the first drive coupling; an actuator member having a first end coupled with the quill and a second end, the actuator member being supported for linear movement with the quill; and a second drive coupling operatively located between the second end of the actuator member and the rotating power take-off.

2. The device according to claim 1 wherein said second drive coupling comprises: a rotating member driven by the rotating power take-off; and an arm having a first end eccentrically coupled to said rotating member and a second end engaged with the second end of the actuator member so as to translate rotational movement of the rotating member into linear movement of the actuator member.

3. The device according to claim 2 wherein the second end of the arm passes through an elongated slot in the second end of the actuator member.

4. The device according to claim 3, wherein the rotating power take-off comprises a take-off pulley mounted to an input shaft of the second drive coupling.

5. The drill press according to claim 1 wherein the first drive coupling includes a pulley and wherein the rotating power take-off includes a first take-off pulley coupled to rotate as one with the pulley of the first drive coupling on a common axis.

6. The device according to claim 1, wherein the second drive coupling comprises: an input shaft coupled with the rotating power take-off; a worm on the input shaft; a worm gear engaged with the worm; and an arm coupled at one end with the worm gear for at least some translational movement with rotation of the worm gear and coupled at a remaining end with the actuator member.

7. The device according to claim 1 wherein the drill press includes: a table at least pivotally supported on the drill press beneath the chuck, the table being characterized by an arcuate recess along one side edge of the table, and the table being sufficiently pivotable to position the recess laterally adjoining the chuck to receive a tool in the chuck.

8. The device according to claim 1 wherein the drill press includes a table having a central opening, positioned to receive a tool in the chuck, and further characterized by a tubular dust evacuator located on an underside of the table, the evacuator having a recessed inlet end located proximal to the central table opening and an outlet end distal to the central table opening, the outlet end being exposed sufficiently on the table to receive and engage an end of a flexible vacuum hose.

9. The dust evacuator of claim 8 formed by two identical semi-tubular shells secured to one another.

10. The dust evacuator of claim 9, wherein the curvilinear open area at the inlet end of the evacuator is at least as great as the cross sectional open area at the output end of the evacuator.

11. In a drill press, a device for imparting oscillatory motion to a shaft mounted for rotation within and for axial movement with an axially movable quill of a drill press, the device comprising: a rigid frame; an input shaft rotatably supported on the frame; a lever movably mounted to the frame and having one end projecting sufficiently from the frame to engage an axially movable quill of a drill press; a drive coupling between the rotatably supported input shaft and the movably mounted lever; a pulley mounted for rotation on the input shaft; and a clutch mounted to selectively engage the pulley with the input shaft.

12. In a drill press including a chuck to receive a tool and a table located beneath the chuck to support a work piece, the table having a central opening to receive a tool in the chuck, a dust evacuator attached to the bottom of the table, the dust evacuator being formed by a pair of mated, semi-tubular shells, an inlet end of the evacuator being located beneath the table opening and generally rectangular in shape with a pair of recesses having generally the same curvature as the table opening and an opposing outlet end more circular in shape to receive a circular vacuum hose.