GB2249991A - Table saw - Google Patents

Abstract

A moving arbor-type table saw includes a cradle assembly (33) within a table housing, (not shown) and having spaced apart upper and lower guide rails (40, 42) between a pair of spaced-apart end plates (34, 35) which are pivotally suspended from the saw table top (15) by pivot mounts (30, 37). A motor mounting carriage (60) is mounted on rollers (65, Fig 5, not shown) which ride along the upper rail (40) to enable the saw (88) to be drawn along a slot (22) in the table top and also carries the weight of the carriage (60), as well as the motor torque. The lower guide rail (42) supports the carriage against transverse loads. A pull rod (130) draws the carriage (60) along the guide rails in a cutting movement. The front end plate (35) of the cradle assembly has an arcuate lower edge provided with sector teeth which engage a pinion gear (165) for tilting the cradle assembly, and therefore the blade (88), about a pivot axis parallel to the blade slot (22), for varying the saw blade angle with respect to the top (15). The motor carriage (60) includes an adjustable motor mount (90) and a right angle drive (102) by which the height of the motor (80) on the carriage (60) may be adjusted from the front wall to vary the extent of projection of the blade (88) through the slot (22). <IMAGE>

Description

TABLE SAW The invention relates to a table saw, and more particularly to a table saw having a guide rail structure under a table top for guiding a saw carriage in reciprocal movement relative to a workpiece on the table top. Such saws are also known as moving arbor saws or inverted radial arm saws.

In known table saws of the kind described, the saw motor is carried by a carriage located beneath the table top. Means are provided for adjusting the saw blade vertically relative to the plane of the table in order to control the depth of cut. Also, the blade may be tilted at an angle to the table top surface in order to produce a bevel cut.

Such saws further typically include a handle attached to the saw carriage and located over the blade to pull the saw in a longitudinal direction through the workpiece. An example of a moving arbor type of table saw is shown in the U. S. Patent No. 2,323,248 to Sellmeyer.

Sellmeyer shows a saw in which the pull handle is associated with the blade guard thereby limiting the use of the saw to applications in which the guard is in place. Such a design prevents the saw from being used for special cuts such as are performed by dado blades in which the saw blade does not penetrate through the entire thickness of the workpiece.

In the Sellmeyer patent, the mechanism for adjusting the angle of the saw blade for a bevel cut includes pairs of gear sets at each end of the saw frame connected by a linkage rod. The angular position of the saw carriage is shown by an indicator located near the pivot point for the carriage.

Sellmeyer also discloses a mechanism for the vertical adjustment of the saw carriage by a crank. The crank is located beneath the surface of the saw table such that access for vertical adjustments is limited. The carriage pivot axis is also below the table top so that tilting of the carriage to tilt the blade changes the amount of blade exposed above the plane of the tabs.

The invention provides a table saw having a saw table structure and a carriage assembly for carrying a saw blade in reciprocal movement relative to the table structure.

The table structure may include two table top halves abutted against each other to form a common blade slot there-between. A cradle assembly is located beneath the table top and includes a first end plate at the front and a second end plate at the back. The end plates are connected by a pair of parallel, vertically-spaced horizontal guide rails. A pivot pin extends inwardly from each end plate and each pin is engaged within a respective pivot block mounted at front and rear locations on the saw top. The pivot blocks may be adjusted laterally to position the cradle assembly precisely parallel to the miter guide slots formed in the table halves.

The invention may be described as a table saw of the sliding or moving arbor type in which a drive motor for the saw is mounted in a carriage, and in which the carriage rolls or slides on guide rails and is positioned beneath or below a saw table top and is movable along the rails for cutting movement of the blade through an elongated slot in the table top by manual movement of the carriage in its cradle assembly, the improvement in mounting the cradle and carriage characterized by a pair of spaced-apart end plates, carriage guide rails extending between and fixed to the end plates, the saw carriage mounted for transverse cutting movement by rolling along the rails, and pivotal mounts on the table top supporting the end plates for pivotal movement on a pivot axis which extends along and parallel to the slot.

The invention may be further characterized by a table saw as defined above in which the guide rails are a pair of tubes which are mounted in vertically offset relation to each other between the end plates thereby forming an upper guide tube and a lower guide tube, and the carriage has a pair of wheels which ride on the upper guide tube and which transfer the weight of the carriage and the torque of the saw drive motor to the upper guide tube, and a pair of laterally spaced rollers on the carriage engage the sides of the lower guide tube and transfer side loads from the carriage to the lower guide tube.

The invention may be further described as a moving arbor table saw which has a top forming a blade slot for receiving a circular saw blade. The top is mounted on a cabinet 11 which has four walls. A cradle assembly is received within the cabinet and has spaced-apart end plates, one end plate positioned adjacent to an inside surface of the back wall and the other end plate positioned adjacent to an inside surface of the front wall. A pair of spaced apart carriage supporting rails extend between the end plates with opposite ends secured to the plates with the rails positioned one above the other, thereby forming an upper rail and a lower rail.The end plates are pivotally mounted to the table saw top so that the cradle assembly is suspended from the top with the rails parallel to the blade -slot. A motor carriage is carried in the cradle assembly by wheels which ride along the upper rail and rolling which guide the carriage by engaging the lower rail. A motor mount on the carriage carries an electric drive motor, and a gear adjusting mechanism on the carriage provides adjustment for the position of the motor mount vertically in the carriage to vary the projection of the blade saw above the top. The cradle assembly is movable on the pivotal support from the top for changing the blade angle with respect to the top. A manual pull rod extends from the cradle assembly through the front wall and for causing cutting movement of the carriage on the cradle assembly.

The invention may be further defined or characterized by sector teeth which are formed on the front end plate remote from the pivot axis, and a drive wheel is mounted on the front wall of the table top support with a pinion gear engaged with the sector teeth so that rotation of the drive wheel causes a tilting movement of the cradle assembly about its axis, together with a mechanism for locking the cradle in a selected adjusted position, and a scale of the angle of tilt.

lhe table saw may be further characterized by the fact that the mechanism for adjusting the position of the motor mount on the carriage includes a right angle gear drive which moves the motor mount vertically on the carriage, and a drive shaft extends between an input shaft of the right angle gear drive and the front wall such that the drive shaft slides along the input shaft when the carriage rides on the rails. The drive shaft is accessible at the front wall for elevating or lowering the motor mount in relation to the carriage.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which: Fig. 1 is a perspective view of a table top saw in accordance with this invention; Fig. 2 is a front elevation of the table saw, with the underlying support frame or cabinet removed for the purpose of clarity, and showing the controls on the front panel or wall; Fig. 3 is a top plan view of the saw top with the saw blade insert and insert retainers removed in the interest of clarity; Fig. 4 is a view looking into the interior of the table top saw with the left-hand side panel removed showing the cradle assembly and carriage, with the top shown in phantom, and with certain of the parts being shown as broken away; and Fig. 5 is a sectional view looking generally along the line 5--5 of Fig. 4 showing details of the carriage rail and wheel arrangement, and details of the right angle vertical height adjustment for the drive motor.

Referring to the drawings, which illustrate a preferred embodiment of the invention, a moving arbor table top saw in accordance with this invention is illustrated generally at 10 in Fig. 1. The saw mechanism is mounted in a housing or cabinet 11 supported on a separate frame or table 12. The saw mechanism as illustrated in Fig. 1 includes the usual fence 14 and fence support rails 14a and 14b, extending respectively along the back and front sides of the top of the housing 11.

The cabinet 11 forms a support for the saw top 15 and includes a front panel or wall 16, a back wall (not shown) spaced from the front wall 16, and a pair of spaced side walls 18 and 19 extending between the front and back walls. All of the controls and levers for the saw 10 are conveniently grouped on the front wall 16.

The saw top 15, as best shown in Fig. 3, is formed in two essentially identical left and right-hand sections 15a and 15b. The top sections are formed of relatively heavy material, such as cast aluminum, and together provide an upper or table top surface 20 for supporting a workpiece, such as a piece of wood or a sheet of plywood.

Each of the table top sections forms part of a saw slot 22 which runs substantially from the front to the back of the saw. Each top section also has a fence guide channel 24 running parallel to the slot 22.

The top sections 15a and 15b are assembled in abutting relation to define the slot 22 with mutually abutting legs which define the ends of the slot. Thus, the section 15a is formed with a long leg 25 at the front of the slot and a short leg 26 at the back. The long leg 25 nests leg 28 of the section 15b and the short leg 26 butts against a long leg 29 of the section 15b.

The legs 28 and 29 of the section 15b are formed with openings which support pillow blocks or pivots 30 attached to the top section 15b. As will be explained below in greater detail in connection with Fig. 4, the pivots 30 provide a depending support for an internal cradle assembly and-provide pivotal movement about an axis which is substantially coincident with the axis of the slot 22.

The cradle assembly 33 is perhaps best shown in Fig. 4. The cradle assembly 33 is positioned in the cabinet 11 and includes a pair of spaced-apart end plates 34 and 35.

The end plate 34 is positioned adjacent the back wall 17, shown in phantom in Fig. 4, while the front end plate 35 is positioned adjacent the inside surface of the front wall 16, also shown in phantom. The upper ends of each of the end plates carry pivot pins 37 which are pivoted from one of the pivot blocks 30.

The cradle assembly 33 further includes a pair of spaced-apart carriage supporting rails which extend fore and aft between the end plates 34 and 35 with opposite ends rigidly secured to these plates. The rails are positioned one above the other, thereby forming an upper rail 40 and a lower rail 42. The rails 40 and 42 may conveniently be formed as tubular cylindrical elements, such as polished tubes, to provide smooth running surfaces.

The opposite ends of the upper tube or rail 40 are received in punched-in annular lips 45 of an end plate and are welded in place by spot welds 46. The bottom tube or rail 42 is also mounted by spot welding at its opposite ends into inwardly punched lips 50 and 52 of the front and back plates. In this manner, a rigid cradle assemble frame is formed by the end plates and the carriage supporting rails.

The entire cradle assembly 33 is suspended from the top 15 with the rails 40 and 42 held in generally parallel relation to the slot 22.

The apparatus further includes a motor mounting carriage 60 carried on the cradle assembly 33. The manner in which the carriage 60 is mounted on the guide tubes or rails is perhaps best seen in reference to the sectional view of Fig. 5. A carriage body 61 carries a pair of laterally or fore and aft spaced grooved wheels 65 which ride along the upper surface of the upper rail 40. The wheels 65 transmit the weight of the carriage 60 to the upper rail 40. The local carrying arrangement is completed by eccentrically mounted idler rollers 68, one for each wheel 65, which are adjusted to run along the bottom surface of the rail 40, to prevent the wheels 65 from lifting off of the rail 40.

The carriage body 61 is guided by a single pair of laterally spaced idler rollers 70 and 72 mounted on a lower body extension 73. The rollers 70 and 72 ride along the laterally opposed surfaces of the bottom rail 42, as shown in Fig. 5. At least one of the idlers rollers, such as roller 72, is on an eccentric mount to provide means for making precise alignment of the carriage 60 with respect to the rails 42. The idler rollers 70 and 72 apply sideways thrusts and loads to the lower rail 42, but the torque of the motor and the weight of the carriage 60 is carried exclusively by the upper guide rail 40. As shown in Fig. 4, circulate felt wipers 75 are mounted on the carriage body 61 on either side of the carriage and wipe the surfaces of the rails clean of any sawdust or dirt.

The carriage 60 provides the means for supporting the drive motor 80. The motor 80 is mounted on the carriage body 61 in such a manner that its shaft 82 and arbor 85 carry a saw blade 88 extending upwardly into the slot 22. The motor is mounted on a motor mount 90 forming a subassembly of the carriage 60. As best shown in Fig. 4, the carriage 60 is formed with a pair of upwardly extending rods 92 which provide for guides for the vertical movement of a plate-like motor mount 90. The mount 90 is formed with a pair of integral sleeves 94, one each received over one of the rods 92. The upper ends of the rods 92 are capped by washers 95 which prevent the motor mount 90 from being extended vertically beyond a predetermined maximum limit.

Small, coil compression springs 97 are threaded over the lower ends of the rods 92 and are compressed by the tubular guides 94, to provide a counter-balance for the weight of the motor 80 on the motor mount 90, to prevent any tendency for the mount 90 to bind on the rods 92 during adjustments in the vertical height of the motor 80.

The motor mount 90 is positioned by a lead screw 100 forming part of a right-angle height positioner or drive 102, attached to the body 61 and forming part of the carriage 60, as shown in Fig. 5. The upper end of the lead screw 100 is fixedly attached by a pin 103 to the motor mount. The lead screw 100 is driven by an internally threaded hub 105 which is rotatably mounted in the right angle drive 102 on a bearing 107. The hub 105 is held in place by a hollow hub 108 on the inside race of the bearing 107 at the upper end of the drive hub 105 carries a bull gear 110.

The gear 110 is in mesh with a transverse spiral drive gear 112. As shown in Fig. 5, the drive gear 112 is formed with a hexagonal opening 114 therethrough, thereby forming the input shaft to the right angle drive. When the carriage 60 is assembled on the cradle assembly 33, a hexagonal drive rod 116 slidably extends through the opening 114 of the worm gear 112.

The rod 116 extends through a flexible coupler 118 and is mounted on a sleeve bushing 119 on the front plate 35. The rod 116 is rotated by a crank 120 for elevating or lowering the position of the motor mount 90 with respect to the blade slot 22. The crank 120 is positioned in front of the front wall 16 through an arcuate slot 122 in the wall 16. A large hand-operated wing nut 125 is threadably received on an outside threaded surface of the bushing 119 and adjacent the wall 16.

Manual means for causing a traversing or cutting movement of the carriage 60 and motor 80 includes a pull rod 130 fixed to the carriage 60 at a vertical post 132 on the body 61. The pull rod 130 extends through a clamping bushing 135 mounted on the front plate 35. The bushing 135 extends through an arcuate slot 136 in the wall 16. A pull knob is carried on the end of the rod 130 and is accessible at the front of the housing 11. A compression spring 142 is carried on the rod 130 between the post 132 and the front cradle plate 35 and serves to urge the carriage from a forward position to a retracted position, in which the saw blade is at a rearward position in the slot 22 as shown in Fig. 3.

For rip-sawing, the carriage 60 may be locked in any predetermined position with respect to the slot 22 by rotating a wing nut 145 on the bushing 135 to clamp it down and about serrated nut legs 146 of the support bushing 135 and press these legs against the rod 130. The carriage 60 may thus be clamped in a predetermined position to permit rip-sawing of parts which are wider or which require cuts which are longer than can be conveniently accommodated by the movement of the carriage 60 and the cradle assembly 33 by the handle 140 and rail 130.

Means for tilting the cradle assembly 33 about the pivotal means defined by the pins 37 and pivots 30 include sector teeth 150 formed in the arcuate bottom of the front plate 35. The teeth 150 are spaced a maximum distance available from the pivot axis defined by the pins 37 to permit the use of relatively large teeth, and to permit the use of accurate and easy-to-read indicia representing the angular position of the saw blade 88 with respect to the top 15. An aperture or opening 152 is provided in the front wall 16 by which angle markings 153 stamped on the front surface of the plate 35 may be viewed through the wall 16, in relation to a pointer 154.

Means for rotating the sector gear portion 150 of the front plate 35 includes a hand crank 160 and a pinion gear 165 which are rotatably mounted on the front panel wall 16 in engagement with the teeth 150. Preferably, about 45' of tilting movement about the pivot axis may be made by rotation of the hand crank 160. An adjusted position may be held by clamping the wing nut 125 against the adjacent front wall 16.

Since the cradle assembly 33 is pivotally mounted from the top 15 at a position adjacent the slot 22, a minimum amount of movement of the blade 88 takes place during adjustments of the blade angle. Also, the extent of projection of the blade through the slot 22 does not substantially change throughout the adjusting range.

The operation of the improved movable arbor table saw in accordance with this invention is largely selfevident from the foregoing description. When wood strips or boards having a width which is accommodated by the available stroke of the carriage 60 are to be cut, they may be put in place on the top 15 by the use of a suitable fence and the motor 80 started. The saw blade 88 is brought forward by simply pulling on the knob 140, thereby pulling the carriage 60 along its rails 40 and 42 to perform a cut. Return movement to the rear or rest position is assisted by the compression spring 142.

If it is desired to fix the saw blade in any given position with respect to the length of the slot 22, the hand wheel 145 may be turned clockwise on its threads to force the fingers 146 of the collar 135 into braking or locking engagement with the portion of the rod 130 extending in front of the wall 16.

When it is desired to elevate or lower the blade 88, this is simply accomplished by and rotating the crank 120, thereby driving the right-hand drive 102 correspondingly to elevate or lower the motor mount 90 in relation to the top 15. The adjusted position of the motor base 90 on the carriage is self-holding due to the high mechanical ratio between the lead screw 100 and the drive gear 112.

The blade angle may be adjusted by rotating the wheel 160 and observing the angle indicia 153 through the window 152. Accurate blade positioning, most important for accurate millwork, may be easily obtained in view of the use of the maximum radial distance from the pivot axis for positioning the angle of the carriage assembly and for reading this angle. The adjusted position is maintained by the clamp nut 125 on the bushing 119.

Claims (10)

1. A table saw of the moving arbor type in which a drive motor for the saw is mounted in a carriage and in which the carriage rolls or slides on guide rails of a cradle assembly and is positioned beneath a saw table top and is movable along the rails for cutting movement of the blade through an elongate slot, wherein the cradle assembly includes a pair of spaced-apart end plates, carriage guide rails extending between and fixed to the end plates, the saw carriage being mounted for transverse cutting movement along the rails, and pivotal mounts on the table top supporting the end plates for pivotal movement on a pivot axis which extends along and parallel to the slot.

2. A table saw according to claim 1, wherein the guide rails are a pair of tubes which are mounted in vertically offset relation to each other between the end plates, thereby forming an upper guide tube and a lower guide tube, and the carriage has a pair of wheels which ride on the upper guide tube and which transfer the weight of the carriage and the torque of the saw drive motor to the upper guide tube, the carriage being provided with a pair of laterally spaced rollers which engage the sides of the lower guide tube and transfer side loads from the carriage to the lower guide tube.

3. A moving arbor table saw having a top forming a blade slot for receiving a circular saw blade, in which the top is mounted on a cabinet support which has four walls, namely, a front wall, a back wall, and a pair of side walls, a cradle assembly in the cabinet which has spacedapart end plates, one end plate being positioned adjacent to an inside surface of the back wall and the other end plate being positioned adjacent to an inside surface of the front wall, spaced-apart carriage support rails extending between the end plates with opposite ends secured to the plates with the rails positioned one above the other, forming an upper rail and a lower rail, the end plates being pivotally mounted to the table saw top, so that the weight of the cradle assembly is suspended from the top with the rails parallel to the slot, on a pivotal axis which is parallel to the slot, a motor carriage in the cradle assembly with wheels which ride along the upper rail, and rollers which guide the carriage by the lower rail, a motor mount on the carriage for the electric drive motor and a gear adjusting mechanism on the carriage for adjusting the position of the motor mount to vary the projection of the saw blade above the top, the cradle assembly being movable on the pivotal support from the top for changing the blade angle with respect to the top, and a manual pull element extending from the cradle assembly through the front wall and for causing cutting movement of the carriage on the cradle assembly.

4. A table saw according to claim 3, including sector teeth on the front end plate remote from the pivot axis, and a drive wheel mounted on the front wall with a gear engaged with the sector teeth so that rotation of the drive wheel causes a tilting movement of the cradle assembly about its axis, a mechanism for locking the cradle assembly in a selected adjusted position, and a scale for indicating the angle of tilt.

5. A table saw according to claim 3 or 4, provided with a mechanism for adjusting the position of the motor mount on the carriage including a right angle gear drive which moves the motor mount vertically on the carriage, and a drive shaft which extends between an input shaft and the front wall such that the input shaft slides along the drive shaft when the carriage rides on the rails, the drive shaft being accessible at the front wall for elevating or lowering the motor mount.

6. A table saw according to claim 3, 4 or 5, wherein the support rails are formed as cylindrical tubes, one positioned above the other.

7. A table saw having a top, a slot in the top for receiving a circular saw blade therethrough, a top support including a front wall, a back wall spaced from said front wall, and a pair of spaced side walls extending between said front and back walls, a cradle assembly in said top support between said walls, including front and rear spaced apart end plates, said rear plate being positioned adjacent to an inside surface of said back wall and said front plate being positioned adjacent to an inside surface of said front wall, a pair of spaced apart carriage-supporting rails extending between said plates and having their opposite ends rigidly secured to said plates, said rails being positioned one above the other in vertically spaced relation on said plates thereby forming an upper rail and a lower rail, pivotal means mounting said plates directly to said top with said cradle assembly suspended from said top and said rails positioned in parallel relation to said slot, said pivotal means forming a pivotal axis parallel to said slot, a motor-mounting carriage carried on said cradle assembly, said carriage having first rolling means riding on said upper rail and second rolling means riding on said lower rail, providing for traversing movement of said carriage on said rails parallel to said slot, a motor mount on said carriage, an electric drive motor positioned on said mount to carry a saw blade with a portion of the blade extending above said top through said slot, means on said carriage for adjusting said motor mount vertically of said carriage to vary the extent of projection of a saw blade on said motor above said top, means for tilting said cradle assembly about said pivotal means for varying the saw blade angle with respect to said top, and manual pull means accessible through said front wall for causing traversing movement of said carriage on said cradle assembly rails.

8. A table saw having a table saw top defining a work surface, a saw slot in said top, said top being supported on a cabinet, a cradle assembly positioned within said cabinet beneath said top, a motor driven circular saw mounted on said cradle assembly such that a portion of said circular saw extends through said slot, a pair of spaced pivots on said top, one each positioned at each end of said slot and defining a single pivot axis therebetween in general alignment with said slot, a corresponding pair of pivot means on said cradle assembly mounted on said pivots and supporting said cradle assembly in suspended relation to said top, and means for tilting said cradle assembly on said pivots for adjusting the angle of said circular saw blade in relation to said work surface.

9. A table saw according to claim 8, wherein said saw table top is formed of cast metal and has means therein defining said blade slot, and said pivots are blocks on said top in alignment with said blade slot and supporting said end plates in suspended relation for pivotal movement beneath said top.

10. A table saw substantially as hereinbefore described with reference to the accompanying drawings.