Machining tools having adjustable fences

A machining tool includes a table, an adjustable fence disposed on the table, a fixing device coupled to the fence and a lever operable by an operator. The fixing device can be operated to fix the fence in position or to permit the movement of the fence relative to the table by the operation of the lever. As a result, a tool is not needed to change the position of the fence relative to the table.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to machining tools, such as circular saws and
 hollow chisel mortises, having adjustable fences for positioning a
 workpiece to be machined.
 2. Description of the Related Art
 A known table saw having an adjustable fence is shown in FIGS. 8 and 9. As
 shown in these figures, a fence 122 is disposed on an upper surface of
 table 101 and has a flat plate 123 and an upright guide plate 126, which
 defines a vertical reference surface 125 for positioning the workpiece.
 The flat plate 123 has an insertion hole 128 formed in the right side
 portion as viewed in FIG. 8. A guide slot 130 is formed in the flat plate
 123 and has an arc-shaped configuration. A first bolt 145 is inserted into
 the insertion hole 128 and engages a first threaded hole 147 formed in the
 table 101, so that the fence 122 can pivot about the first bolt 145. A
 second bolt 151 is inserted into the guide slot 130 and engages a second
 threaded hole 161 formed in the table 101, so that the fence 122 can be
 fixed in position relative to the table 101 by tightening the first bolt
 151.
 In order to change the pivotal position of the fence 122 to perform a
 "miter cut" operation, the second bolt 151 is loosened using a tool and
 the fence 122 is pivoted about the first bolt 145. The movement of the
 second bolt 151 along the guide slot 130 guides the position of the fence
 122. After the desired pivoted position has been reached, the second bolt
 151 is tightened to fix the fence 122 in the desired pivoted position.
 However, in order to change the position of the fence of the known table
 device, a special tool such as a box wrench is required. In addition, the
 operator must operate the tool to engage with and disengage from the bolt.
 Therefore, the known table devices require troublesome operations for
 changing or adjusting the position of the fence.
 SUMMARY OF THE INVENTION
 It is, accordingly, one object of the present invention to teach improved
 machining tools that do not require a tool to adjust the position of the
 fence.
 Preferably, machining tools are taught having a table, an adjustable fence
 disposed on the table, a fixing device for fixing the position of the
 adjustable fence and a lever coupled to the fixing device for rotating the
 fixing device from a fixing position to a releasing position. When the
 lever is moved to the releasing position, the adjustable fence can freely
 move relative to the table in order to re-position the adjustable fence.
 When the lever is moved to the fixing position, the adjustable fence is
 fixed in position relative to the table. In such a design, a tool is not
 needed to change the position of the fence relative to the table, thereby
 simplifying the fence adjusting operation. The lever is preferably
 disposed below the table, so that the space below the table can be
 effectively used.
 Other objects, features and advantages of the present invention will be
 readily understood after reading the following detailed description
 together with the accompanying drawings and the claims.

DETAILED DESCRIPTION OF THE INVENTION
 Machining tools are taught having adjustable fences that preferably can be
 adjusted relative to a table without the use of a tool. Preferably, the
 adjustable fences are utilized with cutting tools, such as table saw, but
 such adjustable tools can be utilized with a variety of machining tools.
 The adjustable fences taught herein are more convenient to use than known
 adjustable fences, which require a tool to loosen and tighten a fixing
 device. Such machining tools may include a table, an adjustable fence
 disposed on the table, a fixing device for fixing the adjustable fence in
 position and a means for operating the fixing device. The means for
 operating the fixing device is preferably a lever, which can be operated
 by hand, although other means for operating the fixing device by hand can
 be utilized. Preferably, the fixing device can be operated to fix the
 fence in position or to permit the movement of the fence relative to the
 table by the operation of the means for operating the fixing device.
 Preferably, the means for operating the fixing device is disposed below the
 table, so that the space below the table can be effectively used. The
 means for operating the fixing device, such as a lever, preferably pivots
 between a fixing position for fixing the position of the adjustable fence
 and a releasing position for permitting free movement of the adjustable
 fence.
 In one representative embodiment, the fixing device may include a first
 screw member and a second screw member that engages the first screw
 member. The first screw member may be fixed in position relative to the
 table. The second screw member may be connected to the means for operating
 the fixing device. Preferably, the second screw member is rotated by the
 means for operating the fixing device between a fixing position and a
 releasing position. For example, in the fixing position the second screw
 member is tightened to fix the adjustable fence in position. In the
 releasing position the second screw member is loosened to permit the
 adjustable fence to move freely.
 Preferably, the first screw is a male screw that extends through the fence
 and the table and has a head that engages the upper surface of the fence.
 The second screw may be a female screw that engages the male screw below
 the table and that has an upper end that contacts the lower surface of the
 table.
 If a lever is utilized as the means for operating the fixing device, the
 lever may also have a means for changing the extending length of the
 lever. This extending length changing means may permit the lever to be
 adjusted in position relative to the edge of the table so that the lever
 can pivot about the fixing device and can be pushed and stored under the
 table when not in use. A holder may be provided to perform this length
 changing function and the holder may include a pair of walls opposed in
 spaced relationship with each other and each including a mounting hole
 formed therein for supporting the lever and permitting the lever to slide
 axially with respect to the holder.
 Preferably, the lever is disposed below the table and includes a grip that
 is disposed on the end of the lever that is opposite to the holder. The
 grip preferably may be grasped with one hand to operate the fixing device.
 The table also may have at least one sidewall with an opening formed in
 the sidewall. Preferably, the end of the lever having the grip extends
 outwardly of the wall through the opening.
 The sidewall may include a first inwardly recessed wall part that has a
 first outer recess with a first bottom. Preferably, when the lever is in
 the fixing position, the lever extends through the slit and past the first
 recessed wall part, such that the grip end of the lever is positioned to
 provide a maximum effective length extending from the first outer recess.
 The sidewall may further include a second inwardly recessed wall part that
 is continuously formed with the first recessed wall part that has a second
 outer recess with a second bottom. Preferably, when the lever in the
 releasing position, the grip end extends through the opening and past the
 second inwardly recessed wall. When the lever is in the releasing
 position, the lever preferably may be moved in the axial direction between
 a storage position and an extended position by means of the holder. In the
 storage position, the grip end may be positioned within the second outer
 recess. In the extended position, the grip end may be positioned outward
 of the second outer recess.
 In another representative embodiment, a resistance device may be provided
 between the lever and the holder and may cause a suitable resistance to
 prevent axial movement of the lever when it is in the storage position.
 Preferably, the resistance device is made of a resilient member, such as
 rubber, is mounted in the holder and contacts the lateral surface of the
 lever.
 Each of the additional features and method steps disclosed above and below
 may be utilized separately or in conjunction with other features and
 method steps to provide improved machining tools and methods for designing
 and using such machining tools. A representative example of the present
 invention, which example utilizes many of these additional features and
 method steps in conjunction, will now be described in detail with
 reference to the attached drawings. This detailed description is merely
 intended to teach a person of skill in the art further details for
 practicing preferred aspects of the present teachings and is not intended
 to limit the scope of the invention. Only the claims define the scope of
 the claimed invention. Therefore, combinations of features and steps
 disclosed in the following detail description may not be necessary to
 practice the invention in the broadest sense, and are instead taught
 merely to particularly describe some representative examples of the
 invention.
 A representative machining tool 1 is shown in FIGS. 1-7, which in this
 representative embodiment is a table saw, and may include a table 10 that
 has a substantially rectangular configuration in plan view. A saw unit
 support bracket 2 may be fixedly mounted on the rear end (left end as
 viewed in FIG. 1) of the table 10. A saw unit 5 may be mounted on the
 upper end of the support bracket 2 so that it can vertically pivot by
 means of a pivotal shaft 3. A motor 6 may be mounted on the saw unit 5 and
 may have a motor shaft on which a circular saw blade (chip saw cutter) 8
 may be removably mounted by means of a clamp device (not shown). A handle
 13 may be mounted on a motor housing 11 with a trigger 12 disposed on the
 handle 13 for turning the motor 6 on and off.
 A blade case 15 may be mounted on the motor housing 11 and may serve to
 cover substantially the upper half of the saw blade 8. A substantially
 arc-shaped safety cover 16 may be mounted on the blade case 15 and may
 pivot about the same axis as the motor shaft to cover and uncover
 substantially the lower half of the saw blade 8. A spring support bracket
 17 may be mounted on the table 10 in a position forward of and adjacent to
 the support bracket 2. A spring 20 may be interposed between the spring
 support bracket 17 and a spring seat 18 that is mounted on the saw unit 5,
 so that the saw unit 5 is normally biased upward.
 In order to cut a workpiece (not shown) placed on the table 10, the
 operator starts the motor 6 by the operation of the trigger 12 to rotate
 the saw blade 8 and, using the handle 13, presses the saw unit 5 downward
 against the biasing force of the spring 20. In response to the downward
 movement of the saw unit 5, the safety cover 16 preferably rotates to
 uncover the saw blade 8. As a result, the saw blade 8 can cut the
 workpiece.
 As shown in FIGS. 1, 2 and 4, an adjustable fence 22 may be disposed on the
 table 10 in a position forward of and adjacent to the spring support
 bracket 17. The fence 22 may comprise a mounting plate 23, a workpiece
 abutting plate 26 and right and left end plates 27. The mounting plate 23
 may contact the upper surface of the table 10 in surface-to-surface
 contact relationship therewith. The abutting plate 26 may be disposed on
 the front end of the mounting plate 23 to extend vertically in the upward
 direction from mounting plate 23, thereby defining a reference surface 25
 for contacting the workpiece. The right and left end plates 27 may be
 disposed on the right and left ends of the mounting plate 23 and may
 extend vertically in the upward direction from the mounting plate 23, so
 that each of the end plates 27 intersect the abutting plate 26 at a right
 angle.
 As shown in FIG. 4, a pin insertion hole 28 may be formed in the right end
 portion of the mounting plate 23. A substantially arc-shaped guide slot 30
 may be formed in the mounting plate 23, which guide slot extends along an
 arc about the pin insertion hole 28. As shown in FIG. 2, the rear portion
 (upper portion as viewed in FIG. 2) of the guide slot 30 may extend into a
 rear protrusion 31 formed on the rear side of the mounting plate 23. An
 indicator 32 may be mounted on the left side base portion of the rear
 protrusion 31. A scale (not shown) may be marked on the upper surface of
 the table 10, so that the indicator 32 will indicate the pivotal angle of
 the fence 22.
 As shown in FIGS. 3 and 4, the table 10 may comprise a horizontal plate 35
 and four sidewalls 36. The horizontal plate 35 has an upper surface that
 defines the table surface. The sidewalls 36 extend vertically in the
 downward direction from front, rear, right and left side ends of the
 horizontal plate 35.
 As shown in FIG. 3, a blade intrusion slot 37 may be formed in the
 horizontal plate 35 on the right side thereof and extend in the forward
 and rearward directions. A substantially cylindrical pin receiving recess
 38 may be formed in the horizontal plate 35 leftward of and adjacent to
 the front portion of the intrusion slot 37. A bolt engaging recess 40 may
 be formed to the left of the pin receiving recess 38.
 Referring to FIGS. 1 and 2, the left rear half of the side wall 36 may
 include a shallow recessed wall part 41 with a bottom and the left front
 half of the side wall 36 may include a deep recessed wall part 42 with a
 bottom. The recessed wall parts 41 and 42 are continuously formed and
 non-recessed wall parts are also formed at the front and rear ends of the
 left sidewall 36. A horizontal lever slit or opening 43 may be formed
 through and between the recessed wall parts 41 and 42.
 As shown in FIG. 4, a pin 45 may be fixedly inserted into the pin receiving
 recess 38 and may have an upper end that extends upwardly from the
 horizontal plate 35 or the table surface. The upper end of the pin 45 may
 be rotatably inserted into the pin insertion hole 28 of the fence 22, so
 that the fence 22 can pivot around the pin 45 as indicated by chain lines
 in FIG. 2.
 As shown in FIGS. 4 to 6, a downward extending flange 39 may be formed on
 the lower surface of the horizontal plate 35 and may have the bolt
 engaging recess 40 with a bottom formed therein, so that the bolt engaging
 recess 40 is positioned on the central line of the arc-shaped guide slot
 30. The bolt engaging recess 40 may include a substantially cylindrical
 bolt insertion hole 48 that extends through the bottom of the bolt
 engaging recess 40. A pair of lateral engaging recesses 50 may be formed
 on each of the right and left sides of the engaging recess 40 in
 communication with the bolt insertion hole 48.
 As shown in FIG. 5, a bolt 51 may be inserted into the guide slot 30 of the
 fence 22 with an upper washer 53 interposed between the head of the bolt
 51 and the upper surface of the fence 22. A pin insertion hole 55 may be
 formed in the shank of the bolt 51 in its diametrical direction, so that
 it is aligned with the lateral engaging recesses 50 of the bolt engaging
 recess 40. An engaging pin 56 may be slidably or forcibly inserted into
 the pin insertion hole 55 and both ends of the engaging pin 56 may extend
 outwardly from the bolt 51 and engage the lateral engaging recesses 50. As
 a result, the bolt 51 is prevented from rotating around its axis relative
 to the horizontal plate 35. The shank of the bolt 51 may have a male
 thread portion 57 that extends below the horizontal plate 35 of the table
 10.
 A hexagonal nut 60 with a bottom may be engaged with the male thread
 portion 57 with a lower washer 58 interposed between the lower end of the
 flange 39 and the upper end of the nut 60. FIG. 5 shows the nut 60 in the
 tightened state. A threaded hole 61 may be formed in the bottom of the nut
 60.
 As shown in FIGS. 5 and 7, a nut holder 71 may have a hexagonal engaging
 hole 62 for engaging the nut 60. A screw insertion hole 63 may be formed
 in the bottom of the engaging hole 62 and may be positioned on the same
 axis as the central axis of the engaging hole 62. A screw 64 may be
 inserted into the insertion hole 63 and may engage the threaded hole 61 of
 the nut 60, so that the nut holder 71 can be fixed in position relative to
 the nut 60.
 The nut holder 71 may have a downwardly recessed lever mounting portion 65
 on the lateral side of the engaging hole 62. The lever mounting portion 65
 may have a substantially rectangular configuration and may have a pair of
 lever support walls 66 that are spaced from each other. The support walls
 66 may have lever insertion holes 67 that have the same diameter and are
 aligned with each other. As shown in FIG. 5, a resistance member 70,
 preferably made of rubber, may be fitted into a recess 68 formed in the
 bottom of the mounting portion 65 such that an upper portion of the
 resistance member 70 extends upwardly from the bottom of the mounting
 portion 65.
 Lever 72 may have a circular configuration in section and may be inserted
 into the lever insertion holes 67 through the slit 43 formed in the left
 side wall 36 of the table 10 (see FIGS. 3 and 4). The lever 72 may have a
 distal end that extends outward from the left sidewall 36. A grip 75 may
 be mounted on the distal end of the lever 72. The lever 72 may have a
 proximal end opposite to the distal end, which proximal end extends
 outward from the holder 71 and may have a removal prevention plug 76
 mounted thereon.
 The operation of the machining tool 1 will now be described. When the lever
 72 is moved forward (upward as viewed in FIG. 3) along the slit 43 to
 pivot the lever 72 around the bolt 51 from a releasing position to a
 fixing position, which fixing position is indicated by solid lines in FIG.
 3, the nut holder 71 and the nut 60 are rotated in such a direction that
 the nut 60 is tightened against the bolt 51. As a result, the fence 22 can
 be fixed in position relative to the horizontal plate 35 of the table 10.
 On the other hand, when the lever 72 is moved rearward (downward as viewed
 in FIG. 3) from the fixing position to the releasing position, the nut 60
 may be loosened, so that the fence 22 can pivot about the pin 45. As a
 result, the angular position of the fence 22 relative to the horizontal
 plate 35 or the table 10 can be changed. After the fence 22 has been set
 to the desired angular position, the lever 72 is returned to the forward
 position, so that the fence 22 can be fixed in position relative to the
 table 10 in the desired angular position.
 Because the lever 72 is slidably inserted into the lever insertion holes 67
 of the lever support walls 66 of the holder 71, the effective length of
 the lever 72 or the length between the grip 75 and the holder 71 can be
 changed. Thus, when the lever 72 is in the releasing position as indicated
 by reference numeral 72b, the lever 72 may be pulled so that the grip 75
 is outside of the recess formed by the shallow recessed wall part 41. When
 the lever 72 is fully extended, the operator can easily pivot the lever
 72. On the other hand, when the lever 72 is in the position between the
 fixing position and in the position as indicated by reference numeral 72a,
 which just before completion of the tightening of the nut 60, the lever 72
 may be pushed under the table 10 so that the grip 75 is positioned within
 the recess formed by the deep recessed wall part 42. The frictional
 resistance caused by the resistance member 70 resiliently contacting the
 lever 72 will hold the axial position of the lever 72.
 As shown in FIGS. 1 and 2, the machining tool 1 also may include a vice
 device 77 that is disposed at the front end of the table 10 and that can
 be utilized together with the fence 22 to fix the workpiece in position on
 the table 10. The vice device 77 is known as a quick vice. The
 construction of the vice device 77 will therefore be briefly explained.
 The vice device 77 may comprise a vice plate 80, a vice screw 82, a screw
 guide 83 and a vice nut 84. The vice plate 80 may have clamp surface 78
 that is positioned opposite to the reference surface 25 of the fence 22.
 The vice plate 80 may be rotatably connected to a vice screw 82 by means
 of a pin 81. The screw guide 83 may be fixed to the upper surface of the
 table 10 and may rotatably support the vice screw 82. The vice nut 84 may
 be supported by the screw guide 83 and may be shifted between a first
 position for engagement with the vice screw 82 and a second position for
 disengagement from the vice screw 82.
 In the representative embodiment of FIGS. 1 to 7, the nut 60 can be
 tightened and loosened by the movement of the lever 72. Therefore, the
 fence 22 can be fixed in position relative to the table 10 without using a
 special tool. Consequently, the adjustment operation for determining the
 angular position of the fence 22 can be easily performed.
 In addition, because the lever 72 is disposed below the table 10, the space
 below the table 10 can be efficiently utilized. Thus, it is not necessary
 to provide space so that a tool can be utilized to loosen and tighten the
 nut, as in known machining tools having adjustable fences.
 Further, because the effective length or the length between the grip 75 and
 the holder 71 can be varied, the operator can move the lever 72 to each
 desired position. Thus, when the operator is not using the lever 72, the
 grip 75 may be positioned in the storage position within either of the
 recessed wall parts 41 and 42 of the sidewall 36 of the table 10.
 Therefore, the lever 72 will not interfere the operation of the saw unit 5
 or other devices.
 Furthermore, because the resistance member 70 is provided to cause
 frictional resistance against the axial movement of the lever 72, the
 lever 72 will not shake or move accidentally in the axial direction.
 The above representative embodiment may be modified in various ways. For
 example, although the fence 22 of the above representative can pivot
 around a pivotal axis, a fence also may be movable along a linear path
 with the aid of an appropriate slide mechanism. In such a case, the
 position of the fence may be adjusted along the linear path. Further,
 although the bolt 51 is fixed in its rotational position relative to the
 table 10 and the nut 60 is connected to the lever 72 for rotation
 therewith, the bolt 51 and the nut 60 may be replaced by a nut and a bolt,
 respectively.
 Further, the lever 72 may be directly connected to the nut 60 or may be
 formed integrally with the nut 60. In such a case, the holder 71 can be
 eliminated. When the bolt 51 and the nut 60 are replaced with a nut and a
 bolt, respectively, the lever 72 may be connected to the head of the bolt.
 In addition, the resistance member 70 may be mounted on the lever 72 so as
 to frictionally contact the holder 71. Furthermore, the resistance member
 70 may be a coil, leaf spring, brush or any other appropriate device for
 providing frictional resistance.