Patent Application
20140174273
The disclosure relates generally to power tools, and more particularly to material guides or fences for a saw device that accurately introduce material into and through a cutting instrument.
The typical saw device includes a cutting instrument, usually a saw blade, attached to a motor mounted beneath a work surface, commonly called a table. The table has an opening that allows a portion of the blade to extend through the table. To make a cut, a user places material on the table and directs the material through the rotating blade. To assist users in making accurate cuts, many table saws are adapted to receive fences or material guides.
One type of fence commonly found on table saws is the rip fence. The rip fence, also known as a guide assembly, is a table saw guide that assists users in making lengthwise cuts through material, as when cutting wood along the grain. Most rip fences traverse the table parallel to the cutting direction of the blade. In order to make cuts of varying width, a user slides the fence along the table closer to or farther away from the blade. To ensure an accurate cut is made, the fence should be securely fastened to the table.
A clamping system is commonly used to secure the rip fence to the table. The clamping system secures the fence to a guide located towards the front of the table and a guide located towards the rear of the table. The guides often extend perpendicularly to the cutting direction of the blade and traverse the entire width of the table. Previously known rip fence clamping systems utilize a rip fence that slides along the guides mounted at the front and the rear of the table. When the user places the fence in the desired position, the user engages a locking mechanism at the front which engages a locking mechanism at the rear that secures both ends of the rip fence to the table.
While clamping systems can adequately secure the fence to the table, some users find that the position of the rip fence can move when being clamped to the table. If the rip fence does move during clamping, the clamped location of the fence causes the material being cut to be cut along a line different than that intended by the user. The user believes that once the rip fence is clamped to the table, the clamping mechanism will pull the rip fence to the intended and desired location. But an alignment mechanism might not work if clamping at the rear end is adjusted incorrectly.
In view of the foregoing, it would be advantageous to provide a rip fence for a table saw where the rip fence provides for increased accuracy in cutting of material. It would also be advantageous if the rip fence could be easily secured to the table. Furthermore, it would be advantageous if the rip fence could be accurately located and clamped in the desired position without resorting to trial and error.
In accordance with one embodiment of the present disclosure, there is provided a guide assembly for aligning a workpiece on a table of a table saw. The guide assembly includes an alignment member having a first end and a second end. The guide assembly also includes a first lock mechanism, located at the first end of the alignment member, to secure the first end to the table saw. The first lock mechanism is adjustable to apply a self-alignment feature. A second lock mechanism is located at the second end of the alignment member, to secure the second end to the table saw. The second lock mechanism is adjustable to apply an adjustable clamping force to the table saw. A linkage is operably coupled to the first lock mechanism and to the second lock mechanism, wherein movement of the first lock mechanism causes the linkage to move the second lock mechanism into engagement with the table saw to secure the second end to the table saw.
In another embodiment, a power saw includes a blade, a table having an opening configured to receive the blade, and an alignment member provided on the table. The alignment member includes a first lock mechanism located at a first end of the alignment member and a second lock mechanism located a second end of the alignment member. The first lock mechanism is adjustable to apply an adjustable self-alignment feature rip fence and the second lock mechanism is adjustable to apply an adjustable clamping force to the rip fence.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one of ordinary skill in the art to which this invention pertains.
The guides 50, 54, illustrated in perspective in
The rip fence 18 includes a first self-alignment and lock mechanism 44 and a second lock mechanism 48 that are selectively moveable between a locked position and an unlocked position. When in the locked position, the first and second lock mechanisms 44, 48 engage the guides 50, 54 in such a manner that the fence 18 is becoming self-aligned prior to being secured to and fixed in place with respect to the blade 22 and table 14. When in the unlocked position, the first and second lock mechanisms 44, 48 disengage from the guides 50, 54 such that the rip fence 18 is free to slide along the table surface. The guides 50, 54 are constructed of a rigid material such as metal or plastic. The shape of the guides 50, 54 permits the rip fence 18 to be easily attached to and removed, and also permits the fence 18 to slide across the surface of the table 14 for positioning by an operator or user of the table saw 10.
Lock mechanism 48 is located towards the rear of the table during a cutting operation. The lock mechanism 48 includes rear housing 106 which is coupled to the guide 100. Housing 106 includes a pivot pin 108 which supports a lock arm 110 for pivotal movement. The lock arm 110 includes a projection 112 coupled to an end 114 which engages a channel 116 defined in the fence guide 54. The projection 112 and the channel 116 include a mating configuration such that engagement of the projection 112 with the channel 116 enables the locking mechanism 48 to establish a locked position at the back portion of the rip fence 18 with respect to the table 14. In one embodiment, the projection 112 extends away from a planar portion 115 of the lock arm 110 and engages a recess 117 of the channel 116. When the rip fence 18 is locked in position, the projection 112 and the recess 117 form an interface. The projection 112 can be formed of a materials selected to increase the coefficient of friction at the interface with the recess 117 to substantially prevent slippage during cutting of a workpiece.
The lock arm 110 rotates about pivot pin 108 into and out of engagement with the channel 116. The projection 112 is pulled into engagement with the channel 116 by movement of the rod 102 responding to actuation of the lock mechanism 44. The rod 102 includes an end 120 which includes threads (not shown) to engage mating threads (not shown) of an adjustment knob 122. The adjustment knob 122 can be rotated about the rod 102 to select the amount of force applied to the guide 54 by the second lock mechanism 48 when the rip fence 18 is locked in place. Rotation of the knob 122 can either shorten or lengthen the effective actuating distance of rod 102 by determining how much of the end 120 extends past a middle portion 124 of the lock arm 110.
The adjustment knob 122 includes a dimension larger than an aperture 126 through which the rod 102 extends. Adjustment knob 122 is held generally fixed against the lock arm 110 by a biasing element, such as a spring 128, held in position on the rod 102 by a stop 130. The spring 128 is a helical spring surrounding the rod 102 and is compressed between the stop 130 and the middle portion 124 of the lock arm 110. By rotating the adjustment knob 122 about the rod 102, the amount of force applied to the channel 116 by the lock arm 110 can be selected. Other types of springs can also be used, such as a leaf spring. As illustrated in
Lock mechanism 44 is located towards the front of the table 14 for alignment of a rip fence for a desired cut of a workpiece. The lock mechanism 44 includes a handle 150 rotationally coupled to a housing 152 via a pivot pin 158. The fixed portion 156 includes a cantilever portion 160 coupled to the guide 100 for support thereof. The fixed portion 156 is fixed with respect to the cantilever portion 160 and to the guide 100. A glide 181 is fixed to the housing 152 and provides a gliding surface for positioning the rip fence 18 on guide 50. A glide 191 is fixed to the housing 152 and provides a gliding surface for positioning the rip fence 18 on guide 54. When unlocked, rip fence 18 moves on guide 50 and 54 on glides 181 and 191, but does not touch the table. During movement on the glides, the rip fence 18 is more or less parallel to the blade 22 where a gap is located between the fence 18 and the surface of the table 14.
The handle 150 includes a link 162 having a first end pivotally coupled to a pivot pin 163 supported by the movable portion 154. A cam link 164 is coupled to a second end of the link 160 by a pivot pin 166 and a cam portion 168 is coupled to the activation member 176. The movable portion 154 also includes a lower portion of handle 170 to make it relatively easy to move the handle 152 from an extended unlocked position (See
The cam portion 168 engages an activation member 176. The activation member 176 is coupled to the fixed portion 156 of the housing 152 and is supported at and rotates about a pivot pin 178. The activation member 176 includes a flat portion 180 and a first side 182 and a second side (not shown) extending away from the flat portion 180 and substantially perpendicular thereto. The pivot pin 178 is coupled to the fixed portion at opposite sides and extends through the first side 182 and the second side. The activation member 176 includes an aperture 184 to accommodate a head 185 of the rod 102. The head 185 is sufficiently larger than the aperture 184 such that the head 185 cannot be pushed or pulled through the aperture 184. The rod 102 includes an anti-rotation portion 186 disposed adjacently to the head 185 which defines a substantially rectangular portion to engage the aperture 184, which includes a rectangular shape slightly larger than the anti-rotation portion 186. Any rotational force applied to the rod about a longitudinal axis is thereby prevented. Other mechanisms for preventing rotation are also possible including different interfaces between the anti-rotation portion 186 and the aperture 184 including, for instance, a keying configuration. In another embodiment, a pin can be inserted through the activation plate 176 and the portion 186 to pivotally couple the end of the rod 102 to the activation plate, which can obviate the need for the head 185.
A locking/self-alignment spring 188, or self-alignment biasing element, is coupled to the activation member 176 with an attachment screw 190 and an adjustment screw 192. The locking self-alignment spring 188, which is resilient, can be formed as part of the activation member 176, or the activation member can include an activation plate separable from the locking self-alignment spring 188. The attachment screw 190 passes through an aperture of the locking self-alignment spring 188 and engages a threaded aperture located in a top portion 194 of the activation plate 176.(See
To secure the rip fence 18 to the guides 54 and 50, the rip fence 18 is placed at a desired location on the table 14. When the handle 154 is in the open position of
As the locking/self-alignment spring 188 moves towards the guide 50, the rod 102 is pulled towards the guide 50 which moves the projection 112 of the lock arm 110 towards the channel 116. Further movement of the handle 170, moves the locking self-alignment spring 188 into engagement with a ledge 200, or lip, of guide 50. Once the locking self-alignment spring 188 engages the ledge 200, it provides a self-aligning feature by pushing the rip fence 18 toward towards the right (as illustrated), till lower portion 189 of glide 181 engages with vertical portion of guide 50 to make rip fence 18 and guiding surface 104 substantially parallel to blade 22. The further movement of the handle 170 increases the amount of force applied by the self-alignment spring 188 to the guide 50. At the same time, the rod 102, which is pulled by rotation of the activation plate 176 towards the left (as illustrated), rotates the lock arm 110 about the pivot pin 108. The spring 128 is compressed against the stop 130 and the projection of the lock arm 110 is pulled into the channel 116 with a sufficient amount of force to lock the projection 112 in the channel 116 of the guide 54 and further engage a lower portion 189 of glide 181 with a vertical portion of guide 50 locking rip fence 18 in place. The amount of force applied to the rear guide 54 can be varied by adjusting the adjustment 122 towards or away from the end 120 of the rod 102 by rotating the adjustment knob 122 about the threads of the rod.
As handle 170 moves to the locking position in direction 172, plate 176 moves via linkage 162 and cam 164. Plate 176 moves spring 188 and rod 102. Tab 196 engages the guide 50 first, and moves rip fence 18 to the right (as illustrated) until part of glide 189 engages with guide 50 and aligns the rip fence 18 to be substantially parallel to blade 22 prior to being locked. When tab 112 engages with guide 54, a locking force F2 is created which is transferred to the front housing via guide 100 and creates reaction force F1. Knob 122 can adjust the locking force F2. Screw 192 can adjust the tab 196 position to insure self-alignment prior to tab 122 engaging guide 116.
The top portion 194 of the activation plate 180 is a passive part of the locking self-alignment spring 188 and moves with movement of the activation plate 176. The bottom portion 196 of the locking self-alignment spring 188, however, is an active part of the locking self-alignment spring and moves in the direction of movement of the activation plate 176 until the bottom portion 196 contacts the guide 50. At contact, movement of the bottom portion 196 towards the guide 50 is restricted, while the top portion can continue to move with the activation plate 176. Further movement of the activation plate 176 after contact with the guide 50 increases the force applied to the guide 50 by the lock mechanism 44 and provides a self-aligning feature by pushing the rip fence 18 toward towards the right (as illustrated), till lower portion 189 of glide 181 engages with vertical portion of guide 50 to make rip fence 18 and guiding surface 104 substantially parallel to blade 22 prior to lock the projection 112 in the channel 116. The increased force is also provided through the rod 102 to the lock mechanism 48 to secure the rip fence 18 more securely to the guides 50 and 54 of table 14.
The aperture 184 is located in the top portion 194 of the locking self-alignment spring 188. The aperture 184 includes a height, h, longer than a width, w, which is sufficiently wide enough to accommodate insertion of the anti-rotation portion 186 of the rod 102 but is sufficiently small enough to insure that the head 185 does not pass through the aperture 184. The height, h, includes a length longer than the side of the anti-rotation portion 186 in contact with the side of the aperture 184 defined by the height. This difference in length enables movement of the head end of the rod 102 within the aperture 184 to accommodate movement of the activation plate 176.
The bottom portion 196 of the locking self-alignment spring 188 includes a slot 210 through which the adjustment screw 192 can be inserted to engage a threaded aperture 212 (See
The bottom portion 196 includes a locking tab 214 which traverses a width 216 of the bottom portion and which extends from a planar surface 218. The intersection of the planar surface 218 with the locking tab 214 provides a groove which engages a portion of the guide 50, typically a portion of the ledge 200. The slot 210 allows for the adjustment screw 192 to be adjusted to a variety of depths with respect to the activation plate 176. When properly adjusted, self-alignment spring 188 provides a self-aligning feature by making the rip fence 18 and guiding surface 104 substantially parallel to blade 22 prior to lock the projection 112 in the channel 116. The locking tab 214 engages the ledge 200 of guide 50 to lock the rip fence 18 to the table saw and prevents rip fence disengagement from guide 50 if some force is applied to handle 152 or housing 156 in an upward direction. Individualized adjustment for a particular table saw is therefore provided including the ability of the rip fence 18 to be accurately aligned in the cutting direction 23 for table saws whose dimensions can vary from one table saw to another table saw due to different adjustment and manufacturing tolerances.
The described embodiments include a rip fence having a first and a second lock mechanism, each of which includes an adjustment mechanism to independently adjust one adjustment mechanism 44 for self-alignment with respect to the other adjustment mechanism 48 for locking force. Because the adjustment mechanisms are independent, the impact of dimensional differences between assembled parts can be reduced or overcome while still maintaining the effectiveness of the self-alignment and lock mechanisms. For instance, the locking self-alignment spring 188 provides an alignment feature to enable self-alignment of the spring 188 to the guide 50, and to therefore provide for optimum alignment of the rip fence 18 with respect to the blade 22 and table 14.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.
