Abstract:
Switch boxes for power tools with safety systems are disclosed. The switch boxes are particularly useful for woodworking equipment such as table saws equipped with safety systems that detect and react to dangerous conditions. The switch boxes may include a power switch, a start/stop switch, a bypass switch and a visual indicator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of U.S. patent application Ser. No. 11/027,322, filed Dec. 31, 2004, which claims the benefit of and priority from U.S. Provisional Patent Application Ser. No. 60/533,598, filed Dec. 31, 2003.  
         [0002]     This application is also a continuation of U.S. patent application Ser. No. 09/676,190, filed Sep. 29, 2000, which claims the benefit of and priority from U.S. Provisional Patent Application Ser. No. 60/157,340, filed Oct. 1, 1999 and U.S. Provisional Patent Application Ser. No. 60/182,866, filed Feb. 16, 2000.  
         [0003]     This application is also a continuation of the following U.S. patent application Ser. No. 09/929,221, filed Aug. 13, 2001, Ser. No. 09/929,227, filed Aug. 13, 2001, Ser. No. 09/929,234, filed Aug. 13, 2001, Ser. No. 09/929,235, filed Aug. 13, 2001, Ser. No. 09/929,236, filed Aug. 13, 2001, Ser. No. 09/929,237, filed Aug. 13, 2001, Ser. No. 09/929,238, filed Aug. 13, 2001, Ser. No. 09/929,240, filed Aug. 13, 2001, Ser. No. 09/929,242, filed Aug. 13, 2001, Ser. No. 09/929,425, filed Aug. 13, 2001, Ser. No. 09/929,426, filed Aug. 13, 2001, Ser. No. 10/053,390, filed Jan. 16, 2002, Ser. No. 10/100,211, filed Mar. 13, 2002, Ser. No. 10/146,527, filed May 15, 2002, Ser. No. 10/172,553, filed Jun. 13, 2002, Ser. No. 10/189,027, filed Jul. 2, 2002, Ser. No. 10/189,031, filed Jul. 2, 2002, Ser. No. 10/243,042, filed Sep. 13, 2002, Ser. No. 10/292,607, filed Nov. 12, 2002, Ser. No. 10/341,260, filed Jan. 13, 2003, Ser. No. 10/345,630, filed Jan. 15, 2003, Ser. No. 10/643,296, filed Aug. 18, 2003, Ser. No. 10/794,161, filed Mar. 4, 2004, Ser. No. 10/923,273, filed Aug. 20, 2004, Ser. No. 10/923,282, filed Aug. 20, 2004, Ser. No. 10/923,290, filed Aug. 20, 2004, Ser. No. 10/932,339, filed Sep. 1, 2004, Ser. No. 10/984,643, filed Nov. 8, 2004, Ser. No. 11/026,006, filed Dec. 31, 2004, Ser. No. 11/026,114, filed Dec. 31, 2004, Ser. No. 11/027,254, filed Dec. 31, 2004, Ser. No. 11/027,322, filed Dec. 31, 2004, Ser. No. 11/027,600, filed Dec. 31, 2004, Ser. No. 11/045,972, filed Jan. 28, 2005, Ser. No. 11/061,162, filed Feb. 18, 2005, Ser. No. 11/098,984, filed Apr. 4, 2005, Ser. No. 11/107,499, filed Apr. 15, 2005, Ser. No. 11/190,111, filed Jul. 25, 2005, Ser. No. 11/208,214, filed Aug. 19, 2005, Ser. No. 11/218,356, filed Sep. 2, 2005, Ser. No. 11/256,757, filed Oct. 24, 2005, Ser. No. 11/348,580, filed Feb. 6, 2006, Ser. No. 11/353,423, filed Feb. 13, 2006, Ser. No. ______, filed Mar. 31, 2006, titled Table Saw Throat Plates and Table Saws Including the Same, of inventors Stephen F. Gass, J. David Fulmer and David A. Fanning, and Ser. No. ______, filed Apr. 10, 2006, titled Brake Mechanism for Power Equipment, of inventors Stephen F. Gass, Joel F. Jensen, Anwyl M. McDonald, David S. D&#39;Ascenzo, and Andrew L. Johnston.  
         [0004]     All of the above applications are hereby incorporated by reference in their entirety for all purposes. 
     
    
     FIELD  
       [0005]     The present invention relates to power tools and more particularly to switch boxes for power tools with safety systems.  
       BACKGROUND  
       [0006]     Safety systems are often employed with power equipment such as table saws, miter saws, band saws, jointers, shapers, circular saws and other machinery, to minimize the risk of injury when using the equipment. Some safety systems include an electronic system to detect the occurrence of a dangerous condition and a reaction system to minimize any possible injury from the dangerous condition. For example, the detection system may detect when the hand of a user approaches or contacts a moving blade, and the reaction system may stop, retract, disable or cover a moving blade upon detection of the dangerous condition.  
         [0007]     The present document discloses switch boxes for use on power equipment with safety systems. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a schematic block diagram of a machine with a fast-acting safety system.  
         [0009]      FIG. 2  is a schematic diagram of an exemplary safety system in the context of a machine having a circular blade.  
         [0010]      FIG. 3  is a perspective view of a table saw with a switch box.  
         [0011]      FIG. 4  shows an embodiment of a switch box.  
         [0012]      FIG. 5  shows the back of the switch box of  FIG. 4 .  
         [0013]      FIG. 6  shows the right half of the switch box of  FIG. 4 .  
         [0014]      FIG. 7  shows the left half of the switch box of  FIG. 4 .  
         [0015]      FIG. 8  shows a paddle switch used in the switch box of  FIG. 4 .  
     
    
     DETAILED DESCRIPTION  
       [0016]     A machine that incorporates a safety system is shown schematically in  FIG. 1  and indicated generally at  10 . Machine  10  may be any of a variety of different machines, such as table saws, miter saws, band saws, jointers, shapers, circular saws, routers, sanders, etc. Machine  10  includes an operative structure  12  having a working or cutting tool  14  and a motor assembly  16  adapted to drive the cutting tool. Machine  10  also includes a safety system  18  configured to minimize the potential of a serious injury to a person using the machine. Safety system  18  is adapted to detect the occurrence of one or more dangerous conditions during use of the machine. If such a dangerous condition is detected, safety system  18  is adapted to engage operative structure  12  to limit any injury to the user caused by the dangerous condition.  
         [0017]     Machine  10  also includes a suitable power source  20  to provide power to operative structure  12  and safety system  18 . Power source  20  may be an external power source such as line current, or an internal power source such as a battery. Alternatively, power source  20  may include a combination of both external and internal power sources. Furthermore, power source  20  may include two or more separate power sources, each adapted to power different portions of machine  10 .  
         [0018]     It will be appreciated that operative structure  12  may take any one of many different forms. For example, operative structure  12  may include a stationary housing configured to support motor assembly  16  in driving engagement with cutting tool  14 . Alternatively, operative structure  12  may include one or more transport mechanisms adapted to convey a work piece toward and/or away from cutting tool  14 .  
         [0019]     Motor assembly  16  includes at least one motor adapted to drive cutting tool  14 . The motor may be either directly or indirectly coupled to the cutting tool, and may also be adapted to drive work piece transport mechanisms. The particular form of cutting tool  14  will vary depending upon the various embodiments of machine  10 . For example, cutting tool  14  may be a single, circular rotating blade having a plurality of teeth disposed along the perimetrical edge of the blade. Alternatively, the cutting tool may be a plurality of circular blades, such as a dado blade or dado stack, or some other type of blade or working tool.  
         [0020]     Safety system  18  includes a detection subsystem  22 , a reaction subsystem  24  and a control subsystem  26 . Control subsystem  26  may be adapted to receive inputs from a variety of sources including detection subsystem  22 , reaction subsystem  24 , operative structure  12  and motor assembly  16 . The control subsystem may also include one or more sensors adapted to monitor selected parameters of machine  10 . In addition, control subsystem  26  typically includes one or more instruments operable by a user to control the machine. The control subsystem is configured to control machine  10  in response to the inputs it receives.  
         [0021]     Detection subsystem  22  is configured to detect one or more dangerous or triggering conditions during use of machine  10 . For example, the detection subsystem may be configured to detect that a portion of the user&#39;s body is dangerously close to or in contact with a portion of cutting tool  14 . As another example, the detection subsystem may be configured to detect the rapid movement of a workpiece due to kickback by the cutting tool, as is described in U.S. patent application Ser. No. 09/676,190, the disclosure of which is herein incorporated by reference. In some embodiments, detection subsystem  22  may inform control subsystem  26  of the dangerous condition, which then activates reaction subsystem  24 . In other embodiments, the detection subsystem may be adapted to activate the reaction subsystem directly.  
         [0022]     Once activated in response to a dangerous condition, reaction subsystem  24  is configured to engage operative structure  12  quickly to prevent serious injury to the user. It will be appreciated that the particular action to be taken by reaction subsystem  24  will vary depending on the type of machine  10  and/or the dangerous condition that is detected. For example, reaction subsystem  24  may be configured to do one or more of the following: stop the movement of cutting tool  14 , disconnect motor assembly  16  from power source  20 , place a barrier between the cutting tool and the user, or retract the cutting tool from its operating position, etc. The reaction subsystem may be configured to take a combination of steps to protect the user from serious injury. Placement of a barrier between the cutting tool and teeth is described in more detail in U.S. Patent Application Publication No. 2002/0017183 A1, entitled “Cutting Tool Safety System,” the disclosure of which is herein incorporated by reference. Retracting the cutting tool is described in more detail in U.S. Patent Application Publication No. 2002/0017181 A1, entitled “Retraction System for Use in Power Equipment,” and U.S. Patent Application Ser. No. 60/452,159, filed Mar. 5, 2003, entitled “Retraction System and Motor Position for Use With Safety Systems for Power Equipment,” the disclosures of which are herein incorporated by reference.  
         [0023]     The configuration of reaction subsystem  24  typically will vary depending on which action or actions are taken. In the exemplary embodiment depicted in  FIG. 1 , reaction subsystem  24  is configured to stop the movement of cutting tool  14  and includes a brake mechanism  28 , a biasing mechanism  30 , a restraining mechanism  32 , and a release mechanism  34 . Brake mechanism  28  is adapted to engage operative structure  12  under the urging of biasing mechanism  30 . During normal operation of machine  10 , restraining mechanism  32  holds the brake mechanism out of engagement with the operative structure. However, upon receipt of an activation signal by reaction subsystem  24 , the brake mechanism is released from the restraining mechanism by release mechanism  34 , whereupon, the brake mechanism quickly engages at least a portion of the operative structure to bring the cutting tool to a stop.  
         [0024]     It will be appreciated by those of skill in the art that the exemplary embodiment depicted in  FIG. 1  and described above may be implemented in a variety of ways depending on the type and configuration of operative structure  12 . Turning attention to  FIG. 2 , one example of the many possible implementations of safety system  18  is shown. System  18  is configured to engage an operative structure having a circular blade  40  mounted on a rotating shaft or arbor  42 . Blade  40  includes a plurality of cutting teeth (not shown) disposed around the outer edge of the blade. As described in more detail below, braking mechanism  28  is adapted to engage the teeth of blade  40  and stop the rotation of the blade. U.S. Patent Application Publication No. 2002/0017175 A1, entitled “Translation Stop For Use In Power Equipment,” the disclosure of which is herein incorporated by reference, describes other systems for stopping the movement of the cutting tool. U.S. Patent Application Publication No. 2002/0017184 A1, entitled “Table Saw With Improved Safety System,” U.S. Patent Application Publication No. 2002/0017179 A1, entitled “Miter Saw With Improved Safety System,” U.S. Patent Application Publication No. 2002/0059855 A1, entitled “Miter Saw with Improved Safety System,” U.S. Patent Application Publication No. 2002/0056350 A1, entitled “Table Saw With Improved Safety System,” U.S. Patent Application Publication No. 2002/0059854 A1, entitled “Miter Saw With Improved Safety System,” U.S. Patent Application Publication No. 2002/0056349 A1, entitled “Miter Saw With Improved Safety System,” U.S. Patent Application Publication No. 2002/0056348 A1, entitled “Miter Saw With Improved Safety System,” and U.S. Patent Application Publication No. 2002/0066346 A1, entitled “Miter Saw With Improved Safety System,” U.S. Patent Application Publication No. 2003/0015253 A1, entitled “Router With Improved Safety System,” U.S. Patent Application Publication No. 2002/0170400 A1, entitled “Band Saw With Improved Safety System,” U.S. Patent Application Publication No. 2003/0019341 A1, entitled “Safety Systems for Band Saws,” U.S. Patent Application Publication No. 2003/0056853 A1, entitled “Router With Improved Safety System,” U.S. Provisional Patent Application Ser. No. 60/406,138, entitled “Miter Saw With Improved Safety System,” and U.S. Provisional Patent Application Ser. No. 60/496,550, entitled “Table Saws With Safety Systems,” the disclosures of which are herein incorporated by reference, describe safety system  18  in the context of particular types of machines.  
         [0025]     In the exemplary implementation, detection subsystem  22  is adapted to detect the dangerous condition of the user coming into contact with blade  40 . The detection subsystem includes a sensor assembly, such as contact detection plates  44  and  46 , capacitively coupled to blade  40  to detect any contact between the user&#39;s body and the blade. Typically, the blade, or some larger portion of cutting tool  14  is electrically isolated from the remainder of machine  10 . Alternatively, detection subsystem  22  may include a different sensor assembly configured to detect contact in other ways, such as optically, resistively, etc. In any event, the detection subsystem is adapted to transmit a signal to control subsystem  26  when contact between the user and the blade is detected. Various exemplary embodiments and implementations of detection subsystem  22  are described in more detail in U.S. Patent Application Publication No. 2002/0017176 A1, entitled “Detection System For Power Equipment,” U.S. Patent Application Publication No. 2002/0017336 A1, entitled “Apparatus And Method For Detecting Dangerous Conditions In Power Equipment,” U.S. Patent Application Publication No. 2002/0069734 A1, entitled “Contact Detection System for Power Equipment,” U.S. Patent Application Publication No. 2002/0190581 A1, entitled “Apparatus and Method for Detecting Dangerous Conditions in Power Equipment,” U.S. Patent Application Publication No. 2003/0002942 A1, entitled “Discrete Proximity Detection System,” and U.S. Patent Application Publication No. 2003/0090224 A1, entitled “Detection System for Power Equipment,” the disclosures of which are herein incorporated by reference.  
         [0026]     Control subsystem  26  includes one or more instruments  48  that are operable by a user to control the motion of blade  40 . Instruments  48  may include start/stop switches, speed controls, direction controls, light-emitting diodes, etc. Control subsystem  26  also includes a logic controller  50  connected to receive the user&#39;s inputs via instruments  48 . Logic controller  50  is also connected to receive a contact detection signal from detection subsystem  22 . Further, the logic controller may be configured to receive inputs from other sources (not shown) such as blade motion sensors, work piece sensors, etc. In any event, the logic controller is configured to control operative structure  12  in response to the user&#39;s inputs through instruments  48 . However, upon receipt of a contact detection signal from detection subsystem  22 , the logic controller overrides the control inputs from the user and activates reaction subsystem  24  to stop the motion of the blade. Various exemplary embodiments and implementations of control subsystem  26  are described in more detail in U.S. Patent Application Publication No. 2002/0020262 A1, entitled “Logic Control For Fast Acting Safety System,” U.S. Patent Application Publication No. 2002/0017178 A1, entitled “Motion Detecting System For Use In Safety System For Power Equipment,” and U.S. Patent Application Publication No. 2003/0058121 A1, entitled “Logic Control With Test Mode for Fast-Acting Safety System,” the disclosures of which are herein incorporated by reference.  
         [0027]     In the exemplary implementation, brake mechanism  28  includes a pawl  60  mounted adjacent the edge of blade  40  and selectively moveable to engage and grip the teeth of the blade. Pawl  60  may be constructed of any suitable material adapted to engage and stop the blade. As one example, the pawl may be constructed of a relatively high strength thermoplastic material such as polycarbonate, ultrahigh molecular weight polyethylene (UHMW) or Acrylonitrile Butadiene Styrene (ABS), etc., or a metal such as aluminum, etc. It will be appreciated that the construction of pawl  60  may vary depending on the configuration of blade  40 . In any event, the pawl is urged into the blade by a biasing mechanism in the form of a spring  66 . In the illustrative embodiment shown in  FIG. 2 , pawl  60  is pivoted into the teeth of blade  40 . It should be understood that sliding or rotary movement of pawl  60  might also be used. The spring is adapted to urge pawl  60  into the teeth of the blade with sufficient force to grip the blade and quickly bring it to a stop.  
         [0028]     The pawl is held away from the edge of the blade by a restraining mechanism in the form of a fusible member  70 . The fusible member is constructed of a suitable material adapted to restrain the pawl against the bias of spring  66 , and also adapted to melt under a determined electrical current density. Examples of suitable materials for fusible member  70  include NiChrome wire, stainless steel wire, etc. The fusible member is connected between the pawl and a contact mount  72 . Preferably, fusible member  70  holds the pawl relatively close to the edge of the blade to reduce the distance the pawl must travel to engage the blade. Positioning the pawl relatively close to the edge of the blade reduces the time required for the pawl to engage and stop the blade. Typically, the pawl is held approximately 1/32-inch to ¼-inch from the edge of the blade by fusible member  70 , however other pawl-to-blade spacings may also be used.  
         [0029]     Pawl  60  is released from its unactuated, or cocked, position to engage blade  40  by a release mechanism in the form of a firing subsystem  76 . The firing subsystem is coupled to contact mount  72 , and is configured to melt fusible member  70  by passing a surge of electrical current through the fusible member. Firing subsystem  76  is coupled to logic controller  50  and activated by a signal from the logic controller. When the logic controller receives a contact detection signal from detection subsystem  22 , the logic controller sends an activation signal to firing subsystem  76 , which melts fusible member  70 , thereby releasing the pawl to stop the blade. Various exemplary embodiments and implementations of reaction subsystem  24  are described in more detail in U.S. Patent Application Publication No. 2002/0020263 A1, entitled “Firing Subsystem For Use In A Fast-Acting Safety System,” U.S. Patent Application Publication No. 2002/0020271 A1, entitled “Spring-Biased Brake Mechanism for Power Equipment,” U.S. Patent Application Publication No. 2002/0017180 A1, entitled “Brake Mechanism For Power Equipment,” U.S. Patent Application Publication No. 2002/0059853 A1, entitled “Power Saw With Improved Safety System,” U.S. Patent Application Publication No. 2002/0020265 A1, entitled “Translation Stop For Use In Power Equipment,” U.S. Patent Application Publication No. 2003/0005588 A1, entitled “Actuators For Use in Fast-Acting Safety Systems,” and U.S. Patent Application Publication No. 2003/0020336 A1, entitled “Actuators For Use In Fast-Acting Safety Systems,” the disclosures of which are herein incorporated by reference.  
         [0030]     It will be appreciated that activation of the brake mechanism will require the replacement of one or more portions of safety system  18 . For example, pawl  60  and fusible member  70  typically must be replaced before the safety system is ready to be used again. Thus, it may be desirable to construct one or more portions of safety system  18  in a cartridge that can be easily replaced. For example, in the exemplary implementation depicted in  FIG. 2 , safety system  18  includes a replaceable cartridge  80  having a housing  82 . Pawl  60 , spring  66 , fusible member  70  and contact mount  72  are all mounted within housing  82 . Alternatively, other portions of safety system  18  may be mounted within the housing. In any event, after the reaction system has been activated, the safety system can be reset by replacing cartridge  80 . The portions of safety system  18  not mounted within the cartridge may be replaced separately or reused as appropriate. Various exemplary embodiments and implementations of a safety system using a replaceable cartridge, and various brake pawls, are described in more detail in U.S. Patent Application Publication No. 2002/0020261 A1, entitled “Replaceable Brake Mechanism For Power Equipment,” U.S. Patent Application Publication No. 2002/0017182 A1, entitled “Brake Positioning System,” U.S. Patent Application Publication No. 2003/0140749 A1, entitled “Brake Pawls for Power Equipment,” and U.S. Provisional Patent Application Ser. No. 60/496,568, entitled “Motion Detecting System for use in a Safety System for Power Equipment,” the disclosures of which are herein incorporated by reference.  
         [0031]     While one particular implementation of safety system  18  has been described, it will be appreciated that many variations and modifications are possible. Many such variations and modifications are described in U.S. Patent Application Publication No. 2002/0170399 A1, entitled “Safety Systems for Power Equipment,” U.S. Patent Application Publication No. 2003/0037651, entitled “Safety Systems for Power Equipment,” and U.S. Patent Application Publication No. 2003/0131703 A1, entitled “Apparatus and Method for Detecting Dangerous Conditions in Power Equipment,” the disclosures of which are herein incorporated by reference.  
         [0032]      FIG. 3  shows a table saw  100 , often called a cabinet saw or tilting-arbor saw, that may include a safety system as described above. Saw  100  includes a table  102  on which a work piece may be cut. The table is mounted on a cabinet  104 . A blade  106  extends up through a slot in the table to cut a work piece. A motor assembly (not shown) is supported inside the cabinet to drive the blade. Hand wheels  108  and  110  may be turned to adjust the elevation of the blade (the height the blade extends above the table) and the tilt of the blade relative to the tabletop. In operation, a user makes a cut by pushing a work piece on the table past the spinning blade.  
         [0033]     Saw  100  and its safety system are controlled by a switch box  112  mounted on the saw. The switch box is shown in more detail in  FIGS. 4 through 7 . The switch box may be mounted to the saw in any known manner, such as by screws extending through mounting flanges. One mounting flange is identified in  FIG. 5  at  113 . The switch box typically would include at least part of the electronics necessary to control the operation of the saw.  
         [0034]     Switch box  112  includes a power switch  114  that switches power to the control subsystem of the saw. In other words, when switch  114  is on, electricity is supplied to circuitry that is part of the control subsystem. Power switch  114  includes a removable actuator  116 . The switch will function when the actuator is present, but cannot be turned on if the actuator is removed. Using a switch with a removable actuator allows a person to control the use of the saw and prevent unauthorized or accidental operation of the switch.  
         [0035]     Power is supplied to switch box  112  by a cord  118  entering into the switch box through the back, as shown in  FIG. 5 . Cord  118  passes through a strain relief  124  as it enters the switch box. The strain relief is made from a metal plate that clamps over the cords as shown in  FIG. 6 . Signals may be sent out of the switch box through cord  120  or, in some applications, through another cord that would exit the switch box from aperture  122 . The cords may connect to various parts of the machine, such as to the reaction system, to a brake cartridge and/or to a motor.  
         [0036]     Switch box  112  also includes a start/stop paddle switch  130  mounted to pivot in and out around pivot  132 . Paddle switch  130  is designed so that a predetermined function of the tool, such as starting the blade spinning in a table saw, is accomplished by pulling the paddle out. Pushing the paddle in causes the predetermined function to stop. Paddle switch  130  is sized large enough so that it can be easily accessed and actuated by a user. For example, a user can bump the paddle switch with a knee or thigh or slap the switch with the palm to stop the predetermined function in a potentially dangerous situation. Paddle switch  130  will not start the predetermined function, however, until and unless power switch  114  is turned on.  
         [0037]     Switch box  112  is formed with projections or walls  134  that extend out and around paddle switch  130  to prevent accidental contact with the paddle causing the tool to start. The switch box is also formed with an indentation  136 . An end of paddle switch  130  extends out and over indentation  136  so a user can reach under the paddle to pull it out and start the machine. Power switch  114  also has walls  138  to protect the power switch from being turned on by accidental contact.  
         [0038]     Switch box  112  includes a user interface to indicate the status of the machine. In the embodiment shown in  FIG. 4  the user interface comprises two light-emitting diodes  140 . One diode may be red, for example, and it could be used to signal a problem or error with the machine. The other diode may be green and it could be used to indicate that the machine is okay and ready to use. The diodes also indicate when power switch  114  is turned on. Alternatively, only one diode or more than two diodes may be used as a user interface, or a LCD display may be used instead of diodes. The user interface may be positioned on an angled surface, as shown, so that it is easier to see by a user standing over the switch box.  
         [0039]     Switch box  112  also includes a bypass switch  141  shown in  FIG. 5 . The bypass switch is used to deactivate the safety system when desired. In the depicted embodiment, the bypass switch is a key switch, so it can only be used with a specific key.  
         [0040]     Switch box  112  is assembled from two halves  142  and  144  that are screwed together. Each half typically would be a molded part made of a plastic such as ABS. Right half  142  is the larger of the two halves and it is shown in  FIG. 6 . It houses a circuit board  150  (which is part of the control subsystem) supported by plastic flanges and tabs, such as flange  152 . The flanges and tabs are configured to hold circuit board  150  in place. The circuit board also may be held in place by a spacer and screw, as shown at  153  in  FIG. 6 . Power switch  114 , cables  118  and  120 , paddle switch  130 , LEDs  140 , and bypass switch  141  would all be electrically connected to the circuit board. Left half  144  of the switch box is shown in  FIG. 7 , and it acts as a lid or cover for right half  142 . With this construction, a user may remove left half  144  to service circuit board  150  or other components without having to remove the switch box from the machine and without having to disconnect switches or other components from the switch box.  
         [0041]     Paddle switch  130  is designed to activate a small tactile switch  160  mounted on circuit board  150 . The tactile switch is an electronic component that may be used in the control subsystem to control the function of the machine. Typically, the control subsystem will include a microprocessor, and the tactile switch would be a logic switch.  
         [0042]     Tactile switch  160  provides an economical way to control the operation of the machine. However, a tactile switch typically requires only a small movement and minimal force to operate, while a user of a machine such as a table saw is accustomed to a switch that requires significant force to operate and that has a solid movement and feel. Paddle switch  130  is designed to provide the user with a robust switch having a positive movement while at the same time triggering tactile switch  160  with only the required force.  
         [0043]     Paddle switch  130  is sandwiched on corresponding posts  162  on the right and left halves of the switch box, as shown in  FIGS. 6 and 7 . The outer surfaces of the two halves under the paddle switch each include a projection  164  that acts as a stop to limit the inward pivoting of the paddle switch. A perspective view of the back of paddle switch  130  is shown in  FIG. 8 , and it includes two tabs  170  and  172 , each tab extending inwardly relative to the switch box from one side of the large end of the paddle. The tabs mesh with corresponding surfaces on the two halves of the switch box, such as surface  173  shown in  FIG. 7 , to provide friction when the paddle is pulled out or pushed in. The two tabs and corresponding surfaces also provide a definite engagement and they may be configured so the paddle “clicks” or “snaps” into place as it moves. Paddle  130  also includes stops  174  and  176  that mesh with corresponding surfaces on the two halves of the switch box to prevent the paddle from being pulled out too far.  
         [0044]     A connecting link  180  extends between paddle switch  130  and a spring  182 . One end of the link is held in a trough  184  in the underside of the paddle switch by a plate  186  that is screwed down over the link. In this manner, the link can pivot slightly in the trough but cannot escape. The link then extends through an aperture  188  in the switch box and connects to spring  182 . Spring  182 , in turn, is connected to an actuator  190  mounted to pivot in the switch box adjacent tactile switch  160 . Actuator  190  includes a tab  192 , as shown.  
         [0045]     When a user pulls paddle switch  130  out, link  180  moves out and stretches spring  182 . Spring  182 , in turn, causes actuator  190  to pivot and tab  192  to contact and trigger tactile switch  160 . Spring  182  acts as a force regulator and limiter to prevent too much force being applied to the tactile switch. Thus, a user may pull paddle switch  130  out with a substantial force while spring  182  causes actuator  190  to apply a regulated, smaller force to the tactile switch. When a user pushes the paddle switch back in to turn off the machine, link  180  moves in and causes spring  182  to move together. The spring then pushes actuator  190  away from the tactile switch. Additionally, the tactile switch in biased toward the off position with a small internal spring force, so the tactile switch itself pushes actuator  190  away when the paddle switch is moved in.  
         [0046]     The switch box is essentially totally enclosed, except for aperture  188  under the paddle, to prevent dust from entering into the switch box. The switch box also includes a wall  200  under paddle switch  130 , and paddle  130  includes a corresponding wall  202  extending in toward the switch box. Those walls limit how far a person may reach under the paddle. The walls also protect connecting link  180  under the paddle.  
         [0047]     Switch box  112  has been discussed as mounted on a table saw. Of course, the switch box may be used with other types of machines and with other power tools having various safety systems.  
       INDUSTRIAL APPLICABILITY  
       [0048]     The systems and components disclosed herein are applicable to power equipment. It is believed that the disclosure set forth above encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. The subject matter of the inventions includes all novel and non-obvious combinations and sub-combinations of the various elements, features, functions and/or properties disclosed herein. No single feature, function, element or property of the disclosed embodiments is essential to all of the disclosed inventions. Similarly, where the claims recite “a” or “a first” element of the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.  
         [0049]     It is believed that the following claims particularly point out certain combinations and sub-combinations that are directed to one of the disclosed inventions and are novel and non-obvious. Inventions embodied in other combinations and sub-combinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different invention or directed to the same invention, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the inventions of the present disclosure.