Abstract:
A power tool and accessories therefor including a variable speed motor for a mortiser, an integrated chisel positioning tool for positioning a chisel in a desired position, and an integrated tool sharpening device mounted directly on the power tool to permit ease and efficiency in the sharpening of tools. Additionally, an improved clamping arrangement is provided that permits firm clamping of a work piece without slippage. Greater flexibility in the hold down may be achieved by using arms for the hold down that are both rotatable about and can be translated along respective horizontal axes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application No. 60/635,895, filed Dec. 14, 2004, which is hereby incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to an improved power tool, and more particularly, an improved mortiser and accessories therefor.  
         [0003]     Power tools, such as hollow chisel mortisers, come in various designs and arrangements. Generally, mortisers include a work table mounted on a base, which can be positioned on a stand or table, or on the ground, a support post which extends above the table and on which a motor for carrying a tool, such as a chisel, is mounted for movement of the chisel in a vertical direction towards and away from the working surface of the table. Additionally, a fence disposed perpendicular to the table&#39;s surface is mounted on the table for movement along the table, and a material stop or hold down mechanism, generally mounted on or to the rear of the fence, is provided for holding down a workpiece on the table surface and/or against the fence. One problem with such hold-down mechanisms has been slippage while the mortiser is in use. Moreover, the range of vertical movement of the hold-down mechanism, in order to hold down various size workpieces to the table, is generally rather limited, particularly in the downward direction, in view of the interference with the vertical movement of the hold down mechanism caused by the fence. Additionally, the known hold-down mechanisms generally utilize a simple setscrew mechanism to hold a bracket used as a material stop. This leads to such hold-down mechanisms being prone to slippage, not being flexible in order to hold down various odd shaped workpieces, except with great difficulty, and having a mechanism that cannot extend close to the work table surface, and thus positively clamp relatively thin workpieces, except with the use of additional blocks or shims.  
         [0004]     A further problem with known mortisers is that the motor utilized to drive the mortising tool (e.g., chisel and auger which may collectively be referred to hereinafter as a chisel), is in general a constant speed motor, and thus is not available for customization of the auger speed to an application. Thus, the use of a fixed speed for the mortising tool often leads to either high-speeds which may cause chisel “burn” or low-speeds which may cause unwanted resistance when using the mortiser. In addition, certain other variables of the use of the mortiser, including various chisel sizes, the hardness of the wood being mortised, the sharpness of the chisels, etc., are affected by the speed. However, current mortising machines do not provide for any mechanism for taking the motor speed into consideration.  
         [0005]     In addition to the above, it has become customary in mortisers to provide a caddy for the mortising tools, as well as for other tools necessary for operation of the mortiser, directly on the mortiser in order to provide ease in changing chisels and/or making such tools readily available and accessible. One common problem with mortising tools is that they often need sharpening, which requires special tools. However, none of the mortisers currently available provide any arrangement for easing the steps of sharpening the chisels or provide any consideration for handling this problem. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]      FIG. 1A  is a perspective view of a mortiser according to the invention;  
         [0007]      FIG. 1B  is a front elevational view of the mortiser of  FIG. 1A ;  
         [0008]      FIG. 1C  is a side elevational view of the mortiser of  FIG. 1A ;  
         [0009]      FIG. 2  is an enlarged partial perspective view of the mortiser of  FIG. 1A  showing a chisel and tool sharpening arrangement exploded from the tool caddy, but with the table and fence removed for clarity;  
         [0010]      FIG. 3A  is an enlarged front elevational view of the mortiser of  FIG. 1A  showing a table, fence and clamp in accordance with the invention, but with the support post for the motor and parts mounted thereon removed for clarity;  
         [0011]      FIG. 3B  is an enlarged side elevational view of the mortiser of  FIG. 3A ;  
         [0012]      FIG. 3C  is an enlarged rear elevational view of the mortiser of  FIG. 3A ;  
         [0013]      FIG. 3D  is an enlarged top plan view of the mortiser of  FIG. 3A ;  
         [0014]      FIG. 3E  is a bottom plan view of the mortiser of  FIG. 3A ;  
         [0015]      FIG. 4A  is an enlarged perspective view of the mortiser of  FIG. 1A  showing the arms of the clamp in a first position;  
         [0016]      FIG. 4B  is an enlarged perspective view of the mortiser of  FIG. 1A  showing the arms of the clamp in a second position;  
         [0017]      FIG. 4C  is an enlarged perspective view of the mortiser of  FIG. 1A  showing the arms of the clamp in a third position;  
         [0018]      FIG. 4D  is an enlarged perspective view of the mortiser of  FIG. 1A  showing the arms of the clamp in a fourth position;  
         [0019]      FIG. 5A  is a perspective view of the mortiser of  FIG. 1  showing a chuck access panel in its open position and a chisel positioning tool in accordance with the invention;  
         [0020]      FIG. 5B  is an enlarged perspective view of the mortiser of  FIG. 5A  showing the chisel positioning tool in a first position;  
         [0021]      FIG. 5C  is an enlarged perspective view of the mortiser of  FIG. 5A  showing the chisel positioning tool in a second position;  
         [0022]      FIG. 6  is a schematic diagram of a motor control arrangement for the motor of the mortiser according to a feature of the invention;  
         [0023]      FIG. 7  is a perspective view of a mortiser according to the invention illustrating an alternate actuator for adjusting the fence, chisel positioning tool, and clamp; and  
         [0024]      FIG. 8  is a perspective view of the mortiser of  FIG. 7  illustrating the clamp in an alternate configuration. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     Turning now to FIGS.  1 A-C, there is shown a mortiser having a base or work table  10  with a flat substantially rectangular upper work surface  12 . It is to be noted that although the base  10  is illustrated as a unitary, one-piece structure, such is not required since the illustrated embodiment of the mortiser is for placing or mounting on a table, workbench or other support. That is, the actual base may be separated into parts, with a main base portion being supported by a secondary base portion, such as for example, a stand or enclosed cabinet which rest on the ground and position the main base portion at a desired vertical level. Additionally, it should be noted that it is also possible for the main base portion to be movable relative to the secondary base portion in any of the x, y and z directions, if desired.  
         [0026]     The tool support or post  14  is mounted on the base  10  adjacent one end thereof, for example, by means of bolts  16 , extending through and perpendicular to the surface  12 . Like the base, it is also possible for the post  14  to be mounted so that it is movable relative to the base if desired. In the embodiment illustrated, however, the post  14  is fixed to the base  10  and the carriage  18  is slideably mounted on the post or tool support  14  for movement towards and away from the surface  12  (e.g., in the embodiment illustrated, the carriage  18  is movable in a vertical direction). Control of the position of the carriage  18  is achieved via a rack  20  mounted on the forward surface of the post or tool support  14 , and engaged by a pinion gear (not shown) within the carriage  18 . Movement of the gear is controlled via a lever  22 , so that movement of the lever  22  in a downward direction will cause the carriage  18  to move downwardly, and vice versa. In the embodiment illustrated, the lever  22  has an elongated shaft  22   a  with an enlarged grip  22   b  located at the distal end thereof. The elongated shaft  22   a  is connected to a collar  22   c  that is secured to the axial shaft of the pinion gear.  
         [0027]     In a preferred form, the mortiser  10  can be customized to the user so that a comfortable operation setting may be obtained. For example, the lever  22 , including shaft  22   a , enlarged grip  22   b  and cap or collar  22   c , may be connected to the axial shaft of the pinion gear on either the left or right side of the carriage  18  to accommodate either left or right handed operators. In the embodiment illustrated, the collar  22   c  of lever  22  is fitted onto the axial shaft of the pinion gear like a socket and extends from the right side of the carriage, which is typically the position favored by most right-handed operators. In addition, the collar  22   c  of the lever  22  may be connected to the axial shaft of the pinion gear in a variety of positions with each position placing the elongated shaft  22   a  and grip  22   b  at a different angle with respect to the carriage  18 . In this manner, the user or operator may place the elongated shaft  22   a  and grip  22   b  at an operating angle that is most comfortable to him or herself. In the embodiment illustrated, the collar  22   c , and thus the shaft  22   a  and grip  22   b , are positionable at sixty degree intervals about the axial shaft of the pinion gear. In alternate embodiments, the collar  22   c , shaft  22   a  and grip  22   b  may be positionable at other angles.  
         [0028]     The length of the lever  22  may also be adjusted to allow operators to further customize the mortiser. For example, in the embodiment illustrated, the elongated shaft  22   a  is inserted into an opening defined by the collar  22   c  until the grip  22   b  has reached a desired distance from the collar  22   c  and then a fastener, such as a set screw (not shown), is inserted into an opening in the collar  22   c  that intersects the opening for shaft  22   a  and is screwed into engagement with the shaft  22   a  to secure the lever  22  into position. In this manner, the collar  22   c  forms a sleeve into which the shaft  22   a  is inserted and can be adjusted to any length desired. In alternate embodiments, the shaft  22   a  and the sleeve formed by collar  22   c  may be threaded to allow the length of the lever  22  to be adjusted by simply threading either more or less of the elongated shaft  22   a  into collar  22   c.    
         [0029]     In the embodiment illustrated, a lift mechanism, such as hydraulic cylinder  19 , is provided to assist the operator in returning the carriage  18  to its uppermost limit of travel. The hydraulic cylinder  19  is connected at one end to base  10  and at the other end to carriage  18  and urges the carriage away from surface  12 . By doing so, the cylinder  19  assists the user in removing chisels that have been inserted into a workpiece and in returning the carriage  18  to its upper or start position.  
         [0030]     The depth of travel of the carriage  18  along the rack  20  may be controlled by a stop  24  that extends across the rack  20  and is mounted in a pair of opposed slots  26  formed in the opposite sidewalls of the post or support  14 , and which can be locked into place by a locking lever or handle  28 . In the embodiment illustrated, the stop  24  preferably has an opening through which the rack  20  may pass when the stop  24  is positioned up or down the post  14 . This configuration allows the stop  24  to be secured at a desired depth along rack  20  and prevents the carriage  18  from being moved downward below this point. In an alternate embodiment, the stop  24  may also have a rear edge facing the rack  20 , such that it can engage a tooth of the rack  20 , thus providing a positive lock that securely locks the stop  24  in place against movement in a vertical direction even upon engagement by the carriage  18 . With this configuration, the bore through which lock  28  passes may be designed to provide enough play to move the stop  24  forward, disengaging the rear edge from the tooth of the rack, so that the stop may be moved into a desired position along the rack  20 .  
         [0031]     In either embodiment, the stop  24  is in substantial alignment with the rack and pinion system and the force created thereby, thus, providing a stronger stop which is capable of preventing the carriage from jamming or racking. Such an in-line configuration overcomes the shortcomings associated with traditional stops, which usually include an offset configuration wherein the stop is positioned on a shaft mounted apart from and parallel to the support  14 . More particularly, the offset configuration of traditional stops typically creates a coupling force which twists the carriage and may cause racking or jamming of the carriage on the rack  20 . Such a configuration may also result in the bowing or bending of the shaft upon which the stop is positioned due to the stop shafts distance from the force applied by the rack and pinion system of the carriage causing the carrier and chisel to bind up and/or possibly even stick in a workpiece during operation. In the embodiment illustrated, however, the stop is positioned in-line with the force generated by the rack and pinion system and prevents such coupling forces that lead to binding or racking.  
         [0032]     Mounted on the end of the carriage  18  opposite post or support  14 , is an electric motor  30  having a chuck  32  (see  FIG. 5A ) located within an access panel  18   a  of carriage  18 . The chuck  32  is used to hold and rotate the auger or drill bit  44   a  of the chisel  44  and may be tightened or loosened using a chuck key in the embodiment illustrated, or using ones hands in an alternate keyless chuck embodiment. In a preferred form, the access panel  18   a  of carriage  18  includes a wide wrap-around door which is preferably hinged to the carriage  18  and has a magnetic lock or latch for securing the door when in its closed position. The access panel may also include a handle, such as raised lip or knob  18   b  which the operator may use to move the access panel between its open ( FIG. 5A ) and closed positions ( FIG. 1A ). The wide wrap-around access panel  18   a  allows the user to access the chuck  32  from the front, left or right, as illustrated in  FIG. 5A , thereby making it easier to operate for both left handed and right handed operators, particularly when a chuck key is required to tighten or loosen the chuck  32 .  
         [0033]     The carriage  18  further defines an opening  18   c  for receiving a bushing  33  (see FIGS.  5 A-C) into which the chisel  44   b  is inserted. In a preferred form, the chisel  44   b  has a sleeve  44   c  that is inserted into the bushing  33  until the shoulder of the chisel sleeve  44   c  abuts the shoulder of the bushing  33 . Before mounting the chisel  44   b , the chisel  44   b  is lowered a desired amount depending on the type of chisel and workpiece the mortiser is being used with, such as for example between approximately 1/16″ to 3/16″, and the chisel is secured into position via a fastener, such as chisel lock  34 . In the embodiment illustrated, chisel lock  34  is a setscrew with an integrated handle  34   a  which allows the chisel lock to be fastened without the need for additional tools. Thus, by rotating the chisel lock in one direction, the setscrew will pass through an opening in the annular wall of bushing  33  and engage the sleeve  44   c  of chisel  44   b  securing the chisel  44   b  in the bushing  33 . Conversely, by rotating the chisel lock in the opposition direction, the setscrew will release the chisel sleeve  44   c  allowing the chisel  44   b  to be removed from the bushing  33  and eventually allowing the bushing  33  to be removed. In the embodiment illustrated, the toolless chisel lock  34  may be rotated in a clockwise direction to secure the bushing  33  and chisel  44  in position or rotated in a counter clockwise direction to release the chisel  44  and bushing  33 . In alternate embodiments a chisel lock with a movable handle may be used to secure the bushing  33  and chisel  44  so that the handle can be moved to avoid interfering with the chuck access door  18   a  and/or the workpiece. For example, in one form, the chisel lock  34  may be provided with a pivoting handle so that the handle may be rotated one hundred and eighty degrees in case it is obstructing the path of the chuck access door  18   a . In yet other embodiments, a slotted T-shaped handle, similar to those used on clamps or vises, or a ratcheting handle may be used so that the handle may be moved to avoid interfering with the mortiser or its components.  
         [0034]     In one form, an integrated chisel offset tool may be provided to assist the operator in positioning the auger  44   a  and chisel  44   b  correctly with respect to the chuck  32  and bushing  33 . For example, in FIGS.  5 A-C, a chisel offset tool, such as spacer or jig  72 , may be used by the operator to mount the chisel  44   b  in bushing  33  at a desired position. In the embodiment illustrated, spacer  72  is mounted to the carriage  18  so that it may be pivoted into alignment with the opening of bushing  33  and used to space the shoulder of chisel sleeve  44   c  from the bottom of bushing  33  as illustrated in  FIG. 5B . More particularly, spacer  72  is a body having a first end  72   a  of a first desired thickness and a second end  72   b  of a second desired thickness, which may be moved to position either of the first or second ends in alignment with the opening of bushing  33 . In a preferred embodiment, the ends of spacer  72  will be able to provide a range of spacing, such as for example spacing of a quarter inch or smaller. In the form illustrated, the first end  72   a  has a thickness of about 3 mm to provide a desired offset for smaller chisels and the second end  72   b  has a thickness of about 4 mm to provide a desired offset for larger chisels. Once the chisel  44   b  has been positioned and secured in bushing  33 , the spacer  72  may be rotated out of alignment with the opening of bushing  33 , as illustrated in  FIG. 5C , so that the mortiser may be prepared for use.  
         [0035]     It should be understood, however, that the integrated offset tool may take any shape and provide any desired amount of spacing for a particular application. In fact, in a preferred embodiment, spacer  72  is mounted to the carriage  18  via a removable fastener, such as bolt  73 , so that the spacer may be removed and replaced with alternate spacers of differing size so that an operator may customize the mortiser and chisel spacing to his or her desired applications. In the form illustrated, spacer  72  defines a bore into which bolt  73  is inserted to fasten the spacer to carriage  18 . The bolt  73  is tightened a sufficient amount to provide a frictional engagement between the spacer  72  and carriage  18  so that the spacer  72  may be rotated to place the first or second ends  72   a - b  in alignment with the opening of bushing  33  and so that the spacer  72  will remain in the position it is placed.  
         [0036]     Once the chisel  44   b  has been secured in bushing  33 , the auger  44   a  is pushed up into the chisel  44   b  and secured into position by tightening chuck  32  in any of the manners discussed above. In the form illustrated, chuck key  32   a  is used to tighten the chuck and secure the auger  44   a  therein. After the auger  44   a  is mounted in the chuck  32 , the chisel lock  34  is released so that the chisel  44   b  may be inserted further into the bushing  33  to ensure that the auger  44   a  and chisel  44   b  are positioned properly for engaging the workpiece. More particularly, the remaining portion of the chisel sleeve  44   c  which was previously prevented from being inserted into the bushing  33  by the presence of spacer  72  will now be inserted into the bushing  33  so that the shoulder of the chisel  44  abuts the outer surface of bushing  33 . This configuration will allow the auger  44   a  and chisel  44   b  to efficiently engage and eject the chips or scrap removed from the workpiece through an opening, such as slot  44   d , in the chisel  44   b . The chisel  44   b  may be positioned so that the slot  44   c  is located in any direction scrap is preferred to be ejected (e.g., forward, backward or to either side). In addition, some chisels  44   b  may be provided with more than one opening, such as slots located on opposing sides of the chisel, so that more scrap may be removed or ejected if desired.  
         [0037]     In yet other embodiments, the chisel positioning tool  72  may comprise a ball and detent system wherein one of the chisel and bushing define a detent and the other of the chisel and bushing have a spring biased ball for mating with the detent. In this manner, the chisel may be inserted into the bushing until the ball engages the detent indicating that a desired position has been reached wherein the chisel is spaced an appropriate amount for the bushing in order to insert the auger. Once the auger has been secured in the chuck, the chisel may be inserted further into the bushing so that the shoulder of the chisel abuts the outer surface of the bushing and the chisel can be secured into its final position before performing work on the workpiece. In a preferred form, the ball will engage a second detent when the chisel has reached its final position to further assist the operator in preparing the mortiser for operation. Additional balls or detents may be provided as desired, such as for example, in order to place chisels of different sizes.  
         [0038]     In yet another embodiment, the chisel positioning tool  72  may comprise a rotatable bushing, wherein at least a portion of the bushing may be rotated into a first position in order to adjust the size of the bushing opening so that the chisel may only be inserted into an initial position in the bushing. After the chisel has been inserted to the initial position and secured, the auger may be inserted into the chuck and secured. Then, the bushing may be rotated to a second position where the chisel is allowed to be inserted into its final position in the bushing and secured.  
         [0039]     A housing  36  containing the controls for the motor  30 , is mounted in a convenient location on the power tool, such as for example adjacent the motor  30 . In the embodiment illustrated, the control switch  38  is a paddle switch which pivots about its upper most point. To activate the mortiser, the lower portion of the switch  38  is pulled out away from the housing and to deactivate the mortiser, the lower portion of the switch  38  is pushed in toward the housing. This type of paddle switch is preferable in that inadvertently bumping the control switch  38  will cause the switch to turn off rather than on. To further reduce the risk of inadvertent operation, the control switch  38  may also be keyed. For example, in the embodiment illustrated, the control switch  38  has a removable key portion  38   a  which prevents the switch  38  from actuating the mortiser if the key  38   a  is not properly positioned thereon. Thus, when the mortiser is not in use, the operator may simply remove the key  38   a  to disable the switch  38 , such as for example by disengaging the paddle switch from the contacts of the inner switch, to prevent the mortiser from being operated. To assist the user in removing the key  38   a , the housing  36  has notches or grooves  36   a - b , which allow the operator to reach around the sides of the actuator or control switch  38  and pull the key portion  38   a  out of switch  38 .  
         [0040]     As noted above, it is desirable in a mortiser to be able to vary the speed of the motor  30 , depending on variables affecting the operation of the mortiser, for example, sharpness of the chisels, type of wood to be mortised, etc. Accordingly, to control the motor  30 , the housing  36  is provided not only with an actuator or control switch  38 , for turning the motor on and off, but additionally with a speed control, such as speed control knob  40 , for a motor control circuit in the housing  36  in order to operate the motor  30  at a desired speed. The specific circuit controlled by the knob  40  may be any conventional motor speed control circuit, depending on the type of motor, which, preferably is a single-phase induction AC motor. An example of a speed control circuit that may be used for this purpose is discussed further below with respect to  FIG. 6 . In a preferred form, the motor  30  is a single-phase induction, ¾ HP, 115V AC motor with a speed variable between a range of about 1,725 RPM and about 3,450 RPM. However, other types of electric motors and motors of other types may conceivably be used, depending on the availability and specific application. For example, a DC motor may be used in place of an AC motor particularly in view of the relative ease in varying the speed of a DC motor.  
         [0041]     Mounted near the upper end of the post  14  and extending in a rearward direction out of the path of travel of the carriage  18 , is a tool caddy  42  for supporting a number of different chisels  44  and other tools so that they will be conveniently accessible for use when necessary. In the embodiment illustrated, the caddy  42  is designed to hold chisels  44 , chuck key  32   a , chuck extension adaptor (not shown), pilots (not shown) and chisel bushings, preferably of ⅝″, ¾″, and 1⅛″ sizes. The caddy  42  is mounted on the post  14  in a suitable manner, for example, by inserting the edge of the caddy into a slot formed in the surface of the post  14  and securing the caddy  42  to the post by fasteners, such as screws  46 . The caddy  42  additionally is supported in a substantially horizontal position by a support, such as gusset member or bracket  42   a , which is integral to the caddy  42  and extends from the bottom of the caddy  42  to the surface of the post  14 .  
         [0042]     Although the caddy  42  is used for convenient storage of chisels and tools, and may on occasion even carry a sharpening tool, no provisions are made in the mortisers to date for enabling the sharpening of any tool directly on the mortiser. Accordingly, a feature of the present invention is a chisel sharpening tool  49  mounted at a convenient location on the mortiser itself, and preferably mounted on the post or tool support  14  as illustrated in  FIG. 2 . In this form, the integrated tool sharpening device  49  comprises a diamond cone sharpening tool that is removably mounted on the upper end surface of the post  14 . The mounting may, for example, be via a bore or opening  14   a  formed or provided in the end surface of the post  14 , into which a shaft  49   b  disposed on the rear surface of the cone  49   a  extends. To secure the shaft  49   b  in the bore  14   a  and prevent rotation of the tool or cone  49   a  during use, the shaft  49   b  is provided with a flat  49   c  which is engaged by a setscrew  55  threaded into a second bore  14   b  located in the side of the post  14 .  
         [0043]     In alternate embodiments, the shaft  49   b  and bore  14   a  may have corresponding shapes which prevent rotation of the cone  49  without the need for an additional fastener, such as setscrew  55 . For example, the shaft  49   b  and bore  14   a  may have corresponding flat surfaces which prevent rotation of the shaft  49   b  in the bore  14   a . It should also be noted that, although a simple cone shape sharpening tool has been shown, any of the well-known sharpening tools for such chisels may be attached to the mortiser at an applicable location. For example, in an alternate embodiment, the sharpening tool  49  may be a chisel cutter rather than a diamond cone. Furthermore, the sharpening center may include sharpening tools with differing characteristics to perform various roles with respect to sharpening the tool. For example, the sharpening system may include a first sharpening tool to perform course sharpening and a second sharpening tool to perform fine sharpening or honing of the tool. The first and second sharpening tools may both be removably mounted to the mortiser or, alternatively, have one mounted on the mortiser and the other mounted in the caddy possibly along with other sharpening tools. In this way, the integrated sharpening system may be used to perform multiple sharpening tasks or steps of sharpening as desired.  
         [0044]     In yet other embodiments, the sharpening system may be located in different locations on the mortiser. For example, rather than mounting the sharpening tool at the top of post  14 , it may be mounted at the rear end of the table  10  with a hold down mechanism, such as a plunger, located above to press the chisel onto the sharpening tool  49  while it is being sharpened to ensure a sharp edge. Alternatively, the sharpening tool may be provided in other positions, areas or zones of the mortiser, such as on top of the fence  52 , which may be more suitable to perform different sharpening tasks.  
         [0045]     The sharpening tool  49  may also be provided as an aftermarket attachment for existing mortisers. For example, the sharpening tool  49  may have a magnetic backing or an adhesive backing that allows the sharpening tool to be fastened or secured to an existing mortiser in any of the positions discussed above. Alternatively, the sharpening tool may be connected to a base or stand for use with a power tool, such as a mortiser. In addition, the sharpening tool  49  may be provided with a modular construction so that the sharpening tool itself may be replaced when desired. For example, the sharpening tool may have a base portion which can be fixed to a mortiser and a removable sharpening portion which can be removed from the base portion and replaced with an alternate sharpening portion. The alternate sharpening system may be designed to perform a different sharpening function than the sharpening portion it is replacing, or may simply be an identical type of sharpening system that is merely meant to replace the original sharpening system.  
         [0046]     In addition to support  14 , the mortiser may also have a fence  52  mounted on the upper table work surface  12 , which is used to position a workpiece, such as wood, so that the chisel  44  may be operated thereon. In the embodiment illustrated, the fence  52  has an L-shaped construction with a generally flat base or support plate  52   a  and a wall  52   b  extending upward therefrom. The base  52  rests on the surface  12  and extends from the upstanding wall  52   b  toward the post  14 . Together, the base  52   a  and upstanding wall  52   b  form a generally flat forward surface that is perpendicular to the upper table work surface  12 . In the embodiment illustrated, an opening  53  is provided in the middle of the upstanding wall  52   b  to provide clearance for hold down clamp  54 . For strength, the ends of the fence wall  52   b  are connected to the base  52   a  via supports such as gusset wall members  52   c.    
         [0047]     The fence  52  is mounted on the surface  12  of the table for movement relative to the post  14 . In the illustrated embodiment, the fence  52  is mounted for linear movement towards and away from the post  14 . To facilitate such movement, the surface  12  is provided with two elongated parallel slots  12   a  and  12   b , which are symmetrically disposed with regard to the post  14  and the carriage  18 , and the fence  52  is provided with a pair of fasteners, such as cam-type clamps  56   a  and  56   b , for securing the fence  52  into a desired position. The clamps  56   a  and  56   b  have portions that extend through respective openings in the fence base  52   a  and slots  12   a  or  12   b , which are connected to bodies, such as nuts  58   a  and  58   b  having widths greater than the width of the slots  12   a - b  (see  FIG. 3E ). Consequently, when the clamps  56   a - b  are engaged by rotating or pivoting the clamp handles downward toward surface  12  causing the cammed surfaces to raise the shafts and nuts  58   a - b  attached thereto, the nuts  58   a - b  will grip the bottom of the table (e.g., the surface opposite surface  12 ), to maintain the fence  52  at the selected position. Conversely, when the handles of clamps  56   a - b  are lifted up, the shafts move nuts  58   a - b  away from the bottom of the table to remove the frictional engagement between the nuts  58   a - b  and the table  10  and allow the fence  52  to be moved or positioned about the upper surface  12 . In the embodiment illustrated, the cam clamps  56   a - b  are high pressure toggle clamps, with one clamp,  56   a , being shown in its release position and the other clamp,  56   b , being shown in its locked or securing position. The handles of clamps  56   a - b  are pivotally connected to shafts which are threaded into nuts  58   a - b . Thus, the handles of clamps  56   a - b  may be rotated to tighten or loosen the handle and shaft with respect to the nut, thereby increasing or reducing the frictional engagement created by the clamp when in its securing position. It should be understood, however, that in alternate embodiments, the handle may operate like a nut with a pivoting handle with the threaded shaft of a bolt extending up through the slots  12   a - b  and respective openings in the fence base  52   a  if so desired.  
         [0048]     To actually position the fence  52  on the surface  12  prior to engagement of the clamps  56   a - b , the rear edge surface of the base  52   a  is connected to another drive mechanism, such as rack  60 , which is positioned parallel to surface  12  and preferably rests thereon. The rack  60  extends from the support  52   a  perpendicular to the front surface of the fence  52  towards the post  14 , where it passes through the post  14  and is engaged therein by a pinion gear (not shown). Control of the pinion gear is carried out via an actuator such as handle or knob  62  which is connected to the pinion gear via an attached shaft. Thus, when the handle  62  is rotated in a first direction, the pinion gear drives the rack in a first direction causing the fence to be moved in the direction of travel of the rack. Conversely, when the handle  62  is rotated in the opposite direction, the pinion gear drives the rack in an opposite or second direction with the fence continuing to be moved in the direction of travel of the rack.  
         [0049]     In a preferred embodiment, handle  62  is mounted at a forty-five degree angle with respect to post  14  so that it is easier for an operator to use when standing in front of the mortiser and not obstructed by the fence  52 . In alternate embodiments, however, handle  62  may extend out perpendicular to the post  14  if desired. In addition, the handle  62  may be formed similar to lever  22  in that it may be fitted onto the gear drive shaft like a socket and capable of being connected to the drive shaft on either side of post  14 . In yet other embodiments, the handles of the mortiser, including handle  62 , may include a clutched handle capable of shifting between an engaged position wherein the handle engages and drives a driven member, such as the axial pinion gear shaft, and a disengaged position wherein the handle disengages from the driven member and is freely positionable in both a clockwise and counterclockwise direction with respect to the driven member. Such a handle may be biased in the engaged position via a biasing mechanism, such as a spring, and may be pulled out from the power tool to compress the spring and disengage the handle from the driven member so that the handle may be repositioned with respect to the power tool and the driven member. Such a handle is disclosed in U.S. Patent Application No. 2004/0070132 A1, which was published on Apr. 15, 2004, and is hereby incorporated herein by reference in its entirety.  
         [0050]     In a preferred form, the mortiser will have a fence adjusting handle  62  extending from both sides of the post  14  in order to accommodate operators that prefer to use their left hand and those that prefer to use their right hand when adjusting the fence position. For example, a first handle may extend from a first side of the support  14  and a second handle may extend from a second, preferably opposite, side of the support  14 , with the handles being connected to a common drive mechanism, such as rack  60 , for moving the fence  52  toward and away from the support  14 .  
         [0051]     In order to secure or clamp the workpiece on the table surface  12  in a horizontal direction against the fence  52 , table surface  12  is provided with a further pair of slots or grooves, such as inverted T-slots  64   a - b , which extend parallel to the slots  12   a - b , and which are open at their upper end. To provide the actual holding of the workpiece, the enlarged head  66   a  of a fastener, such as a bolt  66 , is inserted into the T-shaped slot  64   a  or  64   b , so that a stop, such as roller stop  68 , may be mounted on the portion of the bolt  66  extending above surface  12  by a fastener, such as a nut  70 . The roller stop  68  rests on surface  12  and may be secured at a desired position along the slots  64   a - b  by simply tightening the nut  70 . Once tightened, the roller stop  68  will be prohibited from moving back and forth along the slot  64   a  or  64   b , but will be allowed to rotate about an axis defined by the bolt  66 . With this arrangement, tightening of the nut  70  will secure the roller stop  68  in a desired horizontal position along the table surface  12 , with a workpiece being disposed between the stops  68  and the fence  52 , but allow the user to slide the workpiece along the fence  52  so that multiple mortises may be made in a single workpiece without the need to move either the fence  52  or the stops  68 . In the embodiment illustrated, the nut  70  is in the form of a plastic handle or cap with a threaded insert for receiving the distal end of bolt  66  and the roller stop  68  is in the form of a plastic hub having a rubber sleeve extending around its outer annular surface. In a preferred form, the roller stops  68  may further incorporate ball bearings to reduce friction between the stops  68 , fence  52  and workpiece so that the operator may slide the workpiece along the fence  52  more easily. It should be understood, however, that in alternate embodiments other types of stops, such as rubber blocks, may be used in place of roller stops particularly if the ability to slide the workpiece along surface  12  is not desired.  
         [0052]     A clamping arrangement, such as hold down clamp  54 , is also provided to secure or clamp a workpiece against the surface  12  in a vertical direction so that the workpiece does not get stuck on the chisel  54  when the carriage  18  is raised and lowered via lever  22 . In the form illustrated, the clamping arrangement generally includes a bolt  54   a  extending upward from the surface of the fence base  52   a  and extending perpendicular to the surface  12 . The bolt  54   a  is preferably centrally located about the fence and aligned with the opening  53  located between the upstanding wall members  52   b . To do the actual securing, a body  54   b  is provided with a bore through which the bolt  54   a  extends, and a second body, such as nut  54   c , is fastened to the free end of the bolt  54   a . The body  54   b  may be provided with one or more arms  54   d  that extend from the body  54   b  generally parallel to the surface  12  and extend towards and perpendicular to the surface of the fence  52 . Arms  54   d  are of a length so that they extend beyond the fence  52 , and thus over the area where a workpiece would be positioned against the fence  52 .  
         [0053]     The notch or opening  53  in fence  52  enables the arms  54   d  to extend down to the work table surface  12  and thus enable the clamping of relatively thin workpieces relative to the height of the fence  52 . More particularly, this configuration allows the arms  54   d  to extend through the opening  53  when body  54   b  is lowered beyond the upper surface of the fence  52 . In a preferred form, the opening  53  extends completely through the fence  52  and extends from an upper end surface to a lower end surface of wall  52   b , thus separating the fence wall  52   b  into essentially two spaced wall portions. However, it is understood that a lesser depth extending downwardly from the upper edge of fence  52  can be provided if desired.  
         [0054]     The body  54   b  may be secured about the bolt  54   a  in a desired vertical position by tightening a fastener, such as setscrew  54   e , to lock the body  54   b  in position. In the form illustrated, the setscrew  54   e  is thread through a bore in body  54   b  and engages a longitudinally extending flat  54   f  ( FIGS. 1C and 4C ) located on the surface of the bolt  54   a . Thus, the setscrew  54   e  may be used to position the clamp  54  in a temporary position while a workpiece is inserted between the fence  52  and stops  68  and below the arms  54   d . Once the workpiece has been loaded, the fence  52  and stops  68  may be used to secure the workpiece in a horizontal direction in the manner discussed above, and the setscrew  54   a  may be loosened to allow the body  54   b  to be lowered until the arms  54   d  are positioned on an upper surface of the workpiece. The nut  54   c  can then be rotated into engagement with the body  54   b  to fix the arms  54   d  against the upper surface of the workpiece, thereby securing the workpiece in the vertical direction. In alternate embodiments, the nut  54   c  may be connected to the body  54   b  so that a separate fastener, such as setscrew  54   e , is not needed. For example, nut  54   c  may be connected to body  54   b  so that the body is driven up and down the bolt  54   a  via rotation of the nut  54   c  in a clockwise and counter clockwise manner. With this configuration, a separate fastener is not needed to lock the body  54   b  in a desired position along bolt  54   a  because the nut that is used to drive the body  54   b  into the desired position along bolt  54   a  also retains the body  54   b  in this position.  
         [0055]     With respect to the appendages  54   d  of clamp  54 , it should be understood that the arms may be either fixed or movable and extend from the body  54   b  in any manner so that they pass through the opening  53 . In a preferred form, arms  54   d  are adjustable as illustrated in FIGS.  4 A-D and extend perpendicular to the front surface of the fence. More particularly, arms  54   d  are provided with an extension  54   g  making the arms essentially L-shaped as shown. The extensions  54   b  define elongated slots  54   h , and are connected to the body  54   b  via a fastener, such as bolt  54   i , which extends through the slot  54   h  into the body  54   b , so that the arm  54   d  is mounted for rotation about the axis of the bolt  54   i , which is parallel to the surface  12 . In the embodiment illustrated, each slot  54   h  has an internal shoulder separating the slot into a first bore that is wider and longer than the second bore. In this manner, the bolt  54   i  may be recessed or countersunk into the first bore portion of slot  54   h  so that the head of the bolt  54   i  engages the internal shoulder of the slot to secure the arm  54   d  in position without creating a protrusion extending out from the outer surface of the extension  54   g  and beyond the plane of the fence.  
         [0056]     Since the slot  54   h  extends transverse to the axis of bolt  54   i , the location of the axis relative to the length of the extension  54   g  can be varied. With this arrangement, not only may the vertical position of the arm portion  86  be varied by vertical movement of the body  54   b  along the bolt  54   a  or by the downward or upward position of the bolt  54   i  along the slot  54   h , but moreover the arms  54   d  may be rotated about the axis of their respective bolts  54   i  so that the arms  54   d  are above and over the top edge of the fence  52 , and this rotation may be made independent of one another. In general, the arms  54   d  can be rotated about the axis of bolts  54   i  to any desired position (e.g., closer together, farther apart, etc.) Thus, even workpieces of a thickness or height greater than the height of the fence  52  may be easily clamped, as well as odd-shaped pieces may be clamped simply by adjusting the positions of the two arms  54   d  to whatever position is required in order to clamp the odd-shaped piece. In fact, when the arms  54   d  are positioned above the fence  52 , the outer surface of the arm extensions  54   g  remain coplanar with the outer surface of the fence  52  and effectively serve as an extension of the fence  52 .  
         [0057]     Some of the many positions the clamp  54  may be placed in are illustrated in FIGS.  4 A-D. For example, in  FIG. 4A , the bolts  54   i  fasten the extensions  54   g  at an intermediate position along the slots  54   h  with the slots in a vertical orientation allowing the arms  54   d  to extend down and through opening  53 . In  FIG. 4B , the bolts  54   i  fasten the extensions  54   g  at the end of slots  54   h  with the slots in a vertical orientation so that the arms  54   d  may extend down and through opening  53  to reach their lowermost depth (e.g., for clamping very small workpieces). In  FIG. 4C , the bolts  54   i  fasten the extensions  54   g  at the end of the slots  54   h  with the slots in a horizontal orientation so that the arms  54   d  may extend above the fence  52  and far apart from one another. In  FIG. 4D , the bolts  54   i  fasten the extensions  54   g  at the end of the slots  54   h  with the slots in an angled orientation so that the arms  54   d  may extend further above the fence  52 . It should be understood, however, that the extensions  54   g  and arms  54   d  may be placed in a variety of other positions in order to accommodate different workpieces. For example, some workpieces may require the arms  54   d  to be positioned at different heights and/or positions (e.g., asymmetrical) in order to secure the workpiece in a vertical direction.  
         [0058]     In an alternate embodiment, the appendages  54   d  may be fixed arms extending from the body  54   b  and perpendicular to the front surface of the fence  52  so that they pass through the opening  53 . For example, the arms may be cast as an integral piece of body  54   b  and may extend out from the body  54   b  so that the arms are generally parallel to surface  12 . In a preferred form, a portion of the arms will extend downward from the body and in front of the fence  52  before extending parallel to surface  12  so that the hold down clamp  54  may be used to secure smaller workpieces as discussed above. In yet other embodiments, the appendages  54   d  may have different shapes. For example, the arms  54   d  may be flat L-shaped bars rather than a combination of a flat extension and a round bar as illustrated. Ideally, the power tool will be provided with one clamping mechanism  54  that may be used with other optional items, such as the movable arms and different shaped arms discussed above, so that the operator may customize the clamping mechanism to his or her particular application.  
         [0059]     Regardless of the exact configuration, clamping mechanism  54  may be used to either “hard” clamp a workpiece in situations where the operator does not desire the workpiece to move at all, or simply provide an upper boundary in situations where the operator wishes to be able to slide the workpiece but prevent it from lifting up off of the table surface  12 . If the latter is preferred, arms  54   d  of clamp  54  may also be formed as rollers connected to the body  54   b  to assist the operator in being able to slide the workpiece between the clamp  54 , upper surface  12  and roller stops  68 . For example, the horizontal portion of arms  54   d  may be rotatable with respect to extensions  54   g  so that the horizontal portion of the arms  54   d  rotate when a workpiece is being moved laterally thereto. Although the clamping mechanism  54  is illustrated in conjunction with a mortiser, it should be understood that such a clamping mechanism may be used in conjunction with a variety of other power tools, such as drill presses, band saws, miter saws, table saws and shapers, as well as on its own as a separate clamping fixture for use on bench tops or the like.  
         [0060]     Turning now to  FIG. 6 , there is shown a circuit  100  which may be utilized to control the speed of the motor  30 , and in particular, an AC motor. As shown, the circuit generally includes a connector, such as plug  102 , for connecting the circuit  100  to a voltage source, such as for example, a standard AC outlet. The circuit further includes a full wave bridge rectifier  104  which is connected across the power line via a switch, such as control switch  38  provided on housing  36  ( FIG. 1A ), which is in turn attached to the motor  30 . The DC output terminals of the bridge rectifier  104  are connected across the motor  30 , with one of the outputs of the bridge rectifier being fed to the motor  30  via a silicon-controlled rectifier (SCR)  106 . A portion of the output current of the bridge rectifier  104  is also fed through a variable resistor  108  and an RC network  110  to the control electrode of the SCR  104  to control the gating thereof. A diode  112  is connected in the circuit to protect the circuit against inverse voltage spikes. By varying the position of the center tap of the variable resistor  108 , which center tap is connected to the speed control knob  40  ( FIG. 1A ), the voltage supplied to the motor, and thus the speed of the motor  30 , can be varied.  
         [0061]     It should be appreciated that the embodiments thus far disclosed are mere examples of the various features of the present invention and are not intended to limit the scope of the present invention. For example, it should be appreciated that while the mortiser  10  has been depicted in  FIGS. 1A-1C  as including a single handle or knob  62  for adjusting the location of the fence  52  along the rack  60 , an alternative embodiment may include a fence adjusting handle extending from both sides of the post  14  to accommodate the different preferences of different operators, as mentioned above.  FIG. 7  depicts such an alternative embodiment including a first handle  200   a  and a second handle  200   b , either or both of which may be rotated to adjust the position of the fence  52 . The first handle  200   a  extends from the left-hand side of the post  14  and enables a left-handed operator to comfortably adjust the location of the fence  52 . The second handle  200   b  extends from the right-hand side of the post  14  and enables a right-handed operator to comfortably adjust the location of the fence  52 .  
         [0062]     Additionally, it should be appreciated that while the handle  62  in  FIGS. 1A-1C  is depicted as extending at an angle of approximately 45 degrees relative to the post  14 , in alternative embodiments the handle  62  may extend out from the post at a variety of different angles. For example, the handles  200   a  and  200   b  of  FIGS. 7 and 8 , extend out perpendicular to the post  14 , as mentioned above and depicted in  FIG. 7 . In yet other embodiments, the handle  62  or handles  200   a  and  200   b  may extend out from the post  14  at angles other than 45 or 90 degrees.  
         [0063]     Furthermore, it should be appreciated that while the integrated chisel offset tool has thus far been described as including the spacer  72  depicted in  FIGS. 5B and 5C , it may take any shape and provide any desired amount of spacing for a particular application, as mentioned above. For example,  FIG. 7  depicts an integrated chisel offset tool including a first arcuate spacer  202   a  and a second arcuate spacer  202   b . The first and second arcuate spacers  202   a  and  202   b  are pivotally mounted to the carriage  18  at a common location and secured thereto by a fastener that may or may not be removable such as a threaded bolt, screw, pin or rivet. In a preferred form, the first and second spacers  202   a  and  202   b  are pivotable independent of one another. In the embodiment illustrated, the first arcuate spacer  202   a  is disposed above the second arcuate spacer  202   b . Similar to the spacer  72  discussed above with reference to  FIGS. 5B and 5C , the first and second arcuate spacers  202   a ,  202   b  are provided to assist the operator in positioning an auger  44   a  and chisel  44   b  correctly with respect to the chuck  32  and bushing  33 .  
         [0064]     During installation of the auger  44   a  and chisel  44   b  and depending on the particular application involved, either the first arcuate spacer  202   a  or both the first and second arcuate spacers  202   a  and  202   b  are utilized. After partially inserting the auger  44   a  into the bushing  33 , an operator pivots the desired arcuate spacer(s)  202   a ,  202   b  from a first position or stored position (shown in  FIG. 7 ) to a second position or used position (not shown) in alignment with the opening of the chuck and/or in engagement with the chisel  44   b  to space the shoulder of the chisel sleeve  44   c  from the bottom of the bushing  33 . The arcuate spacer(s)  202   a ,  202   b  engage the chisel  44   b  in a manner similar to that which the spacer  72  engages the chisel  44   b  depicted in  FIG. 5B . Once the auger  44   a  is secured into the bushing  33  with the chisel lock  34 , as discussed above, the operator pivots the arcuate finger(s)  202   a ,  202   b  back to their first positions or stored positions (shown in  FIG. 7 ) so that the mortiser may be prepared for use.  
         [0065]     In one embodiment a thickness of the first arcuate spacer  202   a  is substantially equal to a thickness of the second arcuate spacer  202   b . In an alternative embodiment, one of the first and second arcuate spacers  202   a ,  202   b  is thicker than the other. For example, similar to that described above with reference to the spacer  72 , the first arcuate spacer  202   a  may be 3 mm thick and the second arcuate spacer  202   b  may be 1 mm thick. Therefore, depending on the specific application involved, an operator may select a 3 mm or a 4 mm spacer. It should be appreciated, however, that the arcuate spacers  202   a ,  202   b  may be any desired thickness and they are not limited to the thicknesses described herein. Nevertheless, in the embodiment illustrated in  FIGS. 7 and 8 , a larger spacer is provided when both the first and second arcuate spacers  202   a  and  202   b  are pivoted into engagement with the chisel  44   b  than when just the first arcuate spacer  202   a  is pivoted into engagement with the sleeve  44   c.    
         [0066]     In yet other embodiments, the lower second spacer  202   b  may be designed such that the operator need only pivot this spacer into alignment with the chuck opening and/or in engagement with the chisel  44   b  in order to space the shoulder of the chisel sleeve  44   c  the appropriate amount of distance from the bottom of the bushing  33 . This, in such a configuration, the operator need not pivot both spacers  202   a  and  202   b  into alignment with the chuck opening in order to provide an accurate amount of spacing, but rather, can rely on the distance the spacer is disposed from the chuck opening or bottom of the bushing  33  in order to ensure the proper spacing for the chisel  44   b . Thus, in alternate embodiments, the size of the spacer need not be of concern, but rather, the spacer&#39;s location with respect to the chuck opening and/or the bushing  33  may be used to ensure the proper spacing. Additionally, it should be appreciated that while a mortiser having two arcuate spacers  202   a ,  202   b  has been described herein, an alternative embodiment may include any number of arcuate spacers. Furthermore, while the arcuate spacers  202   a ,  202   b  have been disclosed herein as specifically being arcuate, it is foreseeable that they may be provided in a number of different shapes and sizes such as, for example, straight, V-shaped or other shapes capable of serving the intended purpose.  
         [0067]     While the hold down clamp  54  has been described herein as including appendages comprising adjustable arms  54   d  extending from the body  54   b , in alternate embodiments the hold down clamp may alternatively include fixed appendages extending from the body, as mentioned above. For example,  FIGS. 7 and 8  depict an alternative hold down clamp  206  including a body  208  disposed on the bolt  54   a  (shown in  FIG. 3A ). Similar to the hold down clamp  54  described above, the body  208  is vertically adjustable on the bolt  54   a  and selectively restrained by the nut  54   c . The body  208  includes a support portion  210  and appendage portions  212 . The body  208 , for example, may be formed of cast iron, forged steel, aluminum or some other rigid material. The support portion  210  includes a central bore receiving the bolt  54   a . Each of the appendage portions  212  include an extension portion  212   a  and an arm portion  212   b  forming an L-shape. In  FIG. 7 , the extension portions  212   a  extend generally perpendicularly downward from the support portion  210  of the body  208 . The arm portions  212   b  extend generally perpendicularly from the extension portions  212   a  and through the opening  53  in the fence  52 . Due to the downward offset configuration of the arm portions  212   b  relative to the support portion  210  in  FIG. 7 , the arm portions  212   b  are capable of securingly engaging workpieces having relatively small vertical dimensions. Alternatively, however, the body  208  of the hold down clamp  206  may be inverted or turned upside down, as shown in  FIG. 8 , such that the arm portions  212   b  are upwardly offset relative to the support portion  210 . This upward offset configuration of the arm portions  212   b  relative to the support portion  210  enables the hold down clamp  206  to accommodate workpieces having relatively large vertical dimensions.  
         [0068]     Still further, while it was mentioned above that the lever  22  for controlling vertical displacement of the carriage  18  may be connected to either side of the carriage,  FIG. 7  more explicitly depicts the axial shaft  214  of the pinion gear that enables this. The axial shaft  214  of the pinion gear for driving vertical displacement of the carriage  18  includes opposite ends extending substantially horizontally from opposite sides of the carriage  18 . In each of the figures presented herein, the collar  22   c  (shown in  FIG. 1A ) of the lever  22  is attached to the end of the axial shaft  214  extending from the right-hand side of the carriage  18 . With reference to  FIG. 7  however, it should be appreciated that the collar  22   c  can easily be removed from the right-hand side of the shaft  214  and attached to the left-hand side of the shaft  214  to accommodate an operator seeking to manipulate the lever  22  with his/her left-hand.  
         [0069]     Although the embodiments illustrated show the axial shaft  214  forming a polygonal protrusion over which the collar  22   c  is placed with an internal mating sleeve, it should be appreciated that any mating configuration may be used to join the shaft  214  and the collar  22   c  including the reverse relationship wherein the shaft  214  may have a recess for receiving a mating protrusion or projection from the collar  22   c  in order to form a mating engagement therebetween.  
         [0070]     In summary, a mortiser according to the invention provides a number of generally novel features, which enhances the usability and operability of a power tool. For example, a mortiser according to the invention may include one or all of the described aspects of the invention, for example, a variable speed motor, the ability to sharpen tools directly on the power tool itself, and the novel hold-down or clamping arrangement for a workpiece to securely clamp a workpiece on the work table surface. It should further be noted that although the features and aspects of the invention have been specifically described with respect to a mortiser, certain of the features, in particular the features of the clamping arrangement and the sharpening system, can be used with and are applicable for use with other power tools, for example, with a drill presses if desired. Furthermore, while the features of the invention have been described as an apparatus, it should be understood that a number of novel methods are disclosed herein, including but not limited to a method for controlling the motor speed of a mortiser, a method for clamping a workpiece, and a method for sharpening tools on a power tool.  
         [0071]     It will be appreciated that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.