Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 09/595,742, filed Jun. 16, 2000, and now abandoned which claimed priority to U.S. provisional application Ser. No. 60/140,254, filed Jun. 18, 1999, each of which applications are incorporated herein by this reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to methods and apparatus for forming woodworking joints, especially dovetail and similar joints, and it relates more particularly to devices and techniques for enabling such joints to be cut utilizing a router. 
     BACKGROUND 
     Wooden boxes, drawers and storage chests and a variety of other wooden furniture and other objects often use dovetail joints as a means of securely assembling the sides. Dovetails are used for both their decorative nature and their high strength. Such joints can be made without industrial machinery in one of two principal ways, either using hands tools: saws and chisels, or using power tools such as a router. In both cases, making such ajoint requires a high degree of skill and precision, and in the case of hand tools, time. The desire to save time drives most woodworkers towards the use of power tools, and the need for precision, often in the relative absence of skill, makes jigs or machines that control the power tools desirable. 
     There are two basic approaches possible when using a router. The router can be held stationary and the workpiece moved relative to the position of the router cutter, or the workpiece can be held stationary and the router moved relative to the workpiece. Additionally, in a variation of both basic approached, both the router and the workpiece can be moved. 
     SUMMARY OF THE INVENTION 
     This invention is a machine that facilitates cutting of dovetail and other joints such as box joints using an approach in which the position of the rotating router cutter is maintained stationary and the workpiece is moved relative to the cutter. The machine is typically used with a router mounted upside down in a router table so that the router bit or cutter protrudes through a hole in the tabletop. Such a table is disclosed, for instance in U.S. Pat. No. 5,715,880, but this invention is usable with a wide variety of other router tables. 
     The machine of this invention utilizes an elongated track called a guide that is clamped or otherwise fastened to the router tabletop. Typically, this guide will be positioned so that a router bit or cutter mounted in a router attached to the router table protrudes through the hole in the guide, making it a “center guide.” A lower fence assembly positions a lower fence transverse to the center guide with base wings attached to the lower fence and contacting either side of the center guide so that the lower fence can slide along the center guide and across the router cutter, which passes through an opening in the lower fence. The opening may be filled with sacrificial material such as wood or ultra high molecular weight (“UHMW”) polyethylene. An upper fence that controls the lateral position of a workpiece slides along on the top of the lower fence and can be locked (using a control block and locks associated with it) in position relative to the lower fence. 
     The position of the upper fence relative to the lower fence can be fixed by reference to predetermined stops positioned by the user in a spacer tray (or, alternatively, the user may make a spacer stick) that is locked in the upper fence. The locations of the stops determines the spacing of joint components and controls movement of the machine components so that joint components are formed in the desired locations on workpieces. In some aspects of operation, such as when pins in through dovetail or finger joints are formed, the upper fence is permitted to slide relative to the lower fence during use of the machine. 
     Except when making half-blind dovetail tails, the machine functions by clamping a workpiece against one face of the upper fence so that the workpiece stands upright with its end resting against machine wings that in turn rest just above the table top. The lateral position of the upper fence (and therefore the position of the workpiece clamped to it) is determined by interaction among a control block, the upper fence and the lower fence. 
     The control block can slide along the upper fence or can be locked to prevent such sliding motion. Alternative positions at which the control block is locked to the upper fence are determined by engagement between an indexing pin attached to the control block and holes in spacers positioned in the spacer tray (or holes in a user-made spacer stick), which tray (or stick) is locked into the upper fence during use of the machine. The control block can also be locked to the lower fence so that the relative positions of the upper and lower fences may be secured in a manner limiting or eliminating play between the two fences. 
     “Tails,” such as the tails in a dovetail joint, are cut by locking the control block to both the upper fence and the lower fence, which locates the upper fence in selected predetermined positions relative to the lower fence and prevents sliding movement between the two fences, thereby fixing the lateral position of the workpiece relative to the router cutter. The workpiece clamped to the upper fence is then passed around a router cutter having an appropriate shape, such as a dovetail-shaped cutter, by sliding the workpiece and upper and lower fence assembly along the center guide. The cutter exits the workpiece in a space in the lower fence that may be filled with a replaceable block of ultra high molecular weight polyethylene or other sacrificial material. The upper fence is then repositioned to the next predetermined position by unlocking the two fences and moving the upper fence so that the indexing pin can be received in another hole in the spacers in the spacer tray (or in the spacer stick), and a second cut is made. Multiple tail boards or workpieces can be cut simultaneously, limited only by the size of the machine and its capacity to hold workpieces. 
     “Pins,” such as pins in a dovetail joint, are cut by mounting on the underside of the control block a template having the shape and, typically, nominal size of each pin to be cut. The control block is locked to the upper fence, but that fence is permitted to move relative to the lower fence, allowing the workpiece to move in two directions: (1) laterally relative to the cutter, and (2) forward along the center guide and into the cutter as described above. The workpiece clamped to the upper fence is then forced into the router cutter while the template is rubbed against a tracer pin located in a tracer pin jack secured to the center guide, for instance, by screwing a threaded pin jack base into a threaded hole in the center guide. Contact between the tracer pin and template allows material to be cut away from the workpiece except where the workpiece pin is desired. After formation of a pin in one desired location on the workpiece by removing the adjacent waste, the control block is repositioned on the upper fence by moving the indexing pin to another hole in the spacer tray, and the operation is repeated to form another pin at another desired location. Since lateral positioning of the upper fence is controlled in each instance by the spacer in the same spacer tray (or hole in a spacer stick), joint pins and tails are formed in the same locations. 
     The tracer pins have a conical shape and are used in multiple sizes to make possible a wide range of joint component sizes. The height of each tracer pin relative to the router tabletop and the template is adjustable using the pin jack. This makes possible adjustments in the size of joint pins produced using a particular template, because changes in tracer pin height change the effective diameter of the tracer pin in contact with the template. 
     Joint tails in half-blind dovetail joints are cut with the tail-containing workpiece face down on the wings that lie just above the router table top. The lower fence is fixed in place on the router tabletop, or a stop is utilized to fix lower fence travel along the center guide, to thereby limit the distance the dovetail cutter enters the workpiece as the workpiece travels against the cutter. An auxiliary fence is secured to the upper fence projecting at a right angle from the upper fence (parallel to the center guide). With the upper fence positioned relative to the lower fence with the indexing pin in one of the spacer holes as described above, the workpiece is slid along the auxiliary fence and into the dovetail cutter and then back out. Alternatively, if the lower fence is permitted to move until it reaches a stop, the workpiece is positioned against the auxiliary and lower fences, and the workpiece and fences are slid so that the cutter enters the workpiece until the stop is reached. The upper fence is then relocated by moving the indexing pin to another spacer hole, and the workpiece is again slid along the auxiliary fence and into the dovetail cutter, or the workpiece and fences are slid as described above, to make a second and subsequent cuts. 
     The track or guide and fence components can be made of extruded aluminum, and most of the other components can be made of a variety of metals, including steel, brass, and aluminum as well as other materials, including plastics and other materials. 
     The machine and techniques of this invention facilitate cutting the most common joints, through dovetail, half-blind dovetail and finger joints. The machine can also cut rounded finger joints, double-sided rounded finger joints, double sided dovetails and rounded dovetails. FIG. 21 illustrates some of these joints. With appropriately shaped cutters and templates other joint shapes are also possible. Because it is necessary to have only one template for a particular joint shape, it is practical for the user of the joint-making machine of this invention to make templates and create joints in any desired shape within the broad range of shapes possible. It also makes it economical for a user to purchase alternative templates because only one is need for any desired new shape (within certain size limits for that shape). 
     This invention therefore provides a versatile joint making machine for use with a router to make woodworking joints. This invention is accurate, easy to use, and easy to set up for making a wide range and variety of different joints with user selected spacings of joint elements. Other advantages and benefits of this invention will be apparent to those skilled in the art from the drawings and the following description of the invention and claims. For instance, the capabilities of this invention can be used not only for creating joints but for creating repeating patterns in items such as moldings, an operation that may be facilitated by use of an apparatus controlling vertical positioning of the router bit so that it can be lifted through the router table into the workpiece when desired. Such a device for controlling the vertical position of the router bit is disclosed in U.S. Pat. No. 5,918,652, which is incorporated herein by reference. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the joint making machine of this invention shown mounted on a router table top. 
     FIG. 2 is an exploded perspective view of the principal components of the joint making machine of this invention. 
     FIG. 3 shows the relationship among a dovetail tailboard, pin board, cutter, and template of this invention. 
     FIG. 4 depicts a user made spacer and the spacer tray of this invention and joint components made with the illustrated spacers. 
     FIG. 5 is a perspective of the controller and pin jack of this invention, together with portions of the upper and lower fences, and with lower fence locking screws shown exploded away from the control block. 
     FIG. 6 is an exploded perspective view of the lower fence assembly shown in FIGS. 1 and 2. 
     FIG. 7 is a cross-sectional end elevation view illustrating locking components of the upper and lower fences shown in FIGS. 1 and 2. 
     FIG. 8 is an exploded perspective view of the upper fence assembly shown in FIGS. 1 and 2. 
     FIG. 9 is a top plan view of one end of the upper fence shown in FIG. 1 with a spacer tray located in the fence and the fence lock engaging the end spacer. 
     FIG. 10 is a perspective view of the of the opposite end of the fence shown in FIG. 9 illustrating the clamp shaft nut and the trough in the upper fence in which it seats. 
     FIG. 11 is an enlarged perspective view of the center guide assembly shown in FIGS. 1 and 2. 
     FIG. 12 is a top plan view of a portion of the lower fence and a portion of the center guide assembly illustrating the function of a stop on the proximate end of the center guide assembly. 
     FIG. 13 illustrates the effect of adjusting the height of the tapered tracer pins of this invention. 
     FIG. 14 is a perspective view of the pin jack shown in FIGS. 1 and 2 with part of the pin jack body broken away. 
     FIG. 15 illustrates setting up the spacer tray. 
     FIG. 16 shows locking the spacer tray in the upper fence. 
     FIG. 17 is an exploded perspective view of the auxiliary fence components and their relationship to the upper and lower fences. 
     FIG. 18 is a top plan view of the upper and lower fences positioned on the center guide, with the auxiliary fence mounted and the adjustable depth stop shown mounted on the center guide. 
     FIG. 19 is a front elevation view showing the relationship between a tapered pin and a template during use of this invention to form a pin in a workpiece. 
     FIG. 20 is a cross-sectional view of the control block and a portion of the upper fence show the manner in which the control block locks to the upper fence. 
     FIG. 21 depicts exemplary joints made with the joint making machine of this invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 illustrates an exemplary joint making machine  101  of this invention mounted on a router table top  619 , and FIG. 2 illustrates the machine  101  in an exploded perspective view. For simplicity, threads are not shown in the drawings on all of the components in the exemplary embodiment that are threaded. 
     Operating Principles 
     For joints including a pair of panel shaped workpieces, each workpiece end can be classified as either a tailboard or a pin board. Tailboards, such as tailboard  102  in FIGS. 21 and 3, result from passing a cutter through (or at least into) the board in a straight line leaving a void having the profile of the cutter. Pin boards, such as pinboard  104  in FIGS. 21 and 3 are the result of removing material from a workpiece except where a template prevents material removal. Template shape determines the end or cross sectional shape of the pin board pins. Template shape is directly related to the shape of the cutter used producing the tailboards. This principle is illustrated in FIG. 3, which shows use of a ⅞″ 14° dovetail cutter  302  with a dovetail-shaped template  304  with 14° sides  306  and a nominal width  308  of ⅞″. The template (such as template  304 ) determines the shape of the dovetail pins, and the dovetail cutter determines the shape of the tails. 
     Spacers are used to determine where the centers of both the pins and tails will be located. They can be spaced at regular intervals or at variable intervals. As is illustrated in FIG. 4, a spacer tray  402  with movable spacers  404  or a user-made spacing stick  406  may be used to control the spacing. Because of the use of spacers to determine the locations of each pair of complimentary joint components, only one template is needed for formation of multiple pins, such as pins  110 , in each joint. This simplifies template-making as compared to many conventional joint-making machines in which the template has to have a separate element corresponding to each joint element. 
     The controller  502  illustrated in FIG. 5 is the part of this invention that controls what type of cut is made. The controller  502  comprises three main components, the indexing pin or screw  504 , which rides in the controller body  503 , the template arm  506  and the tracer pin jack assembly  307 . 
     The indexing screw or pin  504  engages the spacers  404  in the spacer tray  402  or the holes  408  in a user made spacing stick  406 . The location of the indexing screw  504  determines where the center of each pin and tail is located in the workpieces. 
     The template arm  506  is used to hold the template  304  that is used when cutting joint pins. The shape of the template is driven directly by the shape of the cutter used to cut the tailboards. Among other shapes, templates may be shaped for through dovetail, half-blind dovetails and finger joints. Experienced users may make their own templates. 
     The pin jack  307  is used in conjunction with the templates to create the pin boards. The tracer pin  305  traces around the template (or, more accurately, the template  304  traces around the pin  305 ) forcing the cutter to follow an identical path and remove waste, thereby forming the pins  110  on the pin board. One template is used for all the pins  110  in a particular joint. 
     The Lower Fence Assembly 
     The lower fence assembly  602 , shown exploded in FIG. 6, provides the connection between the front-to-back motion and the left-to-right motions required to control the compound cuts that form the shaped pins. 
     Fence assembly  602  has two wings  604  and  606  that slide back and forth along the center guide assembly  202  (described below). Wings  604 ,  606  do not directly contact the router table top but rather rest on the center guide rail  204  (as may be seen in FIG. 19) and the tips of nylon thumb screws  624  that are positioned in threaded holes in the wings  604  and  606  or are otherwise secured to protrude from the bottom of the wings, such as, for instance, by positioning nuts above and below the wing  604  or  606 . The upper part  203  of the center guide assembly  202  fits in the gap between the wings  604  and  606 . The edge  608  of each wing that slides along the center guide may be rounded over to minimize the contact area. The width of the gap  610  between edges  608  of wings  604  and  606  is controlled using the two mounting screws  612  for each wing  604  and  606 . The position of the left wing  604  is fixed by shoulder screws  612 . The right wing  606  is allowed to move slightly by using oversize holes  616  in wing  606  through which cap screws  614  are positioned. This permits adjustment of the distance and parallelism between the two wings  604  and  606 . Typically the play between the wings and the center rail should be about 0.003″. This can be set using a sheet of paper between the components when tightening screws  614  in holes  616 . 
     The lower fence  618  has a cutout  620  into which an UHMW polyethylene block  622  or other sacrificial material such as wood is inserted. Two screws (not shown) may be inserted from the top of the guide to secure the block  622 . The purpose of block  622  is to provide a backing for the workpiece to prevent tear out from the router cutter. Additionally, if the UHMW block  622  is positioned proud of the lower fence  618  and flush with the upper fence  702  face  730 , friction between the workpiece and the lower fence  618  will be minimized at the same time that tear-out is reduced. 
     Each wing  604  and  606  has a nylon thumbscrew  624  at the ends of the fence  618 . The ends of screws  624  contact router table top  619  and prevent rocking on center guide  202 . 
     As may be appreciated by reference to FIG. 7, a cross section taken through the lower fence  618  and a portion of the upper fence  702 , lower fence  618  has a longitudinal recess or trough  628  (also identified in FIG.  6 ). Trough  628  has a small ledge  704  protruding from one trough  628  wall  706 . Link block  630  is an elongated bar having (in the illustrated embodiment) a rectangular cross-sectional shape. Link block  630  rests on ledge  704  and is attached to the lower fence  618  with cap screws  632  that are inserted from the front of lower fence  618  (see FIG.  6 ). The purpose of link block  630  is twofold. First, it prevents the upper fence  702  from rotating about a vertical axis. Second, it holds the link foot  708  and link screw  710 . 
     The link foot  708  and link screw  710 , are used to control the sliding fit between the J-hook  712  of upper fence  702  and lower fence  618 . Driving in link screw  710  (clockwise with a right-hand thread) forces down link foot  708 , which is a turned brass part containing a cutout, the profile of which matches the profile of the link screw. A narrow portion of the link foot  708  passes through a hole in the link block  630 . A button  707  of nylon or other appropriately low friction material is pressed into a hole in the lower end of the link foot  708  to provide a low friction bearing surface against the J-hook  712  in the narrower portion of the block. When the link screw is driven in, this button is pressed down against J-hook  712 , and the sliding resistance between upper fence  702  and lower fence  618  is increased and the play is reduced. By retracting the link screw  710  (counter-clockwise with a right-hand thread) the pressure exerted on J-hook  712  by link foot  708  is reduced, the play is increased and the resistance is reduced. Link screw  710  should be adjusted such that there is almost no resistance but also minimal play. On the back of the lower fence  618  a nylon tipped setscrew  714  is used to apply pressure on the upper fence  702  by pressing J-hook  712  against the link block  630  of the lower fence  618 . 
     The Upper Fence 
     Upper fence  702  (shown exploded in FIG. 8) serves as a workpiece holder and couples the workpiece  902  with the shape-controlling components of the machine. While upper fence  702  is denominated a “fence” because of its shape in the embodiment illustrated in the drawings, it could have an entirely different configuration and still serve its function as a workpiece holder. The only practical limitation on the width of joints that can be formed on the joint-making machine of this invention is the capacity of the upper fence  702  to hold a workpiece. In the form of upper fence illustrated as  702  in the drawings, the width of the upper fence limits the width of joint possible, but other workpiece holders could accommodate wider joints. 
     FIG. 8 illustrates the major components of the upper fence  702 . As noted above, the upper fence  702 , which may be conveniently fabricated as an aluminum extrusion, has a J-hook channel  712  protruding from its underside that connects upper fence  702  to lower fence  618 . 
     Front  714  of upper fence  702  has a slot  716  that accepts either the spacer tray  402  or a user-made spacing stick  406 . The spacer tray  402  is held in position using the spacer tray lock  718 . 
     In order to keep the spacer tray  402  aligned with the actual workpiece  902 , the spacer tray lock  718  is connected directly to the right clamp bar  719  shaft  720  via the spacer tray arm  722 . The arm  722  is held vertical by two flats  724  on either side of arm  722  that engage in a rectangular hole  727  in the upper fence  702 . 
     Internally threaded clamp rings  726  secure the threaded clamp bar shafts  720  and  728  to the upper fence  702 . Clamp rings  726  also serve to position the workpiece  902  laterally relative to upper fence  702 . By sizing the diameter of the end spacers  410  the same as the diameter of the clamp rings  726 , alignment of the workpiece  902  and spacer tray  402  are automatic. This is illustrated in FIG.  9 . 
     The spacer tray lock arm  722  and a clamp ring  726  secure the right clamp shaft  720 . As is shown in FIG. 10, the left clamp shaft  728  is held in place by the clamp shaft nut  738  and a second clamp ring  726 . To prevent the nut  738  from turning when the clamp ring  726  disc is tightened, two protrusions  740  from the nut  738  engage in a small trough  735  in the upper fence  702 . 
     As is illustrated in FIG. 9, the workpiece  902  is placed between the vertical face  730  of the upper fence  702  and the clamp bar  719 . Workpiece  902  is slid to the right until it contacts the clamp ring  726  opposite the spacer tray lock  718 . Clamp bar  719  slides along the two clamp shafts  720  and  728 , and is tightened against workpiece  902  using the two clamp knobs  734 . 
     The Center Guide Assembly 
     The center guide assembly  202  illustrated in FIG. 11 is the interface between the rest of the components of this invention and the router table with which it is used. The center guide assembly  202  utilizes a center guide  204  having a longitudinal tee-slot  206  on the underside of the guide  204 . This slot  206  accepts a pair of mini c-clamps  209  that are used to attach the guide to a thin router table like the table disclosed in U.S. Pat. No. 5,715,880 or other similar tables. Alternative fastening arrangements can be made for securing the center guide assembly  202  to other router tables. 
     Guide  204  has one relatively large hole  208  within which the router bit ( 744  in FIG. 18) is positioned. This router bit hole  208  is centered relative to the collet of the router (not shown) as part of the setup procedure. 
     A second, threaded hole  210  in guide  204  holds the pin jack  307  that is used with the templates such as template  304  when forming pins. A rubber stop  212  is secured with a screw  214  on the top at the front of guide  204  so that when the lower fence  618  is pulled back (typically toward the user) during the cutting process, it is stopped by contact between wing  606  and stop  212  before lower fence  618  contacts the pin jack  307 . 
     The Pin Jack 
     The pin jack  307  is used to support the tapered pins  305  that trace around the templates. The pin jack  307  can be used with different diameters of tapered pins  305 . Additionally, each pin  305  has an incremental range of diameters that can contact the template  310  made available by adjusting the height of the pin  305 , as is illustrated in FIG.  13 . FIG. 13 illustrates that at three different heights  309 ,  311  and  312 , the portion of pin  305  contacting the template  310  has a slightly different diameter, thus causing travel around template  310  along different paths  314 ,  316  and  318 , changing the size of the dovetail pin cut and thereby controlling the fit. Such adjustability can also be used to produce joint members having a desired amount of clearance between members so that inlays or the like can be inserted between joint members. If the tapered pin  305  has a 14° taper, that is equivalent to a ratio of 1 to 4. Therefore, by raising such a tapered pin  305  four units of distance, the center of the pin  305  moves away from the template  310  one unit of distance. Since this happens on both sides of the template, the width of the pin is increased two units. This is illustrated in FIG.  13 . 
     As is illustrated in FIG. 14, the pin  305  is positioned in a pin jack dial  320  that is threaded into, and positionable in, a pin jack base  322  to accurately control the height of the tapered pins  305 . The pin jack dial  320  is externally threaded and carries a spring loaded positioner  324  such as a bullet catch that is received in a series of flutes  326  (e.g., eight flutes) on the inside of pin jack body  322  to provide a detent arrangement so that pin jack dial  320  will be retained at a selected one of several rotational positions. By rotating the pin jack dial  320 , the positioner  324  sequentially engages in each flute  326 , temporarily locking the dial  320  in that orientation and preventing unintentional rotation. As the pin jack dial  320  is threaded into the pin jack body  322 , each time the positioner  324  engages, the tapered pin  305  moves slightly up or down depending on which way the pin jack dial  320  is turned. External threads (not shown) on pin jack body  322  secure body  322  within threaded hole  210  in center guide  204 . 
     If the thread used on the pin jack dial  320  and inside pin jack body  322  has  16  threads per inch, for each full revolution the pin jack dial  320  will be raised by 0.0625″. With eight flutes  326  in the pin jack base  322 , each time the detent engages the height will be changed by 0.0078″. With a 14° angle on the tapered pin  305  this means that for each click of the detent, the width of the joint pin cut is increased or decreased by 0.004″. 
     The Spacer Tray 
     The spacer tray  402  shown in FIG. 4 is used to set the spacing of the pins and tails. The end spacers  410  are used to set the width of the material being worked; the intermediate spacers  404  are used to set the centers of the pins and tails. This procedure is explained below and illustrated in FIG.  15 . 
     1. To set the spacer tray  402  begin by locking one of the end spacers  410  in the spacer tray  402  using an appropriate tool such as a hex key to adjust the set screw (not shown) to lock the end spacer  410  in position. 
     2. Decide upon the number of pins or tails in the joint. Slide that number of regular spacers  404  into the spacer tray  402 . There is no need to lock them yet. 
     3. Slide a second end spacer  410  into the spacer tray  404 . 
     4. Position a workpiece board  412  on the tray  402  against the locked end spacer  410  and slide the other end spacer  410  against the opposite edge of the board  412 . Lock the second end spacer  410 . 
     5. Remove the board  412  and set the positions of the pins and tails using the regular spacers  404 . Lock these spacers  404  as well. Extra spacers  404  may be stored in the unused portion of the spacer tray  402 . 
     The spacer tray  402  slides into the mating slot  716  in the upper fence  702 . It is held in place by screwing the spacer tray knob  718  into either of the end spacers  410  as illustrated in FIG.  17 . 
     In order to cut symmetrical dovetails or other joint elements, one joint must be cut with the spacer tray  402  inserted one way, and the opposing joint is cut with the spacer tray  402  inserted in the opposing way. To flip the spacer tray  402 , the spacer tray lock  718  is disengaged, the tray  402  is, slide out, turned around, and reinserted in the upper fence. Then they tray  402  is locked using the other end spacer. 
     The Control Block 
     The control block or controller  502  illustrated in FIG. 5 controls the type of cut begin made, the shape, the fit, and the spacing. 
     When using the control block  502  in conjunction with the templates, it is very important that the template be held in the same position each time that it is used. It is for this reason that the control block  502  has a lock  512  that may be understood by reference to FIG.  20 . Once the control block  502  has been moved into position and the indexing pin or screw  504  has been engaged in a spacer, the control block is locked to the upper fence  702  using the control lock  512 . As is illustrated in FIG. 20, control lock  512  is a screw threaded (threads are not shown in drawing) into control body  503  to bear against control foot  528 , which in turn locks control body  503  to upper fence  702 . 
     When tailboards are being cut, the controller  502  must be locked to the lower fence  618 . This is accomplished using the lower fence lock screws  514 , as illustrated in FIG.  5 . The templates are affixed to the control body  503  via the template arm  506 . The template arm  506  is secured to the control body  503  using the template arm lock knob  516 , which has a tapered point that is driven into a mating tapered hole in the template arm  506 . The template arm is inserted in the slot  518  in the control block such that it mates with the back surface of the slot  518  in control body  503 . The holes for the arm lock  516  are positioned so that driving in the lock  516  pushes the template arm  506  both inward and down. 
     The template arm  506  has a window  520  in the center that allows for greater visibility of the templates. The template arm  506  also has six counterbored and threaded holes  522  into which cap screws  524  securing the templates are affixed. Each template may be secured to the template arm  506  using a pair of template standoffs  526 . The standoffs  526  preferably have cylindrical protrusions on each end that insert into counterbores in the template arm  506  and into matching holes in the templates. Other template securing arrangements are, of course, possible. 
     The Template System 
     Depending upon the type of joint being cut, the style of cutter used, and the material thickness, a different template required for each different joint. Templates are used only for the pin boards; the tail boards are cut using the shape of the cutter. The type of joint is the first consideration that differentiates the templates. Numerous sizes and shapes of templates are possible. Generally templates for forming through dovetails will have a portion with parallel sides joined to a tapered portion. Templates for half blind dovetails will have parallel sides and a half-round end. Templates for finger joints or box joints will have parallel sides. As noted above, templates need not be one-piece structures but can have two or more components to enable adjustment of the width or other attributes of the joint element made with the template. 
     Auxiliary Fence 
     In certain cases it is necessary to make cuts with the workpiece laid horizontally. Such cuts are necessary for example when half-blind tailboards are being made. FIG. 21 illustrates a half-blind tailboard  106 . In these circumstances it is necessary to use the auxiliary fence  736 . The auxiliary fence  736  is attached directly to the upper fence  702  at the location shown in FIGS. 1,  17  and  18 , by attaching an auxiliary fence support  738  to fence  702  with two screws  740 . Auxiliary fence  736  is attached to one end of support  738 . 
     The auxiliary fence  736  is used in conjunction with the depth stop  742  that mounts to the center guide  204 , as illustrated in FIG.  18 . The depth stop  742  controls how far the bit  744  projects in front of the lower fence  618  when the fence  618  and other components are pushed as far along center guide assembly  202  as possible. Depth stop  742  functions by contact between depth stop bumper  746  at then end of stop shank  743  and wing  606 , as illustrated in FIG.  18 . Adjustability may be achieved by rotation of a threaded stop shank or screw  743  within a threaded hole in stop body  745  or by other conventional structures providing an adjustable stop. 
     When making joints that require this type of stopped cut, the workpiece is laid flat on wings  604  and  606  with the workpiece end abutting the lower fence  618  and the workpiece edge forced against the auxiliary fence  736 . Each cut is positioned using the controller  502  and the spacer tray  402 . Each cut is made by pushing the workpiece into the bit  744  as the wings  604  and  606  and fence  618  slide upward in FIG. 18, causing the bit  744  to enter the workpiece the distance permitted by adjustable stop  742 . 
     Summary of Operation 
     Cutting of joint components begins with the setting the spacers that determine where the centers of both the pins and tails will be located. The tailboard is clamped to the upper fence, and a bit appropriate in shape for the joint being cut is secured in the router collet. Using the spacer engagement pin or screw, straight cuts are made through the tailboard centered on each spacer. 
     The tailboard is then removed and the pin board is clamped to the upper fence. A straight bit is secured in the router collet or chuck, and the pin jack is positioned in the center guide. An appropriate template that corresponds to the shape of the bit used for the tailboard is then fastened to the control block using the template lock. Using the spacer engagement pin to successively locate the upper fence relative to the lower fence, the pins are cut out of the end of the pinboard by moving the template and workpiece around the pin jack. 
     Fine adjustment of the width of the pins may be accomplished by adjusting the height of the tapered, height adjustable pin using the pin jack. Raising or lowering the height of the tracer pin can vary the width of the pins on the pin board by very small increments. 
     Possible Modifications 
     As will be understood by those skilled in the art, the principles of this invention can be practiced in a number of alternative structures both similar and dissimilar in appearance and construction to the exemplary embodiment of this invention shown in the drawings and described above. For instance, while anodized aluminum extrusions are excellent materials for several of the guide, fence and control block or body components of this invention, other materials, including machined metals and plastic or plastic composite materials could also be used. 
     Wings  604  and  606  may be made of solid steel, aluminum or other metals and could be solid plastic, plywood or other materials, including composite sheet material having a thermoplastic core bonded between two aluminum skins (e.g., 0.020 inch gauge aluminum sheets) and sold under the name AlucoBond®, available from Alusuisse Composites, Inc., 55 West Port Plaza, Ste. 625, St. Louis, Mo. 63146. 
     Alternative components could also be used. For instance different clamping arrangements can be used for securing workpieces to the upper fence or for securing the center guide to the router table being used. Spring loaded pins could be substituted for some of the locking screws, and other alternative fasteners could also be used. Cylindrical tracer pins could be used rather than the tapered ones shown and described with sacrifice of only the ability to change the effective diameter of the tracer pin by adjusting its height. The ability to adjust joint element size can be achieved by mounting the templates in a manner that permits them to slide back and forth along the template arm. Templates can also be made with adjustable widths by, for instance, making each template from two or more pieces rather than from a single piece. This permits the user to form workpiece pins of variable width by adjusting the template pieces to have a width corresponding to the desired pin width. 
     The lower fence could also be significantly different in shape so long as it provides transverse movement of the workpiece and accommodates lateral movement of the workpiece relative to itself. 
     Different configurations of spacers are possible. For instance, spacers could be mounted directly in or on the upper fence rather than in a tray that is in turn mounted in the upper fence. Engagement between the control block also does not need to be a pin-in-hole arrangement but could be any of numerous engagement or locking arrangements such as a foot or tangent-in-slot arrangement. Indeed spacers could be entirely dispensed with provided that alternative provision is made for locating the places that the workpiece is to be machined. For instance, the workpiece can be marked directly, or the control block or its functional equivalent could be positioned before locking to the upper fence by reference to measuring marks (on a scale or rule) or by reference to stop components other than holes, such as slots, screws, protrusions, edges or spacers or the like. 
     Relocation of components is also possible. For instance, while location of the pattern and tracer pin in the same lateral location as the router cutter facilitates visualization by the operator of cutter action, the pattern and tracer pin could also be located in other locations relative to the router cutter, such as offset to the side or inverted. It is simply necessary for the relative location of the pattern and the portion of a workpiece mounted in the machine being cut to be the same as the relative locations of the pin and the router cutter. 
     Additionally, it is possible to swap the relative locations of the tracer pin and the pattern. While the locations shown in the drawings provide good logical mapping, it is possible to fix the pattern in the center guide or elsewhere so that its position is fixed relative to the router cutter and mount the tracer pin on the control block so that the tracer pin traces around the pattern. 
     With appropriate modifications, the entire apparatus could also be, in effect, inverted 180 degrees or rotated ninety degrees—i.e., the router cutter could protrude down from the router with the end of the workpiece being machined facing up, or the router cutter could be positioned to rotate about a horizontal axis. A dedicated machine  101  of the invention could also be fabricated without a router table top and with appropriate substitute support for the machine  101  components. 
     In another possible relocation, the center guide need not be in the center of the router table aligned with the router bit. One or more guides could be offset from the router bit; the important requirement is simply that there be structure that permits linear motion across the router table top or its functional equivalent so that the cutter can enter and exit the workpiece along a straight line (when tails are being cut). 
     All of these possible modifications, as well as others that will be recognized as possible by those skilled in the art, are intended to be included within the scope and spirit of the drawings and description above and the following claims.

Technology Category: 7