Patent Publication Number: US-2003230359-A1

Title: Mortise and tenon adapters for dovetail jigs

Description:
[0001] This application claims the benefit under 35 U.S.C. § 119(e) of the U.S. provisional patent application No. 60/389,203 filed Jun. 17, 2002. 
    
    
     
       TECHNICAL FIELD  
       [0002] The present invention relates to woodworking tools and more particularly to a system for making mortise and tenon joints using the base of a dovetail jig.  
       BACKGROUND ART  
       [0003] Relatively inexpensive jigs have been designed to produce dovetail joints and finger joints, with a powered router, to joint board ends. Generally such jigs have a base and a finger template. The base has a top surface with a top hold down bar and a front surface with a front hold down bar. For half-blind dovetail joints, the pin board is clamped with the top hold down bar onto the top surface of the base with the end flush with the front surface, and the tail board is offset laterally from the pin board and clamped with the front hold down bar onto the front surface of the base with the end flush with top surface of the pin board.  
       [0004] The finger template extends over the pin board, and has legs that extend down on either side of the pin board to mount on the base. The finger template is vertically adjustable to accommodate different thicknesses of pin boards. The finger template has a plurality of spaced, forwardly projecting fingers. A router sits on the fingers and, with a guide bushing and an upwardly tapering, dovetail bit, cuts the sockets and tails at the same time, with the guide bushing following the fingers of the finger template. The width of the pin and tail boards with such jigs is limited by the width of the front and top hold down bars, and by the distance between the legs of the finger template. U.S. Pat. No. 2,764,191 to Hartmann discloses such a dovetail jig for cutting sockets and tails for a dovetail joint at the same time.  
       [0005] There are many variations to mortise and tenon joints. The mortise is an elongated aperture in a first workpiece with the tenon being cut into the end of a second workpiece to fit into the mortise. A mortise that extends through the first workpiece is known as a “through” mortise while a mortise that does not extend through is “stub” or “blind”. Mortise and tenon joints are used in frame and panel casework, rail and stile door construction, and leg and apron joints for furniture. Mortises have been made with a hammer and chisel, a drill and clean up with a chisel, a mortising machine, and a multi-router machine. Tenons have been made with hand saws, power saws, and multi-router machines. Industrial machines are also available for making mortises and tenons.  
       [0006] A finger template is known for making mortise and tenon joints with the above described jig base. However, this mortise and tenon template has the above described width limitations. This finger template can only make mortise and tenon joints to mount shelves in the sides of cabinets, and is not suitable for making mortise and tenon joints for other furniture and cabinet construction. The guide bushing contacts the fingers on only one side with this finger template, making straight cuts difficult. If a forward shoulder, as well as the side shoulders, is to be cut for a tenon, the guide bushing must move across the forward finger ends. The router is then only partially supported and can tip, creating an unstable and potentially hazardous condition. U.S. Pat. No. 4,428,408 to Grisley discloses a dovetailing jig, including a finger template for making mortise and tenon joints, that is subject to these same limitations.  
       DISCLOSURE OF THE INVENTION  
       [0007] A mortise and tenon joint adapter system for use with a jig base and a router includes a template support, a mortise shelf, a mortise template, a tenon template and a layout guide. The template support mounts on the top surface of the jig base and is secured with the jig base top hold down bar. The mortise shelf is secured to the jig base front surface by the jig base front hold down bar, and is vertically adjustable. The mortise shelf includes a sliding clamp and shelf hold down bars to secure a laterally extending mortise workpiece. The mortise and tenon templates alternately mount on the template support and are adjustable forwardly and rearwardly. Mortising slots and tenoning slots on the mortise and tenon templates, respectively, provide two sided guidance for a guide bushing on the router, and movable stops in the mortising and tenoning template provide length adjustment for mortises and tenons. The layout guides provides precise layout for mortises and tenons, and compensates for the difference between the size of the guide bushing and the size of the router bit. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0008] Details of this invention are described in connection with the accompanying drawings that bear similar reference numerals in which:  
     [0009]FIG. 1 is a perspective view of a mortise and tenon system embodying features of the present invention, configured in the mortise mode.  
     [0010]FIG. 2 is a perspective view of the mortise and tenon system of FIG. 1, configured in the tenon mode.  
     [0011]FIG. 3 is a perspective view of the template support of the mortise and tenon system of FIG. 1.  
     [0012]FIG. 4 a top plan view of a mortise shelf for the mortise and tenon system of FIG. 1.  
     [0013]FIG. 5 is a sectional view taken along line  5 - 5  of FIG. 4.  
     [0014]FIG. 6 is a sectional view taken along line  6 - 6  of FIG. 4.  
     [0015]FIG. 7 a top plan view of a mortise template for the mortise and tenon system of FIG. 1.  
     [0016]FIG. 8 is a sectional view taken along line  8 - 8  of FIG. 7.  
     [0017]FIG. 9 is a sectional view taken along line  9 - 9  of FIG. 7.  
     [0018]FIG. 10 is a top plan view of a tenon template for the mortise and tenon system of FIG. 1.  
     [0019]FIG. 11 is a top plan view of a layout guide for the mortise and tenon system of FIG. 1.  
     [0020]FIG. 12 is a top plan view of a combined mortise and tenon template for the mortise and tenon system of FIG. 1.  
     [0021]FIG. 13 is a perspective view of a mortise and tenon created with the mortise and tenon system of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0022] Referring now to FIGS. 1, 2 and  11 , a mortise and tenon joint adapter system  10 , embodying features of the present invention, for use with a jig base  11  includes a template support  12 , a mortise shelf  14 , a mortise template  15 , a tenon template  16  and a layout guide  17 . The jig base  11  suitable for use with the system  10  has a substantially flat, horizontal top surface  20  and a substantially flat, vertical front surface  21 . A top hold down bar  23  is spaced above and extends laterally across the top surface  20 , and a front hold down bar  24  is spaced in front of and extends laterally across the front surface  21 . The top and front hold down bars  23  and  24  are secured to the top and front surfaces  20  and  21 , respectively, at opposite ends by cam action clamps, threaded studs with wings nuts, or other suitable means. The jig base  11  is generally available commercially with a dovetail finger template or other template that is removed when the jig base  11  is used with the present invention.  
     [0023] The template support  12 , shown in FIG. 3, has a substantially rectangular shape with a flat bottom face  26  and a spaced top face  27 . The top face  27  includes rectangular, flat front portion  28 , a rectangular, flat rear portion  29  that is spaced downwardly from the front portion  28 , and a transverse step face  30  that extends between the front and rear portions  28  and  29 . A front face  31  extends between the bottom face  26  and the front portion  28  of the top face  27 . Two spaced, elongated template guides  33  mount on the front portion  28  of the top face  27 , extending perpendicular to the front face  31 . Two vertical, spaced, threaded template securing apertures  34  are provided in the front portion  28  of the top face  27 , between the template guides  33  and preferably aligned parallel to the front face  31 . The template support  12  mounts on the jig base  11  with the bottom face  26  of the template support  12  on the top surface  20  of the jig base  11 , and the top hold down bar  23  extending over the rear portion  29  of the top face  27  of the template support  12 . Preferably, the front face  31  of the template support  12  is flush with the front surface  21  of the jig base  11 .  
     [0024] Referring to FIGS. 4, 5 and  6 , the mortise shelf  14  include a flat, elongated shelf portion  36  and a support portion  37  that is attached to one of the longer edges of the shelf portion  36  and extends perpendicular to the shelf portion  36 . The support portion  37  is sized and shaped to mount on the front surface  21  of the jig base  11  with the front hold down bar  24  clamping the support portion  37  under the shelf portion  36 . The support portion  37  includes a raised portion  38  that extends above the shelf portion  36 . The mortise shelf  14  is vertically adjustable, and is adjusted by loosening the front hold down bar  24 , moving the support portion  37  up or down relative to the front surface  21  of the jig base  11 , and then retightening the front hold down bar  24 .  
     [0025] The shelf portion  36  has spaced, opposed end sections  40  that extend laterally beyond the ends of the jig base  11  and rearwardly beyond the front surface  21  of the jig base  11 . A shelf hold down bar  41  in each end section  40  extends perpendicular to the front surface  21  and is secured by two spaced threaded bolts  42  that extend upwardly through the respective end section  40 , through springs  43 , through opposite ends of the shelf hold down bar  41 , and into wing nuts  44 .  
     [0026] A sliding clamp  46  has a laterally elongated, flat, horizontal base portion  47  and a upwardly projecting raised portion  48  along the rearward edge of the base portion  47 . Two spaced clamp slots  49  extend rearwardly from the front edge of the base portion  47 , perpendicular to the raised portion  48 . The sliding clamp  46  is secured to the top of the shelf portion  36  of the mortise shelf  14 , with the raised portion  48  opposite the raised section  38  of the support portion  37  of the mortise shelf  14 , by two threaded bolts  50  that each extend downwardly through a washer  51 , one of the clamp slots  49 , the shelf portion  36  and another washer  51  with a wing nut  52  being threaded onto the bolt  50 . The clamp slots  49  provide forward and rearward adjustability for the sliding clamp  46 .  
     [0027] The mortise template  15 , as shown in FIGS. 7, 8 and  9 , is a flat rectangular plate sized and shaped to mount on the front portion  28  of the top face  27  of the template support  12  between the template guides  33 . Preferably the mortise template  15  is at least as thick as the template guides  33 . Two elongated, spaced mortise template support slots  55  through the mortise template  15  extend parallel to the template guides  33  with each being aligned with one of the template support apertures  34 . A machine screw  57 , with a washer  58 , extends through each mortise template support slot  55  and into a template support aperture  34 . The mortise template support slots  55  each have a widened upper channel  59  sized and shaped to receive the head of the machine screw  57  and the washer  58  so that the top of the machine screw  57  is below the top of the mortise template  15  when the machine screw  57  is tightened in the template support aperture  34 . The mortise template support slots  55  provide forward and rearward adjustability for the mortise template  15 .  
     [0028] The mortise template  15  includes a plurality of spaced first mortising slots  61  perpendicular to the template guides  33  and a plurality of second mortising slots  62  parallel to the template guides  33 . Each of the first and second mortising slots  61  and  62  has an upwardly opening upper channel  64  connected to a downwardly opening lower channel  65  by a narrower intermediate passage  66 . The router  68  used to route mortises and tenons is a plunge router, and has a downwardly extending bit  69  and a bushing guide  70  around the upper part of the bit  69 . The width of the intermediate passage  66  is marginally wider than the guide bushing  70  to provide two sided guidance of the guide bushing  70  and exact positioning of the bit  69 .  
     [0029] Movable stops  72  include an upper piece  73  sized to fit into the upper channel  64 , a lower piece  74  sized to fit into the lower channel  65 , and a screw  75 . The upper piece  73  has an unthreaded upper piece hole  77  and an upwardly opening upper piece recess  78 , and the lower piece  74  has a threaded lower piece hole  79 . A movable stop  72  is assembled into a first or second mortising slot  61  or  62  with the upper piece  73  in the upper channel  64  and the lower piece  74  in the lower channel  65 . The screw  75  extends through the upper piece hole  77  and the intermediate passage  66 , and threads into the lower piece hole  79 , with the top of the screw  75  in the upper piece recess  78  and below the top of the mortise template  15 .  
     [0030] The tenon template  16 , as shown in FIG. 10 is a flat rectangular plate sized and shaped to mount on the front portion  28  of the top face  27  of the template support  12  between the template guides  33 . Preferably the tenon template  16  is at least as thick as the template guides  33 . Two elongated, spaced tenon template support slots  81  through the tenon template  16  extend parallel to the template guides  33  with each being aligned with one of the template support apertures  34 . The tenon template support slots  81  are sized, shaped and spaced the same as the mortise template support slots  55  shown in FIG. 8. The tenon template  16  is secured to the template support  12  with machine screws  57  and washers  58 , in the same manner as the mortise template  15 . The tenon template support slots  81  provide forward and rearward adjustability for the tenon template  16 .  
     [0031] The tenon template  16  includes a plurality of spaced tenoning slots  83 , each having an elongated lateral section  84  extending perpendicular to the template guides  33  and two end sections  85  that extend rearwardly from opposite ends of the lateral section  84 . The size and shape of each tenoning slot  83  is the same as the first and second mortising slots  61  and  62 , with the tenoning slot  83  receiving the movable stops  72  and guiding the bit  69  and guide bushing  70  in the same manner as the first and second mortising slots  61  and  62 .  
     [0032] Referring to FIG. 11, the layout guide  17  is a flat piece of transparent material such as plastic. The layout guide has a straight front edge  87  and a plurality of precisely spaced guide lines  88  parallel to the front edge  87 . The distance from the front face  87  to the guide lines  88  is preferably the radius of the guide bushing and the difference between the radius of guide bushing  70  and the radius of the router bit  69 , for different sizes of bit  69  and/or bushing guide  70 .  
     [0033] Referring again to FIG. 1, the mortise for the mortise and tenon joint is created with the template support  12  mounted on the top surface  20  of the jig base  11  and secured by the top hold down bar  23 , the mortise template  15  mounted on the template support  12 , and the mortise shelf  14  mounted on the front surface  21  of the jig base  11  and secured by the front hold down bar  24 . The centerline and endpoints of the desired mortise are laid out on the first workpiece  90 , and, using the layout guide, the endpoints are adjusted outward to compensate for the difference between the radius of guide bushing  70  and the radius of the router bit  69 . The first workpiece  90  is mounted on the mortise shelf  14 , and secured with one of the shelf hold down bars  41  and with the sliding clamp  46 . The mortise shelf  14  is raised so that the top of the first workpiece  90  contacts the bottom of the mortise template  15 , the mortise template  15  is adjusted so that the selected first or second mortising slot  61  or  62  is centered on the centerline of the first workpiece  90 , and movable stops  72  are adjusted to the adjusted endpoints on the first workpiece  90 . The router  68  is adjusted for depth and placed over the selected first or second mortising slot  61  or  62 , and the mortise is routed using normal plunge router techniques.  
     [0034] Referring again to FIG. 2, the tenon for the mortise and tenon joint is created with the template support  12  mounted on the top surface  20  of the jig base  11  and secured by the top hold down bar  23 , and the tenon template  16  mounted on the template support  12 . The dimensions of the desired tenon are laid out on the second workpiece  91 , and, using the layout guide, all four sides are adjusted inward to compensate for the difference between the radius of guide bushing  70  and the radius of the router bit  69 . The second workpiece  91  is mounted on the front surface  21  of the jig base  11  and secured with the front hold down bar  24 , with the top of the second workpiece  91  contacting the bottom of the tenon template  16 . The tenon template  16  and the second workpiece  91  are adjusted so that the selected tenoning slot  83  is aligned with the adjusted dimensions for two sides of the desired tenon. The movable stop  72  is adjusted to prevent the router bit  69  from contacting the template support  12  or the jig base  11 . Two sides of the tenon are routed. The second workpiece  91  is released, rotated  180  degrees, adjusted, and the other two sides of the tenon are routed.  
     [0035] As shown in FIG. 12, the mortise and tenon templates  15  and  16  can alternatively be combined into a single combined template  93 , having first and second mortising slots  61  and  62 , and tenoning slots  83 . As an example and not a limitation, such a template could be used for routing a mortise and then rotated 180 degrees for routing the tenon. Multiple mortise templates  15  and tenon templates  16 , with different layouts and different slot sizes, may be provided. The multiple parallel first mortising slots  61  and second mortising slots  62  shown are provided for multiple mortise applications. The mortise and tenon templates  15  and  16 , with the first and second mortising slots  61  and  62 , and the tenoning slots  83 , firmly support the router  68 , providing a safer jig. The first and second mortising slots  61  and  62 , and the tenoning slots  83  provide two sided guidance for the guide bushing  70 , constraining the guide bushing  70  for easier and more accurate routing of mortises and tenons.  
     [0036]FIG. 13 shows a mortise  95  in the first workpiece  90  and a tenon  96  in the second workpiece  91  made with the system of the present invention. The present invention provides apparatus for making furniture and cabinet mortise and tenon joints using existing dovetail jigs. The higher front portion  28  of the top face  27  of the template support  12  and the vertically adjustable mortise shelf  14  together allow creation of mortises in thicker work pieces than prior jigs. The shelf hold down bars  41  and sliding clamp  46  of the mortise shelf  14  form a means for clamping a laterally extending mortise workpiece and can secure a long workpiece, such as a table leg, for routing a mortise. The movable stops  72  provide accurate adjustment of the length of mortises and tenons.  
     [0037] Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that changes in details of structure may be made without departing from the spirit thereof.