Patent Publication Number: US-2005121107-A1

Title: Blade and apparatus configured for forming tenons

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application claims priority to co-pending U.S. Provisional Patent Application having Ser. No. 60/525,627 filed Nov. 26, 2003 entitled “Blade And Apparatus Configured For Forming Tenons”, having a common applicant herewith. 
    
    
     FIELD OF THE DISCLOSURE  
      The disclosures herein relate generally to forming tenons for woodworking, and more particularly to blades and apparatuses configured for forming tenons.  
     BACKGROUND OF THE DISCLOSURE  
      A mortise and tenon joint is a proven and widely used type of joint used in woodworking. It provides for exceptional strength in joining an end of one piece of wood to another piece of wood (or other suitable material). Furthermore, forming the mortise and the tenon is relatively simple, even for a small shop and hobbyist that is limited to making tenons using a table saw and mortises using a router.  
      To achieve visually appealing and strong mortise and tenon joints, it is important for each tenon of an item to have a snug fit with the respective mortise. It is equally important for the dimensions of each tenon and mortise to be formed repeatably. Without forming each mortise and tenon in an accurate and repeatable manner, the strength and appearance are often compromised.  
      For small shops and hobbyists, the ability of repeatably and accurately form tenons is generally the limiting factor with respect to strength and appearance of mortise and tenon joints. Equipment such as a router provides a means of accurately and repeatably forming mortises. However, the approaches for forming tenons that are known (i.e., conventional approaches) and used by such small shops and hobbyists are limited in their ability to accurately, repeatably and time-effectively form mortises.  
      One conventional approach for forming tenons requires four discrete cutting operations using a table saw. A table saw is fitted with a commercially available saw blade (e.g., a combination blade producing a ⅛″ wide kerf). Through use of a commercially available tenoning jig or a custom fabricated tenoning jig, two cuts separate cuts are made with a work-piece (e.g., a piece of wood) extending lengthwise upward from the surface of the table saw. These two cuts define the thickness of the tenon, the distance from the end of the work-piece to the face of the tenon&#39;s cheek and the side-to-side position of the tenon. Then, an additional cut is made on each side of the work-piece lengthwise along the base of each previous cut. These additional two cuts expose the full face of each cheek and expose the tenon itself. The four cuts required by this approach are time-consuming to make, and often lead to varying distances from the end of the work-piece to cheek, varying tenon thickness and varying side-to-side positioning of the tenon.  
      Another conventional approach for forming tenons requires three discrete cutting operations using a table saw. A table saw is fitted with a pair of commercially available saw blades (e.g., a pair of combination blades) that are spaced apart with a suitable spacer. The spacing between the teeth of the blades is set to achieve the desired tenon thickness. Through use of a commercially available tenoning jig or a custom fabricated tenoning jig, a work-piece is run through the spaced apart blades, thereby simultaneously making two spaced apart cuts that define the thickness of the tenon, the distance from the end of the work-piece to the face of the tenon&#39;s cheek and side-to-side positioning of the tenon. Then, an additional cut (e.g., using a single blade) is made on each side of the work-piece lengthwise along the base of each of the simultaneously made cuts. These additional two cuts expose the full face of each cheek and expose the tenon itself. The three cuts required by this approach are time-consuming to make, and often lead to varying distances from the end of the work-piece to cheek, varying tenon thickness and varying side-to-side positioning of the tenon. However, this approach does save a nominal amount of time over the four-cut approach discussed above and does serve to enhance dimensional accuracy and repeatability associated with the cuts that are made simultaneously.  
      In view of conventional approaches for making tenons using a commercially available table saw and circular saw blades, a method and equipment configured for forming a tenon in a manner that overcomes limitations associated with conventional methods and equipment for forming tenons would be advantageous and useful.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  depicts a side view of a table saw having a circular saw apparatus in accordance with an embodiment of the disclosures mounted thereon.  
       FIG. 2  depicts an end view of the table saw and circular saw apparatus depicted in  FIG. 1 .  
       FIG. 3  depicts a first embodiment of a circular saw blade as disclosed herein.  
       FIG. 4  depicts a second embodiment of a circular saw blade as disclosed herein.  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      Equipment and methods in accordance with embodiments of the disclosures made herein are configured for forming tenons in a manner that overcomes limitations associated with conventional methods and equipment for forming tenons. Specifically, such equipment and methods allow for a tenon to be made using a standard table saw in a manner that requires only one pass of a work-piece, reducing the number of required cuts by at least two relative to conventional approaches. A one-pass approach for forming tenons results in such tenons to be made in a manner that saves time, reduces variability in the distance from the end of the work-piece to the tenon cheek, reduces variability in tenon thickness and reduces variability in side-to-side positioning of the tenon. Accordingly, such equipment and methods provide for more visually appealing and consistently strong mortise and tenon joints to be made with respect to conventional approaches for forming tenons.  
      In one embodiment of the disclosures made herein, a circular saw blade configured for enabling one-pass forming of tenons includes a body and spaced cutting tips attached to the body. The body has a first side, a second side and a cutting edge portion. The spaced cutting tips are attached to and project outwardly from the cutting edge portion of the body. The cutting tips are configured for enabling a one-pass tenon forming operation to be performed. The one-pass tenon forming operation produces a tenon cheek depth of at least about three-sixteenth of an inch.  
      In another embodiment of the disclosures made herein, a circular saw blade configured for enabling one-pass forming of tenons includes a body and spaced cutting tips attached to the body. The body has a first side, a second side and a cutting edge portion. The spaced cutting tips are attached to and project outwardly from the cutting edge portion of the body. Each one of the cutting tips has a first side face disposed adjacent the first side of the body and a second side face disposed adjacent the second side of the body. A cutting edge of each of a first plurality of the cutting tips is tapered toward the first side of the body and a cutting edge of each of a second plurality of the cutting tips is tapered toward the second side of the body. The first side face of each one of the first plurality of cutting tips is laterally disposed by at least one-quarter inch from the second side face of each one of the second plurality of cutting tips.  
      In another embodiment of the disclosures made herein, a circular saw apparatus configured for enabling one-pass forming of tenons includes a pair of circular saw blades and a spacing device disposed between and engaged with a body of each one of the circular saw blades. Each one of the circular saw blades includes a body having a first side, a second side, a cutting edge portion and spaced cutting tips. The spaced cutting tips are attached to and project outwardly from the cutting edge portion of the body. The blades and the spacer are jointly configured for enabling a one-pass tenon forming operation to be performed. The one-pass tenon forming operation produces a tenon cheek depth of at least about three-sixteenth of an inch. Preferably, at least portions of the cutting tips of a first one of the blades are ground simultaneously with at least portions of the cutting tips of a second one of the blades thereby enabling cuts made by each one of the blades to be essentially identical.  
      In another embodiment of the disclosures made herein, a circular saw apparatus configured for enabling one-pass forming of tenons includes a pair of circular saw blades and a spacing device configured for being disposed between and engaged with a body of each one of the circular saw blades. Each one of the circular saw blades includes a body having a first side, a second side, a cutting edge portion and spaced cutting tips. The cutting tips are attached to and project outwardly from the cutting edge portion of the body. Each one of the cutting tips has a first side face disposed adjacent the first side of the respective attached body and a second side face disposed adjacent the second side of the respective attached body. The cutting edge of each of a first plurality of the cutting tips of each blade is tapered toward the first side of the body and a cutting edge of each of a second plurality of the cutting tips is tapered toward the second side of the body. The first side face of each one of the first plurality of cutting tips of each blade is laterally disposed by at least one-quarter inch from the second side face of each one of the second plurality of cutting tips.  
      The width of the cutting tips and the body thickness of circular saw blades as disclosed herein are novel and advantageous relative to conventional circular saw blades. A circular saw blade having cutting tips widths as disclosed herein (e.g., about three-sixteenths inch or wider) teaches away from conventional circular saw blade configurations. Conventional circular saw blades are seeking more narrow kerf widths, not wider.  
      Cutting tips as disclosed herein have a width (e.g., three-sixteenth inch, one-quarter inch or wider) that is specifically configured for one-pass forming of tenons having a cheek depth of about three-sixteenths inches or greater. For example, a circular saw blade that has cutting tips that are one-quarter inch wide allows for one-pass forming of tenons having a cheek depth of nominally one-quarter inch. To produce a comparable tenon using a conventional commercially available circular saw blade would require a minimum of three passes of the workpiece and often results in tenon-to-tenon variability even during the same set-up.  
      Similarly, a circular saw blade body having a thickness as disclosed herein (e.g., three-thirty-seconds of an inch or wider) is specifically suited for forming tenons in a one-pass manner. A relatively thick body provides for increased rigidity (e.g., resistance to bending and twisting) and greater cutting tip bond area (e.g., weld interface). Such increased rigidity contributes to greater accuracy in tenons, less heating of the blade and longer blade life.  
      Referring now to specific drawings,  FIGS. 1 and 2  depicts a table saw  10  having a circular saw apparatus  12  in accordance with an embodiment of the disclosures mounted thereon (i.e., on an arbor of a table saw motor). The circular saw apparatus  12  is configured for enabling one-pass forming of tenons (e.g., a tenon  14  at the end of a work-piece  16 ). The circular saw apparatus  12  includes a pair of circular saw blades  18  and a spacing device  19 . The blades  18  and the spacing device  19  are jointly configured for enabling a one-pass tenon forming operation to be performed. The one-pass tenon forming operation produces a tenon cheek depth D, which is a full cheek depth as opposed to that made using a conventional blade being a partial depth requiring additional cuts to produce the full depth.  
      Each one of the circular saw blades  18  includes a body  20  having a first side  22 , a second side  24 , a cutting edge portion  26  and spaced cutting tips  30  attached to and projecting outwardly from the cutting edge portion  26  of the body  20 . In one embodiment, the body  20  is formed from steel plate (e.g., blanked, laser cut, wire cut water cut, etc) and the cutting tips  30  are carbide inserts welded to the body  20 . The spacing device  19  is disposed between and engaged with the body  20  of each one of the circular saw blades  18 . Preferably, the body  20  of each circular saw blade  18  and the spacing device  19  each include a centrally located arbor passage (not specifically shown) configured for receiving a standard table saw motor arbor, thereby allowing the circular saw apparatus  12  to be mounted on the table saw  10 .  
      Examples of the spacing device include a spacer machined from aluminum or molded from a polymeric material. It is contemplated herein that the blades  18  may each be fixedly attached by securing means (e.g., using screws, rivets hat staking) to the spacing device  19  or held in contact with the spacing device  19  via a nut on an arbor of a table saw motor. In such embodiment, it is contemplated that the blades  18  are precision aligned (e.g., at an arbor hole), whereby each blade is essentially concentric with the other blade.  
      Referring now to  FIGS. 1-3 , each one of the cutting tips  30  have a first side face  32  disposed adjacent the first side  22  of the body  20  and a second side face  34  disposed adjacent the second side  24  of the body  20 . A first plurality of the cutting tips  30  have tapered cutting edges  36  that are tapered toward the first side  22  of the body  20 . A second plurality of the cutting tips  30  have tapered cutting edges  38  that are tapered toward the second side  24  of the body  20 . A third plurality of the cutting tips  30  have tapered cutting edges  40  that are essentially level with respect to the first side  22  and second side  24  of the body  20 .  
      The first side face  32  of each one of the first plurality of cutting tips  30  is laterally disposed by preferably at least one-quarter inch, and as little as three-sixteenths of and inch, from the second side face  34  of each one of the second plurality of cutting tips  30 . Preferably, each one of the third plurality of the cutting tips  30  has a maximum width approximately equal to the lateral distance between the first side face  32  of the first plurality of cutting tips  30  and second side face  34  of the second plurality of cutting tips  30 . Accordingly, in this embodiment, all of the cutting tips  30  are approximately the same width.  
      Preferably, the body  20  of each one of the circular saw blades  18  is generally flat and has a thickness of at least three-thirty seconds of an inch. Suitable pairing of cutting tip width and body thickness have been found to be a one-quarter inch cutting tip width with a three-thirty seconds inch body thickness, and a five-sixteenth inch cutting tip width with one-eighth inch body thickness. In view of the disclosures made herein, other suitable pairings of cutting tip width and body thickness will become apparent.  
      Preferably, at least portions of the cutting tips of one of the pair of blades  18  are ground during their manufacture in a simultaneous manner with at least portions of the cutting tips of the other one of the blades  18 . In this manner, cuts made by each one of the blades  18  are essentially identical. In one embodiment such simultaneous grinding of the cutting tips includes mounting a pair of template blades (e.g., bodies with unground cutting tips welded thereto) on an arbor of a blade-grinding machine with a suitable spacer (e.g., having a thickness slightly greater than the width of the cutting tips) positioned between the pair of blades  18 . Then, the surfaces corresponding to the cutting edge of each cutting tip and/or to the overall diameter of the blade are ground simultaneously to produce a matched pair of blades.  
       FIG. 4  depicts an alternate embodiment of a circular saw blade  118  compatible for enabling one-pass forming of tenons in accordance with the disclosures made herein. The circular saw blade  118  includes a body  120  having a first side  122 , a second side  124 , a cutting edge portion  126  and spaced cutting tips  130 . The cutting tips  130  are attached to and project outwardly from the cutting edge portion  126  of the body  120 . Each one of the cutting tips  130  has a first side face  132  disposed adjacent the first side  122  of the body  120  and a second side face  134  disposed adjacent the second side  124  of the body  120 .  
      A first plurality of the cutting tips  130  have tapered cutting edges  136  that are tapered toward the first side  122  of the body  120 . A second plurality of the cutting tips  130  have tapered cutting edges  138  that are tapered toward the second side  124  of the body  120 . A third plurality of the cutting tips  130  have tapered cutting edges  140  that are essentially level with respect to the first side  122  and second side  124  of the body  120 .  
      The first side face  132  of each one of the cutting tips  130  of the first plurality of cutting tips  130  (i.e., the cutting tips  130  having cutting edges  136  that are tapered toward the first side  122  of the body  120 ) is offset toward the first side  122  of the body  120 . The second side face  134  of each one of the cutting tips  130  of the second plurality of cutting tips  130  (i.e., the cutting tips  130  having cutting edges  138  that are tapered toward the second side  124  of the body  120 ) is offset toward the second side  124  of the body  120 .  
      The first side face  132  of each one of the first plurality of cutting tips  130  is laterally disposed by preferably at least one-quarter inch, and as little as three-sixteenths of and inch, from the second side face  134  of each one of the second plurality of cutting tips  130 . Preferably, each one of the third plurality of the cutting tips  130  has a maximum width approximately equal to the lateral distance between the first side face  132  of the first plurality of cutting tips  130  and second side face  134  of the second plurality of cutting tips  130 . Accordingly, in this embodiment, all of the cutting tips  130  are approximately the same width. Preferably, the body  120  is generally flat and has a thickness of at least three-thirty seconds of an inch.  
      It is contemplated herein that circular saw blades in accordance with embodiments of the disclosures made herein may have any one of a variety of different overall diameters. Such overall diameters may be at least partially dependent upon the width of the cutting tips and the resulting force created at the cutting tips during a tenon forming operation. For example, a blade with five-sixteenth inch cutting tips may preferably have an eight-inch diameter rather than a ten-inch diameter to reduce bending and twisting of the blade body. Tenon length is another factor upon which blade diameter is based. For example, an eight-inch blade can readily produce a tenon having a length of about one and one-half inches.  
      Preferably, the cutting tips of circular saw blades disclosed herein will be configured for minimizing, if not eliminating, rip out of material of a work piece. A person of ordinary skill in the art of making circular saw blades (i.e., an engineer employed by a blade manufacturing company to design blades) will have the knowledge of cutting edge profiles that will minimize, if not eliminate, rip out of material.  
      In the preceding detailed description, reference has been made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments, and certain variants thereof, have been described in sufficient detail to enable those skilled in the art to practice the invention. To avoid unnecessary detail, the description omits certain information known to those skilled in the art. The preceding detailed description is, therefore, not intended to be limited to the specific forms set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents, as can be reasonably included within the spirit and scope of the appended claims.