Patent Publication Number: US-6702269-B1

Title: Truss jigging system

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to a jigging system for work pieces and, in particular, to a jigging system for the assembly of wooden trusses for use in building. 
     The invention relates to an improvement to that disclosed in our Australian Patent No. 694642 (U.S. Pat. No. 5,854,747), the contents of which are incorporated into this specification by this reference. 
     Wooden trusses generally comprise a number of wooden components including a bottom chord, upper chords which are generally arranged in a V-shaped configuration, and connecting pieces or webs between the chords. The chords and connecting webs are joined together by metal connector plates which are usually forced into the wooden components at joints between components on both sides of the truss by a suitable press or the like. Conventionally, the components from which the truss are to be made are laid out on a table which has stops (often referred to as pucks) for setting the position of the chords. 
     The above-mentioned Australian patent discloses an automatic method of moving the stops or pucks to desired locations to set the position of the chords which are to be joined together to form the truss. The formation of the truss from the chords also requires the placement of various tools such as a peak or apex tool and clamp tools in order to define the position of the peak or apex and hold the two chords, which will be joined together to form the apex, in position. Heel tools are also required in order to define the points at which the upper chords will intersect with the bottom chord. The location of these tools is performed manually by locating the tools in position on the table before or after the stops have been automatically moved to define the position of the chords. 
     The need to manually locate the tools increases the time required in order to set up the jigging system for formation of a truss and therefore the time required in order to actually produce a truss. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 is a perspective view of a jigging system according to the preferred embodiment of the invention; 
     FIG. 2 is a greatly enlarged, fragmentary top plan view of the table showing a puck, but with the truss shown in FIG. 1 removed for clarity; 
     FIG. 3 is a section taken in the plane including line  3 — 3  of FIG. 2; 
     FIG. 4 is a section taken in the plane including line  4 — 4  of FIG. 2; 
     FIG. 5 is a fragmentary plan view similar to FIG. 2, but showing an apex tool; 
     FIG. 6 is section taken in the plane including line  6 — 6  of FIG. 5; 
     FIG. 7 is a plan view showing a clamp tool; 
     FIG. 8 is a fragmentary plan view of a guide rail of the preferred embodiment of the invention; 
     FIG. 9 is a section taken as indicated by line  9 — 9  of FIG. 8; 
     FIG. 10 is a schematic view of a control system for controlling the jigging system of FIGS. 1 to  9 ; 
     FIG. 10A is a diagram illustrating how a carriage is moved along the table according to one embodiment of the invention; 
     FIG. 11 is a fragmentary plan view of part of the table showing a heel tool according to a further embodiment of the invention; 
     FIG. 12 is an enlarged top plan view of the heel tool; 
     FIG. 13 is a side view of the heel tool; and 
     FIG. 14 is a section taken in the plane including line  14 — 14  of the heel tool of FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the drawings, an assembly table  10  is shown. Tables of this type may typically be up to 30 meters (100 feet) in length and 4.2 meters (15 feet) in width. The table  10  has an upper platform generally indicated at  12 , formed from solid sheets  12 A or sections or the like which are spaced apart to define a plurality of slots  14  which, in the embodiment of FIG. 1, extend across the width of the table. Rather than extend across the width of the table as shown in FIG. 1, the slots  14  could also extend lengthwise or at an angle across the table if desired. The upper platform  12  constitutes a reaction surface in the preferred embodiment. 
     Arranged for movement along the slots  14  in a manner to be described hereinafter are a plurality of stops or pucks  19 . Typically, the shape of a truss  20  is known and its details are fed into a control system  30 , which controls movement of the pucks  19 . The pucks  19  are then moved in a manner which will be described hereinafter to positions needed to locate the truss components for forming the truss  20 . In the preferred embodiment of this invention, some of the slots  14 , rather than being provided with pucks  19  are provided with other jigging tools. Such jigging tools may include apex tools  19 ′ and clamp tools  19 ″, described hereinafter. It is to be understood that “tools” as used herein includes the pucks  19 , as well as apex tools  19 ′, clamp tools  19 ″ or other suitable jigging tools. Such tools are necessarily arranged on the table  10  to define a jig for assembling the truss. Chords  20 A,  20 B and  20 C from which the truss is to be formed are laid out together with webs  20 D, with the chords abutting the pucks  19 . Connector plates C are located in generally opposed relation on top and bottom of the truss  20  at the joints of the chords  20 A,  20 B and  20 C and the webs  20 D, and the connector plates are driven into the truss  20  in a suitable manner such as by presses or the like (not shown) to form the truss  20 . The truss  20  is removed from the table  10  and new components, such as new chords which are the same as those referred to above, are located in place to form a new truss. If the shape of the new truss is different, the jig tools  19 ,  19 ′,  19 ″ are first moved under the control of a control system  30  (FIG. 10) to new positions for locating truss components of the new truss. 
     FIGS. 2 to  4  are detailed views showing two adjacent table sections  12 A separated by one of the slots  14 . A carriage  100  is arranged within the slot  14  and is moved by a motor M and flexible endless belt  52  (FIG.  10 A). The details of the motor M and belt  52  are fully disclosed in our previously mentioned Australian patent, and will only be briefly described hereinafter. Suffice it to say that the carriage  100  is secured to the flexible belt  52  described in the above mentioned patent for movement along the slots  14  as the belt is driven back and forth by the motor M. There are preferably two carriages per slot  14 . 
     The carriage  100  has a top plate  102  which is supported on steps  106  and  108  of a guide rail  130  by blocks  110  which are attached by welding or the like to the top plate  102 . The top plate  102  supports a puck  19 . Alternatively, the carriage  100  can carry another tool such as an apex tool  19 ′ (FIG. 5) for defining the apex of the truss to be formed or a clamp tool  19 ″ (FIG.  7 ). The apex tool  19 ′ and clamp tool  19 ″ will be described in more detail with reference to FIGS. 5 to  7 . 
     Referring again to FIGS. 3 and 4, the carriage  100  further includes a carriage guide  120  located below the top plate  102 . The carriage guide is guided in the guide rail  130 , in which are defined four channels  131 ,  132 ,  133  and  134 . The rail  130  is supported by a frame (not shown) beneath the table sections  12 A and has inwardly projecting flange portions  171  which define the steps  106  and  108  with the sections  12 A. The carriage guide  120  is of generally box construction having side walls  121  and  122 , top wall  124  and bottom wall  123 . The top wall  124  has extending flanges  128  and the bottom wall  123  has extending flanges  129 . The flanges  128  and  129  ride in the channels  131  to  134  on plastic strips  141  to facilitate sliding movement of the carriage  100  along the rail  130 . The carriage guide  120  is secured to the flexible belt  52  (see FIG. 10A) which is driven by the motor M and drive rollers  46 ,  46 ′ (as disclosed in our previously mentioned Australian patent) so that the carriage  100  is driven along the guide rail  130 . 
     The top wall  124  of the carriage guide  120  carries a cylindrical sleeve  125  having an internal annular upper bushing  127  and an internal annular lower bushing  126  which have a space  144  between them. The puck  19  is provided with a pin  140  which projects downwardly from the underside of the puck. The pin  140  has a circumferential groove  149  in which is located a split ring retainer or circlip  142  (broadly, “resilient locking member”) when the puck  19  is connected to the carriage  100 . Top plate  102  is provided with a hole  161  and the pin  140  passes through the hole and into the sleeve  125  which is aligned with the hole. 
     As the pin  140  moves downward past the upper bushing  127  an into the space  144 , the pin engages the inner diameter of the circlip  142 . The leading end of the pin  140  is tapered, but the main portion of the pin has a diameter larger than the inner diameter of the circlip  142  so that the circlip is resiliently deflected outward from its relaxed position. When the groove  149  of the pin reaches the space  144 , the circlip  142  snaps into the groove, attaching the pin  140  to the carriage. Further movement of the pin  140  axially of the sleeve  125  is resisted by engagement of the circlip  142  with the upper or lower bushings  127 ,  126  at the boundaries of the space  144 . Thus, the pin  100  snaps into a releasable locking engagement with the carriage  100  upon insertion into the sleeve  125 . The pin  140  also couples the top plate  102  to the carriage guide  120 . Thus, when the carriage guide  120  is moved by the flexible belt  52  along the slot  14 , the top plate  102  and puck  19  are moved conjointly with it. As will be apparent from FIGS. 2,  3  and  4 , the top plate  102  slides on shoulders  106  and  108  via blocks  110  as carriage guide  120  and top plate  102  move. 
     A resilient truss component support  150  connected by the pin  140  to the carriage  100  holds a chord (such as the chord  20 B shown in FIG. 3) above a top surface of the upper platform  12  of the table  10 . The support  150  comprises a metal spring plate  152  which has a hole  154  through which the pin  140  passes to that the plate  152  is secured to the carriage  100  on the top plate  102  by the pin  140 . The spring plate  152  extends substantially the length of the top plate  102  and rests at its ends on the top plate  102 . A raised central (“second”) portion  155  is higher than the level of the table sections  12 A. Many or all of the carriages  100  carrying a puck  19  have the support  150  so that the supports collectively hold the chords  20 A- 20 C and webs  20 D off the upper platform  12 . Thus, the truss chords  20 A- 20 C are supported above the level of the assembly table sections  12 A so that tooth connector plates C can be positioned on the sections  12 A beneath the chords  20 A- 20 C. The left heel of the truss  20  is broken away in FIG. 1 to reveal a connector plate C located on the bottom side of the truss. Bottom side connector plates (not shown) are similarly located at the other joints of the truss  20 . 
     The support plate  152  is formed from a resilient spring metal and has an end flange  153  which extends over the end of top plate  102  and into slot  14  so that the spring plate  152  cannot be inadvertently rotated relative to the top plate  102 , and the spring plate  152  can be maintained in the operative position shown in FIGS. 2,  3  and  4  for supporting a chord  20 B. Any tendency for the plate  152  to rotate in the directions indicated by double headed arrow A in FIG. 2 will be prevented by the sides of the flange  153  contacting side walls  12 B of the sections  12 A. 
     The spring metal plate  152  holds the chords  20 A- 20 C in a position slightly above the top of the upper platform  12 . Thus, connector plates can be slid, teeth up, under the chords  20 A- 20 C and webs  20 D at joint locations, or put in these locations prior to placement of the chords and webs on the upper platform  12 . Connector plates are also placed on top of the chords and webs at the joints. To attach the connector plates to the chords  20 A- 20 C and webs  20 D, a suitable press (not shown) applies a downward force to the chords, webs and connector plates. The force of the press overcomes the spring force of the metal spring plates  152 , deflecting the central portion  155  and pushing it down so that the top surface of the sections  12 A of the upper platform  12  can provide a rigid reaction surface opposing the action of the press. The teeth of the connector plates are driven by the press into chords  20 A- 20 C and webs  20 D as a result of the reaction force provided by the upper platform  12 . The spring plates  152  resume their prior configuration as soon as the press force is released. In this way, the carriage  100  is protected from experiencing the high loads from the press while permitting placement of connector plates under the chords and webs. 
     FIG. 5 shows a plan view similar to FIG. 2 except that an apex tool  19 ′ for positively locating the apex of truss  20  is shown. The apex tool  19 ′ has a base plate  250  (closely similar to top plate  102 ) which is provided with a hole  252 . The base plate  250  has a block  110 ′ (FIG. 6) at each end which ride on steps  106  and  108  of the guide rail  130  in the same manner as the blocks  110  attached to the top plate  102  of the carriage  100  described with reference to FIG.  4 . An apex tool cross-member  251  is attached as by welding to the base plate  250  so the base plate (with the blocks  110 ′) and cross-member are a single unit. The cross-member  251  carries a retractable locating finger  253  which has a side edge  254 . The side edge  254  positions an angled end  255  of chord  20 B of the truss  20  (shown in phantom) so that the chord can be correctly located in place at the apex of the truss. The apex tool  19 ′ is moved to the desired position by carriage  100  (as describe above for puck  19 ) so as to locate the locating finger  253  and therefore the edge  254  in the required position. When the chord  20 B is positioned, the locating finger  253  can be withdrawn (as indicated in hidden lines in FIG. 5) so that the other upper chord  20 C can abut against the end of the chord  20 B to thereby position the chord  20 C. The structure and mode of operation of the member  251  is conventional and therefore the apex tool  19 ′ will not be shown or described in any further detail. 
     As best shown in FIG. 6, the blocks  110 ′ of the apex tool  19 ′ ride on the steps  106  and  108  which are formed at the ends of the portions  171  of the guide rail  130 . In this embodiment, the upper plate  102  (with its attached blocks  110 ) of the carriage  100  is removed by simply removing the pin  140  which attaches the top plate  102  to the carriage guide  120  and lifting the top plate  102  out of the slot  14 . The base plate  250  is then placed in the slot  14  on the steps  106  and  108  and the hole  251  aligned with sleeve  125  of the carriage guide  120 . A pin  257  is then pushed through the aligned hole  251  and the sleeve  125  so that the pin  257  secures the apex tool  19 ′ to the carriage guide  120  in exactly the same manner as the pin  140  secures the puck  19  to the carriage guide  120  described with reference to FIG.  4 . In FIG. 5, a pin  140  can be provided by one of the pucks  19  previously described. However, in the embodiment shown the pin  257  is a separate pin which is similar to the pin  140  except that the head  259  is substantially flat since the pin  257  need not form the function of the puck  19 . 
     FIG. 7 shows an embodiment in which a clamp tool  19 ″ is automatically moved by the carriage  100 . In this embodiment, the top plate  102  is located in position in the same manner as described with reference to FIGS. 3 and 4. The clamp tool  19 ″ is secured to the top plate  102  by the same type of pin  257  described with reference to FIGS. 5 and 6 and which passes through a hole  261  formed in the clamp tool  19 ″. However, once again, a puck  19  having the pin  140  could be used instead of the pin  257 . The clamp tool  19 ″ is pivotal about the pin  257  to arrange the tool at right angles with respect to a chord  20 C so that a clamp head  260  can engage the chord  20 C to push the chords  20 A- 20 C and webs  20 D together. Since the clamp tool  19 ″ is at right angles to the chord  20 C, load applied by the chords against the clamp head  260  is in the direction of ram arm  262  and therefore does not tend to rotate the clamp  19 ″ on pin  257 . The clamp tool  19 ″ is of known design except of the inclusion of a hole through which the pin  257  can pass to secure the clamp tool  19 ′ to the top plate  102  of the carriage  100 . 
     It should be understood that in some embodiments of the invention, the carriage  100  is made up of the carriage guide  120  and the top plate  102 . In other embodiments, the top plate  102  is effectively incorporated into the tool (such as the plate  250  which forms part of the apex tool  19 ′) and therefore the carriage is effectively comprised of the carriage guide  120  and the tool defines the top plate (such as plate  250 ) and blocks (such as blocks  110 ′) connected to the plate  250  which slide on the steps  106  and  108  on the guide rail. 
     FIGS. 8 and 9 illustrate in more detail the configuration of the guide rail  130 . As best shown in FIGS. 8 and 9, the guide rail  130  is formed from two inverted L-shaped rail members  301  which are arranged in face to face or mirror image relationship with respect to one another. The rail members  301  have the inwardly projecting flange portions  171  which, together with the sections  12 A define the steps  106  and  108  upon which the top plate  102  or the base plate  250  of the apex tool  19 ′ ride. The flange portions  171  are supported by side walls  302 . The side walls  302  are coupled together by a plurality of lower plates  135  which are welded to lower edges of the side walls at locations spaced along the length of the guide rail  130 . The flanges  171  also each have spaced apart holes  307  which facilitate bolting of the sections  12 A of the platform  12  to the flanges. 
     Elongate bars  305  are welded to the inner surfaces of the side walls  302  of the guide rail  130  so as to define the channels  131 ,  132 ,  133  and  134 . Some of the plates  135  carry sleeves  311  so that jacks or other suitable supporting structure (not shown) can be engaged with the sleeves to support the guide rails  130  above ground level. I-beams (not shown) may be provided between adjacent guide rails  130  for supporting mid portions of the sections  12 A. The I-beams are attached to a conventional frame of the table  10 . Thus, the sections  12 A of the upper platform  12  are supported by the guide rails  130  as well as additional frame members formed at least partly by the I-beams (not shown). 
     A jig tool  19 ,  19 ′ or  19 ″ may be secured to the top plate  102  and carriage  120  which covers substantially the entire plate  102 . If the support of the chord  20 B at that particular top plate  102  is not required, the spring plate  152  can simply be lifted up slightly so as to raise the flange  153  above the top surface of the sections  12 A and then the plate  152  can be rotated about the pin  140  into a position 180° from that shown in FIGS. 2 and 3 to move the spring plate  152  into a non-operative position and out of any interference with the tool to be supported on the top plate  102 . For example, the spring plate  152  could be moved into the non-operative position as shown in phantom in FIG. 7 so that the central portion  155  does not interfere with correct positioning of the clamp tool  19 ″ relative to the top plate  102  and the chord  20 C. This enables the spring plate  152  to be moved out of the way while retaining the spring plate on the apparatus for convenient repositioning should the respective carriage  102  again be required to support one of the chords  20 A- 20 C above the platform  12 . Retention of the spring plate  152  on the carriage  100  also prevents misplacement of the spring plates or accidental loss of the spring plates when they are not in use. 
     FIGS. 10 and 10A schematically illustrate the control system  30  for controlling the jig. The control system  30  includes a portable computer PC which is coupled to a controller  80 . The controller  80  is then in turn coupled to motor M, encoder  68  and also controls solenoid  70  and disc brakes  66 . One controller  80  can be used to control, for example, six pucks  19 , six other jig tools (e.g.,  19 ′,  19 ″), or some combination of pucks and other tools. In the instance where the table  10  has forty-two tools (including pucks  19 ), seven controllers  80  connected to the PC for controlling the jig are used. The controller  80  which controls each set of six tools ( 19 ,  19 ′ or  19 ″) will also control the associated motor M, encoder  68 , brakes  66  and solenoid  70  associated with those tools. 
     Each of the controllers  80  therefore is controlling six of the tools ( 19 ,  19 ′ or  19 ″). The controller  80  obtains information identifying the position of each of the tools which it is to control. The information is fed to the controller  80  from the encoder  68  on the pulleys  46 . It should also be noted that all of the tools could be under the control of a single controller  80  rather than a number of controllers and all driven simultaneously to their desired positions under the command of the controller  80 . Conceivably, a greater number of controllers could be employed. 
     In the preferred embodiment, information relating to a truss layout is fed into the PC and that information is then provided to the controller  80 . Initially, the tools  19 ,  19 ′,  19 ″ are moved to a zero position by the controller  80 . The controller  80  selects one of the tools, e.g., one of the pucks  19 , and knowing the position of the puck  19 , it will compare the required position to the actual position of the puck. A command is issued from the controller  80  to the brake  66  associated with the relevant puck  19  so that the brake is released. An output is supplied to solenoid  70  to ensure that the shaft  60  is moved axially into the position so that the spline  62  or  64  engages the appropriate pulley  46  and a voltage is supplied to the motor M to drive the shaft  60  at high speed. The shaft  60  rotates the pulley  46  to drive the appropriate belt  52  about the pulleys  46  and  48  to move the carriage  100  to the desired position to correctly position the puck  19 . 
     When the puck  19  comes to within a specified distance from its required position (which may be indicated by a number of counts issued from encoder  68 ) the motor speed is switched to low speed by the controller  80 . Typically this will occur after one or two seconds of running. Again, when the puck  19  is within the specific number of counts of the actual position required, the controller  80  issues a signal to disc brake  66  to apply the brake to stop the pulley  46  so that the tool  19  comes to rest at the required position. The motor M is then switched off. The specific number of counts at which the motor is reduced to low speed and at which the brake is applied can be determined by the system response time and could be adjustable and preset in the controller  80 . The controller then selects another tool ( 19 ,  19 ′ or  19 ″) so that the next tool can be moved. The solenoid  79  is operated to disengage splines  62  of the shaft  60  from the pulley  46  and to engage the other spline  64  with its pulley  46 ′. The same procedure as outlined above is then repeated to position the other tools. 
     For any truss configuration only some of the tools  19 ,  19 ′,  19 ″ which may be provided may be used. Those tools which need not be used for a particular truss configuration can be controlled so that they are moved to the edge of the table so that they are completely out of the way of the truss  20  which is to be manufactured. 
     In the preferred embodiment of the invention, the pucks  19  are coupled to top plates  102  and carriages  120  by a pin  140  so that the pucks  19  can be released from any of the respective carriages in a similar fashion to the tools  19 ′,  19 ″. The tools  19 ,  19 ′,  19 ″ are released from their carriage guides  120  by simply prying the pin  140  upward from the sleeve  125  by means of a screwdriver or any other suitable tool. The upward motion of the pin  140  overcomes the spring force of the circlip  142  and drives the circlip out of the groove  149  and into the space  144  so the pin can be withdrawn from the sleeve  125 . The easy removal and replacement of the jig tools  19 ,  19 ′ or  19 ″ enables a particular jig tool to be associated with any one of the carriages  100  associated with any one of the slots  14 . 
     The processor PC will determine at which of the slots  14  the apex  21  of the truss is to be located and will show this either graphically, numerically or otherwise on a display screen. If an apex tool  19 ′ is not already associated with the slot  14 , the apex tool associated with one of the other slots  14  can be removed by releasing the pin  140  as described above and the apex tool snapped into connection with the carriage  100  associated with the appropriate slot  14 . Similarly, other tools such as clamp tool  19 ″ and pucks  19  can be released from particular carriages  100  and connected to other carriages  100  under the direction of the PC. The PC then controls the carriages  100  as described above to position the tools  19 ,  19 ′ and  19 ″ in the required position for enabling the chords  20 A- 20 C (and web  20 D in the embodiment shown in FIG. 1) to be located and fastened together by the connector plates previously described. 
     FIGS. 11 to  14  show a further embodiment of the invention in which a heel tool for locating the heel position of a truss is shown. The heel tool  400  is not movable along the channels  14  as is the case with the tools  19 ,  19 ′,  19 ″ previously described but is fixed in position to the table  10  by pairs of holes  401  and  402  which are provided on some or all of the sections  12 A of the upper platform  12 . In the embodiment shown in FIG. 11, two rows (labeled C and D) of holes  401  and  402  are shown. The heel tool  400  is fixed to one of the hole pairs  401  and  402  in row C on the section  12 A′ shown in FIG.  11 . The holes  401 ,  402  are covered by the tool  400  in FIG.  11 . 
     The tool  400  has a base section  403  and a heel point section  405  which is moveable relative to the base section  403 . As best shown in FIG. 12 which shows the tool more enlarged (and in a more retracted position than in FIG. 11) the base  403  has a recess  431  in which is located a head  409  arranged on a pin  407 , which pin is located in the hole  401  shown in FIG.  11 . The base  403  also carries an elongate hole  415  which carries a floating pin  419  for location in the hole  402  in the section  12 A′ shown in FIG.  11 . The pins  407  and  419 , as well as the holes  401  and  402  are preferably configured similar to the pin  140  and sleeve  125  previously described for secure releasable connection. The floating pin  419  in the elongated groove  415  provides some degree of movement of the pins  407  and  419  relative to one another to ensure that they can properly locate in the precision drilled holes  401  and  402 . The ability to locate the tool  400  on the assembly table  20  and then simply move the heel point section a short distance to define the heel point location enables quick and accurate determination of the heel point location and positioning the tool  400 . 
     When the truss.  20  is being formed, the PC will identify the heel point location for the truss  20  which is to be formed and will then display the holes  401  and  402  to which the heel tool  400  should be attached. The PC will then indicate the amount of movement of the heel point section  405  relative to the base  403  which is required in order to position a heel point locating tab  412  on the tool  400  at the desired point to identify the heel location of the truss  20 . The section  405  carries a scale  411 , and the base  403  a pointer  447 . Thus, the computer can indicate a value on the scale  411  which should be aligned with the pointer  447  to locate the heel point section  405  in the desired position relative to the base  403  for positioning the heel point locating tab  412  at the required place on the assembly table  400 . 
     As is best shown in the cross-sectional view of FIG. 14, the heel point section  405  is formed from a generally C-shaped channel having bottom wall  405 A, end wall  405 C and top wall  405 B. A pair of inwardly directing flanges  455  and  456  define a narrow slot  471  in the heel point section  405 . The base  403  is formed of a generally C-shaped channel having a bottom wall  403 A, a top wall  403 B and end wall  403 C. The walls  403 A and  403 B have free ends  472  which face and generally abut the flanges  455  and  456 . The walls  403 A and  403 B define an open space  460  therebetween and the walls  405 A and  405 B define a cavity  470  therebetween. 
     A locking bar  449  is accommodated in the cavity  470  of the heel point section  405  and has an enlarged head  450  and a stem  456  which projects through the channel  471  between the flanges  472 . A bar  451  is coupled to the stem  456  and projects into the space  460 . Pin  407  carries an integral eccentric  453 . A sleeve  452  is provided about the eccentric so that the pin and eccentric can rotate about the axis L of the pin relative to the sleeve. The bar  451  is welded to the sleeve  452  which holds the sleeve against rotation with the eccentric  453 . 
     In order to lock the heel point section  405  to the base  403  so that the heel point section cannot move relative to the base  403 , a handle  410  mounted on top of the pin  407  is rotated in the direction of arrow F (FIG. 12) so the pin rotates about its longitudinal axis L (FIG. 14) in hole  401 . This rotation causes the eccentric  453  to rotate with the pin  407  and the rotation of the eccentric  453  causes the sleeve  452  to move in the direction of arrow G in FIG. 14 within the space  460  to pull the bar  451  and also the head  450  in the same direction so that the head securely clamps the flanges  455  against the free ends  472  of the walls  403 A and  403 B. Thus, the heel point section  405  is securely clamped against the base  403  so it cannot move. In order to release the heel point section  405  for movement relative to the base  403  either direction of double headed arrow D in FIG. 12, the handle  410  is rotated in the opposite direction to arrow F (back, for example, to the position shown in FIG. 12) so as to rotate the eccentric  453  to move the sleeve  452  in a direction opposite arrow G in FIG.  14 . This causes the clamping pressure supplied by the head  450  which pushes the flanges  455  hard against the free ends  472  to be released. The heel point section  405  can then slide in the direction of arrow D relative to both the locking bar  449  and also the base  403  with the flanges  455  sliding on the free ends  472  of the walls  403 A and  403 B. To prevent rotation of the heel point section  405  about bar  451 , relative to the base  403  into and out of the plane of the paper of FIG. 12, which may be allowed by any tolerance provided for the sleeve  452  and eccentric  453  within the space  460 , a tongue  481  is provided on the heel point section  405  which projects into the space  460  between the walls  403 A and  403 B. 
     According to the preferred embodiment of the invention, the jig system can be automatically set up to receive components of a truss and the truss can be easily manipulated to enable connector plates to be inserted in place for formation of the truss. Thus, not only is set up of the jig quickly effected, but formation of the truss is also more easily and quickly performed. 
     Since modifications with the spirit and scope of the invention may readily effected by persons of ordinary skill in the art, it is to be understood that this invention is not limited to the particular embodiment described by way of example hereinabove.