Patent Publication Number: US-9839956-B2

Title: Feed assembly for a riveting machine and a method of operation of the same

Description:
BACKGROUND OF THE INVENTION 
     Technical Field 
     This invention relates generally to riveters. More particularly the invention is directed to a foot operated riveter. Specifically, the invention relates to a foot operated riveter and a method of using the same, where the riveter includes an enclosed linkage assembly, a detachable feed assembly, and rivet stop on the feed assembly which automatically feeds one rivet at a time to a location where the rivet may be deployed to secure two or more workpieces together. 
     Background Information 
     Riveters, including foot-operated riveters are known in the art. Typically, these machines include a linkage assembly which transfers motion from a foot pedal to a plunger which drives a rivet into workpieces that are to be secured together. The linkage assembly includes two or more linkage arms which pivot relative to each other when the foot pedal is depressed or when pressure on the foot pedal is released. When the foot pedal is depressed, the pivoting linkage arms project for a distance outwardly beyond a back region of the riveter. This makes it necessary for the machine to be positioned a distance away from walls or workbenches, for example, so that there is sufficient room for the movement of the linkage arms. 
     Additionally, presently known riveters typically include some type of feed mechanism that delivers rivets to a location where they are used to secure work pieces together. Only one rivet can be installed at a time and it is typically necessary for the operator to depress a button to move a rivet from a feed assembly to the appropriate location for deployment. The depression of the button requires the operator to take extra time and make a number of additional movements whenever a set of workpieces are joined together. Since the riveter will be used to secure a plurality of sets of workpieces together, the additional time and movements required for moving single rivets into position adds up, and increases the fabrication time and costs involved. 
     SUMMARY 
     There is therefore a need in the art for an improved riveter that addresses some of these issues. 
     The riveter disclosed herein includes a linkage assembly that is completely enclosed within the device. The riveter includes a base and a head which are connected together by a vertical post. The foot pedal extends outwardly from the post and is operatively engaged with a part of the linkage assembly that is entirely enclosed within the interior cavity of the post. The rest of the linkage assembly is enclosed in a cavity in the head of the riveter. Consequently, the riveter disclosed herein has the advantage that it may be positioned adjacent a wall or workbench or other structure. When the riveter is used, the lever arms of the linkage assembly pivot entirely within the post or head of the riveter and thus do not contact any surrounding structures. This configuration makes the riveter more suitable for use in smaller environments and helps make more efficient use of floor space on a shop floor. 
     Still further, the riveter disclosed herein is able to detachably engage one or more of a range of differently configured feed assemblies, each feed assembly being configured to hold and provide a different type of fastener or a different size of fastener for securing workpieces together. Each feed assembly includes a connector that is configured to engage a connection member on the riveter head. The connector is complementary to the connection member. A sample embodiment of a suitable connection member is a shaped slot provided on the riveter. The complementary connector that is provided on each of the different feed assemblies includes a first region that is interlockingly receivable into the shaped slot. A locking member secures the connector in the connection member. This arrangement enables the riveter disclosed herein to be used to secure workpieces together using a wide range of different fasteners, thus making the machine more versatile and therefore more cost effective to own. 
     Furthermore, a feed assembly is disclosed that has a rivet stop that is configured and positioned to automatically control the feed of rivets and other fasteners to a location where they are installed during operation of the riveter. The rivet stop thereby removes the need for the operator to depress buttons to move a single rivet into position prior to installation of the same. The provision of this rivet stop thus decreases the time required to join a number of different sets of workpieces and thus contributes to more efficient and less expensive production of joined workpieces. 
     In one aspect, the invention may provide a riveter and a feed assembly in combination, wherein the feed assembly is adapted to hold and feed a plurality of a first fastener; and wherein the feed assembly is selectively detachably engageable with the riveter. 
     In another aspect, the invention may further provide a riveter, a first feed assembly which holds and provides a plurality of first fasteners and a second feed assembly which holds and provides a plurality of second fasteners; and wherein each of the first and second feed assemblies are selectively detachably engageable with the riveter. 
     In another aspect, the invention may provide a method of using a riveter to secure two separate workpieces together; said method comprising the steps of providing a riveter having a base adapted to rest on a floor surface, a post extending upwardly from the base, a foot pedal extending outwardly from the post, a plunger mounted for reciprocal movement within the head, and a linkage assembly operatively engaged with the foot pedal and the plunger; wherein movement of the foot pedal in a first direction causes the linkage assembly to move the plunger within the head in a first manner; and movement of the foot pedal in a second direction causes the linkage assembly to move the plunger within the head in a second manner; providing a first feed assembly which holds and delivers a type of first fastener for securement of the workpieces; engaging the first assembly with the riveter; and operating the riveter to drive one or more of the first fasteners into the workpieces to secure the workpieces together. 
     In yet another aspect, the invention may provide a method which further comprises providing a second feed assembly which holds and delivers a type of second fastener for securement of the workpieces; selecting one of the types of first or second fasteners to secure the two workpieces together; selecting the associated one of the first and second feed assemblies; engaging the selected one of the first and second feed assemblies with the riveter; and operating the riveter to drive one or more of the selected first or second fasteners into the workpieces to secure the workpieces together. 
     In yet another aspect, the invention may provide a feed assembly for a riveter comprising a tumbler including a feed chute with an opening into which the plurality of the fasteners are adapted to be fed; a raceway extending downwardly from the tumbler and defining a feedslot therein which is adapted to receive fasteners therein one at a time from the tumbler; a pair of opposed spring arms secured to the raceway; a guide block provided on each spring arm; a channel defined between the guide blocks of the two spring arms, the channel being adapted to receive a lowermost fastener from the raceway therein; and wherein the plunger passes through the channel and is adapted to contact the lowermost fastener; and a rivet stop provided on one of the spring arms; said rivet stop being adapted to selectively contact a second from lowermost fastener in the raceway and prevent this second from lowermost fastener from moving downwardly along the raceway. 
     In a further aspect, the invention may provide a riveter which includes a feed assembly that comprises a tumbler including a feed chute with an opening into which the plurality of the fasteners are adapted to be fed; a raceway extending downwardly from the tumbler and defining a feedslot therein which is adapted to receive fasteners therein one at a time from the tumbler; a pair of opposed spring arms secured to the raceway; a guide block provided on each spring arm; a channel defined between the guide blocks of the two spring arms, the channel being adapted to receive a lowermost fastener from the raceway therein; and wherein the plunger passes through the channel and is adapted to contact the lowermost fastener; and a rivet stop provided on one of the spring arms; said rivet stop being adapted to selectively contact a second from lowermost fastener in the raceway and prevent this second from lowermost fastener from moving downwardly along the raceway. 
     In a further aspect, the invention may provide a method of using a riveter to secure two separate workpieces together; said method comprising the steps of providing a riveter having a base adapted to rest on a floor surface, a post extending upwardly from the base, a foot pedal extending outwardly from the post, a plunger mounted for reciprocal movement within the head, and a linkage assembly operatively engaged with the foot pedal and the plunger; wherein movement of the foot pedal in a first direction causes the linkage assembly to move the plunger within the head in a first manner; and movement of the foot pedal in a second direction causes the linkage assembly to move the plunger within the head in a second manner; providing a feed assembly on the riveter which holds and delivers plurality of fasteners for securement of the workpieces; providing a rivet stop on the feed assembly to control the feed of fasteners through a raceway of the feed assembly; and operating the riveter to drive a lowermost one of the fasteners in the raceway into the workpieces to secure the workpieces together. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A sample embodiment of the invention is set forth in the following description, is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. 
         FIG. 1  is a right side elevational view of a foot operated riveter in accordance with an aspect of the present invention; 
         FIG. 2  is an enlarged front elevational view of the foot pedal taken along line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a right side cross-sectional view taken along line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is an enlarged right side elevational view of the head of the riveter; 
         FIG. 5  is a front elevational view of the head of the riveter; 
         FIG. 6  is a left side elevational view of the head of the riveter; 
         FIG. 7  is a rear elevational view of the head of the riveter; 
         FIG. 8  is right side cross-sectional view of the head of the riveter taken along line  8 - 8  of  FIG. 5  with the outer side plate partially cut-away to permit the interior of the head to be seen; 
         FIG. 9  is partial cross-sectional view of the lever assembly which rotates the tumbler taken along line  9 - 9  of  FIG. 5  and showing the lever in a first position; 
         FIG. 10  is a partial cross-sectional view of the lever assembly of  FIG. 9  with the lever shown in a second position; 
         FIG. 11  is a partial cross-sectional view of the lever assembly of  FIG. 9  with the lever shown returning to the initial position and showing rotation of the tumbler caused by the return of the lever to the initial position; 
         FIG. 12  is an enlarged front elevational view of the feed assembly of the riveter; 
         FIG. 12A  is an enlargement of the highlighted region of  FIG. 12 ; 
         FIG. 13  is a right side cross-sectional view of the feed assembly taken along line  13 - 13  of  FIG. 12 ; 
         FIG. 13A  is an enlargement of the highlighted region of  FIG. 13 ; 
         FIG. 14  is an enlarged front elevational view of the feed assembly that is loaded with rivets; 
         FIG. 15  is a right side cross-sectional view of the feed assembly taken along line  15 - 15  of  FIG. 14 ; 
         FIG. 16  is an enlarged front elevational view of the feed assembly with the plunger moved to a riveting position; 
         FIG. 17  is a right side cross-sectional view of the feed assembly taken along line  17 - 17  of  FIG. 16 ; 
         FIG. 18  is a right side cross-sectional view of the feed assembly of  FIG. 17  with the plunger being moved to a retracted position and a next rivet dropping into the feed chute; 
         FIG. 19  is a right side cross-sectional view of the feed assembly of  FIG. 18 , with the next rivet positioned in the ready position for riveting; 
         FIG. 20  is a front view of the feed assembly showing the feed chute with the next rivet positioned and ready for riveting; 
         FIG. 21  is a right side view of the head of the riveter with the feed assembly disengaged therefrom; and 
         FIG. 22  is a right side view of the head of the riveter; showing a second feed assembly loaded with a second type of fastener for securing workpieces together. 
     
    
    
     Similar numbers refer to similar parts throughout the drawings. 
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-21 , there is shown a riveter, generally indicated at  10 . Riveter  10  includes a base  12  that rests on a ground or floor surface  14 , a post  16  extending upwardly from base  12 , and a head  18  mounted on an upper end of post  16 . Post  16  is a tubular member defining a bore therein. A foot operated pedal  20  extends outwardly from post  16  and is operatively engaged with a linkage assembly  22 . Part of linkage assembly  22  is located within the bore of post  16  and another part of linkage assembly  22  is located within an interior chamber of head  18 . A plurality of feed assemblies are selectively detachably engageable with riveter  10 . Each of these various feed assemblies is fabricated to deliver a different type of fastener for joining workpieces together. As illustrated in  FIG. 1 , for example, a first feed assembly  24  is detachably engageable with head  18  of riveter. Linkage assembly  22  is operatively engaged with a lever assembly  26  ( FIG. 5 ) on feed assembly  24 . Riveter  10  is generally operated by depressing foot pedal  20  toward floor surface  14 . The motion of foot pedal  20  causes linkage assembly  22  to move lever assembly  26 . Lever assembly  26  rotates a tumbler  28  of feed assembly  24  causing fasteners, such as rivets,  30  ( FIG. 14 ) within tumbler  28  to be fed into a raceway  32  ( FIG. 4 ). Linkage assembly  22  also moves a plunger  36  ( FIG. 5 ) in one of a first or second manner, depending on the direction of movement of foot pedal  20 . Linkage assembly  22  moves plunger  36  downwardly when foot pedal  20  is moved in a first direction. Linkage assembly  22  moves plunger  36  downwardly into a position where the plunger engages lowermost one of the rivets  30  at the end of raceway  32  of feed assembly  24 . Two separate workpieces  38 ,  40  are positioned above a spreader mechanism  128  extending upwardly from platform  34  on head  18 . Plunger  36  drives the lowermost rivet  30  downwardly and into workpieces  38 ,  40 , securing them together. Linkage assembly  22  may also move plunger  36  upwardly within head  18  when food pedal  20  is moved in a second direction. All of the various components and the operation of riveter  10  will be described in greater detail herein. 
     Before proceeding with the description, a frame of reference is set out herein on  FIGS. 4 and 5  to define three axes of motion through which components of the riveter  10  may move. Vertical motion (up-and-down motion) occurs along an axis “Y”, horizontal motion (back-and-forth motion) occurs along an axis “X” and lateral motion (side-to-side) motion occurs along an axis “Z”. 
     Referring to  FIG. 2 , base  12  comprises a plate  42 , at least a pair of spaced-apart side-bars  43 , and a plurality of adjustable feet  46 . Plate  42  has an upper surface  42   a  and lower surface  42   b . A hole  42   a  is defined proximate each corner of upper surface  42   a  of plate  42  and apertures  42   a  are through holes between upper and lower surfaces  42   a ,  42   b . Holes  43   a  are also defined between upper and lower surfaces of side-bars  43  and hole  42   a  and  42   a  are aligned with each other. A shaft  44   a  of a bolt  44  is inserted through each set of aligned holes  42   a ,  43   a  and a ground-engaging member  45  is threadably engaged with the end of each bolt  44 . The user will rotate members  45  about an axis extending through shaft  44   a  in one of a first and second direction to alter the distance between lower surface  42   b  of plate  42  and the floor surface  14 . The user will selectively adjust each foot  46  so that plate  42  is substantially horizontally leveled. 
     As shown in  FIGS. 2 and 3 , post  16  is a generally hollow tubular member having a peripheral wall  16   a  that bounds and defines an interior cavity  16   b . A mounting bracket  48  is provided at a lower end of post  16  and a plurality of fasteners  50  are used to secure bracket  48  to plate  42 . An aperture  52  is defined in a front region of peripheral wall  16   a  and this aperture  52  is in communication with cavity  16   b . An upper end of post  16  is secured to a housing  54  of head  18  by a plurality of other fasteners  56  as will be further described herein. 
     Referring to  FIGS. 1-3  foot pedal  20  includes an elongate leg  58  that may be comprised of one or more members. As illustrated, leg  58  may include a first member  58   a  and a second member  58   b  that are secured together by any suitable means, such as by way of a locking member  60 . A pressure pad  62  is engaged on an upper surface of leg  58  at a first end thereof and a rubber stop  64  is engaged on a lower surface of leg  58  and at the first end thereof. The second end of leg  58  is engaged to a first arm  22   a  of linkage assembly  22  by way of a first pivot rod  66 . Spacers  68  are engaged with leg  58  via fasteners  70  and a bushing  72  may be provided on each spacer  68  to ensure fluid movement of foot pedal  20 . 
     Linkage assembly  22  further includes second arm  22   b  ( FIGS. 1 and 8 ) which is secured to first arm  22   a  by way of a second pivot rod  74 . Second spacers  76  separate second arm  22   b  from the interior surfaces of housing  54  of head  18 . Second spacers are secured to housing  54  by fasteners  78  and a bushing  80  is provided to ensure fluid movement of second arm  22   b , as will be further described herein. 
     Housing  54  of head  18  comprises a plurality of sheets of a material, such as metal, which form first and second sides  54   a ,  54   b  and front/top/back  57  of housing  54 . The sheets of material may be bolted together, such as by fasteners  55  and  56 . Spacer blocks  53  ( FIG. 7 ) and  59  ( FIG. 8 ) may be positioned to provide stable locations into which fasteners  55 ,  56  are secured. Spacer block  53  extends partially into interior cavity  16   b  of post  16  and partially into cavity  82  of head  18 . Fasteners  56  secure spacer block  53  to the sides  54   a ,  54   b  of housing  54  and to the side walls (not numbered) of post  16 . Fasteners  55  secure spacer block  59  to front/top/back  57  of housing  54 . Alternatively or additionally, the sheets of metal may be welded together. Sides  54   a ,  54   b  and front/top/back  57  of housing bound and define an interior cavity  82  ( FIG. 8 ) within which various components of riveter  10  are located. Housing  54  protect such components. 
     Head  18  further includes a first mounting block  84  ( FIG. 21 ) and a second mounting block  87  ( FIG. 8 ) that are secured to housing  54  by way of fasteners  85 . Blocks  84  and  87  may be fabricated from a solid piece of metal. Block  84  includes a front face  84   a , a rear face  84   b , a top face  84   c , and a bottom face  84   d . Block  87  includes a front face  87   a , a rear face  87   b , a top face  87   c , and a bottom face  87   d . Block  87  is positioned between side walls  54   a ,  54   b  of housing  54 . Block  84  is positioned adjacent side wall  54   a  and generally aligned with and proximate to block  87 . It will be understood that blocks  84  and  87  may instead comprise a single unitary block and side wall  54   a  of housing  54  may include a cut-out to allow a portion of this single block to extend outwardly from the interior  82  of housing  54 . 
     Block  84  defines a slot  86  therein and with which feed assembly  24  is detachably engaged by way of a connector that is at least partially complementary shaped to slot  86 .  FIG. 21  shows that slot  86  is generally horizontally oriented, i.e., aligned parallel to horizontal axis “X”. It will be understood, however, that slot  86  may be differently oriented and that feed assembly  24  will be configured to interlockingly engage with slot  86  no matter the orientation of that slot. Slot  86  is shaped so that a complementary shaped first region of feed assembly  24  will dovetail therewith. Slot  86  may be generally T-shaped in cross-section as shown in  FIG. 8 , for example. Feed assembly  24  includes a connector having a first region  132  that is complementary to the T-shaped slot  86  and this first region  132  dovetails with slot  86 . It will be understood that slot  86  and first region  132  may be of any other suitable complementary cross-sectional shapes to interlockingly dovetail with each other. Furthermore, every additional feed assembly that is to be engaged with riveter  10 , such as second feed assembly  224  ( FIG. 22 ), will include a connector that is at least partially complementary to the cross-sectional shape of slot and is configured and oriented to be received in slot  86 . This arrangement ensures that any additional feed assembly may be selectively detachably engaged with riveter  10  in the place of feed assembly  24 . This will be further described herein. 
     An opening (not numbered) to slot  86  is defined in front face  84   a  and rear face  84   b  ( FIG. 7 ) of block  84 . Additionally, an opening (not numbered) to slot  86  is defined in an appropriate face of head  18 . Obviously, the two openings are aligned with each other. As is evident from  FIG. 5  and  FIG. 13 , T-shaped slot  86  includes a first narrower but taller region  86   a  and a second wider but shorter second region  86   b . Regions  86   a  and  86   b  extend for substantially the entire length of slot from front face  84   a  to rear face  84   b . An assembly stop  88  ( FIG. 7 ) extends outwardly from an interior wall of block  84  which defines slot  86 . Assembly stop  88  is a projection positioned a spaced distance inwardly from the opening to slot  86  in front face  84   a  of block  84  and therefor from the front face of housing  54  or head  18 . Assembly stop  88  extends into slot  86  and is provided to limit the inward travel of feed assembly  24  away from the front face of head  18  which defines the opening to slot  86 . This positioning of assembly stop  88  ensures that any feed assembly, such as feed assembly  24 , will be positioned on block  84  in an operational position. 
     As shown in  FIGS. 8 and 13 , block  87  defines a vertically oriented bore  90  therethrough which originates in top face  87   c  and terminates in bottom face  87   d . Bore  90  is spaced a distance inwardly from each of front face  87   a  and rear face  87   b . A bushing  91  lines bore  90 . Riveter  10  further includes a plunger  36  which has a first end  36  and a second end  36   b . First end  36   a  of plunger  36  is secured to a front end of second arm  22   b  of linkage assembly  22  by a rod  92 . The body of plunger  36  passes through a hole (not numbered) in bushing  91  positioned in block  87 . Although not illustrated in the figures, plunger  36  includes a recess defined in second end  36   b  thereof. A first end of a replaceable tip  37  is received in this recess. A handle  39  with a threaded shaft  39   a  extending outwardly therefrom is provided to lock tip  37  in this recess in plunger  36 . A free end of shaft  39   a  is inserted through an aperture in the side wall of plunger  36 . Handle  39  is rotated in a first direction to cause the free end of the shaft  39   a  to advance inwardly into the recess and contact the side of tip  37 . Further rotation of handle  39  in the first direction will clampingly lock tip  37  against a portion of the interior surface of plunger  36  which defines the recess therein. When it is desired to remove tip  37  and replace it with a differently configured tip, handle  39  is rotated in a second direction to break the clamping contact between shaft  39   a  and tip  37 . Tip  37  will then be able to move out of the recess and the end of a replacement tip will be inserted into recess and locked into position by rotating handle  39  in the first direction. Tip  37  has a rivet-engaging end  37   a  which contacts the head of a rivet  30  held by feed assembly  24  when riveter  10  is being used. The use of riveter  10  will be later described herein. 
       FIG. 8  shows that the rod  92  operatively engaged with linkage assembly  22  passes through a slot  94  defined in first end  36   a  of plunger  36 . Rod  92  also extends through a pair of vertically-oriented and aligned slots defined in opposing side walls  54   a ,  54   b  of housing  54 . One of these slots is shown in  FIG. 6  and is identified by reference character  96 . When foot pedal  20  is depressed and released, rod  92  is caused to move vertically up and down in slots  96  and as a result, plunger  36  is caused to move vertically up and down within the hole in bushing  91 . The movement of plunger  36  in turn moves tip  37  vertically up and down. 
     The reciprocal vertical travel of plunger  36  through the hole in bushing  91  and parallel to axis “Y” is adjustable. To that end, housing  54  defines a further pair of aligned slots  100  therein with each slot  100  being defined in one of the side walls  54   a ,  54   b  of housing  54 . A first slot  100  is illustrated in  FIG. 4  and the other slot  100  is illustrated in  FIG. 6 .  FIG. 8  shows that a third mounting block  102  is secured to housing  54  adjacent rear face  87   b  of mounting block  87  by way of fasteners  104 . Blocks  87  and  102  may be welded or otherwise secured to each other to provide more strength and stability to housing  54  or may even be part of a single integral block.  FIG. 8  also shows that a slot  106  is defined in second block  102  and this slot  106  is aligned with slots  100  in the side walls of housing  54 . A dial  108  is mounted within slot  106  by way of a threaded rod  110 . (Rod  110  passes through an aperture (not numbered) within dial  108 .) An additional vertical slot  112  ( FIG. 6 ) is defined in one of the side walls of housing  54 . An adjustment pin  114  is provided on rod  110  and this pin  114  extends through vertical slot  112 . When dial  108  is rotated about a vertical axis that extends through rod  110 , because pin  114  is captured within slot  112 , the rotation of the dial  108  will cause rod  110  to move vertically upward or downward. This vertical motion along axis “Y” will cause the upper end  110   a  of rod  110  to move toward or away from second arm  22   b  of linkage assembly  22 . When second arm  22   b  pivots in response to the depression or release of the foot pedal  20 , the lower surface  23  of second arm  22   b  will move relative to upper end  110   a  of rod  110 . The distance between upper end  110   a  and lower surface  23  dictates the length of travel of plunger  36  along axis “Y”. When plunger  36  moves downwardly, lower surface  23  of second arm  22   b  will contact upper end  110   a  of rod  110  and further downward motion will be prevented. If it is determined that the distance plunger  36  is moving downwardly is insufficient then dial  108  will be rotated in a first direction to move upper end  110   a  further away from lower surface  23 . If it is determined that the distance plunger  36  is moving downwardly is too great, then dial  108  will be rotated in a second direction to move upper end  110   a  closer to lower surface  23 . 
     Block  87  further defines a recess  116  in top face  87   c  thereof. A compression spring  118  anchored at a first end on second arm  22   b  of linkage assembly  22  has a second end that is received in recess  116 . When second arm  22   b  moves in response to foot pedal  20  being depressed, as will be further described herein, plunger  36  is moved downwardly to cause a rivet  30  in raceway  32  to secure workpieces  38 ,  40  together. This downward motion of plunger  36  causes spring  118  to be compressed. When pressure on foot pedal  20  is released, compression spring  118  assists in moving plunger  36  and second arm  22   b  back to their at-rest position. 
       FIG. 8  shows that a stop  120  is provided on housing  54  in a position beneath lower surface  23  of second arm  22   b  and in a location proximate pivot  74 . Stop  120  limits the vertical downward motion of second arm  22   b  as second arm  22   b  pivots about rod  74 . 
     A third block  122  ( FIG. 8 ) is mounted to housing  54  by way of fasteners  124 . The upper surface of third block  122  serves as the platform  34  of head  18 . A through-hole  126  is defined in block  122  and a spreader screw  128  extends upwardly through hole  126  and toward tip  37 . Spreader screw  128  includes an upwardly extending tip  128   a  that is sized to be received into an opening at the bottom end of a tubular shaft  30   b  of a rivet  30  and to split and spread that shaft  30   b . The configuration of the spreader screw  128  and the manner in which it functions is known in the art and thus will not be further described herein. 
     Feed assembly  24  is a detachable component that is selectively engaged with riveter  10 . Feed assembly  24  comprises tumbler  28  and a raceway  32 . A mounting block  130  ( FIG. 4 ) is provided on raceway  32 . As indicated previously, the connector which secures feed assembly  24  to riveter  10  includes a generally T-shaped first region  132  (best seen in  FIG. 13 ). First region  132  extends outwardly from mounting block  130  and is insertable into the opening (not numbered) in head  18  and front face  84   a  of block  84  and into slot  86  defined therein. First region  132  is interlockingly engageable in slot  86  and is movable therealong. First region  132  may be slid along slot  86  to the point that the connector engages assembly stop  88  so that feed assembly  24  is in the operational position. 
     The connector on feed assembly  24  also includes a locking member for locking feed assembly  24  to riveter  10  in a fixed position when feed assembly  24  is in this operational position. The locking member prevents relative motion between first region  132  of connector and slot  86  and thereby between feed assembly  24  and head  18 . The locking member may comprise a thumbscrew  134  ( FIG. 4 ). When thumbscrew  134  is rotated in a first direction, thumbscrew  134  urges first region  132  into frictional locking engagement with the portions of mounting block  84  which define slot  86 . Thumbscrew  134  is thus in a locked position, locking first region  132  to mounting block  84  and preventing relative motion between first region  132  and slot  86 . This prevent relative motion between feed assembly  24  and head  18  of riveter  10 . Thumbscrew  134  is rotated in a second direction to an unlocked position, thereby releasing pressure on first region  132 . When this occurs, relative motion between first region  132  and slot  86  is again possible. Consequently, feed assembly  24  is able to move relative to head  18 . Feed assembly  24  is only able to be engaged with or disengaged from riveter  10  when thumbscrew  134  is rotated in the second direction. Riveter  10  is only able to rivet workpieces together when feed assembly  24  is engaged therewith and thumbscrew  134  has been rotated in the first direction. 
     Referring to  FIG. 5 , tumbler  28  includes a first section  28   a  that is fixed to block  130  and the upper end  32   a  of raceway  32 . Tumbler  28  further includes a second section  28   b  that is rotatably engaged with first section  28   a  and is adjustably secured thereto by a securement member  28   c . A feed chute  136  is connected to first section  28   a  and includes an opening (not shown) in the upper end  136   a  thereof. Rivets may be fed into first section  28   a  of tumbler  28  through feed chute  136  and rivets then proceed from stationery first section  28   a  to rotatable second section  28   b . Lever assembly  26  is provided to cause second section  28   b  of tumbler  28  to rotate. Referring to  FIGS. 9-11 , lever assembly  26  includes a lever arm  138  that is mounted on a shaft  142  that connects lever arm  138  to first section  28   a  of tumbler  28 . A spring  140  is connected at a first end to feed chute  136  and at a second end to lever arm  138 . Lever arm  138  is rotatable about a horizontal axis which extends along shaft  142 . This rotation is caused by movement of rod  92  which is connected to plunger  36 . As plunger  36  is moved downwardly in response to depression of foot pedal  20 , lever arm  138  moves from a first position shown in  FIG. 9  to a second position shown in  FIG. 10 . This downward motion, indicated by arrow “A” in  FIG. 10 , stretches spring  140 . As plunger  36  moves upwardly when pressure is removed from foot pedal  20 , spring  140  returns to its original length, pulling lever arm  138  upwardly in the direction of arrow “B” ( FIG. 11 ) and returning lever arm  138  to the first position. The upward motion of lever arm  138  causes shaft  142  to rotate in the direction of arrow “C” ( FIG. 11 ) and this rotation in turn causes rotation of second section  28   b  of tumbler. 
     Rivets fed into the opening in upper edge  136   a  of feed chute  136  drop through first section  28   a  into the rotating second section  28   b  and subsequently are fed one at a time through an opening (not shown) in tumbler  28  and into a feedslot  142  ( FIG. 12 ) defined in raceway  32 . Although it is not obvious from the figures, feedslot  142  is generally T-shaped in cross-section and includes a narrower region  142   a  and a wider region  142   b . Rivets  30  are shown in  FIG. 14  stacked one above the other within feedslot  142 . As is evident from  FIGS. 14 and 17 , each rivet has a head  30   a  and a shaft  30   b . Heads  30   a  are captured within the wider region  142   b  of feedslot  142  and the tubular shafts  30   b  extend outwardly through the narrower region  142   a  of feedslot  142 . Rivets  30  slide downwardly through feedslot  142  until the lowermost rivet  30  enters a bottom region  32   b  ( FIG. 5 ) of raceway  32 . When a plurality of rivets  30  are engaged in feedslot  142 , heads  30   a  thereof will butt up against one another in feedslot  142  as illustrated in  FIG. 17 . This arrangement causes the rivets to be generally equally spaced from each other along feedslot  142 . Heads  30   a  progressively slide down feedslot  142  as each lowermost rivet is engaged by plunger  36  with workpieces  38 ,  40  positioned adjacent spreader  128   a.    
     Referring to  FIGS. 5, 7 and 12 , a pair of spring arms  144 ,  146  are secured by fasteners  148  to a front and back region, respectively, of raceway  32 . A lower end of each spring arm  144 ,  146  is respectively secured to a tapered guide block  150 ,  152  by way of additional fasteners  154 .  FIG. 13  shows that guide blocks  150 ,  152  define between them a tapered channel  156 . Channel  156  is configured to permit a rivet  30  to drop into the same and caused to be oriented with the shaft  30   b  thereof extending vertically downwardly and projecting out of the bottom end  156   a  of channel  156 . When a rivet  30  is so positioned, the opening to the bore defined in rivet  30  will be disposed in alignment with a spreader  128   a  extending upwardly from spreader screw  128 . This is illustrated in  FIG. 14 . When the movement of first region  132  and thereby feed assembly  24  is halted by assembly stop  88 , plunger  36  will be positioned so as to pass through channel  156  between guide blocks  150 ,  152  on the feed assembly  24  and will be correctly aligned with spreader  128   a  on spreader screw  128 . 
     A rivet stop  158  is secured to one or the other of spring arms  144 ,  146  and may particularly be secured to one or the other of guide blocks  150 ,  152  provided on spring arms  144 ,  146 .  FIGS. 12-13A and 16  show rivet stop  158  secured to guide block  150  by way of a fastener  160 . Rivet stop  158  is a generally J-shaped member that includes a shaft  159  and a hook  162 . Shaft  159  has straight side edges  159   a ,  159   b  and bottom edge  159   c . First side edge and second side edge  159   a ,  159   b  are substantially parallel to each other and are spaced from each other. Bottom edge  159   c  extends between side edges  159   a ,  159   b  and is oriented at right angled thereto. Shaft  159  also has a exterior surface  159   d  and an interior surface  159   e.    
     Hook  162  includes a projection  162 A and has a curved upper edge  162   a  and a generally V-shaped tip  162   b . Tip  162   b  extends for a distance outwardly beyond second side edge  159   b  of shaft  159 . Tip  162   b  also includes a shoulder edge  162   c  disposed generally at right angles to second side edge  159   b . Curved outer edge of head  162  intersects the shoulder edge at an acute angle. The acute angle is approximately 45 degrees. 
     As best seen in  FIG. 13 , shaft  159  of rivet stop  158  also includes a first section  158 A and a second section  158 B. First and second sections  158 A,  158 B are disposed at an angle α to each other and that angle α is from about 133 degrees up to about 137 degrees. A suitable angle between first and second sections  148 A,  158 B is approximately 135 degrees. First section  158 A comprises head  162  and an upper region of shaft  159 . Second section  158 B is comprised of the rest of the length of shaft  159  and may include the majority of the length of shaft  159 . Second section  158 B is substantially vertically oriented and is secured to a substantially vertical side wall of guide block  150 . First section  158 A extends upwardly and outwardly beyond an upper wall of guide block  150  and is oriented substantially parallel to a bottom end  32   b  of raceway  32 . First section  158 A is positioned alongside a lowermost region of feedslot  142  and in such a manner that tip  162   b  extends partially across the width of feedslot  142 , as is shown in  FIG. 12 . 
     Rivet stop  158  is positioned so that when rivets  30  are received in raceway  32  and spring arms  144 ,  146  are in an at-rest position ( FIG. 14 ), tip  162   b  of head  162  of rivet stop  158  will extend between a shaft  30   b  of a lowermost rivet  30 A ( FIG. 15 ) and a shaft  30   b  of a second from lowermost rivet  30 B. Tip  162   b  therefore separates rivet  30 B from rivet  30 A and substantially prevents rivet  30 B and therefore the other rivets in feedslot  142  from sliding vertically downwardly in feedslot  142 . This enables the riveter  10  to be used to install rivet  30 A without rivet  30 B accidentally sliding down raceway  32  and blocking the downward movement of tip  37 . During installation of rivet  30   a , tip  37  of plunger  36  moves through channel  156  and thereby causes spring arms  144 ,  146  to move from an at-rest position ( FIG. 14 ) to an operational position ( FIG. 16 ). As this occurs, tip  37  moves guide blocks  150  and  152  laterally apart from each other, thereby moving spring arms  144 ,  146  laterally apart from each other. Since rivet stop  158  is mounted on guide block  150  or spring arm  144 , rivet stop  158  is also caused to move laterally and outwardly away from guide block  150 . This lateral movement shifts tip  162  into a position where it no longer extends across feedslot  142  and therefore no longer can prevent shaft  30   b  of rivet  30 B from being pulled downwardly by gravity. Consequently, rivet  30 B can start to move vertically downwardly and into channel  156  as plunger  37  withdraws therefrom. Rivet  30 C thus is able to slide downwardly along feedslot  142  into the position previously occupied by rivet  30 B. As plunger tip  37  withdraws from channel  156 , rivet  30 B drops into the position previously occupied by rivet  30 A and guide blocks  150 ,  152  move laterally inwardly toward each other. The lateral inward movement is thus also imparted to spring arms  144 ,  146  and to rivet stop  158 . The tip  162  of rivet stop  158  moves between the shaft  30   b  of rivet  30 B and the shaft  30   b  of rivet  30 C. Installation of rivet  30 B will allow rivet  30 C to slide down feedslot  142  and into channel  156  as previously described. 
     It will thus be understood that the configuration of the components at the lower end of raceway  32 , and particularly the configuration and placement of rivet stop  158 , enables riveter  10  to be automatically reloaded with rivets. This reloading may occur without the operator having to stop working and physically depress a button or make some other movement to cause a new rivet to be positioned for installation. Additionally, the movement of plunger  36  not only automatically reloads a rivet, such as rivet  30 B, into the channel  156  between guide blocks  150 ,  152 , the plunger  36  also causes rotation of tumbler  28  via lever assembly  26 . The rotation of tumbler  28  in turn causes a new rivet to drop out of tumbler  28  and into the upper end  32   a  of raceway  32 . Thus, the operator will only have to address the loading or reloading of rivets  30  when all the rivets rotating within tumbler  28  have been moved into raceway  32  and are beginning to be used up. 
     Foot operated rivet riveter  10  is used in the following manner. The operator positions two workpieces  38 ,  40  to be secured together above spreader screw  28  on platform  34 . The operator depresses foot pedal  20 , moving pedal  20  downwardly in the direction of arrow “D” ( FIG. 1 ). This motion causes first linkage arm  22   a  and second linkage arm  20   b  to pivot relative to each other. The rotation of second linkage arm  20   b  drives plunger  36  downwardly in the direction of arrow “E” ( FIGS. 15 and 16 ). Bottom end  37   a  of tip  37  is caused to move into channel  156  between guide blocks  150 ,  152  causing them and the spring arms  144 ,  146  engaged therewith to move apart from each other in the direction of arrow “F” ( FIG. 16 ). As tip  37  continues to be moved downwardly by plunger  36 , a bottom end  37   a  thereof contacts the head  30   a  of rivet  30 A. Rivet  30 A is captured in channel  156  of guide blocks  150 ,  152 . As plunger  36  continues to move downwardly rivet  30 A is driven downwardly until its lowermost end contacts the upper workpiece  38 . Continued downward motion of rivet  30 A causes rivet  30 A to be punched through upper workpiece  38  and lower workpiece  40  and ultimately spreader  128   a  of spreader screw  28  enters the bore  30   c  ( FIG. 17 ) of rivet  30 A. The contact between shaft  30   b  of rivet  30 A and spreader  28  causes shaft  30   b  to radially split, spreading out for a distance along the underside of lower workpiece  40 , thereby joining upper and lower workpieces  38 ,  40  together. 
     Additionally, because spring arms  144 ,  146  have separated from each other because of the movement of plunger tip  37  therethrough, rivet stop  158  is moved out its arresting position shown in  FIG. 14  to its inactive position shown in  FIG. 16 . Thus, the next rivet in the raceway  32 , namely rivet  30 B, is no longer prevented from sliding down feedslot  142 . When the operator lifts his or her foot off foot pedal  20 , pedal  20  moves in the opposite direction to arrow “D”. This cause first and second linkage arms  22   a ,  22   b  to pivot in the opposite direction, thereby raising plunger  36  in the opposite direction to arrow “E”. As earlier described herein, the upward movement of plunger  36  results in the rotation of second section  28   b  of tumbler  28 , and a new rivet (not shown) drops from tumbler  28  into raceway  32 . When tip  37   a  moves past rivet  30 B, gravity takes rivet  30 B and it drops into channel  156 . By this point, spring arms  144 ,  146  are returning to their at-rest position ( FIG. 14 ). This causes upper edge  162   a  of rivet stop  158  to contact the head  30   a  of the next rivet  30 C ( FIG. 15 ), preventing the same from sliding into channel  156 . The operator will then position then next workpieces to be joined above spreader  28  and repeat the aforementioned process. 
     If it is decided to change the type of component that is to be used to fasten workpieces together, feed assembly  24  is removed by simply rotating the thumbscrew  134  in the appropriate direction to release pressure on first region  132 . Feed assembly  24  is then separated from riveter  10  as indicated by the arrow in  FIG. 21 . 
     A second feed assembly  224  ( FIG. 22 ), which is configured to provide second fastener components  230  which differ from rivets  30 , is then slid into slot  86  of mounting block  84  in order to engage assembly  224  with riveter  10 . (Second fastener components  230  may differ from rivets  30  in any of a variety of ways. By way of example only,  FIG. 22  shows second fasteners  230  that have larger shaft diameters than the rivets  30 .) Second feed assembly  224  includes a tumbler  228  (including fixed and rotating regions  228   a ,  228   b  and a securement member  228   c ), a feed chute  336  having an opening (not shown) defined in end  336   a ; and a raceway  232 . Raceway  232  has a first end  232   a  which is in communication with the interior of tumbler  228 . Spring arms  344 ,  346  are secured to raceway  232  and guide blocks  350 ,  352  extend downwardly from spring arms  344 ,  346 . Second fasteners  230  are placed into the opening in end  336   a  of feed chute  336 , drop into tumbler  228  and are fed, one-at-a-time, from fixed region  228   a  of tumbler  228  into rotating region  228   b  thereof. The fasteners  230  then move one-at-a-time into feedslot  342 . As with feed assembly  24 , second feed assembly  224  is provided with the components necessary to interlockingly dovetail with the cross-section shape of slot  86 . Consequently, second feed assembly  224  includes a connector comprising a mounting block  330  which has a first region  332  that is of a complementary configuration to the T-shaped slot  86  defined in block  84  of riveter  10 . A locking member  334  is also provided on connector to lock second feed assembly  224  to riveter  10 . 
     In order to use second feed assembly  224 , it may be necessary to change the tip  37  of plunger  36  so that it is suitably configured to install the second fasteners  230 . The operator will release rotate handle  39  in the second direction, pull tip  37  out of a recess (not shown) in the second end  36   b  of plunger  36  and will replace it with a new tip  237  that is configured to suitable engage and secure second fasteners  230 . Once tip  237  is inserted into the recess in plunger  36 , handle  39  is rotated in the first direction to lock tip  237  to plunger  237 . Similarly, it may be necessary to also replace spreader screw  128  with a differently configured spreader screw  328  so that second fasteners  230  may be installed in the workpieces to be joined. In order to replace spreader screw  128 , the bolt at the lower end of spreader screw  128  is disengaged and the spreader screw  128  is threadably disengaged from the through-hole  126  ( FIG. 8 ). The replacement spreader screw  328  is then threadably inserted into the through-hole and a bolt is engaged with the lower end of spreader screw  328 . 
     Second feed assembly  224  is engaged with riveter  10  in the exact same manner as is feed assembly  24 . Thus, the first region  332  of the connector on second feed assembly  224  is introduced into the opening to slot  86  in first face  84   a  of block  84 . Second feed assembly  224  will be moved along slot  86  until the connector engages stop  88 . At this point assembly, second feed assembly  224  is in the operational position. Locking member  334  of the connector is then moved from an unlocked position to a locked position by rotating the locking member  334  in the appropriate direction. The tip  237  of plunger  36  will extend through a channel (not numbered but similar to channel  156 ) in guide blocks  250 ,  252  of the second feed assembly  224  in the same manner as feed assembly  24  is engaged by tip  37  of plunger  36 . Plunger  36  is used in the same manner as plunger  36  to drive a lowermost one of the second fasteners  230  into two or more workpieces in order to join the workpieces to each other. 
     Second feed assembly  224  is also provided with a rivet stop  358  that is substantially identical in structure and function to rivet stop  58 . 
     Thus, riveter  10  may be set up to use one or the other of feed assemblies  24  or  224  depending on which of the fasteners  30  or second fasteners  230  are required for joining workpieces, such as  38  and  40 , together. In each instance, because of the enclosed linkage assembly  22  in post  16 , the riveter  10  may be positioned directly adjacent vertical structures such as walls without interfering with the functioning of the riveter  10 . Furthermore, the provision of rivet stops  158 ,  358  on the respective feed assemblies  24 ,  224  ensures automatic feeding of fasteners  30  or  230  during use of the riveter  10 . 
     Riveter  10  is used to secure two separate workpieces  38 ,  40  together by the method of:
         providing a first feed assembly  24  which holds and delivers a type of first fastener  30  for securement of workpieces  38 ,  40 ;   engaging first assembly  24  with riveter  10 ; and   operating riveter  10  to drive one or more of first fasteners  30  into workpieces  38 ,  40  to secure the workpieces together.
 
The method may also comprise:
   providing a second feed assembly  224  which holds and delivers a type of second fastener  230  for securement of workpieces  38 ,  40 ;   selecting one of the types of first or second fasteners  30  or  230  to secure two workpieces  38 ,  40  together;   selecting the associated one of first and second feed assemblies  24  or  224 ;   engaging the selected one of first and second feed assemblies  24  or  224  with riveter  10 ; and   operating riveter  10  to drive one or more of the selected first or second fasteners  30  or  230  into workpieces  38 ,  40  to secure the workpieces together.
 
The step of engaging the selected one of first and second feed assemblies  24  or  224  with riveter  10  includes:
   inserting a first region  132  or  332  of a connector on the selected one of first and second feed assemblies  24  or  224  into a slot  86  on a head  18  of riveter  10 ;   moving first region  132  of the connector along slot  86  in a first direction.
 
The step of engaging further includes:
   contacting an assembly stop  88  on head  18  of riveter  10  with a first end of first region  132  or  332  of the connector; and   engaging a locking member  134  or  334  to prevent further motion of first region  132  or  332  of the connector along slot  86 .
 
The step of engaging locking member  134  or  334  includes:
   rotating locking member  134  or  334  in a first direction;   applying pressure on first region  132  or  332  of the connector; and   urging first region  132  or  332  of the connector into frictional engagement with a wall of riveter  10  which defines slot  86  within which first region  132  or  332  of the connector is received.
 
The method may further comprise:
   depressing foot pedal  20  in a first direction “D” ( FIG. 1 );   moving plunger  36  downwardly to drive a lowermost of the selected one of first and second fasteners  30  or  230  disposed in the selected one of first and second feed assemblies  24  or  224  through workpieces  38 ,  40 ;   joining workpieces  38 ,  40  together;   releasing foot pedal  20  so that foot pedal  20  moves in a second direction (opposite to direction “D”);   moving plunger  36  upwardly away from workpieces  38 ,  40 ; and   removing joined workpieces  38 ,  40  from riveter  10 .
 
The method may further comprise:
   sliding a plurality of the selected one of first and second fasteners  30  or  230  along a feedslot  142 ,  342  in the selected one of first and second feed assemblies  24  or  224 ;   positioning the lowermost of the plurality of the selected ones of the first and second fasteners, such as rivet  30 A, in a position to be engaged by plunger  36  when plunger  36  moves downwardly (in the direction “E”— FIG. 15 ).
 
The method may further comprise:
   positioning workpieces  38 ,  40  to be joined above a spreader  128  or  328  on riveter  10 ;   depressing foot pedal  20  to move plunger  36  downwardly toward spreader  128  or  328 ;   contacting the lowermost of the plurality of the selected ones of the first and second fasteners, such as rivet  30 A, with a tip  37  or  237  of the plunger;   driving the lowermost of the plurality of the selected ones of the first and second fasteners, such as rivet  30 A, downwardly and into workpieces  38 ,  40  to be jointed;   spreading a shaft  30   b  of the lowermost of the plurality of the selected ones of first and second fasteners, such as  30 A, using spreader  128  or  328 .
 
The method may further comprise:
   selecting new workpieces to be joined together above spreader  128  or  328 .
 
The method may further comprise:
       

     selecting the other of first and second fasteners  30  or  230  to join the new workpieces together; 
     changing a tip  37  or  237  of plunger  36  to be complementary to the selected other of first and second fasteners  30  or  230 ; and 
     changing spreader  128  or  328  to be complementary to the selected other of first and second fasteners  30  or  230 . 
     The method may further comprise: 
     
         
         
           
             rotating locking member  134  or  334  in a second direction; 
             releasing pressure on first region  132  or  332  of the connector; 
             moving first region  132  or  332  of the connector along slot  86  in a second direction until first region  132  or  332  of the connector moves out of an opening to the slot  86 ; and 
             engaging the other of first and second feed assemblies  24  or  224  with riveter  10 .
 
The method may further comprise:
 
             inserting a first region  132  or  332  of a connector on the selected other of first and second feed assemblies  24  or  224  into the opening to slot  86 ; 
             moving first region  132  or  332  of the connector of the selected other of first and second feed assemblies  24  or  224  along slot  86  in the first direction; 
             contacting assembly stop  88  with first region  132  or  332  of the connector of the selected other of the first and second feed assemblies  24  or  224  to halt further movement thereof in the first direction; and 
             engaging a locking member  134  or  334  on the selected other of first and second feed assemblies  24  or  224  to lock the selected other of the first and second feed assemblies to riveter  10 .
 
The method may further comprise:
 
           
         
       
    
     depressing foot pedal  20  of riveter  10  in a first direction “D” ( FIG. 1 ); 
     moving plunger  36  downwardly to drive one of the selected other of first and second fasteners  30  or  230  disposed in the selected other one of first and second feed assemblies  24  or  224  through new workpieces  38 ,  40  to be joined; 
     joining new workpieces  38 ,  40  together; 
     releasing foot pedal  20  so that the foot pedal moves in a second direction; 
     moving plunger  36  upwardly away from the joined new workpieces  38 ,  40 ; and 
     removing the joined new workpieces  38 ,  40  from riveter  10 . 
     In accordance with another aspect, the invention may provide a method of using a riveter  10  to secure two separate workpieces  38 ,  40  together; said method comprising: 
     providing a feed assembly  24  on riveter  10  which holds and delivers plurality of fasteners  30  for securement of workpieces  38 ,  40 ; 
     providing a rivet stop  158  on feed assembly  24  to control the feed of fasteners  30  through a raceway  32  of feed assembly  24 ; and 
     operating riveter  10  to drive a lowermost one of fasteners  30 A in raceway  32  into workpieces  38 ,  40  to secure the workpieces together. 
     The method may further comprise: 
     inserting a rivet stop  158  between the lowermost of the plurality of fasteners  30 A and the second from lowermost of the plurality of fasteners  30 B. 
     The method may further comprise: 
     inserting a tip  162   b  of rivet stop  158  between the lowermost of the plurality of fasteners  30 A and the second from lowermost of the plurality of fasteners  30 B; 
     The method may further comprise: 
     flexing spring arms  144 ,  146  of feed assembly  24  away from each other (in the direction of arrows “F”— FIG. 16 ); 
     breaking contact between rivet stop  158  and the second from lowermost plurality of fasteners  30 B. 
     The method may further comprise: 
     
         
         
           
             inserting a tip  37  of plunger  36  into a channel  156  between guide blocks  150 ,  152  on spring arms  144 ,  146 ; 
             contacting head  30   a  of the lowermost fastener  30 A with tip  37  of plunger  36 ; 
             moving plunger  36  downwardly; 
             driving a shaft  30   b  of lowermost fastener  30 A into two workpieces  38 ,  40 ; and 
             joining two workpieces  38 ,  40  together.
 
The method may further comprise:
 
           
         
       
    
     moving plunger  36  upwardly; 
     moving the second from lowermost fasteners  30 B into channel  156  between guide blocks  150 ,  152 ; 
     moving spring arms  144 ,  146  toward each other; 
     bringing a curved outermost edge  162   a  of rivet stop  158  into contact with a shaft  30   b  of a third from lowermost fastener  30 C; and halting movement of the third from lowermost fasteners  30 C down raceway  32 . 
     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
     Moreover, the description and illustration of an embodiment of the invention is by way of example only and the invention is not limited to the exact details shown or described.