Abstract:
A fish tape has a galvanized wire core wrapped by a twin-ribbon stainless steel sheath. The fish tape is flexible enough to be convenient to handle and store in a coil while still being stiff enough to fish through a conduit. A driver may be used to push or pull the fish tape. The driver has a housing with drive and pressure rollers therein for engaging the fish tape. The drive and pressure rollers each have curved and flat grooves for engaging a fish tape. The drive roller is driven by first and second right angle gears from a drive shaft which is connectable to the chuck of a hand drill. The drive shaft is arranged to be parallel to the fish tape. The driver housing has a slot for receiving the fish tape by moving the tape perpendicular to the length of the tape. A retainer is movable to open and close the housing slot.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application is a divisional of application Serial No. 09//827,021, filed Apr. 5, 2001.  
         BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to fish tapes, and more particularly, to novel systems and methods for threading electrical wires through installed conduit systems. Fish tapes are elongated members which are pushed through a conduit. Electrical wires are attached to the fish tape and then the fish tape is pulled back through the conduit, carrying the wire or wires with it. Typically a fish tape is formed of a flat, spring steel material. Fish tape lengths range from 25 feet to 200 feet. The tape is usually stored in coiled form in a case or reel. Most commonly the fish tape is reeled out by hand. Orientation is extremely important in reeling a fish tape up onto a spool or reel. Enclosed reels provide no rapid method for deployment or retrieval. Moreover, ergonomic factors have received only minimal attention. Thus, a user typically requires approximately 15 minutes to deploy and use 100 feet of fish tape. After deployment, a user attaches to the end of the fish tape an electrical wire or wires that are to be pulled back through the conduit. Pulling the fish tape back out typically takes additional time and physical effort of pulling, snagging, forcing and wrestling. In the best systems available, the fish tape may be retrieved into a case as it is being drawn back through the conduit, pulling its load. However, a user must often abandon such retrieval into the encased reel in order to pull directly on the tape against the load of friction, snags and other obstructions. One of the reasons is the traditional spring steel fish tape is a highly unruly material in that it always wants to spring out to a straight, elongated condition; it has to be forced into a coil shape on a reel.  
           [0003]    Meanwhile, pushing tapes by hand is slow and unsteady. A static coefficient of friction is greater than a dynamic coefficient of friction. Accordingly, keeping a tape moving can considerably ease the number of snags due to friction. There are several devices in the prior art with powered drivers for deploying and/or retrieving fish tape. Examples are shown in U.S. Pat. Nos. 2,729,424; 3,145,972; 3,220,700; 3,258,246; and 5,692,662. Of these U.S. Pat. No. 3,220,700 discloses use of a hand drill to power the device. However, in general the prior art drivers are bulky and relatively clumsy to use and require a separate motor included in the driver.  
         SUMMARY OF THE INVENTION  
         [0004]    In view of the foregoing, it is a primary object of the present invention to provide a simple, high speed driver for threading wires through conduit. The driver is powered by an ordinary hand drill. The driver has a housing with a main shaft and an idler shaft mounted parallel to one another in the housing. A drive roller is mounted for rotation on the main shaft and a pressure roller is mounted for rotation on the idler shaft. The rollers are aligned with one another to define a throat along the tangents to the rollers that are parallel and closest to one another. The throat has an axis that is perpendicular to the main and idler shafts. The throat is adapted to receive a fish tape therein along the throat axis. The rollers are engageable with a fish tape placed in the throat to drive the fish tape. A drive mechanism includes a first right angle gear in driving engagement with the drive roller. A drive shaft is mounted for rotation in the housing parallel to the throat axis and extending to a proximal end exterior of the housing. The proximal end is engageable with a hand drill. A second right angle gear meshes with the first right angle gear and is mounted for rotation with the drive shaft. This arrangement allows the user to hold the drill and driver with one hand while leaving the other hand free for holding a ladder or the fish tape.  
           [0005]    The driver housing has a slot for providing access to the throat. A retainer arm is movable to open or close the slot. The retainer arm can prevent the fish tape from canting in the throat. The pressure roller and drive roller each have two grooves, one designed for engaging a flat fish tape and one for engaging a fish tape having a generally circular cross section. A quick release mechanism is provided to allow fast and easy locking and unlocking of the pressure roller.  
           [0006]    The present invention also concerns a new fish tape material. This tape is generally round in cross section. It has an inner wire rope surrounded by an armor wrap around the wire rope. This construction provides lateral stiffness balanced with a selected amount of lateral flexibility. The fish tape supports axial compression and tension when forced through a conduit. The armor wrap comprises two separate ribbons of stainless steel with no gap between adjacent convolutions of the wrap. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a perspective view of the fish tape driver of the present invention.  
         [0008]    [0008]FIG. 2 is a top plan view of the fish tape driver.  
         [0009]    [0009]FIG. 3 is a front elevation view of the fish tape driver.  
         [0010]    [0010]FIG. 4 is a side elevation view of the fish tape driver.  
         [0011]    [0011]FIG. 5 is a front elevation view of the fish tape driver, with the front of the housing removed to reveal the interior components.  
         [0012]    [0012]FIG. 6 is a perspective view of the case with the cover removed and portions broken away to reveal interior components.  
         [0013]    [0013]FIG. 7 is a perspective view of the stud plate.  
         [0014]    [0014]FIG. 8 is an elevation view of the post.  
         [0015]    [0015]FIG. 9 is a perspective view of the clevis.  
         [0016]    [0016]FIG. 10 is a view of the fish tape of the present invention with a portion of the wrap cut away to reveal the core.  
         [0017]    [0017]FIG. 11 is a cross section of the armor wrap wire used in the fish tape of FIG. 10.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    FIGS.  1 - 4  illustrate the fish tape driver  10  of the present invention. The driver has a two-piece housing including a case  12  and a front cover  14 . The case and cover are joined at a separation line  16 . The case  12  has an upstanding, U-shaped enclosure  18  while the cover  14  has a similar enclosure  20 . Together the enclosures define a pressure roller chamber with an opening  22  (FIG. 2) in the top. There is a circular boss  24  extending from the face of the cover  12 . Just above the boss  24  there is a band  26  where the cover  14  has increased thickness for reinforcement. A similar band  28  is formed on the case  12 . Embossments  30  are located on the exterior of the enclosures  18  and  20 . These are intended to provide wear pads. The housing is preferably molded of suitable plastic material, such as glass-filled ABS or glass-filled nylon. Alternately, the housing could be die cast metal.  
         [0019]    The left side of the housing, as seen in FIG. 3, has a slot  32  formed therein. The slot provides access to the interior of the driver housing. The slot is bounded by C-shaped extensions  34  extending from both the case  12  and cover  14 . Adjacent the extensions  34  are pivot heads  36 . The pivot heads mount a retainer  38 . The retainer has two arms  40  joining a bar  42 . The arms have eyelets that fit over the pivot heads to mount the retainer on the housing. The arms  40  bend around the extensions  34  so the bar  42  is normally aligned with the slot  32 . The retainer pivots upwardly from the position shown in FIG. 1 to open the slot  32  for insertion of a fish tape. Gravity will normally cause the retainer to fall to the closed position shown, with the C-shaped extensions  34  limiting movement of the arms  40 . Together the extensions  34  and the retainer  38  help hold a fish tape in the driver by preventing it from canting about a vertical axis.  
         [0020]    The interior of the driver  10  is shown in FIGS. 5 and 6. These views show the case  12  with the cover removed. The case includes a plurality of reinforcing webs  44 . At the intersection of four of these webs are sockets  46  that receive screws (not shown). The screws join mating sockets in the cover to hold the two pieces of the housing together. The case also has a wall  48  to which a metal mounting plate  50  is attached by screws  52 . The bottom of the plate  50  is beveled at  54  to clear the curving sides of cover and case. The lower portion of the mounting plate has an opening  55  (FIG. 6) which allows passage of a drive roller as will be explained below. Screws  56  attach front and rear lower bars to the mounting plate  50 . Only the front lower bar is visible at  58 . The rear lower bar is behind the drive roller and not visible in FIGS. 5 and 6. The front and rear lower bars are connected by a lower strap  60 , which is connected to the bars by screws  62 . The lower bars and strap and mounting plate form a box frame around the drive roller. A similar box frame is formed at the top of the mounting plate  50  by front and rear upper bars, the front bar showing at  64  in FIG. 5. Screws  66  attach the bars to the mounting plate. Screws  68  attach an upper strap  70  to the front and rear upper bars. Between the upper bars there is a cross-shaped stud plate  72  screwed to the mounting plate  50  and strap  70  to complete the upper box frame.  
         [0021]    Details of the stud plate  72  are shown in FIG. 7. It has a body portion  74  with a central bore  76  through the body portion. A counterbore  78  extends into the body from one face thereof. A threaded set screw opening  82  extends through the body to the central bore  76 . A pair of arms  84  extend from the body and have threaded bores  80  which receive the screws from the mounting plate  50  and strap  70 . The stud plate  72  mounts a stud  86 . The stud has a threaded shank that extends upwardly through the central bore  76  and a head  88  that fits in the counterbore  78 . A set screw  90  threaded in opening  82  engages the stud shank and fixes the stud  86  to the stud plate  72 .  
         [0022]    The stud  86  supports a post  92 , details of which are shown in FIG. 8. The post is generally cylindrical with a threaded axial bore  94  and a transverse bore  96  near its upper end. The post  92  is adjustably mounted on the stud by means of the engaging threads in the bore  94  and on the shank of the stud  86 . The transverse bore  96  of the post carries a pivot shaft  98  on which a locking lever  100  pivots. The locking lever  100  includes a cam  102 . A washer may be placed underneath the cam to serve as a wear pad. The locking lever  100  and cam  102  provide a quick locking capability for holding the pressure roller in a desired position, as will be explained below  
         [0023]    The upper box frame mounts a clevis  106  for vertical movement therein. Details of the clevis  86  are shown in FIG. 9. The clevis has a block  108  connected to two depending forks  110 . There is an opening  112  in the block  108 . Each fork  110  has an elongated slot  114  through which the arms  84  of the stud plate extend. This allows the clevis to move up and down. The forks  110  also have apertures  116  which receive an idler shaft, shown at  118  in FIG. 6, on which a pressure roller  120  is mounted. The pressure roller has bearings which allow it to rotate on the shaft  118  carried by the clevis  106 . The pressure roller has two grooves formed in its surface. There is a flat or rectangular groove  122  and a curved or concave groove  124 . Returning to FIGS. 5 and 6, it can be seen that the clevis  106  is urged upwardly by a compression spring  125  which rests on the top of the stud plate body  74 , surrounding the stud  86  and engaging the underside of the clevis block  108 . The upward movement of the clevis is limited by the cam  102 .  
         [0024]    A main shaft  126  is fixedly mounted in the case  12  and extends almost the fill width of the case. At the right end, as seen in FIG. 5, the main shaft is fastened to a web  44 A of the case. At the left end the main shaft is fastened to the lower strap  60 . As can be seen the main shaft  126  extends through the opening  55  in the mounting plate  50  and through the lower box frame. Mounted for rotation on the main shaft is a drive roller  128 . Needle bearings may be used to mount the drive roller. The left end of the drive roller has two grooves similar to those on the pressure roller  120 . There is a rectangular groove  130  and a curved groove  132 . These are aligned with the similarly shaped grooves  122  and  124  of the pressure roller. Together the grooves define a pair of throats  134  and  136 . Each throat is tangent to the rollers  120  and  128  at the point where the rollers are closest to one another. Thus, in the illustrated embodiment, the throat extends perpendicular to the plane of the drawing of FIG. 5, i.e., in and out of the paper. The throats each defme an axis that is perpendicular to the main shaft  126  and the idler shaft  118 . Each throat is adapted to receive a fish tape of particular shape therein along the throat axis.  
         [0025]    The drive roller  128  further includes at its right end, as seen in FIG. 5, a first right angle gear  138 . In the illustrated embodiment this is a bevel gear formed integrally with the drive roller. It will be understood that a separate gear in driving engagement with the drive roller could be used or other forms such as a worm and gear could be used.  
         [0026]    A drive shaft  140  is mounted for rotation in the boss  24  of the cover  14 . The drive shaft is shown in FIG. 5 although the cover is removed in this view. The drive shaft  140  is parallel to the throat axis. The drive shaft extends to a proximal end  142  outside of the cover of the housing, as seen in FIGS.  1 - 4 . The proximal end  142  has a hexagonal cross section which is engageable with the chuck of a hand drill or other power source. A hand drill is preferred because almost all electricians have such a tool. The proximal end of the shaft may include a flange  144  and split washer  146  for retaining the drive shaft  140  in the boss  24 . A second right angle gear  148  is fixedly mounted on the drive shaft  140  for rotation with the drive shaft. The second right angle gear is a bevel gear having teeth  150  meshing with those of the first right angle gear. Thus, the second right angle gear transfers rotation of the hand drill to the drive roller  128 .  
         [0027]    The use, operation and function of the fish tape driver are as follows. Some electricians using a steel band type fish tape prefer to uncoil the entire fish tape and lay the entire length on the floor prior to fishing it through a conduit. Others will leave it in its case and feed it out as needed. Other types of fish tape may also be left in the case and fed out of the case as it is fished through the conduit. In either case, a fish tape is readied for use with the driver  10  and the proximal end  142  of drive shaft  140  is locked in the hand drill chuck. Locking lever  100  is pivoted to a generally vertical position to release the cam  102 . If need be the lever  100  is rotated to rotate the post  92 , moving the post upwardly on the stud  86 . This allows the clevis to move upwardly under the force of spring  125  and thereby open the throats  134 ,  136 . The retainer  38  is lifted up to expose the slot  32  in the housing. A portion of the fish tape is then moved perpendicular to its length into the slot and into one of the throats  134 ,  136 . The throat used depends on the cross sectional shape of the fish tape. For round tapes the throat  136  with the curved grooves  124  and  132  is used. For rectangular fish tape the throat  134  with the flat grooves  122  and  130  is used. Thus, the driver accommodates any type of fish tape without having to change the rollers. It will also be noted that the slot allows the fish tape to be inserted into the driver without having to thread the leader through the driver. That is, the fish tape will have a connector on its end for attachment of the wires. The connector has a much larger cross section that the rest of the fish tape. That connector does not have to fit through the driver because the tape will be inserted into the driver at a point on the tape behind the connector.  
         [0028]    Once the fish tape is in the throat the retainer  38  is allowed to drop down over the slot opening to help hold the tape in place. Then the clevis  106 , and thus the pressure roller  120 , is pushed down onto the fish tape. The post  92  may also be rotated down onto the stud  86  to adjust the length of the stud/post combination. Once the proper length is obtained and there is adequate pressure on the tape, the locking lever  100  is pivoted to cause the cam  102  to engage the top surface of the clevis block  108  (through the washer if present) and thus lock the clevis  106  in position. The driver and hand drill combination is then carried to the conduit and the fish tape leader is then threaded into the conduit. The back side of the housing is pressed up against the conduit and the drill is activated to drive the drive shaft  140 , second right angle gear  148 , first right angle gear  138  and drive roller  128 . The pressure on the fish tape from the pressure roller  120  creates sufficient friction to result in the fish tape being driven into the conduit. When the leader comes out of the other end of the conduit the hand drill is shut off and the wires are attached to the leader. The drill direction is reversed and the fish tape is pulled back through the conduit by activating the drill. When the wires emerge the drill is shut off. If no further use is anticipated the tape can be removed by releasing the locking lever cam  102 . The spring  125  will lift the pressure roller  120  somewhat. If further clearance is needed to open the throat and allow removal of the tape, unscrewing the post  92  will allow the pressure roller to rise some more. With the retainer  38  lifted the fish tape can then be removed out the slot  32  of the driver.  
         [0029]    It will be noted that the right angle drive members allow a compact arrangement with the hand drill axis parallel to the fish tape. This permits manipulation of the drill and driver combination with a single hand. The other hand remains free for holding a ladder or the like. Also, the retainer arm allows the access slot to open and close. The arms of the retainer close around the fish tape at both the front and back sides of the housing. This plus the C-shaped extensions  34  prevents the fish tape from canting or wobbling in the throat of the rollers.  
         [0030]    The improved fish tape  152  of the present invention is shown in FIG. 10. The tape has a wire rope core or center  154 . In one embodiment this may be a .072 inch diameter 1×13 galvanized cable. The core is covered by a wrap or sheath made of two ribbons  156 ,  158  of armor wrap wire. This wire has a generally rectangular cross section as shown in FIG. 11. In the described embodiment the wire wrap has a width W of about .100 inches and a height H of about .015 inches. The corners have a radius as shown. The armor wrap wire may be a stainless steel, and the wire rope core may be formed of carbon steel or stainless steel. Use of stainless steel in both the wire rope and the flat wrap is preferred for its corrosion resistance. The wrap is applied with no gap between the convolutions. This gapless construction aids in preventing snagging as the fish tape is fished through a conduit.  
         [0031]    In an alternate embodiment the fish tape may be composed of .125 diameter armor core cable. This embodiment may rely on .093 diameter  1×l9  galvanized cable. Around the cable is wrapped flat, stainless steel wire. Each of the described embodiments forms a round, stiff, yet somewhat flexible line. This line has the ability to be pushed and pulled through conduit very effectively, bending in any direction needed, as many times as needed, yet providing compressive and tensile strength and stiffness along its axial direction. The circular or cylindrical wrap orientation allows obstructions to slide by. The circular wrap of the ribbon or wrap component around the fish tape also gives the ability to easily push through even more than the four ninety-degree turns permitted in 100 feet of conduit.  
         [0032]    The fish tape of FIGS. 10 and 11 is tremendously strong and can withstand tensile forces in excess of 1800 pounds. It is round and not flat. On the outward end of the tape is an eyelet that is used to attach cables, wires etc. to be pulled back through conduit. At 1800 pounds of tension, a stainless steel eyelet on the end failed, not the tape itself. The surface of the armoring sheath is also very hard. When pliers were used to grip the line, no scoring or damage was observed to occur on the stainless steel wrap. Neither the sheathing, nor the wire rope making up the fish tape were observed to rust, even when used in wet, muddy conditions, or when stored in a closed case. Flexibility is not changed due to temperature differences and other weather conditions that might greatly affect the performance of a conventional fish tape.  
         [0033]    Electricians find that the flexible tape of the present invention is sufficiently stiff to move through a conduit under compressive forces. However, the lateral rigidity is substantially less. For example, the line will fall to the ground immediately upon exit from a conduit, thus falling away from the panel to curl up on the floor. By contrast, conventional steel fish tapes often spring uncontrollably upward, due to their great lateral stiffness, striking the panel and potentially causing electrical shorts or other obstructions. The lack of lateral rigidity of the present invention permits it to be used with a case or reel of the type shown in U.S. Pat. No. 5,423,516, the disclosure of which is incorporated herein by reference. The fish tape does not have the tendency to spring out so it can be coiled easily on the external circumference of a drum, without the need for the control springs used in the first embodiment of U.S. Pat. No. 5,423,516.  
         [0034]    From the above discussion, it will be appreciated that the present invention provides a semi-stiff fish tape for deploying into conduits and for drawing wires back through the conduits. The fish tape is easily deployed and retrieved by a user cranking a portion of the case or with the driver described above.  
         [0035]    While a preferred form of the invention has been shown and described, it will be realized that alterations and modifications may be made thereto without departing from the scope of the following claims. For example, the case  12  may have a conically shaped nose portion at the slot  32  to help align the housing with the opening of a conduit.