US3031727A - Connectors - Google Patents

Description

G. G. NESBITT May l, 1962 CONNECTORS 2 Sheets-Sheet 1 Filed Jan. 20, 1958 INVENTOR, George G. Nesb/'H AT TOR N EYS G. G. NESBITT May 1, 1962 CONNECTORS 2 Sheets-Sheet 2 Filed Jan. 20, 1958 LLM F ign-8 INVENTOR.

ATTORNEYS aired titates atet duce 3,631,727 Patented May 1, 1%62 3,03L727 CNNEQTRS George G. Nesbitt, Denver, Colo., assigner to Denver Wood Products Company, Denver, Colo., a corporation oli lolorado Filed lian. 20, 1953, Ser. No. 709,818 3l Claim. (6l. Ztl- 92) This invention relates to connectors and more particu larly to connector plates for abutting structural members whereby the structural members may be rigidly and securely fastened together and retained in abutting relation.

ln home construction it has been determined that detinite savings in material and labor requirements may be made through the use of pre-assembled units, such as Wooden roof trusses, wall panels and the like. Thus using pre-assembled Wooden roof trusses provides one eiiective means of reducing the cost of small dwelling constructions. Where short spans from Wall to Wall are designed in a building, for example 25 to 35 feet, the use of the pre-assembled trusses can result in a cost saving in labor and, also, a reduction in the total amount of lumber utilized as compared with conventional rafter and joist construction. In addition to these savings in material and labor, such pre-assembled roof trusses otter advantages of flexibility in planning and in the speed and efficiency of erection procedures at the building site.

While many types of pre-assembled wooden roof trusses have been proposed, the most commonly used pre-assem` bled device is a single plane truss, that is one in which the major load supporting members are in a single plane. The members of the truss are joined together by some sort of connectors such as metal plates, plywood gussets, and the like. Such trusses are usually manufactured at a plant and then transported to the building site.

Included among the objects and advantages of the present invention is to provide a connector plate which may be utilized as a connector for abutting structural members. The plate is made of relatively thin metal but its construction makes it strong and it produces a strong joint between structural members. The connector plate of the invention provides a quick and easily used centering means for permitting the use of a nailing gun, thereby `ermitting the construction of trusses or panels in the ield without the use of expensive jigs, presses and the like. The connector plate provides means for applying uniform pressure on each of the members of the joint regardless of the dimension of the structural members, and, also,.for applying a uniform pressure on each nail. A novel heel plate for a wooden truss is provided which joins the truss members together at the heel, and, also, provides a positioning means for the truss on wall sections.

These and other objects and advantages of the invention may be readily ascertained by referring to the following description and appended illustrations in Which:

FEC. l is a side elevational view of a section of the connector plate showing the construction of nail holes and embossed guide in enlarged detail;

FIG. 2 illustrates one method of producing heel plates, according to the invention, from a strip of sheet metal;

FlG. 3 is a detailed View of an apex or ridge joint of a single plane truss member utilizing a plate according to the invention;

FIG. 4 is a side elevational view of a clear span truss member utilizing the connector of the invention;

FIG. 5 is a perspective View of a heel plate form of th connector of the invention; j

FlG. 6 is a perspective view of a heel plate showing a modified truss construction and illustrating the novel truss positioning means;

FIG. 7 is a perspective View of a nailing gun and its positioning means for use with a connector plate according to the invention; and

FIG. 8 is a plan view of a section of joined nails for use in the gun of FIG. 7.

In general the connector plate of the invention comprises a piece of sheet metal having a plurality of nail holes punched therethrough from the top side, leaving the underside of the sheet with a plurality of jagged projections through which a nail may be inserted. Each nail hole has an embossed, concentric ring around the hole spaced a sufficient distance therefrom to leave an annular portion of the original sheet in its original plane inside the ring. The plates may be made in any desired shape, but the most common forms are rectangular and trapezoidal. A heel connector plate for the heel joint of a single plane truss according to the invention may be readily prepared from a strip of sheet metal. The plates are arranged with fold lines and have a plurality of nail holes with embossed guide members. The fold lines permit bending the plate so as to encompass three sides of a heel joint of a single plane truss, and includes a tab which is arranged to lie flush with one side of a Wall partition. When the tab is pulled out perpendicular to the plate, there is provided an anchor and an automatic positioning member for the truss on supporting Wall sections.

The gusset or connector plate of the invention is illustrated in detail in FIGS. 1 and 2, and in FIG. 1 there is shown a section of a portion of the plate 10. The plate is preferably 20 gauge, galvanized or galvanealled steel, having a thickness of about 0.0359 inch. Spaced throughout the plate is a series of punched out nail holes l1 having a small diameter hole 12 which is of a size to grip the nails used for fastening the plate to a structural member. Each nail hole has a plurality of jagged, pointed projections 13 which result from the metal being pushed and ruptured during the formation of the hole. The projections 13 are irregular and sharp and extend a short distance beyond the surface of the plate. The holes l2 are such a size as to grippingly engage a sixpenny nail which is the nail most commonly used with the connector plate. Concentrically surrounding each nail hole and extending in a direction opposite from the nail holes is an embossed ring 14 having an outside diameter A of approximately 1%@ of an inch, a maximum height of the tip of the embossed ring is approximately one-quarter of an inch above the bottom of the plate. As illustrated in FIG. 3, the nail holes with their embossed rings are staggered along horizontal and lateral lines so that the holes are not positioned closely adjacent each other, and are thus arranged so that the nails will engage the abutting members of a joint and so as not to fall closely together in the same Woodgrain. Even with a substantial change in angle of interception of the various members, for example angles D and C between brace member 20 and the upper cord member 21 of the ridge connector, the nails engage the structural members andare not positioned closely together.

In connecting a plate to Wooden members, a nailing gun, which may be of compressed air, electric or other type of nailing gun, may be used to drive a nail through the hole 12 into the wooden member. One very effective gun for use in nailing the plate to structural members is a Cyclomatic Pneumatic nailer 30 made by the California Wire Corporation, which utilizes one and one-half inch long siXpenny T nails 36. T nails 36 are so called because instead of having a circular head, they have a lateral head 37 not substantially greater in width than the Width of the nail, which permits the nails to be glued or otherwise secured together much in the fashion of the staples of an ofce stapler. The pneumatic nailer 30 contains a magazine 35 in which a plurality of the joinedtogether T nails 36 may be inserted and the nailer used in a manner of a stapler.

The stapling gun or nailer 3i) is shown in FIG. 7 where the pneumatic gun is supplied with air from an air hose 3l connected through the handle 32. The compressed air operates a Vpneumatic piston for forcing the nails through an outlet. The nose 34 of the nailer is curved at 33 so as to fit around the circular embossed ring around each nail hole on the plate. The inside curve 33 of the nose 34 corresponds to the curvature of the embossed ring so that the nail discharge hole of the gun is centered above the nail hole 12 of the plate. A magazine 3S holds a supply of nails attached together for use in the machine.

In one form, a plate 40, FIG. 3, is a rectangular plate having a plurality of the nail holes and embossed circles therearound arranged to hold the ridge joint or connection of a truss, FIG. 4, consisting of upper chord members 21 and 22 and lower chord members 26 joined together. The holes in the plates are arranged so as to provide a nail'hole directly above the wooden members of trusses, even when there are various pitched roofs. The braces and 23 may be at various angles, shown by angles D and C. In this case the plate 4t) is made large enough to provide a secure fastening for the joint of all four wooden members.

In making a prefabricated truss, a plate 40 is placed on one side of the ridge joint of the wooden members, which have been cut to size and positioned, preferably in a simple jig. The plate 40 is nailed in place by means of the nailing machine. In turn each joint has a plate nailed in position, .as plates i2 over the joint of the supports and the chords. Heel plates 4i-4 are nailed in position. The truss is then turned over and another plate 4t) is placed on the opposite side of the truss in rnirror image relationship to the plate 461 in place on the ridge to provide a connector on each side of a single plane truss. Another plate 42 is placed on the opposite side of the truss aligned with the corresponding one over the particular joint. In the truss shown in full in FIG. 4, the upper chord members 22 and 2l form the roof supporting members above the rafter members 26. The rafter members 26 are joined by a rectangular plate 4i and additional braces 24 and 25 are connected in place by means of connector plates 42 which are -arranged to hold the brace members on the respective support members. The heel plates 44 are of a special shape, illustra-ted in detail below, and they are arranged to hold the heel joint of the truss.

The heel plate 44 is a trapezoidal piece of sheet metal having a plurality of nail holes centered in embossed rings and positioned throughout its extent. The nail holes are arranged in position to align the nail into the wooden members even for various pitched roofs. In FIGS. 5 and 6 two different pitched roofs are illustrated,

where FIG. 5 shows a lower pitched roof than in FIG. 6.

In `FIG. 5 the upper edge 47 of the plate is shown out of alignment with the top edge of the Wooden member 22, and in FIG. 6 it is shown in alignment showing the different roof pitches. are so positioned as to provide in the upper chord suftlcient wood into which the nail may be driven for adequate holding. In a similar manner the holes in the lower part of the heel plate are arranged to hit solid Wood on the lower chord to provide secure holding for nails which are driven through the holes. Both sides of the heel joint are covered by the heel plate.

As manufactured, the plates 44 are cut from a single strip of material, illustrated in FIG. 2, in adjoining trapezoidal arrangement, the adjacent members being reversed to reduce the waste of material. The cut lines 48 are arranged at the correct angle to provide a trapezoidal shape. A pair of fold lines 49 are provided generally centerwise of each plate, spaced apart the thickness of In each case, however, the nail holesl the bottom chord, providing means for turning up the two outer edges, shown in FIGS. 4 and 6, for extending around the heel joint of the truss. A three-sided cut 50 in the narrow center area of the plate between the fold lines, leaves a tab 5l cut out of the plate. The tab may be shortened to less than the length of the three-sided cut or it may be left the same length, depending on the use to which it is to be put. The tab 51 is supplied with punched out nail holes 52 arranged in spaced positions therein. The tab 51 is maintained in the plane of the center area of the plate until the prefabricated truss is placed in position spanning wall members 53, shown in FIG. 6. When the truss is in position, the tab 5i is pulled down in alignment with the inner surface of the wall and then is nailed to the wall with the nails being driven perpendicularly into the top plate of the wall. Any vertical movement of the truss subjects the anchoring nails primarily to shear stresses. This not only anchors thel truss to the walls, but positions the truss on the walls maintaining exact spacing for the span. Since the chord members are precut and the trusses preassembled, their dimensional tolerances may be maintained very low, providing exact spacing of the wall members.

The truss made with the plates may be assembled in the field, since the automatic nailer is easily transported and a source of compressed air may be, likewise, readily available at the building site. By utilizing such a nailing gun with the plate of the invention, the same amount of pressure is exerted on each nail and on the plate surrounding the nail regardless of whether or not the lumber is exactly dirnensioned. Therefore, the plate may be used when abutting members are not exactly the same thickness and the holding power ofeach nail will be the same. The projections i3 bite into the wood when a nail is driven through the plate, increasing the area of Contact and thereby increasing the holding power of the nail. The nails are tightly held in the plate resulting in a very strong connection.

In an actual test trusses were made from such plates similar to the one shown in FIG. 4. Several 28 feet span trusses with a 4/ 12 roof pitch were fabricated using the connector plates at the points shown. In order to test the trusses under actual conditions which might be encountered, the three trusses were installed on a small section of stud wall on 24 inch centers. Half inch plywood sheathing was installed on the upper chords simulating a roof sheathing. One-half inch dry wall was installed on the rafter or lower chords, simulating a ceiling. All the nailing of the sheathing surfaces was done in strict accordance with the standard practice of housing. The three trusses were braced to prevent side sway, and a load was applied in increments of approximately eleven pounds persquare foot. As each increment of the load was applied, deflection measurements were made, and after the loading was completed the live load was removed and the deflection readings were again taken to see how much permanent set remained in the truss. The maximum effective live load was approximately ll9 pounds per square foot, or 3.96 times the design live load. Under the maximum live load the maximum deflection at the mid-point of the center truss was 1.78 inches,` which is the deflection under approximately four times the design load. After the tests were completed, one of the heel connectors was removed and the nail holes in the wood inspected. The nail holes in the lower chord were elongated approximately two times their normal diameter, but the nails in the upper chord member were not noticeably deformed, indicating that no excessive load had been imposed on the material in bearing through the connector plate. The connector plate then was tested to determinate the holding power of the nails. On the test of a plate made with 2O gauge steel, the holding power was shown to be 255 pounds per nail, while the maximum strength developed was 299 pounds and miuimumwas 217 pounds per nail. Assuming a factor safety of 2.5 the maximum design load each nail is about 102 pounds, providing an exceptionally strong holding power for a nail with an excellent margin of safety. Since thev nails are tightly held in the plate, the plate contributes to the strength of the joint.

While the invention has been described by reference to specific embodiments, there is no intent to limit the spirit and scope of the invention to the precise details so set forth, except insofar as defined in the following claim.

I claim:

A heel plate connector for joining the heel joint of abutting upper and bottom wooden truss members lying in the same plane and each heel plate connector arranged for resting on a wall section for anchoring a completed truss to such a wall section at substantially right angles to said bottom truss member, comprising a sheet of metal having a pair of substantially parallel planar polygonal portions attached at substantially right angles to an intermediate planar portion, said planar polygonal portions arranged to overlie a substantial portion of the heel joint of said abutting members for nailed connection thereto through a plurality of nail receiving openings spaced in rows throughout the extent of said planar polygonal portions, said planar polygonal portions tapering across their upper edges whereby they are encompassed within the external surfaces of the truss to be joined, each nail receiving opening being encompassed by a concentric annular ring spaced from the opening and projecting outwardly from one face of the sheet and a circumferential portion bordering each nail receiving opening and extending outwardly from the opposite face of the sheet, the sheet metal between each said nail receiving opening and its concentric annular ring forming an annular bearing portion in position to bear against a member into which nails are driven through said nail receiving opening and arranged to support the headed portion of said nails and apply uniform pressure against said member into which the nails are driven, the intermediate planar portion having a pair of spaced apart slits adjacent its sides and extending through a portion thereof and terminating within its ends and having another slit interconnected with said pair of slits to detine at least one displaceable pull-out tab of substantial strength and in which one end of the pull-out tab is interconnected with one portion of said intermediate planar portion, there being end portions of said intermediate planar portion interconnecting said polygonal portions, and each end portion of the intermediate planar portion interconnecting said planar polygonal portions being of sufficient extent and strength to Substantially counteract twisting movement between said planar polygonal portions when secured to upper and bottom truss members.

References Cited in the file of this patent UNITED STATES PATENTS 918,522 Faller Apr. 20, 1909 1,015,402 Romunder Ian. 23, 1912 1,296,337 Sullivan Mar. 4, 1919 1,844,823 Rosenberg Feb. 9, 1932 1,945,925 Stiefel Feb. 6, 1934 2,084,758 Anderson June 22, 1937 2,317,125 Barnett Apr. 20, 1943 2,477,163 Barnett July 27, 1943 2,666,238 Hagedorn Ian. 19, 1954 2,722,468 Perrin Nov. 1, 1955 2,827,676 Sanford Mar. 25, 1958 FOREIGN PATENTS 144,853 Great Britain June 24, 1920

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