US 3295405 A
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Description (OCR text may contain errors)
Jan. 3,1967 J. 5. BURKE 3,295,405
GRIP PLATE FOR WOODEN TRUSS MEMBERS Filed Sept 5, 1964 ooooooooo,oo oooo ooqooc'o ooooo ob oooo coo 00000000 ogooeooopoo INVENTOR- JAMES STANLEY BURKE A TTOR NE Y6 United States Patent 3 295,405 GRIP PLATE FOR WOODEN TRUSS MEMBERS James Stanley Burke, 7100 Coral Way, Nliami, Fla. 33155 Filed Sept. 3, 1964, Ser. No. 394,285 1 Claim. (CI. 8513) This invention relates to improved grip plates or connectors for wooden structural members and particularly to metal connector or grip plates provided with a plurality of integral punched or formed projections adapted to be impressed into the surfaces of the wooden structures.
It is a particular object of the present invention to provide metal connector or gusset plates for roof trusses adapted to inexpensively and effectively distribute loads on the structure over a relatively large area, thus improving the strength of the joints.
A further object is to provide improved grip plates for roof trusses, whereby simple and lightweight trusses can readily be inexpensively fabricated from standard 2 x 4s and the like.
Other objects and advantages of the construction of the present invention are provided by a grip plate for securing abutting wooden members together comprising a metal plate member, a plurality of wood-penetrating members formed from said plate member and generally extending from one face thereof, each of said woodpenetrating members consisting of an upstanding substantially continuous circular wall portion adjacent the one face of the plate member and having a pointed tooth or prong portion of a particular shape generally smoothly contoured from one side of each arc of the circular wall portion. The several prongs have differing shapes as one progresses about the circular wall, for a purpose to be more fully described hereinafter.
The invention will be more particularly described with reference to the illustrated embodiments thereof shown in the accompanying drawings wherein:
FIG. 1 is a side elevational view of a fragmentary portion of a conventional roof truss made of wooden members and embodying the grip plate of the invention;
FIG. 2 is an enlarged perspective view of a portion of the grip plate of the invention;
FIG. 3 is a fragmentary sectional view substantially on line 33 of FIG. 2 showing the contour of certain teeth of the grip plate prior to its application to the wooden truss members;
FIG. 4 is a fragmentary sectional view like FIG. 3, but taken along the line 44 of FIG. 2;
FIG. 5 is a fragmentary sectional view showing the grip plate of FIG. 3 after application to a wooden truss member, including one of the attaching nails;
FIG. 6 is similar to FIG. 5, but shows the grip plate of FIG. 4 after attachment to a Wooden trust member; and
FIG. 7 is an enlarged perspective view like FIG. 2 of a portion of the grip plate showing the contours attained by the several teeth thereof after application to a wooden trust member; but with such wooden member removed for purposes of illustration.
Referring to the drawings and, in particular, to FIG. 1 thereof, a fragmentary portion of a typical roof truss is shown consisting of a bottom chord member 10 and a top chord member 12 which is in abutting relationship with the extended end of the bottom chord member.
The complete roof truss, which is not shown, would include a further top chord member of complementary slope to that of the top chord member 12 which would join such member in abutting relationship at the roof apex and extend downwardly from such junction to abut the opposite extended end of bottom chord member 10.
A plurality of web members may be provided intermediate the top and bottom chord members of the complete roof truss; such web members being in abutting contact at each end thereof with the chord members.
At each of the points of abutting contact between the lower chord member, the upper chord members, and the web members, there is provided a grip plate or gusset member generally designated 14. Each of the grip plates 14 may be identical in form and size; however, in general, the size and shape ofeach of the grip plates 14 is determined by the particular portion of the total load at the particular joint. By sizing the grip plates 14 for each of the particular abutting joints of the roof truss, it is possible to materially reduce the cost of the metal grip plates employed on a roof truss and also reduce assembly time without sacrificing the strength of the finished roof truss.
Each of the grip plates 14 generally comprises a metal plate member 16 which may consist of a l2, 18 or, for example, ZO-gauge, preferably galvanized, steel plate. Each of the plates 16 is provided with a plurality of assemblies of wood-penetrating members 18, 2t 22 and 24, which wood-penetrating members are formed from the plate 16 and extend or project from the inner face 26 of each plate.
Each of the wood-penetrating members has as a base element an arcuate wall portion more clearly shown in FIGS. 2 and 4, and generally designated 28. The interrupted circular wall portions of the invention are arcuate in plan and consist of four sections of substantially 90 length punched or pressed from the metal of the plates 16.
In forming the base element wall portions 28, the punch and die units are shaped and sized so that each of the arcuate sections is substantially continuous with its adjacent section to provide an extremely rigid and unyielding cylindrical construction.
Each of the four base elements extends upward from the inner face 26 of the plate to provide the different pointed tooth portions 18, 20, 22 and 24 which are generally smoothly contoured prolongations of their respective base elements. The teeth 18 are the longest and provide an initial wood penetrating action.
Further, as illustrated in FIG. 3, each of the teeth 18 is curved outwardly of its corresponding base section arcuate wall portion in a serpentine or lazy-S configuration in vertical cross section to improve the gripping ability of each of the wood-penetrating members, as more clearly illustrated in the sectional view of the attached plate shown in FIG. 5. It will be particularly noted that each tooth 18 of the wood-penetrating members is initially vsmoothly curved outwardly a very slight amount in a shape which promotes its entry into the wooden truss member along a curving path whereby an extended gripping surface is provided which resists movement of the attached plates away from their surface contact with the wooden members forming the truss.
The near prong 24 and the far prong 20 to the rear thereof are asymmetrical in shape as is evident in the sectional illustration of FIG. 3. It will also be noted that both of these prongs are cut away or relieved at their base portions 30. Prong 24 is a mirror-image of prong 20, and, as shown in FIG. 4, each prong is curved outwardly of its corresponding base section arcuate portion a slight amount in a serpentine or lazy-S configuration in vertical cross-section to improve the gripping ability. Due to such configuration and the relieved base portion 30, prongs 20 and 24 are free to follow a spiral path into the wooden truss in a manner similar to a wood screw. In general each of the relieved base portions of prongs 20 and 24 is defined by a first edge tapering toward the base of prong 18 and a second edge sloping upwardly from adjacent the base of the prong 18. Such spiral or twisting action of prongs 20 and 24 as they enter the truss members can be noted in FIG. 6, from which it will be apparent that, the grip plate 14 is firmly held in surface contact with the wooden truss member 10.
The short upstanding tooth 22 is the last member to penetrate the wooden truss element 10 as the grip plate 14 is attached thereto. Tooth 22, unlike the teeth 18, 20 and 24, is not curved outwardly. It'relies entirely upon its arcuate base element wall portion 28 to give it strength, and penetrates the wood at an angle of substantialy 90 so as to resist any movement of the grip plate.
In order to improve the gripping ability of the grip plates and to further reduce the tendency of the plates to move away from their surface engagement with the truss members, particularly during transportation of a roof truss from the assembly plant to a job site, each of the plates is provided with a plurality of bores 32, which bores are adapted to receive stitching nails 34. In general, it has been found suitable to use one 1 /2 inch round or square shanked barb nail 34 for every four square inches of metal of the grip plates.
The number of wood-penetrating assemblies, 18, 20, 22, 24 in each grip plate may be varied depending upon the gauge of the metal of the grip plates and the total load which the roof trusses are adapted to withstand; however, where the wood-penetrating members are provided with a cylindrical base wall construction ,28 of a height approximately equal to the gauge of the metalplate 14 and the four teeth as shown, one wood-penetrating assembly for each 1.5 square inches of metal has been found to be very satisfactory where such wood-penetrating assemblies are arranged in rows as illustrated in FIG. 1.
Other geometric arrangements of the wood-penetrating members in the plate may be made without departing from the principles of the present invention as will be apparent to those skilled in the art.
It has been found that joints formed from pieces of 2x4-inch nominal dimension fir, joined by a pair of exterior grip plates where the grip plates comprised 20-gauge galvanized steel, 3%x9 /2 with 104 effective teeth and 10 1 /2 inch 6d nails per plate, under a total load of 10,900 pounds and a tensile load of 6,000 pounds, moved across the joint on the average about .016 inch, well within the standard requirements of, for example, the,
Federal Housing Administration.
Referring to the perspective view of FIG. 7, wherein the grip plate 14 after attachment to the Wooden truss member 10 is shown, but with member 10 removed; the outwardly curved path and hook action of the tooth 18, and the screw-like spiral entry of teeth 20 and 24 may be more readily visualized than in the sectional views of FIGS. 5 and 6.
As further illustrated in FIG. 7, the hole for the stitching or anchor nails 34 may be punched out by means of an appropriate die so as to leave it with ragged edges 36 extending from the inner face 26 of grip plate 14. In one embodiment a square-3 di W Used P dt four upstanding edges 36 which help to resist movement of the attached plate.
The grip plates constructed in accordance with the teachings of the present invention may be applied ,to wooden truss members according to any of the well known methods of attachment. That is, they may be applied manually by driving them into place with blows of a workmans hammer, in certain instances with an inter: vening block being utilized to distribute the impactforces over the plate area; or they may be applied by passing the truss members and overlying grip plates through one or more pinch roll assemblies. Further, the stitching nails may also be applied manually or by machine means which may simultaneously drive the desired pattern of a number of nails.
From the foregoing description, it will readily be seen that the improved grip plate of the present invention fullycular openings therein and a plurality of wood penetrating I members extending upwardly from adjacent the perimeter of said openings comprising a first prong having an arcuate base portion, said prong tapering inwardly as it extends away from said base portion and terminating in a blunt flat end portion, said prong in vertical cross section having a lazy S shape configuration with said lazy S facing away from said opening, two other prongs disposed on opposite sides of said lazy S prong and having 1 an edge joined to the adjacent edge of said lazy S prong to provide arcuate portions extending above the plate 7 opening, said two prongs each having a first edge defined by a relieved base portion tapering toward the base of said first prong and the other edge thereof sloping up- I wardly from adjacent the base of the first prong thereby defining a dog ear configuration in vertical cross section,: and having pointed end tips, said dog ear prongs being i shorter than said lazy S prong,'and a straight prong disposed between the sides of said dog ear prongs opposite. said lazy S prong, said straight prong terminating in a 1 generally arcuate configuration, said straight prong forming substantially a right angle with said plate and having its opposite lower edges cut away to form a space between it and said dog ear prongs, said straight prong being shorter than said dog car prongs.
References Cited by the Examiner UNITED STATES PATENTS 649,761 5/1900 Saltzkorn et al. 2,282,624 5/1942 Upson et al -11 2,425,025 8/ 1947 Boisselier. r 3,031,727 5/ 1962 Nesbitt 851 1 FOREIGN PATENTS 651,149 10/1962 Canada.
CARL W. TOMLIN, Primary Examiner.
PARSONS, JR., Assistant Examiner,