Block-type construction toy

A building block for a construction toy is characterized by having one or more studs projecting from one side and a corresponding number of recesses formed in the opposite side. The studs and recesses are of an equilateral polygonal configuration, preferably having an even number of sides, preferably eight. At least some of the surfaces of the studs are formed to have a negative taper, making the studs slightly larger at the top than at the base. The recesses also are formed such that the walls have a slight negative taper, making the recesses slightly narrower at the open end than farther down in the recess. When a pair of blocks is assembled by inserting one or more studs of one block into one or more recesses of an adjacent block, the negatively tapered configuration of the studs and recesses provides for a tactilly sensible snap action, which is pleasing to the user and also provides a secure assembly. The height of the studs, in relation to their width, is relatively low, which facilitates disassembly of connected blocks, when desired, by applying tilting force to the blocks.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention is directed to construction toy sets, and more 
particularly to improvements in construction toy sets of the type in which 
the components are individual blocks formed with projecting studs and/or 
recesses to enable assemblies to be constructed by joining projecting 
studs of one block with recesses of another. 
In general, construction toys utilizing blocks with studs and recesses are 
well known and are commercially available. The present invention is 
directed to improved features in building blocks of this general type, to 
the end of making them easier and more desirable to use, more securely 
joined when assembled, yet readily disassembled when desired. 
In a preferred form of the invention, individual building blocks are 
comprised of upper and lower shells, formed of injection molded plastic, 
which are joined together, preferably permanently, to form a lightweight, 
hollow block. For convenience, but without intending any limitation, one 
of the halves may be referred to herein as the top and the other as the 
bottom. 
One or more studs, integral with the top of the block, extend upward 
therefrom and, in a preferred embodiment, a corresponding number of 
recesses of similar configuration are formed in the bottom of the block. 
It is also contemplated that, in certain cases, blocks may be provided 
with only studs or only recesses, or with studs and recesses in different 
number. 
Although other configurations are possible and contemplated within the 
basic teachings of the invention, in a particularly preferred and 
advantageous form of the invention the studs and recesses are configured 
in the form of equilateral octagons. In each block, the studs and recesses 
are of equal number and are arranged in coaxial pairs, with each stud 
being coaxial with a corresponding recess on the opposite side of the 
block, and the sides of all of the studs and recesses being oriented in 
the same manner. 
In accordance with one of the features of the invention, the side walls of 
the recesses are formed to give the recesses a slight negative taper. That 
is, the width of the recess opening, at the surface of the block, is 
slightly less than the width of the recess at a distance from its surface 
opening. In a similar manner, some or all of the side walls of the 
projecting studs are configured to provide a slight negative taper, such 
that the cross section of the stud at the base is slightly smaller than at 
the top, and at least some of the width dimensions at the top of the stud 
are at least slightly greater than the width of the openings into the 
recesses. Accordingly, in order to insert a stud into a recess, the end of 
the stud has to be forced into the recess opening, and the assembly is 
accomplished with a tactilly sensible snap action effect. Once assembled, 
the parts are securely held in place by the fit of the reversely tapered 
stud and recess walls. 
Desirably, the studs are of substantially greater width than height. This 
is made possible and practicable by relying upon the snap fit interlock of 
the studs and recesses, to maintain adjacent blocks in assembled relation, 
rather than relying on a simple friction fit as is customary with such 
devices. The relatively short projecting length of the studs facilitates 
disassembly of connected blocks by enabling one block to be more easily 
tilted with respect to another, providing leverage to effect separation of 
the interlocking parts. 
In an advantageous form of construction toy building block according to the 
invention, the blocks are formed with opposite side walls which are spaced 
apart and parallel, and end walls arranged in the form of three sides of 
an octagon. In a block with a single projection and/or single recess, the 
body of the block is of octagonal configuration arranged concentrically 
with the stud and/or recess, with side walls of the block body being 
parallel with corresponding side walls of the stud and/or recess. For 
larger blocks, formed with a plurality of sets of studs and/or recesses, 
the side walls are appropriately elongated. 
For a more complete understanding of the above and other features and 
advantages of the invention, reference should be made to the following 
detailed description of preferred embodiments of the invention and to the 
accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to the drawings and initially to FIGS. 1-6 thereof, there are 
shown three example styles of building blocks according to the invention. 
Block 10 of FIGS. 1-2 is formed with a single stud 11 on its top wall 12 
and a single recess 13. Block 20 of FIGS. 3-4 is formed with a pair of 
studs 11 on its top wall 15 and a pair of recesses 13 on its bottom wall 
16. Block 30 of FIGS. 5-6 is formed with three studs 11 on its top wall 17 
and three recesses 13 in its bottom wall 18. In each of the illustrated 
embodiments, the studs are formed in coaxially aligned pairs. However, as 
will become apparent, the blocks may be configured with various 
combinations of studs and recesses, including all studs or all recesses, 
combinations of studs and recesses on the same and different sides, etc. 
The illustrated embodiments should therefore be considered as reflecting 
only general principles of the invention and not as limiting the scope 
thereof. 
Pursuant to one aspect of the invention, the studs 11 and recesses 13 are 
configured in the form of equilateral polygons of substantially the same 
size, so that studs 11 of one block can be inserted into recesses 13 of a 
second block in one of a plurality of angular orientations, as determined 
by the number of sides of the polygon. To particular advantage, the studs 
and recesses are formed as equilateral octagons, providing for assembly of 
two blocks in any of eight possible orientations. 
The blocks may of course be of any suitable size. For purposes of 
illustration, the blocks 10, 20, 30 may have a body thickness T (i.e., not 
including the projection of the studs 11) of about 3/4 inch and an overall 
width W of about 1 1/4 inches. The block 10 of FIGS. 1-2, having a single 
stud and a single recess, is formed with opposed parallel side walls 21, 
and pairs of opposite end walls 22, 23, 24, also arranged in parallel 
relation. For the single stud block 10 the respective pairs of end walls 
22-23, 23--23 and 24--24 are spaced apart the same distance W as the side 
walls 21, i.e., 1 1/4 inches in the illustration, so that the body walls 
21-24 also form an equilateral octagon, with the stud 11 and recess 13 
being arranged coaxially, centered with respect to the body walls 21-24, 
and with the several walls of the stud 11 and recess 13 being aligned in 
parallel relation to the body walls 21-24. 
The two-stud block 20 illustrated in FIGS. 3-4 is comprised of elongated 
side walls 25, joined at the ends by end walls 22-24 of the same 
configuration as the end walls 22-24 of the single stud block 10 of FIGS. 
1 and 2. The width and thickness of the two-stud block 20 are the same as 
for the single stud block 10. The overall length of the block 20 is, 
however, twice the "length" of the single stud block. 
The axes 26 of the studs and recesses 11, 13 of the block 20 are aligned in 
a common plane bisecting the block 20 between its side walls 25. The axes 
26 are spaced apart in a direction lengthwise of the block by a distance 
equal to the basic block width W, and the distance from the axes 26 to the 
adjacent end walls 22-24 (as well as to the opposite side walls 25) is 
equal to W/2. Accordingly, the length of the block 20 equals W*2. 
As will be appreciated, the geometry of the blocks 10, 20 is such that two 
single stud blocks 10 may be assembled stud-to-recess with a two-stud 
block 20, on the same side of the latter, with adjacent side/end walls of 
the smaller blocks 10 abutting in the center of the larger block 20, and 
the remaining side/end walls of the smaller block being aligned with 
corresponding walls of the larger block. 
The three-stud block 30 of FIGS. 5-6 is of the same width and thickness as 
the blocks 10, 20 previously described and has further elongated, parallel 
side walls 27 joined by end walls 22-24. The axes 28 of the three stud s 
and recesses 11, 13 are spaced apart by the distance W, and the end walls 
22-24 are spaced from the endmost axes by a distance W/2. The overall 
length of the block 30 is thus W*3. The length of a block is thus seen to 
be a function L=W*n, where n=the number of studs and/or recesses. 
To advantage, the blocks 10, 20, 30 are formed by precision injection 
molding of a plastic material, such as ABS. The blocks are formed in upper 
and lower half sections 30, 31, or 32, 33, or 34, 35 as shown in FIGS. 8, 
9 and 10 respectively. The half sections may be formed with wall 
thicknesses of, for example, 0.63 inch, to provide a lightweight and 
inexpensive construction. Desirably, the half sections are designed to be 
permanently joined to form a hollow block body, with studs and recesses 
formed integrally therein. 
As shown in FIGS. 7-10, the upper half section of each block body is formed 
with a projecting lip 36 extending continuously around the periphery of 
the block and received in a complementary peripheral recess 37 to form a 
tight, secure closure of the two half sections and to accurately position 
the respective half sections in proper alignment. Additionally, each upper 
half section is provided with a plurality of integral alignment pins 38 
which project below the peripheral lip 36 and are engageable with a snug 
friction fit in correspondingly positioned sockets 39 in the lower half 
sections of the blocks. Once assembled, the half sections form a rigid and 
durable block, which is solid in appearance but is light in weight and 
easily handled during play and during assembly and disassembly of 
structural combinations. Although it is possible to separate the upper and 
lower block halves after assembly, it is generally contemplated that the 
blocks will be permanently assembled. 
Preferably, the blocks are brightly and distinctively colored according to 
size. Typically, both half sections of a block are formed of plastic 
material of the same color. However, it may be desired in selected cases 
to assemble blocks using half sections of contrasting colors. 
As shown in FIGS. 11-16, and in accordance with a feature of the invention, 
both the studs and recesses 11, 13 are configured to have a slight reverse 
taper, such that the top of a stud has slightly greater dimensions than 
the opening into a recess, providing an interference fit at the beginning 
of assembly of one block to another. The nature of the reverse taper 
configuration is such that, once a stud is forced into the entrance 
opening into a recess 13, the respective elements are combined with a snap 
action effect. This not only provides for a secure combining of blocks, 
but also provides a satisfactory "feel" to the user during the assembly. 
As shown in FIGS. 13 and 14, for example, the side walls 41 defining the 
recesses 13 form a slightly acute angle with respect to the bottom wall 14 
of the block. Typically, an acute angle of 89.degree. between the inner 
surfaces 42 of the side walls 41 provides a one degree negative taper in 
the recess. Desirably, the mouth dimension of the recess, between opposed 
inner walls surfaces 42 is 0.500 inch at the surface of the bottom wall 
14, and the width of the recess is slightly larger than that nearer the 
inner surface 43 of the recess bottom wall 44. Typically, as will be 
hereinafter described, the outer edges of the studs 11 are rounded off. 
Accordingly, the corners 45, joining the side walls 41 with the bottom 
walls 44 of the recesses may be correspondingly rounded with a corner 
fillet, as indicated at 45. The widest portion of the recess 13 in such 
cases will be adjacent the beginning of the corner fillet 45, indicated by 
the dotted line 45a in FIG. 13. 
FIGS. 11 and 12 illustrate an advantageous configuration of the studs 11 
according to the invention. Nominally, the studs 11 are formed with side 
walls 46, 46a forming a substantially equilateral octagon, with the width 
of the stud between first alternate parallel walls 46 being formed at 
about 0.494 inch, and with slightly greater width between second alternate 
walls 46a of about 0.500 inch, to mate with the recesses 13 as described 
with respect to FIGS. 13, 14. The studs 11 project upward from the surface 
of the top wall 12 a distance substantially less than the width of the 
studs. Thus, in a typical and advantageous embodiment of the invention, 
the stud height may be about 0.188 inch for a stud having a nominal width 
of 0.500 inch. Desirably, where the stud side walls 46, 46a join, the 
corner is rounded with for example a radius of 0.125 inch, as indicated at 
47 in FIG. 11. Likewise, where the side walls 46, 46a join with the stud 
top wall 48, the corners are rounded as at 49, with a typical radius of 
about 0.063. 
Pursuant to the invention, selected ones of the stud side walls are formed 
to have a negative taper, so that upper portions 50 of the studs are of 
greater width dimensions than lower portions 51 thereof (see FIG. 12). In 
the particular embodiment illustrated, alternate side walls 46a are 
provided with a negative taper configuration, and preferably a center 
portion 52 thereof is provided with the desired negative taper. Thus, as 
indicated in FIG. 11, the alternate walls 46a are provided with vertically 
extending rib-like center projections 52 consisting of lower portions 53 
forming a slightly acute angle with the surface of the top wall 12 and 
extending upward from said surface for a portion of the height of the 
stud. For example, in a preferred embodiment, the negatively tapered 
portion may extend upward approximately 0.072 inch. An intermediate 
portion 54 of the rib-like projection 52 may extend generally straight, 
i.e., at right angles to the surface of the top wall 12 continuing to an 
upper portion of the rib-like projection, where the projection is rounded 
at 55 to merge with the top wall 48. 
Thus, in the illustrated form of the invention, the width between the 
parallel flat surfaces of the alternate stud side walls 46 advantageously 
is slightly less than the nominal width between the surfaces 42 of the 
recesses at the entrance thereto. In one advantageous form of the 
invention, for recesses having a width between opposed side walls of 0.500 
inch, the width between alternate stud side wall surfaces 46 may be 0.494. 
The width across the alternate side wall surfaces 46a may be about 0.500 
inch. The width across the ribs 52, measuring from the upper portions 54 
thereof, is slightly greater than the entrance width of the recesses 13, 
preferably about 0.502 inch. As shown in FIG. 11, the projecting ribs 52 
comprise only a portion of the width of the alternate side walls 46a. In a 
typical embodiment, the width of the ribs may be about 0.063 inch. The 
arrangement is such that, the projecting ribs 52 of the studs 11 provide 
an interference fit with the entrance opening of the recesses 13, 
requiring the studs to be forced through the entrance. Once partially 
inserted into the recesses, however, wider upper portions of the studs are 
received in wider inner portions of the recess. Desirably, there is a 
distinct snap action effect to this assembly, as the wider portion of the 
stud passes through the narrower entrance of the recess, which can be 
tactilly sensed through the fingers of the user. This provides a 
satisfying confirmation that the assembly has been properly completed. 
Additionally, the negatively tapered configuration of the recesses 13 and 
the projecting ribs 52 on the studs 11 tends to provide a physical 
dovetail-like locking action, significantly beyond mere friction, to 
secure the blocks in their assembled relation. 
FIGS. 15 and 16 illustrate an assembled stud and recess pair. As will be 
evident in FIG. 15, for example, the narrow entrance opening of the recess 
13, as indicated at 56 in FIG. 15, will have to be deformed slightly to 
accommodate entry of the projecting rib portions 52. The plastic material 
used in the forming of the block parts, although rigid for most practical 
purposes, has sufficient elasticity to accommodate the necessary 
deflection during entry of the stud 11 into the recess 13. Once assembled, 
the studs are held snugly by the side walls of the recess. And because of 
the dovetail configuration of the stud and recess walls, the parts are 
retained very effectively against accidental separation. 
Disassembly of assembled blocks when desired is facilitated both by the 
geometry of the studs and recesses and that of the block bodies 
themselves. Thus, where the side and end walls of the block bodies join 
with the top and bottom walls thereof, a generously rounded contour is 
provided. In one advantageous form of the invention having general 
dimensions as heretofore described herein, these generously rounded 
contours, indicated at 60, 61, 62 in FIGS. 8-10 may have a radius of about 
0.188. This provides for a limited fingertip access between assembled 
blocks, in order to obtain a grip thereon and exert some leverage. Thus, 
when two blocks are joined, depending upon the orientation thereof, a 
groove for finger access is defined by at least one of the rounded edges, 
and in some cases by the combined space of two rounded edges. 
Additionally, the relatively short height of the studs 11, in relation to 
their width, enables leverage to be exerted on the blocks by tilting one 
side or one end thereof, or tilting a block from side to side. Such 
tilting action partially separates the blocks and facilitates the complete 
separation of a stud from the recess in which it had been inserted. 
The device of the invention, although a precision molded product, can be 
mass produced on an economical basis. The blocks can also be manufactured 
in a wide variety of sizes and shapes and are by no means limited to the 
illustrative examples specifically shown and described herein. 
Accordingly, reference should be made to the following appended claims in 
determining the full scope of the invention.