US2718072A - Educational device - Google Patents

Description

T. J. DOUGLASS, JR

EDUCATIONAL DEVICE Sept. 20, 1955 Filed June 1, 1954 l In 4 a 8 m 6 u o mD J 5 A M M ATTORNEYS.

United States Patent 2,718,072 EDUCATIONAL DEVICE Thomas J. Douglass, Jr., Mount Olive, 111. Application June 1, 1954, Serial No. 433,343 3 Claims. (Cl. 35-26) This invention relates to an educational device. The device of this invention is particularly useful in instruct ing students of descriptive geometry, of drafting, and of statics. However, its usefulness is not confined to those fields, and the device has application to the fields of painting, architecture, photography and many others.

It is frequently difficult for a person to visualize the projection of a three-dimensional object on a flat surface, and far more diflicult accurately to envision the corresponding projections of the object on plane surfaces at right angles to the flat surface and to one another, which projections are necessary to delineate the whole of the object.

One of the objects of this invention is to eliminate or minimize these difficulties in perception.

Another object is to provide a device by which the principles of descriptive geometry may be illustrated.

Another object is to provide a device by which various drafting problems may be solved.

Another object is to provide a device by which, in the study of statics, non-coplanar vectors may be illustrated.

Other objects will become apparent to those skilled in the art in the light of the following disclosure.

In accordance with this invention generally stated, a device is provided wherein a plurality of substantially transparent plane members, contiguous ones of which extend at non-reentrant right angles to one another, are mounted on a support for rotation with three degrees of freedom through a substantial arc. The plane members are so mounted as to be maintainable in anygiven position within that are. An object to be considered is mounted within the compass of the plane members.

The plane members are preferably sheets of clear plastic or glass. They may, however, consist of grids or screens through which an object can be seen. Also, though such an arrangement has certain disadvantages, the plane members may be defined by open frames.

The object to be viewed is preferably mounted on the support on which the plane members are mounted, and is fixed with respect to the plane members.

The plane members are preferably mounted on the support for rotation about the point at which lines normal to the center of the plane members intersect.

In the drawing, Figure l is a view in perspective, partly broken away, of a device constructed in accordance with one embodiment of this invention, illustrating the orthographic projection of an object;

Figure 2 is a top plan view, partly broken away, of the device shown in Figure 1 with the object removed;

Figure 3 is a fragmentary sectional view taken along the line 3-3 of Figure 2 withthe cube shown in tilted position in dotted lines; and

Figure 4 is an enlarged, fragmentary view, partly in section, showing the mounting ball and collar on the support of the device.

Referring now to the drawing for an illustrative embodiment of this invention, reference numeral 1 indicates the complete device. In the embodiment shown, the device is provided with a base 3, and an upright support in "the form of a post5. The post 5 is made up of a base section 6, the lower end of which is fixedly mounted in a boss 4 in the center of the base; a spindle section 7; and a mounting pin Q.

The spindle section 7 is coaxial with the rest of the post 2,7 18,0 72 Patented Sept. 20, 1955 5 but is of reduced diameter with respect to the base section 6, to provide a shoulder 8 at the juncture of the spindle section 7 and the base section 6.

The mounting pin 9 has. a smaller diameter than the spindle section 7 so as to provide a shoulder 10 at the juncture of the mounting pin 9 and the spindle section 7.

A ball 15, with a diametric bore 17, is revolvably mounted on the spindle section 7, resting on the shoulder 8. The mounting pin 9 extends above the ball 15.

A collar is rotatably mounted on the ball 15. The collar 20 is made up of an inner ring 21 and an outer ring 23. The inner ring 21 is U-shaped in cross-section, with a pair of legs 24, the free ends of which engage the surface of the ball on opposite sides of a plane through the center of the ball, and a web joining the legs 24. The legs 24 may be made as separate, washer-like pieces, with the web 25 serving as a spacer between them.

The outer ring 23' fits snugly around the perimeter of the inner ring 21, and is anchored against axial displacement by means of flanges 26. When the legs 24 and web 25 are made as separate pieces, the outer ring 23, with its flanges 26, serves to hold the pieces of the inner ring in assembled position. The outer ring 23 carries four ribs which extend from the ring at quadrants. The ribs may be secured to the collar 20 in any suitable manner, as

ice

. by welding them to, or by swaging their ends in the outer ring 23.

Mounted on the outer ends of the ribs 30 is a square frame 31. The frame 31 is provided with a vertical, opentopped channel 32. Mounted on the frame 31 and with its ,lower edges seated within the channel 32 is an openbottomed cube 35. The cube 35 is composed of a top plane 37, a front plane 38, a back plane 39, a left side plane and a right side plane 41. The planes 37, 38, 39, 40 and 41 are, in the embodiment shown, made of transparent plastic.

The front plane 38 meets the top plane 37 in a line 61, the right side plane 41 in a line 62, and the left side plane 40 in a line 63. The top plane 37 meets the right side plane 41 in a line 64 and the left side plane 40 in a line 65. The back plane 39 meets the top and side planes in lines corresponding to those in which they meet the front plane.

In this embodiment, an edge-delineating and reinforcing framework 44, made up of thin rods, extends along each of the vertical and upper horizontal edges of the cube, as indicated in Figure 3. The framework rods are preferably striped to represent the dot and dash lines by which the separation of the various planes is commonly illustrated (see Fig. l).

The size and position of the cube 35 are such that the 2 center of the ball 15 is substantially at the center of the cube.

The legs 24 of the collar 20 fit tightly enough around the ball 15 to maintain the cube 35 in any position to which the cube 35 may be rotated, but still permit ready the object may be of different and more complex configuration.

The object 45 is mounted sufficiently far above the ball 15 to be clear of the collar 20 in any position of the collar.

The device of this invention may be used in various different ways. The following described operations of the embodiment shown are merely illustrative of the uses to which the device may be put.

In teaching orthographic projection, the cube 35 is rotated so that the front plane 38 is parallel with a front 55 of the object 45, the right side plane 41 is parallel with a corresponding side 56 of the object 45, and the top plane 37 is parallel with. the top 57 of the object 45. When the cube 35 is in this position, one can obtain views of the object in front, back and side elevations simply by viewing the object directly on lines normal to the front plane 38, back plane 39, left side plane 40 and right side plane 41. A top plan view is had by viewing the object directly on a line normal to the top plane 37.

' In order to obtain auxiliary elevations, it is only necessary to rotate the cube 35 through less than ninety degrees in such a way that the top plane 33 remains parallel with the top of the object 45. The views observed on a line normal to the front, back and side planes of the cube are auxiliary elevations.

The positions on a flat sheet of paper of folding lines and image planes relative to one another are easily visualized, since if the front plane 38 is taken as the plane of the paper on which the front elevation is to be drawn, the proper orientation of the top plan view is had simply by considering the meeting line 61 as the folding line, as shown in Figure 1. Moreover, an elevation at right angles to the front elevation is properly oriented by considering the meeting line 62 as the folding line, as shown in Figure 1.

To obtain a view in perspective, the cube 35 may be rotated in such a way that none of the planes of the cube are parallel with major planes of the object 45. In any .view, but particularly in views in perspective and views of auxiliary elevations, an advantage of the use of transparent material to define the planes of the cube 35 lies in the fact that the angles between the lines of the object may easily be measured simply by laying a protractor or the like against the plane of the cube 35 through which the object is being viewed. This also has especial utility in the resolution of vectors in statics problems.

In solving problems in descriptive geometry, it is frequently desirable to use a four-step procedure. For example, if one were attempting to find the true size and shape of a plane figure, such as the surface of the bevel 46 of the object 45, one can proceed as follows. First, one finds the true length of one line in the plane. This can be done by rotating the cube 35 until one of its plane surfaces is parallel with one of the lines defining the bevel 46. For example, the front plane 38 may be made parallel with a front line 50 of the bevel 46. It can be seen that the cube is still permitted two degrees of freedom, while the front plane 38 remains parallel with the line 50. Second, the view is found in which the line 50 appears as a point. This is done by rotating the cube in such a way, while maintaining the front plane 38 parallel with the line 50, as to bring the right side plane 41 to a position normal to the line 50. The line 50 then appears as a point on the side planes. It can be seen that while the side plane 41 and the front plane 38 are maintained in their respective positions with respect to the line 50, the cube 35 is still capable of one degree of freedom. Third, the plane object (the bevel) is viewed as an edge in side plane 41. The position of side plane 41 is determined when the line 50 is made normal to it. However, it is necessary to observe the plane of the bevel 46 as an edge in order properly to position the cube 35 in the fourth step. Fourth, while the front plane 38 is maintained parallel with line 50 and the side plane 41 is maintained normal thereto, the cube 35 is rotated to the position at which the top plane 37 is parallel to the top of the object, viewed as an edge in the side plane 41. This can be done by making the line 64 parallel to the edge, since only one degree of freedom is permitted. If now, the object is viewed directly on a line normal to the top plane 37, the plane of the bevel 46 will appear in its true size and true shape. While these steps may seem elementary with respect to the plane surface of the bevel 46, the same steps will lead to the solution of the problem with respect to plane surfaces of any shape, oriented in any position with respect to the horizontal.

In solving statics problems involving non-coplanar vectors, the vectors may be represented by wires or by lines drawn on the surface of a solid object. The true length of each of the vectors may be obtained by viewing it through a plane of the cube parallel to the line. The orientation and dimensions of a plane defined by any two intersecting vectors can be determined by finding the position of the cube 35 in which one of the vector lines appears as a point on one plane of the cube, and the intersecting vectors appear as an edge in a plane of the cube at right angles to the first plane. The plane of the cube at right angles to both of the said planes is now oriented parallel with the plane of the vectors, and the length of the resultant vector may be plotted on that plane of the cube and its orientation with respect to a reference noted.

Numerous other uses for the device of this invention and numerous variations in its construction within the scope of the appended claims will be apparent to those skilled in the art in the light of the foregoing disclosure. For example, while in the preferred embodiment the image plane members form an open-bottomed cube, it can be seen that the device can be suspended upside down, or some of the planes may be omitted, leaving two or more contiguous planes. The ribs from the universal mounting may extend normally to the image plane members so as to form a viewing guide.

Thus it can be seen that a simple but very useful educational device is provided, by which the solutions of difiicult problems of descriptive geometry, drafting and statics may be illustrated.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. A device of the character described comprising an open-bottomed hollow cube, the sides and top of which are substantially transparent, said cube being mounted on a support extending upwardly within the cube and provided with a ball upon which a collar is mounted for rotation through a substantial arc in any direction, ribs secured to said cube and to said collar whereby said cube is mounted for rotation on said ball, and means on said support for mounting an object.

2. A device of the character described comprising a base, an upright support mounted on said base, a ball carried by said support and an object carried by said support above said ball, a collar mounted on said ball for rotation through a substantial arc, ribs secured to and extending from said collar, and an open-bottomed, transparent-sided cube mounted on said ribs, said collar being positioned substantially at the center of said cube.

3. A device of the character described comprising an open-bottomed hollow cube, the sides and top of which are substantially transparent, said cube being mounted on a support extending upwardly within the cube and provided with a universal mounting capable of rotation through a substantial arc in any direction, ribs secured to said cube and to said universal mounting whereby said cube is mounted on said universal mounting, and means on said support for mounting an object within the confines of said cube.

References Cited in the file of this patent UNITED STATES PATENTS 812,408 Dickerson Feb. 13, 1906 1,639,448 Ashbrook Aug. 16, 1927 2,319,162 Short May 11, 1943 2,335,941 Howard Dec. 7, 1943 FOREIGN PATENTS 673,326 Great Britain June 4, 1952

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