V-Cube 7

The V-Cube 7 is a combination puzzle in the form of a 7×7×7 cube. It was invented by Panagiotis Verdes and is produced by the Greek company Verdes Innovations SA. Like the 5×5×5, the V-Cube 7 has both fixed and movable center facets.

The puzzle consists of 218 unique miniature cubes ("cubies") on the surface. Six of these (the central tiles of the six faces) are attached directly to the internal "spider" frame and are fixed in position relative to one another. The V-Cube 6 uses essentially the same mechanism, except that on the latter the central rows, which hold the rest of the pieces together, are completely hidden.

There are 150 center pieces which show one color each, 60 edge pieces which show two colors each, and eight corner pieces which show three colors each. Each piece (or quintet of edge pieces) shows a unique color combination, but not all combinations are present (for example, there is no piece with both red and orange sides, since red and orange are on opposite sides of the solved Cube). The location of these cubes relative to one another can be altered by twisting the outer layers of the Cube 90°, 180° or 270°, but the location of the colored sides relative to one another in the completed state of the puzzle cannot be altered: it is fixed by the relative positions of the fixed center squares and the distribution of color combinations on edge and corner pieces.

Currently, the V-Cube 7 is produced with white plastic as a base, with red opposite orange, blue opposite green, and yellow opposite black. The fixed black center piece is branded with the letter V. Verdes also sells a version with black plastic and a white face, with the other colors remaining the same, solid plastic versions with the plastic the colour itself and no stickers, flag variations of 7x7s including Germany, Poland, Russia etc.

Unlike the flat-sided V-Cube 6, the V-Cube 7 is noticeably rounded. This departure from a true cube shape is necessary, since the mechanism used on this puzzle would not function properly with layers of identical thickness. Other means (such as magnets) would be required. Note from the image at right that if a 7×7×7 were to be constructed with layers of identical thickness the corner pieces (shown in red) would lose contact with the rest of the puzzle when a side was rotated 45 degrees. The V-Cube 6 and V-Cube 7 both solve the problem by using thicker outer layers. The rounded shape of the V-Cube 7 results in corner stickers that are similar in size to the center stickers, which helps hide the unequal thickness. The 7×7×7 is the only "pillowed" cube allowed in competition by the World Cube Association; all others are banned.

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Wikipedia