Adjustable carriage and optimized bearing surface means

An apparatus for performing work in three dimensions including:

• a frame including:
• four stationary corner rails disposed vertically along a Z-axis and in a rectangular array, each of said stationary corner rails including a lower end and an upper end, said four stationary corner rails including a first corner rail, a second corner rail positioned adjacent said first corner rail, a third corner rail positioned adjacent said second corner rail, and a fourth corner rail positioned between said third corner rail and said first corner rail, wherein each of said four stationary corner rails defines at least a first frame mounting surface, a second frame mounting surface, and a rail bearing surface, said rail bearing surface being disposed between said first and second frame mounting surfaces, said first frame mounting surface being disposed orthogonally with respect to said second frame mounting surface;
• a bottom support secured proximate said lower end of each of said four stationary corner rails such that said lower end of each of said four stationary corner rails is fixed relative to said lower end of each other of said four stationary corner rails;
• an upper support secured proximate said upper end of each of said four stationary corner rails such that said upper end of each of said four stationary corner rails is fixed relative to said upper end of each other of said four stationary corner rails, said upper support including:
• a first upper rail secured between said upper end of said first and second corner rails, said first upper rail being disposed along an X-axis;
• a second upper rail secured between said upper end of said second and third corner rails, said second upper rail being disposed along a Y-axis;
• a third upper rail secured between said upper end of said third and fourth corner rails, said third upper rail being disposed along said X-axis and parallel with said first upper rail;
• and
• a fourth upper rail secured between said upper end of said fourth and first corner rails, said fourth upper rail being disposed along said Y-axis and parallel with said second upper rail;
• wherein said X-axis and said Y-axis are orthogonally-disposed with respect to each other and with respect to said Z-axis;
• wherein:
• said first upper rail is secured between said first frame mounting surface of said first corner rail and said second frame mounting surface of said second corner rail;
• said second upper rail is secured between said first frame mounting surface of said second corner rail and said second frame mounting surface of said third corner rail;
• said third upper rail is secured between said first frame mounting surface of said third corner rail and said second frame mounting surface of said fourth corner rail;
• and
• said fourth upper rail is secured between said first frame mounting surface of said fourth corner rail and said second frame mounting surface of said first corner rail;
• a working head assembly defining a first end and a second end, said first end being moveably engaged with said first upper rail and said second end being moveably engaged with said third upper rail such that said working head assembly is limited to movement along said X-axis with respect to said frame, said working head assembly extending along said Y-axis, said working head assembly including a working head moveably engaged with said working head assembly such that said working head is limited to movement along said Y-axis;
• a carriage assembly defining first, second, third, and fourth corners each moveably engaged with said first, second, third, and fourth corner rails, respectively, such that said carriage assembly is limited to movement along said Z-axis, said carriage assembly defining an upper side and a lower side;
• wherein:
• said carriage assembly first corner is moveably engaged with said first corner rail bearing surface;
• said carriage assembly second corner is moveably engaged with said second corner rail bearing surface;
• said carriage assembly third corner is moveably engaged with said third corner rail bearing surface;
• and
• said carriage assembly fourth corner is moveably engaged with said fourth corner rail bearing surface;
• and
• a working surface mounted on said carriage assembly upper side.