Pipe Joint
This drawing shows the joint between two pipes; a thick pipe with diameter of 2 inches and a thin pipe with diameter of 1.5 inch. The pipes are neither centered nor meeting at a straight angle. The bottom part of the drawing shows the vertical projection of the pipes and the top part shows the frontal projection. The green circle on the right side of the drawing is the projection of the thin pipe onto a plane vertical to the thin pipe and is used in the constructions of the intersection of the pipes in the vertical and frontal projections. When the point A" is dragged around the green circle, the point A will trace the red curve, which is the vertical projection of the intersection of the two pipes. The green egg-shaped curve is the intersection unfolded; when wrapped around a 2" pipe, it will show where to cut the pipe to get a hole that fits a 1.5" pipe. When the blue curve is wrapped around a 1.5" pipe, it will show where to cut the pipe so that it will fit against a 2" pipe.
