A double thread screw drawn by drawing diagonal lines in between the pitch. The double thread screw is a screw with threads bunched together between the pitch.
Anthony, Gardner C. Elements of Mechanical Drawing (Boston, MA: D. C. Heath & Co., 1904)
2400×2157, 385.2 KiB
1024×920, 65.8 KiB
640×575, 36.2 KiB
320×287, 15.3 KiB