The invention provides a combined plotting instrument for
involute and an
ellipse. The combined plotting instrument comprises a gear case and a vertical supporting part; two gears are arranged in the gear case, the gear case and the two gears are coaxially installed, an
involute plotting device is arranged on one side of the gear case, and an
ellipse plotting device is arranged on the other side of the gear case; the
involute plotting device comprises a rotating rod, a guide rail rod, synchronous pulleys, a sliding block, a plotting pen, a connecting rod, a moving block, a tensioning device and a driving synchronous
pulley; the
ellipse plotting device comprises a suspension arm, a fixing shaft, transverse moving blocks, a fixing rod, a supporting frame, synchronous pulleys, a large gear, a small gear, a plotting pen vertical rod, a plotting pen rotating rod and an ellipse plotting pen. According to the curve plotting instrument, the involute plotting device and the ellipse plotting device are arranged, therefore, both an involute curve and an ellipse curve can be plotted, the defects that in the prior art, plotting is difficult and complex are changed, the plotting steps are simple, the track is precise, and the plotting instrument is easy to manufacture and achieve and is an ideal plotting tool for teaching and learning.