Tailstock Setover for Taper Turning

S = OAL x (D - d) / (2 L). The step people miss: the setover scales with the OVERALL length between centers, not the taper length, because the whole part pivots about the headstock center. A 12 in part with a 1.500-to-1.000 in taper over 8 in needs 0.375 in of setover; if the taper ran the full length it would be just (D - d)/2 = 0.250 in. Offset the tailstock away from the tool to put the small end at the tailstock. Shallow tapers only -- the method swings the center holes off axis, so steep tapers want a taper attachment or the compound. A setup aid; check the first part.

S = OAL x (D - d) / (2 L); per-inch setover = (D - d) / (2 L). When L = OAL it reduces to S = (D - d) / 2.

Lathe tailstock setover for taper turning between centers - first-principles as in Machinery's Handbook (Industrial Press), by name; public domain.

Pure geometry, public; the offset comes from the part length and the taper diameters.

Estimate. AHJ and licensed professional govern.

Field names used by the API: overall_length_in, large_dia_in, small_dia_in, taper_length_in, setover_in, per_inch_setover_in

• Overall length OAL is the full length between centers; the setover scales with it, not the taper lengthtailstock-offset geometry
• Shallow tapers the method swings the centers off axis, so it suits shallow tapers; steep tapers need a taper attachment or compoundmachine practice