lathe tailstock center hole sizing

[bobc]

i'm looking for a formula or calculator for minimum center hole diameter to workpiece weight.
we use a 70 degree center, and work piece weight runs from 1/2 ton to 80 tons.
i need something to convince our customer base to agree with changing something we have all over looked over the years.
currently the small(1 5/8" diameter) center holes used on some of the heavier products are working on the roll lathe tailstock centers forcing us to redress at frequent intervals.
the larger center holes(3" diameter) work well. the tailstock centers on the finish lathes are heat-treated H-13 and the center plugs are usually flame-hardened 1045 at minimum.
thank you in advance,
bobc

 

[EdDanzer]

The best method to determine capacity is finite element analysis. To get correct answers the analysis should be done with gap or non linear methods. If you are good with math and need only approximate values, the Machinery Handbook has formulas that will help.
Are you using live or dead centers? If you are rotating on a dead center it probably will fail.