crank it!

[Tony Wells]

Can't quite see how offsetting the ts would work, Bill. Since you can't offset the headstock center (not the center drilled in the part), offsetting the tailstock (again, not the center drilled in the part) all that could do is throw the centerline between the drive center and the tailstock center out of line, resulting in a taper in whatever you are turning.

Of course, using multiple centers drilled in the part would yield offset journals/crankpins. But, the centers on the lathe describing the centerline of the machine must be aligned, as you said. Even if you could offset both the headstock, and the tailstock, as long as they were aligned, you get a true journal, not one with a throw.

Your method of multiple centers as you have drawn will work, however. The tailstock is not set over for that.

Edited for spelling

 

[Tony Wells]

I figured you knew that a taper would result from an offset ts, which made me wonder why you redlined that statement in the quote. I agree with the multiple centerhole method completely. I always work in a chuck rather than strictly between centers, unless I need virtually zero runout. Then, by all means, tailstock pressure must be controlled, even to the point of temperature compensation.