Wigglers

[Toolmaker51]

Only 1 year, 8 months, 22 days [908,630 minutes] past-post. But good work doesn't disappear.

The pump center is an easy build, user friendly, and stores in a minimal space.
Also not particular to precise overall straightness as a gimbal or orbiting pointer.
Long as center drill on part and point of rod mate correctly, length negates relative error at tailstock. Closeness of indicator to part will generate nearly 100% of available sensitivity.

Certain indicating methods should be utilized for practice and a sense of "oh yeah, this works too".
Back in the day [waaay pre me even] wigglers, simple lever indicators
and toolmaker buttons were THE standards of precision setup.
Even center to center work evolved this way...long before the milling machine, jig bore. or anything with means to orientate a fully independent 3 axis coordinate.

And for readers, Marv's ball & socket wiggler corresponds to pictured lever indicator in what way...? Click the jpeg for a hint.