center finder

Much like finding the 'shift' key? ;)

nb

That's not what he is talking about. Something with 2 dowels marked midway between. Set over board edge, twist til a dowel touches each side, the mark on the jig hows center.

Actually, ec has trouble expressing himself coherently - he/she/zit could mean practically anything.

Centerfinders for locating the center axis of turning stock (round or square) are quite common in the 'lathe' section of tool catalogs, or as notbot pointed out, a center finder head for a combo square is designed for the purpose.

Apparently, "dadiOH" has a similar problem. ;)

nb

It's easy on a lathe; even a pencil sharpener always finds the center of the pencil (but you gotta cut your way there).

Yes, I know. I don't recall any using a cross piece though, other than the rule of a combination square. It is true that OP could express himself more clearly but what he said was sufficient to recall other things tnan the type you mrntioned, assuming some familiarity with home made jigs and the ability to think a bit non-conventionally.

I made one for my lathe 40+ years ago. Simple to make, simple to use. Finds the center of squares, not squares and round.

gives me an idea one side for round stock and flip it over for square

but usually square is not a problem however multipurpose tools are best even if they see minimal use

I said that poorly. The one Pictured works for Squares, Not squares, and rounds and not rounds. In other words, it finds the center for all spindle turnings, regardless if square, round or in between. If you look, the jig is a V that fit's rounds and squares:

Make the one pictured. It is not multipurpose, it is just a center finder for lathe turnings. If you have an out of square "square, or out of round, "round" and draw four lines approximately 90 degrees apart, you will get a little square box directly in the center.