In article ,
Wayne Lundberg wrote:
A modification of Grant's idea would be to use a piece of ground stock, do
your center drilling with your three jaw on both ends, then set it up with a
dog and face plate as though to cut but instead of cutting use your dial
indicator to see what is happening. Then make your fixes.

However, instead of using the 3-jaw to drill the centers (I
presume close up to the chuck to minimize flex), I would suggest using a
4-jaw and taking the time with an indicator to make sure that those
centers are *on* center. Otherwise, you could get false indications
depending on the orientation of the bar during the measurements.

Obviously, if your 3-jaw is a set-tru type, and you take the
time to set it true for each operation, this is as good as the 4-jaw for
the purposes.

Best, of course, would be if the ground stock was ground between
centers, so it already has the center holes. :-)

Good Luck,
DoN.

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