To get a really accurate placement, the next thing to do is indicate in
the rotary table. Here you can see my rather old Starett Last Word
indicator. I put it in a collett and preload it a bit. In the photo
it looks like the tip of the indicator is hanging in space, but it is
actually touchng the back of the hole in the rotary table. I then
run the table through 360 degrees of rotation watching for the maximum
deflection on the indicator. If there's more than a thou or so of
deflection, then there's probably some debris on the insidie of the
hole which needs to be removed. I'll then rotate the spindle 90 degrees
to the left and 90 degrees to the right. The true center will be
half way between the two readings.
I like to make sure that when I do the final adjusting for centering that
I'm on the same side of the backlash as I'll be using when I'm cutting.
So if the cutter moves from the center to the right side, then I want
the cutter moving in the same direction when I'm doing the center
adjustment. If I'm on the wrong side of the backlash, then I'll over
compensate and start over now coming from the correct side.
Smaller...
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