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Posted to rec.crafts.metalworking
Bill Schwab
 
Posts: n/a
Default Test indicator dumb questions

Hello all,

With respect to dial test indicators, I am struggling with understanding
auto-reverse. It appears to be good, but what is it? I see lots of
mention of not needing to flip a lever; are such indicators obsolete
now? Is there any reason one would want one?

It might help to start w/ my import's behavior: the dial advances
clockwise from zero regardless of the direction of motion of the point.
It looked weird at first (the dial markings suggest it would do
something else), but I figured it was probably by design, having
something to do with an indicator version of backlash near zero.

When indicating a vise or a part, I use the cross travel to make contact
with the point and then continue moving to get a non-zero reading and
work relative to that. I don't bother to move the dial, though it might
be smart to "permanently" offset it so that I'm working at zero vs. 15.

While not in the market right now, I am thinking ahead to a rotary table
and wondering how I am going to align it. A centering indicator is one
option, but it looks a little long for a mill-drill. I might be able to
make it work by mounting it in an R8 collet, bumping in the table, and
then changing back to my ER chuck for normal work. With the mill's
dials locked, (if needed) I could move the table to free up space under
the spindle, change, and then start work with the RT's axis at zero on
the dials.

Is there an easier way? Is there another type of indicator I should
consider?

Bill