In article , Gunner says...

How long are the pointers supposed to be? Perhaps Ive had a stroke
or its a case of brain fade..but doesnt the length of the pointer make
a difference as to the actual measurement displayed on the dial?

If this is a plunger type, where the point travels in a straight
line and actuates a rack inside the instrument, then the
length of the pointer (which screws into the plunger, using
an unusual fine thread like 4-48 or something) then the
length does not count.

If it is a type similar to a last word, where the pointer
swings in an arc, then the dial reading will indeed depend
on the length of the pointer from pivot to tip. The longer the
pointer, the more sensitive it will be, ie, for a given tip
deflection, you will see a bigger dial reading.

If this is the type, and you want to check that the one
you have is more or less correct, then simply put the
indicator in a lathe toolpost and use your crossfeed dial
to wind in a given amount of travel. The only important
issue is that the angle between the infeed and the
length of the pointer's axis should be nearly 90 degrees.

In those kinds of pivot pointer indicators the error between
the actual travel and the indicated travel goes pretty much
like the cosine of the error angle you need to get it really
misaligned by a lot before you begin to see much discrepancy.

But as mentioned, these devices work best as a null indicator,
where one is trying to zero out some error.

Jim

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