Just got the import coaxial indicator from Enco.

The main spindle on this thing, and thus the entire body, wobbles with a
TIR of 0.020" at the lower end. In other words, the axis of the unit is
offset (or bent?) from the axis of the stub that goes into the machine
collet.

Is this a defect, or a feature?

--Remember what Gomez said when he saw his son for the first
time: "It's an Adams!". It's an Enco! Next time buy quality, heh.

--
"Steamboat Ed" Haas : Just another fart in
Hacking the Trailing Edge! : the Elevator of Life...
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

On Wed, 06 Jul 2005 03:22:20 -0500, Richard J Kinch
wrote:

Just got the import coaxial indicator from Enco.

The main spindle on this thing, and thus the entire body, wobbles with a
TIR of 0.020" at the lower end. In other words, the axis of the unit is
offset (or bent?) from the axis of the stub that goes into the machine
collet.

Is this a defect, or a feature?

It sounds like it's unable to pull up all the way. This wouldn't
hurt function as long as you take up that slack in use so the dial
registers all motion, but it's a defect rather than a feature.

I seem to recall that the first one I got from the "old Enco" was
defective. They replaced it cheerfully at no charge.

Don Foreman writes:

It sounds like it's unable to pull up all the way.

I took it apart and the rotating shaft part itself is what's off. This
looks like a ground and polished rod, about 1/2" dia x 4" long.

I was thinking maybe it is supposed to be offset a bit to somehow guarantee
some wobble to work with? The instructions aren't at all clear. But
they're in Engrish.

Don Foreman writes:

This wouldn't hurt function as long as you take up that slack in use ...

You might think that. But it does seem to be a problem, because when the
indicator probe is offset from the spindle axis, this adds a component to
the indication that is not aligned with the X or Y direction, making it
nearly impossible to zero in on the sweet spot. You are hunting around a
two-dimensional space for a null, but without a monotonic slope to follow.

Essentially you are trying to zero out two different, independently (mis)
aligned offsets at the same time, the spindle to the indicator, versus the
spindle to the work, and the axes of table motion affect each differently.
So no matter how I turn the dial body or twiddle the leadscrews, the last
few thou won't disappear. You zero one axis, and the other unzeroes.

On Wed, 06 Jul 2005 03:22:20 -0500, Richard J Kinch
wrote:
Just got the import coaxial indicator from Enco.
The main spindle on this thing, and thus the entire body, wobbles with a
TIR of 0.020" at the lower end. In other words, the axis of the unit is
offset (or bent?) from the axis of the stub that goes into the machine
collet.
Is this a defect, or a feature?
I have the same co-ax indicator, and it did not wobble in
operation. The wobble is apparently a defect and not a feature
but this may not affect operation as the body is stationary
[although it does move up and down on the shaft] during
operation.


Now the had part ...

I had used this indicator a total of 5 times in about as many
months and when I went to use it the last time the indicator
would not move unless the tip of the pointer was at least a inch
away from center.

Disassembly showed the tip on the AGD1 indicator had snapped
where it screwed into the indicator stem. Examination with a
magnifier shows the typical gray matte fracture of a hydrogen
embrittlement failure. Apparently the tip was hard chrome plated
and never baked. I don't know if the indicator has a US standard
4X48 thread or some metric thread as I can't get the broken stem
out. Anyone have a suggestion? (other than buying a Blake?)

MY APOLOGIES.

This was all due to a bad R8 3/8" collet, not the indicator.

I was using an untried R8 collet that came with an old machine. Looks like
the previous owner ruined it and just put it back in the set.

I 3-jaw chucked the indicator in the lathe, and the TIR was only 0.001,
within the chuck's holding error.

On Wed, 06 Jul 2005 15:40:08 -0500, Richard J Kinch
wrote:

Don Foreman writes:

This wouldn't hurt function as long as you take up that slack in use ...

You might think that. But it does seem to be a problem, because when the
indicator probe is offset from the spindle axis, this adds a component to
the indication that is not aligned with the X or Y direction, making it
nearly impossible to zero in on the sweet spot. You are hunting around a
two-dimensional space for a null, but without a monotonic slope to follow.

Essentially you are trying to zero out two different, independently (mis)
aligned offsets at the same time, the spindle to the indicator, versus the
spindle to the work, and the axes of table motion affect each differently.
So no matter how I turn the dial body or twiddle the leadscrews, the last
few thou won't disappear. You zero one axis, and the other unzeroes.

If the shaft wobbles it is definitely defective. There is no
perceptible play in mine. If I center on something that is round and
smooth, as a ground endmill shank held vertical in the vise, the
needle doesn't even quiver as I turn the mill spindle.

I bet they'll exchange it for a good one. They're very handy gadgets
at times. I used mine today to center on a hole I wanted to make
larger by boring but keep the same center.

I have no complaints about the Enco coaxial indicator. I can't say
the same about their boring head as compared to a Criterion head.
They look nearly identical but they sure don't work the same!