Fine Centering Scope - update

The scope came from Enco a few days ago.

It took some fiddling to figure out how to use it, but it does work.

It's not as large as I had feared.

It takes about 3" from tip of the collet or chuck holding it to the work surface. I was not able to use it in a 3/8" R8 collet without extending the quill, as the calibration routine starts with sighting with the dogleg arm along the table (parallel to the T-slots). In the one direction (arm to the left), all is clear and getting one's right eye to the eyepiece isn't a problem. In the other direction (arm to the right), the quill handwheel is in the way. With the quill down or a long collet in place, one can get it far enough down to get the left eye to the eyepiece.

The dogleg with the eyepiece is about 5/8" in diameter and 3" long.

Only the big knurled knob is adjustable. The black eyepiece is not adjustable, and one focuses by moving the quill or knee up and down.

The optical system seems well-corrected, well enough for such uses. The whole image circle is crisp.

It does seem worth the $170.00.

Once I got it aligned the first time, finding scribed crosses was easy, and so the scope is proving to be a timesaver.

Joe Gwinn

Reply to
Joseph Gwinn
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According to Joseph Gwinn :

Good.

Does that include the clearance necessary to bring the surface into focus?

O.K.

O.K. Sort of as I expected -- though the eyepiece might have been adjustable to allow you to adjust for a sharp image of the internal reticle -- useful if you need strong glasses and can't work with the scope eyepiece otherwise.

For your eyes, at least. Do you wear glasses (other than safety glasses)? If not, that might be a problem for some.

Good!

Glad to hear that.

Enjoy, DoN.

Reply to
DoN. Nichols

Yes, it does. About 1" of the 3" is the air gap between the lens and the work surface.

I used it with eyeglasses.

Without glasses, my general sphere error due to myopia would be corrected by using a somewhat different focus distance. However, my astigmatism would remain uncorrected. I haven't tried it this way, because my experience with other optical systems is that I do need the glasses to see clearly.

Thanks, and thanks to all who helped me with their experience. At base, I was buying this scope sight unseen.

One thing - now I can see the table motion when the X and Y clamps are tightened.

Joe Gwinn

Reply to
Joseph Gwinn

According to Joseph Gwinn :

O.K. That is good news.

[ ... ]

Except that the built-in cross-hairs would be unsharp while the scribe line would be sharp, so you are better off with the glasses no matter what. A focus adjustment at the eyepiece would allow you to bring the crosshair into sharp focus first, and only then would you adjust the Z-axis to bring the scribe into focus.

O.K. And as pointed out above -- without the eyepiece focus option, you really should not try to use it without your glasses, as it introduces errors.

[ ... ]

That shows you how much more resolution you are getting with the positioning.

Enjoy, DoN.

Reply to
DoN. Nichols

Good point.

I also got the $80 co-ax indicator clone from Enco. It seems to work well. I does have a spring-loaded point the goes into center-punch dimples, allowing one to use the co-ax to center on a punch dimple. I did try it, and this does work. But it takes far more space than the optical fine centering scope.

Joe Gwinn

Reply to
Joseph Gwinn

Right! You want the image plane to coincide with the reticle plane to eliminate that parallax error whether or not they are similarly sharp.

Focus as well as you can on the reticle, then adjust objective-to-target to place the image plane on the reticle.

If the ocular is not adjustable, then do what you can to make the reticle as sharp as possible with eyeglasses or whatever. Get the reticle in focus with a blank background. Look away at infinity and then back until you have best focus with minimal eye adaptation. Then adjust the objective-to-target focus or distance so the image is in same focus as the reticle and they are coplanar.

When this is right, the crosshairs won't move WRT target as you move your viewpoint around the exit pupil of the scope.

Reply to
Don Foreman

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