Acquired Optical Centering Scope - How to Use?

Just picked up a "Center Scope" by the Center Scope Instrument Company of Las Angeles, Ca. I'm having trouble seeing much (or getting a sharp image) thru the eyepiece. SPI seems to have acquired the production rights to this product and all major catalogs still list these devices.

link to SPI catalog page 98:
Swiss Precision Instruments

Unfortunately, I can't find a viewable or downloadable manual for one of these things. Some of the specific questions I have are:
1. What is the adjustment know on the front, and how is it used?
2. Does it have to be at a specific height above the surface that you are trying to center?
3. Do you have to shine a light (such as a microscope light) on the area you are trying to view?
4. There is a "nosepiece" that has an angled face. Any Idea what it is or how to utilize it?



The product specs says it only has a viewing area of .100" and a 45x magnification.

http://i72.photobucket.com/albums/i1...b/DSCN3436.jpg http://i72.photobucket.com/albums/i1...b/DSCN3437.jpg http://i72.photobucket.com/albums/i1...b/DSCN3439.jpg

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Originally Posted by Jim Caudill

Just picked up a "Center Scope" by the Center Scope Instrument Company of Las Angeles, Ca. I'm having trouble seeing much (or getting a sharp image) thru the eyepiece. SPI seems to have acquired the production rights to this product and all major catalogs still list these devices.

link to SPI catalog page 98:
Swiss Precision Instruments

Unfortunately, I can't find a viewable or downloadable manual for one of these things. Some of the specific questions I have are:
1. What is the adjustment know on the front, and how is it used?
2. Does it have to be at a specific height above the surface that you are trying to center?
3. Do you have to shine a light (such as a microscope light) on the area you are trying to view?
4. There is a "nosepiece" that has an angled face. Any Idea what it is or how to utilize it?

The product specs says it only has a viewing area of .100" and a 45x magnification...

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!. Calibration adjustment. See below.
2. Yes, it has to be focused on your part, which is easy to do on a vertical mill.
3. An ordinary machine lamp is sufficient to illuminate your scribe mark. Dykem is helpful to make the lines easy to see.
4. The angled reflector will deflect a horizontal beam of light down onto the work. I don't need that feature on my scope.

Mark out your workpiece with scribed lines where you want a hole or whatever you are trying to locate. Usually, you will make two lines crossing at 90 degrees. Once the scope is chucked in your vertical mill and focused on the work, turn the eyepiece to the right and move the table until the crosshair is on the scribed line. Then turn the eyepiece to the left and see if the crosshair still lines up. If it does not, turn the calibration knob to move the crosshair half way toward the line. Repeat until the crosshair is on the line with the eyepiece turned both left and right. Now the scope is calibrated. Lastly, turn the scope so the eyepiece is facing forward and move the table to line the crosshair up with the other scribed line.

Larry

Thank you Larry for a thorough and concise explanation of how to use this tool.

Jim

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Originally Posted by L Vanice

Mark out your workpiece with scribed lines where you want a hole or whatever you are trying to locate. Usually, you will make two lines crossing at 90 degrees. Once the scope is chucked in your vertical mill and focused on the work, turn the eyepiece to the right and move the table until the crosshair is on the scribed line...

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What you will find is scribe lines made this way will look very wide at 45x. The intrinsic accuracy of your microscope should be at least 0.001", but it will be limited by the accuracy of the centering/calibration proceedure, which means wide scribe lines are an issue.

If you search for "microscope graticule" on eBay you will find ones with crosshairs and 100 divisions, each 0.1mm (~0.004") apart, for $15, which is probably the cheapest way of getting the fine lines you need for proper centering of it. Doing this centering proceedure isn't a one-time deal, since it is something you should check each time you mount the microscope in your mill. Sometimes you may use the scope just to get fairly close to a mark, in which case it might not be too critical, but when you really do need it for, say, precisely parking your mill over a broken 4-40 screw in order to drill it out, you'll want it centered to 0.001"

For some jobs you may find circle marked graticules easier to use. With the high magnification you won't be able to do direct setting relative to the circles on other than very small holes. However if you are using the table feeds and DRO to centre on a relatively wide linear feature by locating two sides and splitting the difference its often easier to judge when a circle mark just cuts the visible edge rather than trying to see when a cross hair line is accurately superimposed. Especially if the contrast is bad or shadows interfere, that angled mirror can make a big difference there. Similarly the straight cross hair can be easier when picking up the edge of a round hole or curved surface.

Such refinements are hardly needful for normal use but they can come into their own when reverse engineering or identifying layout / machining errors on a part. Especially the ones which almost fit where trying to pin down where that "half thou interference error" lies is pretty much impossible by simple conventional means. Sort of manual CMM.

Clive

Very useful for lining up headtock and tailstock on long centre lathes. String a piano wire between the two and away you go. Regards Tyrone.

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Originally Posted by Clive603

For some jobs you may find circle marked graticules easier to use. With the high magnification you won't be able to do direct setting relative to the circles on other than very small holes...

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With any microscope, higher magnification isn't necessarily better. Some things are best done at 10x and others at 1000x. A centering microscope is no different in this regard.

In principle, higher magnification lets you locate positions with better accuracy, but in practice the reduced field of view that comes with that added magnification is a limitation. The ideal centering microscope might have a zoom range of 10x-40x, but the market for these microscopes must be so limited that none has a zoom feature (or, if they do, I'm unaware of it).

I have a Titan Y-1, whose 20x, 0.38" field of view, and 0.001" resolution (with circles on the graticule every 0.01") is ideal for me. I can center it on a 1/4" hole, and still resolve locations to 0.001". For me, higher magnification would be worse, because of the reduced field. I don't know about the particular instrument described by the OP, but it might be possible to substitute a lower magnification eyepiece to increase the field of view (it depends on the optical design, since there might or might not be vignetting of the image earlier in the optical train).

This type of scope is used where I work. We call it a bombardier scope. It's used on a Kern for picking up features in order to do 4th and 5th axis work where you can't use traditional means of locating the part because the parts are generally made of material that doesn't allow it to be touch with anything other than a cutting tool. These parts are usually in the .100 range in size

Useless for picking up scribe lines. If you can't do that with a wiggler somethings wrong.

Tom

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Originally Posted by 67Cuda

These parts are usually in the .100 range in size

Useless for picking up scribe lines. If you can't do that with a wiggler somethings wrong.

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I agree about the scribe lines. If lines scribed in Dykem give you the accuracy you need for whatever it is you are doing, you don't need a centering microscope. The last time I used mine was a few months ago when I needed to remove three broken 3.5mm screws in a 100-year old part given to me to repair. In order to use as large a drill bit as possible, but still not damage any of the threads, locating the centers of each of the screws to ~0.001" was essential. This was a piece of cake with a centering microscope, but it would have been a nightmare without one.