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Need a glass chart for your Optical Comparator?

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  • Need a glass chart for your Optical Comparator?

    Clough42 just put out a video laser etching a new one, I thought it was pretty cool.

  • #2
    I remember the shadow graph in the die shop where I worked the end of the 70s, it was big by comparison, can’t recall the maker but it stood on the floor, there was a filing cabinet with it full of acetate printed or plotted sheets you could plop on the machine, gears, screw threads showing tolerances loads of them,
    screens with radial patterns, grids all sorts of weird and wonderful overlays ( that rarely got used)
    nice fix didn’t know it was even possible, I enjoyed that


    • #3

      I have a Nikon comparator with a bunch of extra plastic overlays. This gives me an idea to make some special ones using a diode laser mounted on my mill.


      • #4
        I have not finished the video (I will) but it looks like great idea. However I do not think that a laser is needed for making new glass reticules for optical comparators or other optical instruments.

        Any computer printer can print on thin, flexible, transparent medium which is available in any office supply store or numerous sites on the web. The transparent plastic sheet can then be bonded to a piece of glass, frosted glass if it is used for a screen, with an appropriate adhesive. Depending on just where the focal plane is, front of back of the glass, the image can be either normal or reversed to allow the image side of the transparent print medium to be in contact with the frosted side of the glass.

        The same idea works for fully transparent glass (not frosted) so the reticule can be at any point in an optical path. Of course, removable overlays are even simpler as you do not need to glue them to any glass. I would suggest a transparent cover sheet to protect the markings if the ink side of an overlay is going to be exposed. Transparent, plastic laminating sheets are readily available in all sizes. Protective sprays are also easily available (Krylon, Rustoleum, and others).

        Laser and ink jet printers normally have a 8.5" wide printing path making about 8" to 8.5" the maximum width of such a print. BUT there are larger format printers that can handle wider print mediums. My Brother, ink jet printer is a ledger or 11" x 17" size and can easily print images up to 10" wide, actually some fraction larger (10.25"?). At about $150 new it was one of my better investments as many schematics and large drawings are a lot easier to read when printed in a larger size. Like the smaller ink jet printers, it also does copying, scanning, and faxes.

        That Rustoleum frosted glass spray looks like a very nice idea. That should save the need to purchase frosted glass. But I suspect any glass shop can provide frosted glass cut to any diameter or many other shapes. Actual frosted glass will be a lot more durable. Another option is to purchase frosted plastic print medium which is also widely available. I was able to find a self adhesive version with just a few clicks.

        The advantages to using inexpensive, standard printers on thin plastic medium include: cost, simplicity, high quality, full color, and time. The process is also applicable to many other marking tasks like making front panels for mechanical and electronic control panels. I have, for instance, made full color, front panels for electronic projects with the process. With a clear. laminating sheet over the transparent printed label the panel will last almost as long as one made by painting or etching processes. And with a lot less trouble and expense.
        Paul A.
        SE Texas

        And if you look REAL close at an analog signal,
        You will find that it has discrete steps.