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Thread: Use for glass lenses

  1. #1
    OptiWizard
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    Use for glass lenses

    I have five drawers of crown glass lenses. Any suggestions for them other than throwing them in the recycling? My only thought is that they might be of use to a glass blower. I suspect the two response from a blower would be:
    1. What the hell do you expect be to do with those?
    2. Holly crap. I haven't seen that quality glass in years. How much do I have to pay you?

  2. #2
    Master OptiBoarder
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    The only thing I can think of is to grind them into some discontinued frames and donated to lions club. Might be helpful to some if you can do a bunch of plus spheres? (like readers)

  3. #3
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    Quote Originally Posted by mervinek View Post
    The only thing I can think of is to grind them into some discontinued frames and donated to lions club. Might be helpful to some if you can do a bunch of plus spheres? (like readers)
    Good idea except the glass edger, heat treater, and drop ball tester went on a dump run last year. For the younger members of the audience, a drop ball tester is what we tossed our coat on when we returned from the afternoon coffee run.

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    You actually had to drop ball test lenses yourself?

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    Quote Originally Posted by Lelarep View Post
    You actually had to drop ball test lenses yourself?
    After I unsaddled my horse Tillyer that I rode in on. (Bonus points for those who get the horse name reference.)

    Yes we did. Edge. Safety bevel. Heat treat. Ck for a good Maltese cross in the polariscope. Pray. Drop ball. If the lens showed a good Maltese cross in the polariscope it would only break if the job was overdue and the pt. was going to go ballistic if the didn't get their glasses TODAY.

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    Quote Originally Posted by waynegilpin View Post
    Good idea except the glass edger, heat treater, and drop ball tester went on a dump run last year. For the younger members of the audience, a drop ball tester is what we tossed our coat on when we returned from the afternoon coffee run.

  7. #7
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    Quote Originally Posted by Lelarep View Post
    You actually had to drop ball test lenses yourself?
    The FDA still requires all glass lenses to be individually drop ball tested. The test should be done after finishing and before mounting. So if you are edging glass you need to drop ball test every lens, with some exceptions explained in FDA code 21 CFR 801.410(C)(3). Even if you handstone a bit off a previously hardened and tested lens, the lens needs to be hardened and tested again.

  8. #8
    Compulsive Truthteller OptiBoard Gold Supporter Uncle Fester's Avatar
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    When an accidentally inserted plastic lens catches fire in the 1,200 F kiln never ever try to put the fire out by directly blowing on it. The resulting now blast furnace generated fireball rolls back at you.

    Eventually your eyebrows grow back.


    Or so I'm told.

  9. #9
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    Quote Originally Posted by Uncle Fester View Post
    When an accidentally inserted plastic lens catches fire in the 1,200 F kiln never ever try to put the fire out by directly blowing on it. The resulting now blast furnace generated fireball rolls back at you.

    Eventually your eyebrows grow back.


    Or so I'm told.
    Excellent advice, for life in general. If it's a fire larger than a match, you generally can't "blow" it out. All one does at that point is provide a pressurized stream of 16% oxygen to said fire.

    Quote Originally Posted by Kwill212 View Post
    The FDA still requires all glass lenses to be individually drop ball tested. The test should be done after finishing and before mounting. So if you are edging glass you need to drop ball test every lens, with some exceptions explained in FDA code 21 CFR 801.410(C)(3). Even if you handstone a bit off a previously hardened and tested lens, the lens needs to be hardened and tested again.
    Good to know. I have literally never had to deal with glass lenses, outside of theory, materials lab in college, in a trial frame, and some horrifying stories from professors and consumers, so I had no idea.

    What can I say? Some of the contributors here have been in practice (and subsequently retired) rather longer than I've been alive. It's why I'm a member here, I never fail to learn things from the members here.

    Quote Originally Posted by waynegilpin View Post
    Good idea except the glass edger, heat treater, and drop ball tester went on a dump run last year. For the younger members of the audience, a drop ball tester is what we tossed our coat on when we returned from the afternoon coffee run.
    It's actually too bad you tossed them, some museum or college might have wanted them for a display.

    I actually got a chance to use something similar to a drop ball tester in lab once, the professor wanted to demonstrate how strong plastic lenses are now. So I volunteered. I remember it was some kind of device loaded with a rather large spring, with a steel ball at the end, apparently the spring was meant to allow for a compact device, so one didn't need a larger drop height (and probably to provide a fully contained device that had easily repeatable results). At that point, being much younger, stronger, and dumber, I yanked that thing back as hard as I could and let it rip. It was easy to see that his demo lens had taken a beating over the years, with some rather obvious damage. Well, having given it everything the device had, it actually managed to decimate the lens on impact. The professor was speechless for a moment and then said "That's not what I was trying to demonstrate..." and put a brand new lens in it and asked someone else to do it. Of course, that time, the device hit the surface of the new lens and the outcome was entirely uneventful.
    Last edited by Lelarep; 07-22-2020 at 01:19 PM.

  10. #10
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    Quote Originally Posted by Uncle Fester View Post
    When an accidentally inserted plastic lens catches fire in the 1,200 F kiln never ever try to put the fire out by directly blowing on it. The resulting now blast furnace generated fireball rolls back at you.

    Eventually your eyebrows grow back.


    Or so I'm told.
    Saw that once at AO. The tech that did it insisted that it was a glass lens. Unfortunately for her the job tray was white (plastic lenses) not grey (glass lenses) and the other lens in the tray was plastic.

  11. #11
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    Quote Originally Posted by waynegilpin View Post
    Saw that once at AO. The tech that did it insisted that it was a glass lens. Unfortunately for her the job tray was white (plastic lenses) not grey (glass lenses) and the other lens in the tray was plastic.
    What, you've never seen someone get glass for one lens and plastic for the other?

  12. #12
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    Quote Originally Posted by Lelarep View Post
    it was some kind of device loaded with a rather large spring, with a steel ball at the end, .
    We had a sales rep bring one of those in to demonstrate to the MD's how much safer her lenses were vs the inferior lenses that I was using. She asked me for a sample lens from our inventory. After demonstrating hers, she warned everyone that our inferior lens was about to shatter. It didn't on the first try, or the second, or the third. At that point she checked the lens and was upset that it was also pcarb. I was confused. "Oh you wanted to demonstrate the impact resistance of your pcarb to one of our CR-39's? I'm sorry. I'll go get a CR-39 for you." The docs accused me afterwards of screwing up her demo on purpose. Who? Me?

  13. #13
    Master OptiBoarder
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    I gave a box of glass lenses to a customer of mine years ago. Here is what she did with them. They were fired in a kiln.
    Click image for larger version. 

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  14. #14
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    Very nice.

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    Where in CT are you located? Perhaps I could take them.

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    Quote Originally Posted by Uncle Fester View Post
    When an accidentally inserted plastic lens catches fire in the 1,200 F kiln never ever try to put the fire out by directly blowing on it. The resulting now blast furnace generated fireball rolls back at you.

    Eventually your eyebrows grow back.


    Or so I'm told.
    Funny

  17. #17
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    Quote Originally Posted by jefe View Post
    Where in CT are you located? Perhaps I could take them.
    Southeastern CT, near New London. But I do get up to the Manchester area once or twice a month.

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