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Thread: Optical centre punch

  1. #21
    olderdan's Avatar
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    Hi knoba
    I found your optical punch design on your website before joining HMT. I copied it right away and it has been my go to marking punch ever since. I have used a HSS punch and all acrylic for the rest and made two optics, one with crosshairs and one with a bullseye (this is my favourite) I even copied the storage tin. Many thanks for the idea and everyone should make one, it never misses the mark.

    Optical centre punch-imgp0034.jpg

    Well deserved award
    Regards
    Olderdan
    Last edited by olderdan; 10-29-2017 at 10:11 AM. Reason: ommision

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    Jon (10-29-2017)

  3. #22
    Christophe Mineau's Avatar
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    Agree with olderdan, but can somone explain how to polish the acrylic lens ?
    Cheers !
    Christophe
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    Visit my Website : http://www.labellenote.fr/
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    olderdan (10-30-2017)

  5. #23
    olderdan's Avatar
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    Quote Originally Posted by Christophe Mineau View Post
    Agree with olderdan, but can somone explain how to polish the acrylic lens ?
    Acrylic is one of the easiest materials to polish, after removing any machining marks with 1200 grit wet & dry any metal polish (or jewellers rouge if you have any) hand worked will quickly do the job.

  6. #24
    Christophe Mineau's Avatar
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    OK thanks, I think I had bad experience in the past, maybe I was too fast on the polishing disk, will try by hand next time.
    Thanks !
    Cheers !
    Christophe
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    Visit my Website : http://www.labellenote.fr/
    Facebook : La Belle Note
    All my personal works, unless explicitly specified, are released under
    Creative Commons BY-NC-SA license.

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    olderdan (10-30-2017)

  8. #25
    Toolmaker51's Avatar
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    In the trade, these are known as bombsights.
    My optical center punch is commercially made, it's a long time 'friend'. I have no clue about the optic radius, actual magnification or focal length, but it must be relatively high.
    I'm near-sighted yet cannot use it without eyeglasses, that would make the focal length at least 18". It's not crosshairs but a .003 dot, slightly wider than a fine scribe line. It will locate centers within .002 all day.
    There is no reason to suspect knoba's is any less accurate, therefore a worthwhile project.
    Last edited by Toolmaker51; 04-03-2018 at 04:10 AM.
    Sincerely,
    Toolmaker51
    ...we'll learn more by wandering than searching...

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  10. #26
    Okapi's Avatar
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    Quote Originally Posted by Christophe Mineau View Post
    OK thanks, I think I had bad experience in the past, maybe I was too fast on the polishing disk, will try by hand next time.
    Thanks !
    Hi Christophe,
    You can found polishing paste for watch synthetic glasses which goes for cleaning and polishing all optical sights or protecting glasses in the workshop, the result is spectacular only with a clean cloth and some human oil… ;-)


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