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  1. #1
    Join Date
    Nov 2006
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    Default Centre punch mark magnifer

    Dear members,

    My eyesight is failing rapidly, so I need help.

    I have seen a jigger that was made in plastic, so I will try to describe it. It was circular about 50mm in dia and stood about 30mm high. In the top were two holes about 10mm in dia. One hole on one side, the other hole opposite. In one hole was a centre punch, in the other was a clear perspex rod with a domed top and cross hairs underneath.

    Looking down through the perspex, one could see two cross hairs, highly magnified, enabling it to be positioned exactly over two scribed lines.

    In position, the magnifer was removed, and replaced with the centre punch. A light wack, and a centre punch mark appeared, right on the spot.

    What's it called, and where do I buy one?

    Regards,

    Ken

  2. #2
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    SUNSHINE COAST QLD
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    Default

    Some call it a scribe point,, and it could be what you talking about is a punch centre,, not too sure,,
    www.artemiswroughtiron.com.au
    classic creations/blacksmithing
    "possibilities are endless"

  3. #3
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    Default

    Ken,is this what you are looking for?
    Mike
    "Working to a rigidly defined method of doubt and uncertainty"

  4. #4
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    Default

    What a neat little tool. I might have to get me one of them.

  5. #5
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    Default

    Are they available on OZ or do you have to buy from the US?
    Hooroo.
    Regards, Trevor
    Grafton

  6. #6
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    Apr 2005
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    Default

    Buy?

    It's not like this is beyond someone capable of a modicum of care. A piece of clear plastic, made round in a set size, a piece of drill rod the same OD and a base made of whatever you have.

    Takes a little experimenting to get the lens correct, but during machining a little polish applied to the end, while wet, will show you what the lens is doing. Once it's correct, polish it out and it will work fine. I am sure there are directions on the net somewhere.

    If you must 'buy', these are not a rare and strange thing and you should be able to find one somewhere for a reasonable price.

  7. #7
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    Default

    Giday Schtoo,

    Sounds like you have made one of these optical centre punches. If you have, can you knock up a quick drawing, I reckon this would be a great little project for us novices. Units I've seen on the web are priced around the $50 to $60 mark.

    $50 is worth saving while having a bit of fun. There is no greater satisfaction than making one's own tools.

    Hope you can knock up a sketch,

    Regards,

    Ken

  8. #8
    Join Date
    May 2007
    Location
    Ballarat,victoria
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    Default

    Heres a few websites where they make there own .

    http://www.nucleus.com/~harlan/punch.html

    http://www.gadgetbuilder.com/OpticalPunch.html

    Hope this helps .

    Cheers Plushy

  9. #9
    Join Date
    May 2007
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    Ballarat,victoria
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    75

    Default

    Or buy one here .

    http://www.timbecon.com.au/products/...ols-321_1.aspx


    Google is your Friend

    Plushy

  10. #10
    Join Date
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    Default

    Dear Plushy,

    Two holes are better than one, for storage reasons.

    Well, it seems no one has a drawing, will have to design my own.

    Can someone please tell me what radius needs to cut into the top of the perspex rod. Let's say its 12mm dia at the top, then reduced down to 10mm for the shaft. Is there any correspondence between the length of the rod, and the radius?

    The rest I can work out myself, and when drawn up, will be submitted to this forum for all to share.

    Regards,

    Ken

  11. #11
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    Default

    I have not made a whole one, just the optics for one. I used an existing punch-stand like device and made an optic doohickey to fit that. It works ok, but not worth the effort of replicating from scratch.

    The optic rod is nothing really special, A large radius on the eyeball end IIRC, Something like 4-8 inches radius is enough, with a cross carefully scribed with a razor blade in the flat end. I might have done something else with the centre though, I can't remember right now. A good polish (the finer the better, I have a small tub of clear plastic polish, something so fine it hardly works till you need it to.) and Bob's yer uncle. I'd follow what those other sites have posted, since I made my quick and ugly version after seeing them.

    If you can, I'd also try and make the body out of something that will allow some light to pass. I dunno if it will make things much better, but I can't help but think that a solid chunk of metal is going to make things rather dim at the mark.

  12. #12
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    Dear Members,

    I have prepared a drawing, in pdf format, of my interpretation of an optical centre punch. This might help a novice, like me, to make one.

    I guessed at the radius on top of the acrylic rod. Until I get around to making one myself, I won't know if it's right or not.


    Regards,

    Ken

  13. #13
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    Dodgy brother

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    Rough enough, Ken.


    The beatings will continue until morale improves.

  14. #14
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    Jan 2004
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    Mackay North Qld
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    Default Radius Cutter for Optical lens

    Ken,
    If you read the text in links the radius for the lens was 9/16".
    The radius was cut using a tool post mounted radius cutter also described therein. The text mentioned a material called Lucite.
    In the links on those pages are descriptions and plans for the radius cutter.It is on my list of tools to make.

    Cheers
    Grahame

  15. #15
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    Hi Grahame,

    I missed the bit about the radius, but picked it up on a second reading.

    Must get by gogs fixed or ease back on the "medicine".


    Thanks old son,

    Ken

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