DIY Ground Glass

Discussion in 'Camera Building, Repairs & Modification' started by Andrew O'Neill, Aug 27, 2010.

  1. Andrew O'Neill

    Andrew O'Neill Subscriber

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    Will need to make one once I have the 14x17 back completed. Can anyone point me to a website or how to get started? Thank you.
     
  2. Ian Grant

    Ian Grant Subscriber

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  3. Cruzingoose

    Cruzingoose Member

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    You can try a 1/32" glass from your local hardware store and sodium hydroxide. Just brush it on, wait a few minutes and rinse off. It leaves a fine grain very smooth surface.
     
  4. Wade D

    Wade D Member

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    Ian has a great tutorial on making a ground glass here on APUG. I've made one for my 4x5 using his technique. Not hard to do at all.
     
  5. carnago

    carnago Member

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    Interesting.
    What concentration NaOH:H2O? Or simply bare grains?
     
  6. anon12345

    anon12345 Member

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    Do you know how it compares to Armour Etch, as far as an evenly smooth surface?

    http://www.armourproducts.com/ecom-catshow/Armour_Etch.html
     
  7. richard ide

    richard ide Subscriber

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    I seriously doubt that sodium hydroxide will etch glass. And I am not lye-ing to you. ;<)
     
  8. Jim Chinn

    Jim Chinn Member

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    I experimented with armour etch on some 4x5 glass. I could never get an even surface brushing it on but I did get a fairly usable glass by floating it, although I did get some around the edges on the clean side. I don't think it would be feasible with a glass that big.
     
  9. anon12345

    anon12345 Member

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    I have used it to make some 8x10's. And yes brushing is tricky if you want an even finish. I seal and tape the back side as to keep it from being etched. I found that diluting the paste to a thin consistency works fairly well. The results are as bright as any commercial gg I have seen. It's not perfect by-far, but you can make a functional gg in just a few minutes.
     
  10. Joe VanCleave

    Joe VanCleave Member

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    I've had good results using 600 grit emory on a random orbit sander, on 2mm Lucite sheet plastic, available from big box hardware stores in US. It's not glass, but it's also inexpensive and easy. And the results are pretty good.

    I've also done the same with the 8.5"x11" plastic fresnel sheet magnifiers, available from Staple's office supply. The reverse side is flat, and takes the emory sanding pretty good. Then orient the sanded side toward the lens, and you have a GG with built-in fresnel.

    ~Joe
     
  11. Andrew O'Neill

    Andrew O'Neill Subscriber

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    I ended up just sanding a piece of plexi with medium sand paper on orbitable hand sander. Worked really well. No "hot spots". Won't have to worry about breaking the GG either.
     
  12. E. von Hoegh

    E. von Hoegh Member

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    A 14x17 - inch sheet of 1/32" glass? at a hardware? and lye etches glass? Alternate universe, perhaps??
     
  13. jon.oman

    jon.oman Member

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    A couple of good ideas Joe!
     
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  15. Sethasaurus

    Sethasaurus Member

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    Sodium Hydroxide won't do anything to glass.

    I've used the technique Ian uses and it works very well. It takes longer than an orbital on some plexi, but if you want to keep it old-school and use glass, the grinding paste is the best way.

    One idea I had was to get the guys that do sand-blast etching on glass to do a piece, but I haven't found anyone local yet..
     
  16. mgb74

    mgb74 Subscriber

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    I made a 4x5 ground glass using Ian's approach. Using rock polishing grit as I had some available. Seemed to work pretty well, though it's easy to miss very small spots unless very careful. I just used 1/8" thick glass from hardware store. I did use sandpaper on edges first so they weren't too sharp.
     
  17. keithwms

    keithwms Member

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    Get a tube of valve grinding compound from the auto or hardware store. Get two pieces of glass or plexiglas. Mix a bit of the compound into water to make a paste, apply between the sheets of glass, and rub them together, as randomly as you can. Easy and safe. And you get two pieces of GG.

    NaOH(aq) will etch glass but it is very slow with most glass.
     
  18. Newt_on_Swings

    Newt_on_Swings Member

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    My dad told me how he made one once when he was much younger out of a scrap piece of glass. I took him a week using fine sand and water by the river, to grind down by hand.

    One of his many stories, he also made a contact printer as well. My favorite of his tales is how he constructed his own quartz radio out of random parts, and how he strung up a complex antenna array on the roof of his house to get reception from around the world. All by reading instructions from books.
     
  19. Cruzingoose

    Cruzingoose Member

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    Sorry if I misled you. I thought it was the active ingredient in Armour Etch (the product I was referring to but could not remember for the life of me). If thinned slightly and applied generously, it will give an even etching.
     
  20. dehk

    dehk Member

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    Why don't you just use some WAO white aluminum oxide and do it right?

    get them at http://gotgrit.com/

    I've bought from the store before, didn't have a problem with it.
     
  21. steven_e007

    steven_e007 Member

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    Over the years I have tried Sand blasting (far too coarse!!) bead blasting (better but still too coarse) valve grinding paste (better again and now getting into the 'usable' range) and orbital and vibration sanders using aluminium oxide (better again if you can avoid hot spots and unevenness).

    None of them give nearly as good results as using some fine powdered grit and using a glass block as a grinding blank. Find the instructions that Ian Grant posted here on APUG.
     
  22. holmburgers

    holmburgers Member

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    And use TrueVue UltraVue glass. 2.0mm thick and blocks 98% of reflections with a coated surface. Nothing I hate more than seeing my reflection in the GG...
     
  23. BobD

    BobD Member

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    I'm curious -- why does the block have to be glass?
     
  24. BrianShaw

    BrianShaw Member

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    I think it is believed that a glass block will be perfectly flat, leadingto a more consistent ground flass surface.
     
  25. Ian Grant

    Ian Grant Subscriber

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    Because the grits grind both surfaces, if the material's softer it'll get ground in preference to the glass if harder the ground particles from it will interfere with the grits ands it can scratch the glass being ground.

    When grinding plastics glass tends to cause scratches very easily, so you grind with something similar.

    Ian
     
  26. E. von Hoegh

    E. von Hoegh Member

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    No. If the material is softer, the abrasive will embed in it, forming a lap, grinding the harder material. It doesn't have to be a block of glass, a block of steel will work as well. One advantage of using a block of hard material is the fact that the abrasive will not embed, making it easier to attain a random pattern.