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Making a METAL HALIDE Exposure Unit

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Making a METAL HALIDE Exposure Unit

Postby BoliMan » Fri Nov 03, 2006 3:30 am

Where can I find plans to make a high quality exposure unit that uses a bright but very small metal halide lamp at the bottom of a "funnel"? I would like to know the essentials of such a unit. I have read all the posts / articles I could find here but did not get what I needed.

We want to do very detailed high definition printing in a dozen or more layers on glass so we need the accuracy of having a small bright lamp as far from the screen as possible to minimize undercutting when exposing. We want to expose a large screen - outside frame dimensions approximately 34" x 48".

I do NOT want to make one of the simple exposure units that use a series of black light or fluorescent tubes; we want a small very bright light.

Any place I can download plans for a METAL HALIDE exposure unit(or other small lamp)?

If not, what are some of the essentials? What lamps/ballasts? How far should the lamp be from the exposure surface? Should the sides of the funnel be black? White? Mirrored? What color/type of set up light? How much bigger should the glass surface be than my largest frame?

Also... this may be a crazy question, but what about using a camera flash unit and doing a series of flashes to expose the screen (I assume these cannot be "on" for very long without overheating).
Also... this may be a crazy question, but what about using a camera flash unit and doing a series of flashes to expose the screen (I assume these cannot be "on" for very long without overheating).
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Postby d fleming » Fri Nov 03, 2006 11:22 am

Buy a commercially made exposure unit and vacuum frame. Use aluminum pre stretch frames. I have newmans, I used to use them to restretch my aluminum frames and glue myself. Nowadays I just order frames stretched and have my supplier restretch frames as needed. I can't stretch and glue them myself as well or as cheap as they do. The time in stretching, maintaining, etc.,isn't worth the result. If you are trying for high end and just getting in to screening, especially on glass, you have a huge learning curve to overcome for what you are trying to do. Use yellow mesh to help with light control. Your film output better be very good as well. You may want to look into a digital flatbed that can print on glass if there is such an animal on the market. Don't know myself, just a thought. You most likely will have trouble after trouble trying to learn to screenprint and building your own equipment at the same time while expecting high end results. Distances and exposure times should be on an info sheet with your film/emulsion (whichever you decide on) for different light sources. Use those numbers as a starting point and do a step wedge test to determine best distance and time for exposure in your given situation. Good luck.
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exposure unit

Postby doncw » Sun Dec 16, 2007 12:25 pm

Hi
I bought a used polychrome plate maker on Ebay for $150 and converted it. I have around $300 in it now and can burn
screen in the 7-10 second range
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