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Thread: Another UV Light Box (16x20)

  1. #1
    Jim Sidinger
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    May 2006
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    Another UV Light Box (16x20)

    I have been thinking about exploring salt printing for a while and finally have gotten off my duff to begin. One step is to build a UV Light Box. In researching the subject, I have found several good sources from which to steal (ahem, "borrow") ideas - including several here in DIY especially a recent one by jp498. Also, I got a lot of local help from fellow LF'ers Keith Pitman and Jeff Graves.

    I finally settled on a 12 bulb T8 design which could accommodate a 16x20 printing frame - more than I think I will ever need but I've been burnt before by not building to an adequate size and having to re-do.

    A couple of notes on things I did a little differently than most of the DIY units I saw:

    1. I liked the idea of lining the box with reflective material to increase UV effectiveness but rather than use the insulative stuff I found a Nashua product called "Extreme Weather Foil Tape" which is a thick aluminum foil with super hot/cold resistant adhesive. Easy to apply and takes up little room.

    2. Rather than buy light fixtures I bought the 'tombstone' light tube holders (Leviton 23351, 60 cents/piece) and I found a ballast which ran 4 lights (Fulham Work Horse WH5-120-L ballast $16.59/piece) requiring only 3 rather than 6 for my 12 bulb unit. The tombstones screwed right onto the board on one side and the ballasts on the other. Wiring was straight forward and I saved some $$.

    3. I cut the main board with the lamps & ballasts about 1" smaller than the inside of the box frame and mounted it via L-brackets. This allows the air to be brought up from below evenly around the entire periphery of the light source. Better airflow has meant cooler operation. Mounting the axial fan (Grainger 4WT47) on the top center of the box seemed to work fine.

    4. I used 2 switches: one for lights and one for fan. Figured I might want to continue to cool box after lights were out.

    Well, after it was all done, I ended up with what you see below.

    Front View, door closed
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    Front View, door open
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    Board with tombstones attached
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    Inside detail
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  2. #2
    Jim Sidinger
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    Re: Another UV Light Box (16x20)

    Had a couple of questions so thought I'd reply via post.

    1. The shiny stuff under the ballasts is the same Extreme Foil which I put under them to act as a heat sink. The ballasts are marked to 70 C / 158 F and, while not enough to ignite wood, thought I'd be better off with spreading heat around.

    2. I was asked how the fan was mounted so am including the picture below.

    3. The ballasts are instant start type so that's why I chose the shunted tombstones.

    4. & yes, in addition to pizza you can also do "Hot Pockets". :>)

    View showing fan mounting & wiring
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  3. #3

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    Re: Another UV Light Box (16x20)

    This looks like a great project, what do you estimate the total cost to be? Are you going to make your own contact frame as well? have fun salt printing, its a really fun process

    d

  4. #4
    Vaughn's Avatar
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    Re: Another UV Light Box (16x20)

    I noticed you used a BLB tube. They work fine. The BL tubes are the same, but without the internal visible light filter, thus cheaper.

    The manufactured units I have seen used cross ventilation instead of the top. I suppose both work equally well...I know the cross ventilation pulls air across the ballasts fairly well, and if yours are electronic, they might not heat up as much as the conventional. The main advantages of the cross ventilation is that I am always putting stuff on top of the unit...the disadvantage is having to keep the unit's sides clear (can't shove it in a corner).

    Nice work! Vaughn

  5. #5
    Jim Sidinger
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    Re: Another UV Light Box (16x20)

    D,
    Thanks, it was interesting and I think I learned more about UV light printing and functionality by doing the research to design. Plus it was kind of fun. Hadn't done a project like this in too long.

    I figure that the entire cost was about $390. But I made a couple of choices which increased costs by choosing to use cabinet grade plywood and brass fittings. Also, I bought BLB bulbs instead of BL because my Home Depot had a 'deal' on them due to an overstock. However, I probably could have saved even more if I had shopped for BL's. They are less expensive/bulb.

    I found an 11x14 Formulary frame on Craigs List pretty reasonable so did not build. If/when I go 16x20 will definitely build unless I can score a similar deal.
    Last edited by denverjims; 27-Sep-2013 at 11:04. Reason: acknowledge who replying to

  6. #6
    Jim Sidinger
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    Re: Another UV Light Box (16x20)

    Vaughn,
    Thanks, & you are right about BLB's being more expensive but found some at a discount which made it closer to BL price.

    Thought about ventilation issue cross/vertical. These ballasts are instant start electronic - from my research better and more reliable than the magnetic - but are still marked as potentially getting to 70 C. I guess I was more concerned with getting air evenly out of the exposure compartment which is why I went with this design. Too much heat can cause sensitized salt paper to brown based on my readings.

    I designed with 2 1/2 inches of space from ballast top to fan bottom distance and, with the heat sink aluminum under the ballasts figure that will be better circulation than if they were inside a standard light fixture. Fan has 130cfm capacity and the entry for air at bottom is 6"x9".

    Top vs. side: - potato - potaato (I hope).

    Click image for larger version. 

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  7. #7
    jp's Avatar
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    Re: Another UV Light Box (16x20)

    Looks great! (perhaps better than mine)

    Mine doesn't get hot. I don't worry about it getting hot. The printing frame is FAR cooler than when I printed with a metal halide light. My case fan isn't very powerful. It would probably be fine without a fan, but I prefer it to run cool.

  8. #8
    Jim Sidinger
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    Re: Another UV Light Box (16x20)

    Quote Originally Posted by jp498 View Post
    Looks great! (perhaps better than mine)

    Mine doesn't get hot. I don't worry about it getting hot. The printing frame is FAR cooler than when I printed with a metal halide light. My case fan isn't very powerful. It would probably be fine without a fan, but I prefer it to run cool.
    Thanks jp,
    As I said, your unit gave me a good start in design. Had to tinker though. I guess that's what we do...

    Jim

  9. #9
    Jim Sidinger
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    Re: Another UV Light Box (16x20)

    Quote Originally Posted by denverjims View Post

    I figure that the entire cost was about $390.
    Sorry, that should have said $290.

  10. #10
    Jim Graves Jim Graves's Avatar
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    Re: Another UV Light Box (16x20)

    Congratulations ... Really nice design and well executed. Thanks for posting it.

    Where did you get the light sockets ... and what are the part numbers or relevant.specifications?

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