Designing a tube system for large prints.

Discussion in 'B&W: Film, Paper, Chemistry' started by jstraw, May 31, 2007.

  1. jstraw

    jstraw Member

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    What I have in mind is a pvc tube, 8" diameter and slightly longer than 20" in length. This would accommodate a sheet of 20x24 paper since the inner circumference of an 8" tube will be just under 25". If it's too tight, I'll go to a 24" length and roll the paper the other way.

    The tube would either use one or a series of well fitted trough shaped pans (yet to be identified with a couple of inches of chemistry in the bottom.

    Prior to washing the ends would be uncapped and the tube would be rolled with gloved hands in the trough(s).

    For washing, I have an idea about using a pair of end caps, with a round hole cut in the center of the caps. A water hose would feed a low-flow in one end and the water would drain out the opposite end. The donut caps would ensure a certain depth of water in the tube. The tube would be turned during washing by a Uniroller.

    Here are the design challenges I've identified.
    1. A mechanism to make sure the wet paper doesn't roll up on itself in the tube, overlapping or collapsing on itself.
    2. Identifying a vessel that would be optimal as the development trough.

    Any ideas, comments or observations?
     
  2. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    If you hunt around you may be able to find one. Mine was made by Unicolor.
     
  3. jstraw

    jstraw Member

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  4. bdial

    bdial Subscriber

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    I have a Cibachrome tube for 16x20, the interior is plain, if that helps. The diameter is about 6 inches. Jobo tubes have ridges that are supposed to catch the two edges of the paper and keep it sprung against the wall.
     
  5. Konical

    Konical Subscriber

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    Good Evening, Jstraw,

    I think that David is correct; I seem to recall seeing an occasional very large drum (maybe for up to 24") on E-Bay. I can't recall any brand name(s).

    Years ago, I made my own from a piece of plastic tubing to which I glued one complete end cap and a second partial cap (about a 6" diameter hole in the middle for adding and dumping chemicals). It was either 8" or 10" in diameter and long enough to take 40" wide paper. I had no problem with the paper, Ilford RC, flopping loose during the processing. It adhered pretty well to the inside of the drum. I rotated manually on a bed to which I attached four upturned furniture casters. I had to work under safelight, of course, because one end of the tube was not light-tight. For the project I was working on, I just took the prints outside (it was spring, fortunately) and washed with a garden hose. The whole business was extremely makeshift--but it worked.

    Konical
     
    Last edited by a moderator: May 31, 2007
  6. photographs42

    photographs42 Member

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    I do up to 20x24 in trays but I’ve been using PVC pipe for larger for about 20 years. I have an 8” x 38” tube that I do up to 24x36. I use end caps. One is a full cap and the other has a 2” hole in it. (I assume you are doing B+W, by the way, PVC pipe isn’t light proof.)

    There are a few tricks to learn, some specific to the larger sizes, but the general process is pretty easy. First, you need a sink. The end caps leak. It takes very little solution (I use a half gal. For the bigger prints but half that would work for 20x24. I simply put the print in the tube, lift the open end and pour in the developer, slip on the cap, lower it onto the rollers and let it run. The first rotation is a bit critical in that the print must “stick” to the tube. Once stuck, it will stay there. At the end of the cycle, raise the end, remove the cap and pour the dev. out and continue with the other liquids.

    The removable cap must have a hole or you can’t get it off. The liquid seeps in around the cap and a vacuum is formed when you pull on it. Also, the hole gives you a place to insert your fingers to pull on it.

    For the size you have in mind, I would make it at least 1” longer than 20”. The paper grows when wet. ( a 36” fiber base print will grow almost 2” in length when wet.)

    Getting it out is a bit tricky also. There are two ways that work for me. One is to peel the print away on one edge and roll it into a smaller roll and carefully lift it out. The other way works best with larger prints. Peel the corners loose and in a smooth motion pull it out and let it drop into the sink wit running water in it.

    More later if you’re interested.

    Jerome
     
  7. jstraw

    jstraw Member

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    No doubt collapse would be less of a problem, as would washing, with RC paper.
     
  8. donbga

    donbga Member

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    Washing FB paper in large drums is problematic. RC works much better.
     
  9. argus

    argus Member

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    jstraw,

    I an currently making a tube system of 170cm wide.
    Therefore I use PVC pipes of 31,5cm diameter, cut in half over the length.

    I will post pictures when they are ready.

    We also have a roller system to roll the paper on for easy handling.

    Greetings,
    Geert
     
  10. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I have drums of various makes and sizes. The biggest is the 20x24" Unicolor.
     
  11. juan

    juan Subscriber

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    I use fiberglass screens behind my negatives when developing in tubes. I wonder if similar screens would be useful in removing prints from tubes?
    juan
     
  12. Donald Miller

    Donald Miller Member

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    A couple of ideas on design. First your idea of 8 inch tube is good. I would take a strip of 1/4 inch thickness acrylic and using a table saw cut the strip to the appropriate width with an bevel to the inside of the tube this would be glued to the inside of the tube to allow the print to be retained by this strip.

    Next go to a sheet metal shop and have a piece of 18 guage stainless rolled into a ten inch diameter trough with ends welded into the trough. Next fashion a drive mechanism using a small gear motor like that used by the unicolor roller base. Have this mounted over the trough with a swing away base so the print tube can be inserted. Cut and glue small radius strips to the exterior ends of your tube to cut down on the friction of the tube/trough interface.

    This will allow processing in a limited space with a relatively small amount of chemistry...if you want you can go higher tech and incorporate a multichannel timer and use it to control drain and fill of the developer, stop, and fix...even replenishment if you wish. Should you wish to go this direction, you can use peristaltic pumps to control fill rates etc.
     
  13. jstraw

    jstraw Member

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    I think the custom, stainless trough is a good idea. The rest of your ideas would be amazing but not critical for what I have in mind so I'll file them away as future refinements. I am thinking about forgoing the trough all together and just using the donut end caps all the time and pouring the solutions into the tube, rather than putting the tube in a trough. Key to this is that at least one of the end caps would have to be easily removable but not leaky.

    This way the whole works would simply be motorized by setting it on the Uniroller.

    The acrylic bevel retainer is a perfect idea. What might be simpler is to use pvc glue to glue a small radius pvc tube inside the large tube, running it's length. It would have the same effect. Maybe I could take a piece of 6" pvc and cut a series of rings that would be glued inside the 8" tube at intervals to perform this function and also prevent the wet paper from collapsing in on itself.
     
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  15. Bob Carnie

    Bob Carnie Subscriber

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    Regarding washing in a tube.
    I do not think it to be problematic, as most of the action is the chemicals leaching out of the paper. so filling and dumping should be sufficient of course a hypo clear rinse would be needed before final wash.
     
  16. Konical

    Konical Subscriber

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    Good Morning,

    "This way the whole works would simply be motorized by setting it on the Uniroller."

    I would worry about a very large drum on common motor bases. I have a 16 x 20 Chromega which I use on a Beseler rotator. With chemicals inside, it's definitely heavy and somewhat awkward. Keeping it centered and balanced on the rotator demands constant attention. A 20 x 24 drum would be even more problematic. I'd also be concerned about overstressing the small motor with relatively heavy loads.

    My own very large home-made drum has walls which are about 1/4" thick. It's far too heavy and awkward to be used on any motor base I've ever seen. Since doing 36" wide (or larger) prints is hardly an everyday experience for me, I find that manual rotation on the upturned furniture casters (mentioned in my previous message in this thread) is perfectly satisfactory.

    Unless you anticipate some kind of mass production, I'd say, "Keep it simple."

    Konical
     
    Last edited by a moderator: Jun 1, 2007
  17. w rollinson

    w rollinson Member

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  18. Bob Carnie

    Bob Carnie Subscriber

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    This sounds like a good idea. we uses a screen material for holding prints on a K16 unit . Jstraw you may want to look into this idea in your large tubes.
     
  19. Changeling1

    Changeling1 Member

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  20. jstraw

    jstraw Member

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    That looks interesting and I could simplify that design a great deal since I don't need mine to be light tight.
     
  21. jstraw

    jstraw Member

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    That looks very promising.

    One big complicating factor is that I plan to use FB paper and I will have to adequately wash the prints in whatever sort of tube system I wind up using unless I come up with a better way of washing the prints.
     
  22. donbga

    donbga Member

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    You can't adequately was FB prints in a tube. The paper base absorbs fixer and cannot be washed throughly when in contact with the back of a tube. That includes tubes with ribs.
     
  23. jstraw

    jstraw Member

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    You've tried?
     
  24. dancqu

    dancqu Member

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    There are some others. Certainly there are enough
    of that size tray available. I've an issue of Camera and
    Darkroom which details the development of large prints
    using a single tray. I'm not any way near 20x24 but I
    do use a single tray.

    I've made the method very convenient by using one-shot
    chemistry. No stop is needed and a Single very dilute fix
    yields Great LE. The same one tray can be used for
    washing though that implies a few at the most
    prints per day. Dan
     
  25. donbga

    donbga Member

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    Yes. Its difficult to get water moving around the back of the print. Also pulling a large FB print from a tube is more difficult than RC, plus as you know there is a significant difference in the time required to wash fiber compared to RC.

    I would develop, stop, and fix in the tube and wash in a tray. You can use a Kodak tray siphon with the tray sitting on your kitchen counter if space is an issue.

    Big trays go for naught these days on eBay.
     
  26. jstraw

    jstraw Member

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