roller base

Discussion in 'Darkroom Equipment' started by RobC, May 28, 2008.

  1. RobC

    RobC Member

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    Which is the better option for a roller base, the auto reversing ones or the one way only bases?
    And, for the auto reversing bases, what is largest circumferance tank you can use on them so that you get full rotation and some before its reverses?
     
  2. Barry S

    Barry S Member

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    I'm using a Chromega non-reversing base to spin my Jobo 3010 Expert Drum with Pyrocat-HD. It seems to work fine without any streaking or uneven development. I've heard of some people disabling the reversing circuit on rollers because of issues where the developer didn't completely cover the tank surface, but I've also heard some folks recommend a reversing system. I don't think the Jobo system reverses--does it? Probably best to just disable the reversing circuit.
     
  3. RobC

    RobC Member

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    If the rotation does not do a full roatation of the tank and then some, then you have problems as part of the film will never get immersed in developer. Hence why I think people disable the reversing. But if it does a full rotation of the tank and then some, then there would be no problem and I think possibly more even development due to a more randomised flow pattern. This may not be such a problem on expert tanks, but for roll film it could be, which is why I asked whether reversing on non reversing tanks were better.

    more opinions greatfully received, thanks.
     
  4. Konical

    Konical Subscriber

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    Good Morning, Rob,

    I ordinarily use a non-reversing Beseler base. My normal procedure is to lift the drum and reverse it every thirty seconds during processing, but I'm not sure I really need to do so. I have a second base which does have the reverse function, but it doesn't seem to allow a complete 360 degree turn with each cycle, so it is also, for me, a single-direction unit.

    Konical
     
  5. pwitkop

    pwitkop Member

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    They do reverse (at least the ones I've used cpe2, and a cpp we had at school), IIRC every 5 revolutions or so. No worries with these about not completing a revolution; they turn around a central axis.

    Peter
     
  6. nworth

    nworth Subscriber

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    I've used the DevTec (non-reversing), the Jobo, and the Beseler (both reversing) with equally good results. I think it would only be fussy if you used a marginal amount of solution.
     
  7. RobC

    RobC Member

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    So the concensus seems to be that one way rotation works perfectly OK with no uneveness of development.

    Curious, I wonder what the big deal is with jobo expert tanks?
     
  8. DannL

    DannL Member

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    Just for some extra input, I use several of the Model 352 Unicolor Unirollers. Both reverse. I use them without fail to develop both sheet film (9x12cm, 4x5 and 8x10) and prints of varying sizes.

    With a Chromega 8x10 drum (4-1/2" dia) it reverses approx. every 1-1/2 revolutions.

    With a Unicolor 8x10 drum (4-3/4" dia ) it reverses approx. every 1-1/3 revolutions.

    With a Unicolor 11x14 drum (5-5/8" dia) it reverses approx. every 1-1/4 revolutions.

    Approx. 4 seconds per revolution.

    Approx 1/4 of any given tank is not occupied by film or paper when the maximun size sheet is inserted. This is the area occupied by the chemicals when first poured into the tank. In this way the chemistry hits the film/paper all at once, when the motorized base is initially turned on.

    Cheers.
     
    Last edited by a moderator: May 31, 2008
  9. edtbjon

    edtbjon Member

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    Well, they are very easy to load compared to e.g. the Jobo reel tanks or a CombiPlan. Just slide the film into the hole. (Well, with the 3010 there can be 2 films in one hole, but it's still very easy.) Also, when using enough chemicals (which is very little btw.) and proper rotation the end result is usually flawless, with totally even development.
    I've used the two other systems here mentioned, apart from the Expert drums, and I feel much more secure when using the Expert drum. There is very little "fiddling around" compared to other systems.
    (I have "of course" also developed in trays, but any of the above mentioned systems are much better than fiddling in the dark and wet for too long time hoping that everything is allright and that you havn't messed it up when you finally reach the fixer.)

    //Björn
     
  10. Jim Cole

    Jim Cole Member

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    Rob,

    I use a Jobo 2553 drum (cog lid) to develop my 4x5 sheet film. I am fairly new at this but here are my experiences.

    I started with a Beseler non-reversing drum and picked up the tank and flipped it over every 30 seconds or every minute during my testing. I fumbled the tank once and developer went everywhere. Oh, well at least it was just test film.

    I decided to get a Unicolor reversing motor to try it out. The motor would reverse about every 1.25 turns with the 2553 and my first sheets came out unevenly developed. I then disassembled the Uniroller and disengaged the reversing lever and moved the reversing switch to the outside of the casing. It looks like now I am getting perfectly developed negs by flipping the directional switch about once a minute during the critical chemical stages.

    No more flipping of the drum with the possible messy results. Flipping the switch yourself lets you accommodate whatever size drum you want to use.

    Hope this helps.


     
  11. RobC

    RobC Member

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    Thanks for that info.
    As it happens I have durst electric roller base arriving tomorrow. Its one way only so I will have to flip the tank around which is OK since I will be using a 2551 which has the lid on it and not a cog. I know you have sorted your procedure, but a big rubber stopper which you can get from chemical lab supplies would stop the risk of spilt chemistry with the 2553 cog lids. Or buy a a top with the lid for your tank. That would make getting chemistry in and out easier.
     
  12. Jim Cole

    Jim Cole Member

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    Actually I do have another lid with the rubber cap, but I find it easier to put chemicals in and pour them out using the cog lid without having to first remove the necessarily tight fitting cap. I can be more time precise this way. Now that I do not have to handle the tank so much, I doubt I will have another mishap. Oops, did I just jinx myself?