Durst RCP20

Discussion in 'Color: Film, Paper, and Chemistry' started by Giorgio_23, Sep 6, 2010.

  1. Giorgio_23

    Giorgio_23 Member

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    Hello, I found a Durst RCP 20 processor and i would like to use it for 8x10 color paper processing... The problem is that this Durst works with a long time of developing and bleaching-fixing... about 2,20 minutes. I'm using the Tetenal Kit 5l that is for 35° developing, 45 seconds for each bath. I'm trying it with drum at 30° for 1,20 minutes, and it seems to work fine! If I try to work at 20° the processing time should be about 2,20 minutes... So, according to you can I use Durst RCP20 with chemicals at 20° and 2,20 minutes for each bath?

    Or, do you know if is possible to modify Durst rcp20 time processing (for 45'' or 1,2 minutes processing?)

    p.s.
    last question: can you suggest me a good color processor machine up to 20x24''? I'm using a 3063 jobo drum, but I would like to process all formats of paper in the same machine.

    thank you!
     
  2. Andrew K

    Andrew K Subscriber

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    yes you can modify the RCP 20 to speed up the process, but sorry I can't remember how it was done..

    A friend of mine used to use one for color and black and white processing - he had a switch on it which changed the motor speed.

    If you are only going to use 1 processing time then I would replace 1 of the gears on the drive unit - changing the size of it will change the running speed of the machine..

    You do not have to get exactly 45 seconds in each bath - 40 or 55 seconds will work just as well - as long as it is the SAME time every time

    Cheers
     
  3. fotch

    fotch Member

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    If you Google for info, you will find you can change two gears to get the proper speed for RA 4. I have a RCP20 and loved using it with the old EP-2 process. One of theses days, I may convert mine, meanwhile, I will use my Jobo.
     
  4. fotch

    fotch Member

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  5. Giorgio_23

    Giorgio_23 Member

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    For a 20° processing any experiences?
    However thanks for your help
     
  6. mtjade2007

    mtjade2007 Member

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    I have modified my RCP-20 back and forth many times. It is not difficult to do. There are a set of plastic gears that you need to deal with. One is on the driving shaft from the motor and the other is on the long driving shaft for the rack rollers. The gears can be taken off without much difficulty. I got a couple of gears found from an electronics surplus store for a few dollars. I was able to match them to speed up the driving shaft for the rack rollers to about 1 minute for the developer and blix bath. This is still still slower then 45 second desired. But The RCP-20 temperature can be lowered to maybe around 80 degrees for this 1 minute development time.

    I also modified it again to change the gear ratio so that the time becomes 3 min and 30 seconds. I thought to use it as a C-41 processor. I can use C-41 RA chemicals as it needs less than 3 minutes to bleach the film and I can run the fix and final rinse cycle on separate tanks. Well, I never get to use it yet though. I may reverse it back to the gear set for 1 minute process time for RA-4 again.

    RCP-20 uses a toothed belt for linking the gears. So the gears do not contact each other. The gears are industry standard gears and so is the belt. You can find different sizes of them for the conversion. The motor mount is adjustable so you can move the motor either closer or farther between the gears. Just adjust it so that the belt is tightly wrapped on the gears.
     
  7. thedancefloor

    thedancefloor Member

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    I've re-geared my RCP20 for RA4 also. I 3d printed some XL pitch gears that work with the original belt. The motor has 36 teeth and the other one has 11. Prints take about 40 seconds in each bath.

    I'd really like to use the machine for proofing 4x5 negatives in the studio. How do I figure the gear ratio to make the machine run at 3:30 for C41?

    Here's what I'm using so far:
    RA4 - 36 teeth on Motor gear : 11 teeth on Racks gear = 3.27:1 = 40 sec
    B&W - 20 teeth on Motor gear : 25 teeth on Racks gear = = 0.8:1 = 140 sec - original gear set

    I'm going to try this next:
    C41 - 14 teeth on Motor gear : 25 teeth on Racks gear = 0.56:1 = 200 sec
    Do these numbers look right?
     
    Last edited by a moderator: Nov 29, 2015
  8. fotch

    fotch Member

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    Wow, 3d printed.. Keep us posted. Good luck.
     
  9. raymondvanmil

    raymondvanmil Member

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    Hi. Could you please post the 3d files, or point me to them. At at the point of buying a machine like that and I do have a 3d printer! Would just be great not to have to look or design those gears myself.
     
  10. fotch

    fotch Member

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    You can buy the gears off the shelf. I use to have the info somewhere, its just a matter of getting the right gearing.
     
  11. thedancefloor

    thedancefloor Member

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    https://drive.google.com/folderview?id=0ByPRo2_iUslnT0UxZ0MtNzJ6aVE&usp=sharing
    Here are the .stl files I exported from Autocad.

    But my Autocad/Windows is crashed right now so I don't know which file is which.
    One of these files: (1.stl,2.stl,3.stl) is an 11 tooth gear for the rotating shaft that turns the rollers. The bore needs to be filed out a bit to fit the shaft. The other two files are my first attempts at making the 36 tooth gear.

    And these files are my second attempt at the 36 tooth gear. Has an outer ridge to keep the belt from sliding off (which will be slightly larger on the next version). These are the same file with slightly different center bore diameters. One of these files: (RCP_1a.stl,RCP_2b.stl,RCP_2b.stl) fits nicely onto the motor shaft without filing. :smile:

    I've printed them with PLA, but when the machine gets hot, the 36 toothed gear melts off the motor shaft! So I'm planning to preheat the chemicals and just run the machine intermittently to keep things at 38c. If that doesn't work, I'm going to have the 36 tooth motor gear printed in ABS. If that doesn't work, I'll order a metal one.

    Let me know what you come up with!
     
  12. raymondvanmil

    raymondvanmil Member

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    could you please give me some more info or point me in the right direction, can't fin dit anywhere, already got the machine in the house...
     
  13. AgX

    AgX Member

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