My DIY film processor

Discussion in 'Darkroom Equipment' started by Greg Davis, Sep 5, 2010.

  1. Greg Davis

    Greg Davis Subscriber

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    I have been building a film processor for my darkroom to allow better temperature control than what my Unicolor motor base can provide. Taking a note from Jobo, I use their drums, but everything else is off-the-shelf parts from the hardware store or kitchen supply store.

    The base is a 36x18 inch piece of melamine intended to be a bookshelf. I reinforced it with perforated angle steel and bolts to prevent sagging, then installed leveling feet. The water tank is a stainless steel buffet tray from the kitchen store with a perforated tray to provide a raised surface above the heating element.

    The heater and pump are from a pet store and hold the water steady at 100°F very well. The thermostat on the heater only goes to 92°, but it had a slot in the back for an allen wrench to adjust it, so while it reads 92° on the dial, the actual temperature is 100°F. The pump is a small submersible one for lizard tanks.

    The drum is supported by two stainless steel rods that rest in some of the perforations of the inner tray. The rollers are teflon rod that came with centered holes, I just cut them to length. I am still building the motor section, but it is the guts of a Unicolor base put into a new box, and I have removed one of the large wheels from the axle, then extended the axle and placed a large fender washer on the end to connect to the magnet on the base of the drum. I'll post pictures of that part once I finish it.

    I built this for the challenge, and for the fact that I can easily replace any part without having to hunt down old Jobo parts. My motor may eventually give out, but I'll cross that bridge when I get there.
     

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  2. jeroldharter

    jeroldharter Member

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    Excellent beginning. Looks nice too. A couple of thoughts.

    I wonder about a longer tray or a two tray setup, one for the drum and the other for chemicals. I often do a large run of multiple drums so it is nice to have a tempering bath with the chemicals ready to go.

    It the temperature adjustable? Phototherm made submersible heating elements with a thermostat that work very well and would be goof for your setup, perhaps with a very small aquarium pump to circulate the water.

    Do the rollers also work with Expert drums? I use a smattering of 1500, 2500, and expert drums.

    Obviously, the motor is going to be the most difficult part. I don't mind manually emptying the drum and pouring in new chemicals. But the motor is the real labor and drudgery saver. It would be best I think if the motor moved a mechanism that could rotate any type of drum from BTZS tubes to Jobo Expert drums without need a special attachment point like a cog lid or a magnet. Kind of like a rotisserie basket or some mechanism that does not require the use of one brand/style of drum. I don't know how to do that but I think that a clever craftsman could develop a new, poor man's Jobo with off the shelf parts and good craftmanship that many people would buy.
     
  3. Exeter2010

    Exeter2010 Member

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    Greg - Wow! This is excellent and from the looks of it, I'd prefer it to any Jobo for the reasons you stated. Do you have any drawings, plans or part lists for this that you'd be willing to send? I'd sure like to try to tackle one like this myself.

    Very nice job!

    Regards,
    Phil Maus
     
  4. Greg Davis

    Greg Davis Subscriber

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    Jerold, I only want to use this for film, so I used the largest food tray available, which will take an 11x14 Jobo drum. Since I max out at 8x10 for my film, this isn't a problem. I have used an expert drum, but like the 2500 and 2800 series drums for film. Obviously if someone were going to build one themselves, they should make it to fit their needs. As the last image shows, I can get 5-6 glass beakers with the chemicals into the water bath for tempering, and yes, the heater uses a thermostat and is adjustable. I paid $20 for it. I agree that more universal connection to the motor would allow several types of drums to be used, but since I only use one type and diameter, I designed it for the quickest and easiest type for my workflow.

    Phil, no I don't have any plans, as I have made it up as I went along. But I can tell you what parts I have gotten if you need it.
     
  5. AgX

    AgX Member

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    I like the idea of using a buffet-stove tray.

    It seems you used cramps to fix the rods an the bushings on the rods. I have not come across SS cramps so far though.
     
  6. tim k

    tim k Member

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    I like it. But what are you pumping?
     
  7. Greg Davis

    Greg Davis Subscriber

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    Tim, I fill the serving tray with water and use the pump to circulate it to keep the temperature steady as the heater warms it, the photos do not show water in the tank. AgX, I used these.
     
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  8. tim k

    tim k Member

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    Ah, that makes sense. I've been trying to figure how to set up a pump to cool my water bath, thought you might have my solution.
     
  9. jeroldharter

    jeroldharter Member

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    Eager to see your pictures with the motor.
     
  10. Andrew K

    Andrew K Subscriber

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    Great idea...I had been wondering what to do when my Jobo eventually gave up the ghost.....

    I'm curious to see how well the drums will drive with chemistry in them if you are not directly coupling the motor to them? Also are you going to rotate the drums in 1 direction, or have 2 way rotation like a Jobo does?
     
  11. Greg Davis

    Greg Davis Subscriber

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    The motor will be attached to the drum via the drum's magnet, and it reverses every rotation.
     
  12. atlcruiser

    atlcruiser Member

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    About how fast does the JOBO drums turn? What does the change in direction really do? I am on the same basic track as the OP and need some info...this is a nice set up so far :smile:
     
  13. hrst

    hrst Member

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    Change in direction is used so that the chemicals are mixed randomly, instead of exhausted developer "dragging" along the film which could cause some streaking. When it stops suddenly, the chemical in motion spreads everywhere.
     
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  15. SMBooth

    SMBooth Member

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    You could offset the rollers so it rocks instead of reversing if you making your own
     
  16. Andrew K

    Andrew K Subscriber

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    Can I ask - how are you making the motor reverse direction?
     
  17. SMBooth

    SMBooth Member

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    Depends on the sort of motor, if its a permanent magnet DC motor then just reverse the connection with a relay and timer.
     
  18. AgX

    AgX Member

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    Off-setting the rollers would mean to actually let the rollers untouched but to install a kind of cam-ring on the lower part of the drum.

    But still this would yield a rather constant flow (depending on the cam though). Reversing would induce turbulances and thus more mixing of the processing solution.
     
  19. Greg Davis

    Greg Davis Subscriber

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    I am using the motor and gearbox from a Unicolor motor base. It is already set to reverse itself, all I am doing is putting it in a different case than the original.
     
  20. jeroldharter

    jeroldharter Member

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    I heard of someone using the wheels of an RC car as a rotation motor. I wish I was handy with electronics...
     
  21. alexhill

    alexhill Member

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    This is AWSOME! I, and perhaps many others, would apprete it very much if you did a write up on the build. A site like instructables.com is a really easy way to make such a write up.

    Thank you so much for sharing this!
     
  22. MartinP

    MartinP Member

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    Nicely done ! An idea to make the drum/tank drive even more universal (in place of only Jobo magnet coupling) might be to have one driven square shaft with longitudinally adjustable 'wheels' to transfer the rotation and then another, moveable, undriven shaft to provide the other half of the support for the drum/tank. Like many people I had vague ideas about a Jobo replacement, but you have progressed much further ! :smile:
     
  23. Alessandro Serrao

    Alessandro Serrao Member

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    Be careful that the water pump has a maximum temperature allowed, typically 35°C. You're not supposed to go past this limit otherwise the resin insulator inside the pump start to melt with the risk of an electric shock.
     
  24. bblhed

    bblhed Member

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    As a DIY person I have to say that I really like what you have done so far, can't wait to see the finished product. Good luck.

    I know that you are trying to stick with parts that you can use your car to go and get if you need to replace them, but I would like to recommend McMaster Carr http://www.mcmaster.com as a parts source, they have just about everything you might need and generally can have it at your door next day even with ground shipping.
     
  25. Farside

    Farside Member

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    Bit of an old thread I know, but reading it gave me cause to speculate what would happen if, instead of a reversal taking place, there was an eccentric flange on the drum. After all, Jobo themselves sold a 15xx tank with an extended flange on it to allow use on the older machines. The exact same flange with a wobble, would give a fair old bit of essentially random distribution inside.
     
  26. CatLABS

    CatLABS Subscriber

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    Of course that's not a problem anymore as it might have been 3-4 years ago...

    But whatever happened with this project? It seemed to have lots of promise, and was really cool looking too?