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Thread: Midtone Machines - Automatic Film Processing Machine

  1. #21

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    Re: Midtone Machines - Automatic Film Processing Machine

    Quote Originally Posted by AndrewBurns View Post
    Do the JOBO expert drums show any issues with chemistry not getting to the back of the film? I've used the 'taco method' for developing my 4x5 sheet film with a hair band to hold the film and there was a mark where the band was touching the back of the negative and the anti-halation layer didn't go away (it wasn't noticeable in the scan at least). I do like the 'mail tube' idea of holding film, specifically because it can hold a wide variety of film sheet sizes without modification.
    Jobo drums are not cylinders. They are barel shaped so there is little if any contact between the back of the film and the drum.

  2. #22

    Re: Midtone Machines - Automatic Film Processing Machine

    Pretty clever, and definitely something I could imagine making work in the machine.

    Maybe of interest I got a quote from the only place I'm aware of in my country (New Zealand) that processes E-6 sheet film and they want $17 NZD per sheet of 4x5 processed...

    Also currently getting quote for 3D printing some prototype components and received a shipment of sample power supplies today, things moving along at pace.

  3. #23
    Tin Can's Avatar
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    Re: Midtone Machines - Automatic Film Processing Machine

    Jim,

    Now that barrel shape impresses me.

    I have not heard of that before.

    Perhaps I will try one of these very expensive plastic cans.

    Thank you!

    Quote Originally Posted by Jim Noel View Post
    Jobo drums are not cylinders. They are barel shaped so there is little if any contact between the back of the film and the drum.
    sin eater

  4. #24

    Re: Midtone Machines - Automatic Film Processing Machine

    New post, this time with detail of the developing tank design.

    http://midtonemachines.com/news/the-develop-tank/

    I've also included a shot of some parts I've ordered in for prototyping and I have some 3D printed developing tank pieces on the way for doing fit and functional checks before getting the final versions made.

  5. #25
    Peter De Smidt's Avatar
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    Re: Midtone Machines - Automatic Film Processing Machine

    Great work! I've never seen a tank with a horizontal seam like that. Making it leak proof won't be a challenge?
    “You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
    ― Alexander Den Heijer, Nothing you don't already know

  6. #26
    Foamer
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    Re: Midtone Machines - Automatic Film Processing Machine

    I've been doing fine processing B&W with my Patterson tank and SP-445. However, if I read it right you're designing your machine to do C-41? If so, yes I'm interested. Mostly 4x5 but also 35mm and 120.


    Kent in SD
    Qui sedes ad dexteram Patris,
    miserere nobis.

  7. #27

    Re: Midtone Machines - Automatic Film Processing Machine

    Quote Originally Posted by Peter De Smidt View Post
    Great work! I've never seen a tank with a horizontal seam like that. Making it leak proof won't be a challenge?
    Peter, the now discontinued Phototherm used a very similar tank and I can see why after going through the design process myself. Because the liquid level never gets above just under half-way up the tank the seam and spindle pass-through only need to be light-tight and not water tight. The JOBO design means there's no seam but because the entire tank rotates you can only get chemicals in and out through the middle of the tank, which means you need a lifting mechanism as well which this design doesn't.

    Quote Originally Posted by Two23 View Post
    I've been doing fine processing B&W with my Patterson tank and SP-445. However, if I read it right you're designing your machine to do C-41? If so, yes I'm interested. Mostly 4x5 but also 35mm and 120.


    Kent in SD
    Kent, yep this will be capable of doing everything, C-41, E-6, B&W, either with standard pre-set programs or whatever you want to program in (I plan for a large touch screen and some buttons as the interface). Personally I really want it for doing 4x5 E-6 film but I also shoot a lot of 4x5 Ektar and 35mm of all types.

  8. #28
    Peter De Smidt's Avatar
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    Re: Midtone Machines - Automatic Film Processing Machine

    Quote Originally Posted by AndrewBurns View Post
    Peter, the now discontinued Phototherm used a very similar tank and I can see why after going through the design process myself. Because the liquid level never gets above just under half-way up the tank the seam and spindle pass-through only need to be light-tight and not water tight. The JOBO design means there's no seam but because the entire tank rotates you can only get chemicals in and out through the middle of the tank, which means you need a lifting mechanism as well which this design doesn't.
    Got it. Neat!
    “You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
    ― Alexander Den Heijer, Nothing you don't already know

  9. #29

    Re: Midtone Machines - Automatic Film Processing Machine

    Hi there, cool project just like an updated Phototherm, I am not sure if the hairdryer is used to maintain temp or just drying?

    I have also played around with silicone heaters on tanks metal and thermoset plastics, I am not sure how they would fare with thermoformed 3D printed plastics after a while. Something you may need to design for, or perhaps have a stainless steel element sealed on the bottom (I have done this for my nova clones)

    Otherwise, why not make use of spindle for temperature maintenance (although close to film) which brings me to another question; the chemicals will be preheated before coming into the tank correct?
    The Container Lab
    www.thecontainerlab.com/blog

  10. #30

    Re: Midtone Machines - Automatic Film Processing Machine

    Yes the bulk of the heating is done using an immersion heater in a separate tank prior to pumping into the development tank, heating the development tank is just required to prevent the chemicals cooling down over the few minutes they're in there. The final tanks will likely be made from a polyurethane compound using vacuum resin casting (I don't think production volumes will be high enough to justify injection molding) which has a heat deflection temperature around 72 degrees Celsius. Realistic film developing process temperatures will be more like 40 degrees C so I don't think there will be a problem with deformation, but if there is during development I might have to look into more heat resistant plastics.

    As I mentioned in the blog I'd rather not have any kind of electrical contacts on the developing tank because they're sure to get unreliable eventually given that the tank is being connected and disconnected every cycle. This means that any temperature maintenance has to happen from the outside of the tank.

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