Dave Jeffery
16-Mar-2010, 13:31
I'm building a processor that will rotate both drums and BTZS tubes at the same time for 4x5 film development.
A programmable digital motor controller can be programmed to rotate a drum, reverse rotation and also sweep the motor back and forth. There is also some speed adjustment possible in both directions.
Ultimately I would like to program both drums and tubes to spin with the same cycle so lots of sheets of film can be processed at the same time. The agitation cycle must also allow individual tubes to be processed at different times. Both the drums and the tubes can be removed quickly but it seems like the initial agitation should happen for both the drums and tubes at the same time to get the development started. The drums can be pulled early or idividual tubes can be pulled early, and a duty cycle can continue for the tubes or drums left in the processor.
By adjusting the size of the pulleys I can make the drum turn at the same rotation rate as the tubes, faster or slower.
An array of light tight drain and fill flanges will allow a number of tubes and drums to be quickly drained and filled with stop bath so the time and effort needed to handle large drums and 6 tubes will be simplified greatly.
This will be for developing TMY-2 in divided D-23 and possibly 2-bath Pyrocat.
The most important idea is to avoid too much agitation which is why a number of people don't use rotarty processors. Now that the exact timing, speed and rotation control of the drums and tubes can be programmed with a digital motor controller I'm hoping that over-agitation can be totally avoided.
A few questions to gather some ideas.
1. Should the drums rotate more than one revolution in relation to the tubes say at 1 1/4 turns for the drum to 1 turn of the tube?
2. With agitation cycles timed to occur at regular intervals at 1/4, 1/2 and 3/4 points of development more cycles of this same interval can be programmed allowing development time to be staggered for various drums and tubes. One drums cycle could be started and just prior to the next agitation cycle starting, another drum or a number of tubes could be agitated separately and when the processor stops turning they are inserted into the processor for the rest of the cycle. Can anyone imagine why this wouldn't work?
3. The motor can be programmed to turn very slowly. Instead of just having the drums and tubes sitting at a complete stop would a very slow rotation be advantagious at any time during the cycle such as during the initial stage of development?
4. As a new light tight drum drain and fill design is in the works I can either modify and existing Jobo Expert drum or make a drum that holds individual PVC tubes. Is there anyone that thinks that the Jobo drums are a whole lot better than a large drum with individual PVC tubes?
5. Are there any design ideas that you think would be important for a drum that holds PVC tubes? Do the tubes need to be held to the inside of the drum or will having them roll over each other be OK and possibly help the agitation?
6. Can anyone imagine why film cannot be processed in drums and tubes at staggered intervals but at basically the same time as mentioned above?
I didn't have time to proof read this so please excuse any hacks. Gotta run.
Any feedback is appreciated.
A programmable digital motor controller can be programmed to rotate a drum, reverse rotation and also sweep the motor back and forth. There is also some speed adjustment possible in both directions.
Ultimately I would like to program both drums and tubes to spin with the same cycle so lots of sheets of film can be processed at the same time. The agitation cycle must also allow individual tubes to be processed at different times. Both the drums and the tubes can be removed quickly but it seems like the initial agitation should happen for both the drums and tubes at the same time to get the development started. The drums can be pulled early or idividual tubes can be pulled early, and a duty cycle can continue for the tubes or drums left in the processor.
By adjusting the size of the pulleys I can make the drum turn at the same rotation rate as the tubes, faster or slower.
An array of light tight drain and fill flanges will allow a number of tubes and drums to be quickly drained and filled with stop bath so the time and effort needed to handle large drums and 6 tubes will be simplified greatly.
This will be for developing TMY-2 in divided D-23 and possibly 2-bath Pyrocat.
The most important idea is to avoid too much agitation which is why a number of people don't use rotarty processors. Now that the exact timing, speed and rotation control of the drums and tubes can be programmed with a digital motor controller I'm hoping that over-agitation can be totally avoided.
A few questions to gather some ideas.
1. Should the drums rotate more than one revolution in relation to the tubes say at 1 1/4 turns for the drum to 1 turn of the tube?
2. With agitation cycles timed to occur at regular intervals at 1/4, 1/2 and 3/4 points of development more cycles of this same interval can be programmed allowing development time to be staggered for various drums and tubes. One drums cycle could be started and just prior to the next agitation cycle starting, another drum or a number of tubes could be agitated separately and when the processor stops turning they are inserted into the processor for the rest of the cycle. Can anyone imagine why this wouldn't work?
3. The motor can be programmed to turn very slowly. Instead of just having the drums and tubes sitting at a complete stop would a very slow rotation be advantagious at any time during the cycle such as during the initial stage of development?
4. As a new light tight drum drain and fill design is in the works I can either modify and existing Jobo Expert drum or make a drum that holds individual PVC tubes. Is there anyone that thinks that the Jobo drums are a whole lot better than a large drum with individual PVC tubes?
5. Are there any design ideas that you think would be important for a drum that holds PVC tubes? Do the tubes need to be held to the inside of the drum or will having them roll over each other be OK and possibly help the agitation?
6. Can anyone imagine why film cannot be processed in drums and tubes at staggered intervals but at basically the same time as mentioned above?
I didn't have time to proof read this so please excuse any hacks. Gotta run.
Any feedback is appreciated.