ChrisN
Striving
In this thread I opened a discussion about the use of highly-diluted developers, which lead to a mechanical agitation processor I've been working on. During that discussion several contributors made the point that continuous rotation in one direction was likely to produce "flow marks" adjacent to the sprockets, caused by too-regular flows of developer in that area leading to uneven development.
Over several tests I found that was often true to varying degrees depending on time and developer concentration. I tested with agitation in two configurations: one with the tank rotated around the centre of the cylinder (as with Jobo rotary processor), and a second with the tank tumbled end-over-end (as with normal inversion agitation).
These tests were all made with continuous agitation in one direction at 4 rpm, as this was the simplest to implement.
Even with continuous agitation I did find a couple of interesting variations that showed some promise. The first of these was to modify a Paterson spool to allow it to slide freely on the centre column. The idea was that if the spool was free to move as the tank slowly tumbled end-over-end, more random flows of developer might be achieved. To some extent this worked but minor edge marks were still apparent. A second approach was to minimise flow volume and velocity by filling 95% of the volume of the tank with developer, using a small 1-reel tank. The Paterson 1-reel tank was filled with 510ml of water and 4ml of LC29 developer. A roll of PAN-F (50 iso) was developed for 60 minutes at 20c with continuous tumble agitation at 4rpm, and showed good contrast and even development.
I eventually concluded that I needed to find a way to either reverse the direction of rotation (as with Jobo) or with tumble agitation find a way to produce intermittent agitation more like the conventional process.
That lead me to investigate simple timers. I have no skills in electronics although I can manage a soldering iron and understand basic DC circuits. In Australia a company called Jaycar sells electrical and electronic components and kits: I found one of their kits that looked like it would do the job, offering two cycling switching states and the ability to set varying times to each. One problem is that the 12v DC motor that drives my device needs to be allowed to come to a complete stop (1 to 2 seconds) before reverse polarity current is applied to reverse the direction of rotation. I therefore needed a circuit that would allow me to run the motor in one direction, then stop for two seconds, then run it in the opposite direction, then stop for two seconds, then repeat. Using the Jaycar timer kit I would need three timers to achieve that. At $35 each that was starting to look expensive.
Some more thinking brought me to another solution, using intermittent tumble agitation. Using a single timer I could incorporate a micro-switch to stop the rotation of the motor when the tank was aligned in the vertical (normal) position. When the device is switched on the timer (in its “ON” state”) directly powers the DC motor for 20 seconds through one side of a SPDT relay switch. This tumbles the tank for about one and a half rotations. After the 20 seconds the timer flips to its “OFF” state which powers the DC motor though the other side of the SPDT relay switch and a normally-closed micro-switch. This “OFF” state is timed to run for 70 seconds. The tank has been tumbled for 20 seconds by the “ON” timer, then the “OFF” timer takes over and keeps it going for about 10 seconds until the micro-switch is opened when the tank is rotated to the point where the tank is vertical (normal). With the micro-switch open, power to the DC motor stops, rotation stops, and the timer ticks down its remaining 60 seconds with tank not moving. Then the whole process starts again.
So this gives me a gadget that will slowly agitate my tank for two rotations (about 30 seconds), then let it rest for one minute, then repeat the agitation, etc. I can adjust the timing of both the agitation and the resting states to give me longer agitation and/or longer resting states. This should be good for trialling semi-stand development regimes that require a little agitation every 15 or 30 minutes.
Testing so far with TRI-X developed for 20 minutes in ID-11 1+3 at 20c shows results that I can’t distinguish from the results I get with my normal development routine with manual agitation by hand (four inversions every minute).
Why bother? Well, I like the idea of semi-stand or similar processes that use a small amount of developer (call me cheap!). I’ve also enjoyed the challenge of making this gadget work and thinking about the mechanics of the film development process.
Photos to come.
Over several tests I found that was often true to varying degrees depending on time and developer concentration. I tested with agitation in two configurations: one with the tank rotated around the centre of the cylinder (as with Jobo rotary processor), and a second with the tank tumbled end-over-end (as with normal inversion agitation).
These tests were all made with continuous agitation in one direction at 4 rpm, as this was the simplest to implement.
Even with continuous agitation I did find a couple of interesting variations that showed some promise. The first of these was to modify a Paterson spool to allow it to slide freely on the centre column. The idea was that if the spool was free to move as the tank slowly tumbled end-over-end, more random flows of developer might be achieved. To some extent this worked but minor edge marks were still apparent. A second approach was to minimise flow volume and velocity by filling 95% of the volume of the tank with developer, using a small 1-reel tank. The Paterson 1-reel tank was filled with 510ml of water and 4ml of LC29 developer. A roll of PAN-F (50 iso) was developed for 60 minutes at 20c with continuous tumble agitation at 4rpm, and showed good contrast and even development.
I eventually concluded that I needed to find a way to either reverse the direction of rotation (as with Jobo) or with tumble agitation find a way to produce intermittent agitation more like the conventional process.
That lead me to investigate simple timers. I have no skills in electronics although I can manage a soldering iron and understand basic DC circuits. In Australia a company called Jaycar sells electrical and electronic components and kits: I found one of their kits that looked like it would do the job, offering two cycling switching states and the ability to set varying times to each. One problem is that the 12v DC motor that drives my device needs to be allowed to come to a complete stop (1 to 2 seconds) before reverse polarity current is applied to reverse the direction of rotation. I therefore needed a circuit that would allow me to run the motor in one direction, then stop for two seconds, then run it in the opposite direction, then stop for two seconds, then repeat. Using the Jaycar timer kit I would need three timers to achieve that. At $35 each that was starting to look expensive.
Some more thinking brought me to another solution, using intermittent tumble agitation. Using a single timer I could incorporate a micro-switch to stop the rotation of the motor when the tank was aligned in the vertical (normal) position. When the device is switched on the timer (in its “ON” state”) directly powers the DC motor for 20 seconds through one side of a SPDT relay switch. This tumbles the tank for about one and a half rotations. After the 20 seconds the timer flips to its “OFF” state which powers the DC motor though the other side of the SPDT relay switch and a normally-closed micro-switch. This “OFF” state is timed to run for 70 seconds. The tank has been tumbled for 20 seconds by the “ON” timer, then the “OFF” timer takes over and keeps it going for about 10 seconds until the micro-switch is opened when the tank is rotated to the point where the tank is vertical (normal). With the micro-switch open, power to the DC motor stops, rotation stops, and the timer ticks down its remaining 60 seconds with tank not moving. Then the whole process starts again.
So this gives me a gadget that will slowly agitate my tank for two rotations (about 30 seconds), then let it rest for one minute, then repeat the agitation, etc. I can adjust the timing of both the agitation and the resting states to give me longer agitation and/or longer resting states. This should be good for trialling semi-stand development regimes that require a little agitation every 15 or 30 minutes.
Testing so far with TRI-X developed for 20 minutes in ID-11 1+3 at 20c shows results that I can’t distinguish from the results I get with my normal development routine with manual agitation by hand (four inversions every minute).
Why bother? Well, I like the idea of semi-stand or similar processes that use a small amount of developer (call me cheap!). I’ve also enjoyed the challenge of making this gadget work and thinking about the mechanics of the film development process.
Photos to come.
Attachments
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rxmd
May contain traces of nut
Very nice!
Now all you need is a set of tanks with a magnet valve each, a film development tank with a magnet valve at the bottom for flushing, a Paterson lid with a hole in the middle and possibly another magnet valve, a few pipes and you can do fully automatic film development, from dry to washed.
In that case you might think of replacing your simple timers with an Arduino (you can even buy a readymade Arduino kit if you want all the tinkering, but none of the soldering). This should give you all the flexibility you want in programming the agitation rhythms and the like.
Your installation looks a bit like a Heiland TAS, which is sold at RH Designs for 870 EUR, so you get an idea what Chris' gadget is worth
Now all you need is a set of tanks with a magnet valve each, a film development tank with a magnet valve at the bottom for flushing, a Paterson lid with a hole in the middle and possibly another magnet valve, a few pipes and you can do fully automatic film development, from dry to washed.
In that case you might think of replacing your simple timers with an Arduino (you can even buy a readymade Arduino kit if you want all the tinkering, but none of the soldering). This should give you all the flexibility you want in programming the agitation rhythms and the like.
Your installation looks a bit like a Heiland TAS, which is sold at RH Designs for 870 EUR, so you get an idea what Chris' gadget is worth
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Tom A
RFF Sponsor
Chris, that looks interesting (and a bit scary!). I have been sketching on a design for a rotary processor ( in anticipation of my Uni-Roller croaking)! Probably will have forward/backward rotation and a slight up down "tipping" movement (only about a 5-10 degree tilt).
Probably will use it as a fall/winter project. I have a box full of various sized ball-bearings that can be used for the device too.
Did you put the rotisserie motor back on the grill?
Probably will use it as a fall/winter project. I have a box full of various sized ball-bearings that can be used for the device too.
Did you put the rotisserie motor back on the grill?
NaChase
Well-known
I am not the least bit acquainted with Britishisms, but the term "boffin" still comes to mind. In a good way of course.
ChrisN
Striving
Tom - yes, the BBQ rotisserie motor has failed and been replaced with a nice little geared 12v motor. I found this on ebay; 4rpm motor with postage from Hong Kong for under $20. When the parcel arrived I found two motors in the pack! So I have a spare for my next project!
And Nick - thank you! I happily wear the label "boffin" with pride.
And Nick - thank you! I happily wear the label "boffin" with pride.
Attachments
ChrisN
Striving
RXMD - thanks for the pointers to TAS processor and the Arduino kit. It loooks like the path I've travelled has been travelled by many others before me! But it's fun to make the journey myself.
dfoo
Well-known
I process most of my film on a uniroller color processor in a 2 or 5 reel patterson tank. This particular processor only rolls in a single direction and I haven't noticed any uneven development with XTOL 1+2... for a normal scene I develop TMAX 400 for 12.5 minutes at 20C.
hans voralberg
Veteran
Very interesting, you happen to document it enough for a assembly manual?
ChrisN
Striving
Hi Hans - no I'm sorry but I never document anything! However the pics in this thread and the other should give you a good idea. I have worked largely with what I had available.
__hh
Well-known
Keith
The best camera is one that still works!
Bravo ... I love this sort of thing Chris.
'Appropriate technology' at work!
'Appropriate technology' at work!
oftheherd
Veteran
Well done! That burning smell is me thinking ...
tlitody
Well-known
Ok lets all be boffins. My idea is that you don't use rotation. You use vibration cos that will be much easier to implement and you can use any tank you like providing you can attach it to a vibrating base. Then all you need is a motor with an offset weight and a timer switch to switch it on and off at adjustable time intervals.
Providing the vibration is sufficient, then mixing of chemicals will occur and will it should be more robust than having to move a whole tank on a spindle.
Methinks you can already buy vibrating bases from scientific lab equipment suppliers. Damn, someone already thought of it. Still, no harm in trying to reinvent the wheel.
Here you go, all you need is a clamping device on the plate for your tank and to put a timer on the power input line.
https://extranet.fisher.co.uk/insight2_uk/getProduct.do?productCode=SGM-120-010W&resultSetPosition=2
Providing the vibration is sufficient, then mixing of chemicals will occur and will it should be more robust than having to move a whole tank on a spindle.
Methinks you can already buy vibrating bases from scientific lab equipment suppliers. Damn, someone already thought of it. Still, no harm in trying to reinvent the wheel.
Here you go, all you need is a clamping device on the plate for your tank and to put a timer on the power input line.
https://extranet.fisher.co.uk/insight2_uk/getProduct.do?productCode=SGM-120-010W&resultSetPosition=2
tlitody
Well-known
Damn, now you got me thinking. Maybe vibration wouldn't replenish enough chemical between the film on the spool. Not sure.
The thing with the jobo rotary processors is that you don't need enough chemical to cover all the film all the time. So its saves on costs.
The thing with the jobo rotary processors is that you don't need enough chemical to cover all the film all the time. So its saves on costs.
Tom A
RFF Sponsor
I once experimented with a magnetic agitator and film developing. This is a small platform with a rotating magnet in it and a small (1") magnet in the bottom of the filmtank. The magnet rotates and "stirs" the chemistry. Usually used for mixing chemicals - but I wanted to see if it could be used for developing too.
When spinning it sets up a vortex in the tank - problem was that you got serious "drag" along the edges of 35mm film. The sprockets created cavitations that streaked the film.
Funny enough, it worked quite well with sheet film 4x5" and 8x10" and at a slow "spinning" rate.
They are fine for mixing developer - but you do introduce a lot of oxygen into the mix and that tends to lower the lifespan of the soup.
Vibration tables does not provide enough flow to exchange fresh developer with exhausted developer - particularly with larger tanks. The back and forth rotating is probably the best way still to get a consistent flow - possibly with a small up/down movement added.
I used to have a platform in my sink for print agitation, hinged at the long end, and a small motor attached to an old camshaft from a V8 - a belt drove the shaft and it would gently move the platform up/down and keep developer/stop/fix flowing and refreshing - without me having to stand there and do it by hand! Great for large print runs.
In N.America these things are known as "Rube Goldberg" machines - and somehow tends to work quite well.
I admit, that just like Chris, the fun is in the design and problems solving - once it is built and works - it just becomes another piece of machinery!
At the moment I have a couple of these ideas floating around and roughly sketched up, the aforementioned agitator and a vacuum system for pulling developer through a fine microfilter. If you use the lab-filters - the process is slow enough to oxidize the developer before it has dripped through! The vacuum should speed it up - i hope.
When spinning it sets up a vortex in the tank - problem was that you got serious "drag" along the edges of 35mm film. The sprockets created cavitations that streaked the film.
Funny enough, it worked quite well with sheet film 4x5" and 8x10" and at a slow "spinning" rate.
They are fine for mixing developer - but you do introduce a lot of oxygen into the mix and that tends to lower the lifespan of the soup.
Vibration tables does not provide enough flow to exchange fresh developer with exhausted developer - particularly with larger tanks. The back and forth rotating is probably the best way still to get a consistent flow - possibly with a small up/down movement added.
I used to have a platform in my sink for print agitation, hinged at the long end, and a small motor attached to an old camshaft from a V8 - a belt drove the shaft and it would gently move the platform up/down and keep developer/stop/fix flowing and refreshing - without me having to stand there and do it by hand! Great for large print runs.
In N.America these things are known as "Rube Goldberg" machines - and somehow tends to work quite well.
I admit, that just like Chris, the fun is in the design and problems solving - once it is built and works - it just becomes another piece of machinery!
At the moment I have a couple of these ideas floating around and roughly sketched up, the aforementioned agitator and a vacuum system for pulling developer through a fine microfilter. If you use the lab-filters - the process is slow enough to oxidize the developer before it has dripped through! The vacuum should speed it up - i hope.
ChrisN
Striving
I think my original inspiration for this came from watching the paint mixing machine at the local hardware store, which clamps a can of paint into a frame that then shakes furiously. That might produce some interesting agitation marks on the negative!
And Australian outback travellers have long used the vibration of a moving vehicle on rough roads to wash their clothes. Take a large plastic bucket with a sealed clip-on lid, add soiled clothing, water and soap powder, then secure the bucket to the roof-rack, preferably in a location that maximises vertical movement. After a few hours on your typical outback dirt roads the washing is done! With that approach I could probably do large quantities of film all at once!
I'd really like to see what other people can do with this idea, so please share what you come up with.
And Australian outback travellers have long used the vibration of a moving vehicle on rough roads to wash their clothes. Take a large plastic bucket with a sealed clip-on lid, add soiled clothing, water and soap powder, then secure the bucket to the roof-rack, preferably in a location that maximises vertical movement. After a few hours on your typical outback dirt roads the washing is done! With that approach I could probably do large quantities of film all at once!
I'd really like to see what other people can do with this idea, so please share what you come up with.