Interesting machine. I'd be worried about that method of agitation though. The builder really needs to analyze the resulting negatives for development uniformity.
In his meticulous testing, Richard Henry constructed an automatic agitation machine, although it was only for agitation and did not automatically pump chemistry in/out. In testing for uniformity and agitation patterns with inversion agitation, he found that not only were complete inversions required, but that when inversions are machine controlled some rotation about the tank axis was required in order to "randomize" the agitation.
This was exactly the question I had when seeing the machine's agitation. Because the motion is always the same will there be the possibility of something like like "surge marks?" With people the motion will always be different.
Originally Posted by Michael R 1974
Then there is the problem of the tank not being fully inverted. If you look at a diagram of Kodak's recommended method, not only is the tank inverted but it is also given a swirl each time.
One other point. Since highly conductive solutions will be used has the unit been tested for electrical safety?
Originally Posted by Gerald C Koch
Gerald, it's only a DIY apparatus, thus on the builder's own risk. It is not for sale, nor did the bilder released plans.
It was nevertheless introduced at a german forum to serve as kind of incentive for own DIY Versions.
Sorry for being not clear enough on this matter.
It should run on low-voltage and thus an, external solid-state and thus most probabably tight, in-line transformer could be used.
The builder employed 12V and 5V and used a PC-power supply, though I don't know where he placed it.
I would place the electronics above chemistries level in a tight box.
If I were to build a device for tanks that can hold 120 film (and I have given this some consideration), I'd make sure it would be roller type, not inversion/tilt type. It has always struck me that one has to prepare 500ml for a single roll of film, and with a roller tank system one could reduce this to 250ml or less. And I would likely do without the pump system, cleaning out the tubing would likely require more effort than pouring the liquids by hand, at least for low volume processing.