A small 24 V centrifugal pump moves the water in the JOBO CPE2 bath. Five-probe logs before and after: heating speed barely changed, the bottles ran close together, and the bath now shows the thermostat’s on/off cycles.
The JOBO CPE2 and CPE2+ are still among the most common rotary processors in home darkrooms, but they are decades old, and the small plastic parts go first: the bottle frame cracks, drum rollers and their holders go missing, knobs break or simply disappear. Original spares are hard to find, and when one does turn up, it usually costs far more than a small piece of plastic should. So I designed printable replacements and upgrades for my own CPE2 and collected them in one open repository: ...
The Problem with Existing Film Tanks If you develop film in a darkroom, you know the frustration: almost every tank on the market leaks chemicals from the top when inverted. Paterson, AP, and most other systems all have this issue. The only exception is Jobo — but it comes at a cost. Inversion agitation is inconvenient, messy, and completely incompatible with automated film development setups where precise chemical dosing matters. ...
Open Hardware Reels: A Better Way to Develop Film I have designed a new type of open-source film developing reel specifically optimized for 3D printing. While many designs exist online, most are not tailored for home manufacturing, leading to failed prints or poor functionality. These reels are fully compatible with the standard systems like Paterson system and can be printed at home using common materials like PETG without supports and from two pieces. ...