Paterson Reel for 4x5 Sheet Film (6 Sheets)

This is an easy-loading reel for developing up to 6 sheets of 4x5 film with a standard Paterson system.

Sheets are slid in via the entry slots and are kept in place with keeper tabs on the top and bottom.

This design was inspired by the Jobo system reels for 4x5 film, with modifications made for printability and the additional sheet retention made necessary by the greater sheet deformation needed to fit inside the smaller diameter of Paterson tanks.

I have tested this design, developing all 6 sheets at once, and found that sheets develop evenly without scratches or deformation.

PLA held up just fine to C-41 development chemicals and temperatures.

Developing more sheets at once with the Paterson system is highly desirable – especially when using chemicals one-shot – since non-rotary development with the Paterson system requires high volumes of chemicals.

Print notes

• I've only printed at 0.2mm layer height with a 0.4mm nozzle, but taller layers for faster prints may work well.
• 100% infill is recommended because of how thin the features are. It should not increase print time or material utilization much.
• No support material is required.
• Rough printed surfaces in the tracks may scratch the film or prevent film insertion, so check your print. You might need to go over the track surfaces with a small knife, depending on the quality of your print.

Usage notes

• The top and bottom pieces twist and snap together, just like other Paterson reels.
• Load sheets “emulsion in” (towards the center post) to ensure even development and minimize the risk of scratching the emulsion.
• Sheets must be loaded straight, or they will catch on the support ribs.
• When loading, make sure sheets are fully seated by pushing back on them after insertion. They should catch on the keeper tabs, and not slide back out.
• Test the reel with a scrap sheet of film BEFORE USING IN THE DARK to make sure that all tracks are clear of obstructions caused by printing artifacts, and that the print quality was good and the reel will not break.

Known issues and future work

• I cannot speak to long-term usage or reliability as I've only used this reel system twice.
• There may be ways to improve the design to reduce the likelihood of the reel scratching the film.
• The snap fit tolerance may not maintain across other printers. Please leave a comment if the two pieces do not snap together nicely.
• Material usage on the post of the top reel could probably be reduced without sacrificing robustness.