pulley system (block and tackle) with gear bearing pulleys

For my previous design I added some rims to emmett's gear bearings, and I thought that this called for using it as a pulley - so for the mechanical marvels competition I made a pulley system (block and tackle) to combine 3 mechanical marvels:

Ropes with a single pulley were used since at least 3000 years ago. The block and tackle with multiple pulleys is assumed to be a more than 2200 years old invention by Archimedes.

Bearings are quite old, too: To decrease friction, the Celts used cylindrical pieces of wood near the axis. Ball bearings were used by the Romans about 2000 years ago. A herringbone gear bearing is of course much more modern :)

First uses of wooden helical threads are documented to be also at least 2000 years old and used in screw presses (for grapes or olives) in the Mediterranean area. Earliest documented metal screws were (rarely) used by the Romans about 1500 years ago for pompous insignia brooches. Metal screws as fasteners became common in the 18th century in the course of the industrialization.

I made a coplanar design (all pulleys in the same plane) corresponding to typical drawings. Using all pulleys (as shown in the image) it has a theoretically advantage of 4:1. Lifting a 15kg load however required a force equivalent to 5.1kg, so friction in the 4 pulleys reduces the advantage effectively to 3:1 (for holding in place or slowly lowering, a lower force is needed). 15 kg doesn't at all feel near it's limit, so I guess it should be able to handle quite some more load.

The screw bolts are printed horizontally for strength, but to be printed without support I needed to cut of a bit of the screw. I designed a head that goes well with that restraint and also has a retro look; maybe even a steampunk look if printed in brass color filament (I have none)… They take about one turn to screw/unscrew.

I made eyes instead of hooks for strength; either knot the rope to the eye every time or ignore the eye part and use the bolt itself for attaching the rope (as shown in the image).

Printing

I uploaded two 3mf files with embedded settings for PrusaSlicer. Both files have to be printed twice for a full set, with a total of about 18 hours and 200g of filament. I used 4 perimeters for strength. If you want to print both pulleys in one go, use Output options - Complete individual objects (the 3mf file has that already set). I used 0.2mm layer height and a 0.4mm nozzle with recycled Prusament PLA.