Medieval Mechanical Crane

A Brief History of the Medieval Mechanical Crane

The medieval mechanical crane was a vital tool during the Middle Ages (5th–15th centuries), used to build cathedrals, castles, and fortifications. Its origins trace back to ancient Greek and Roman lifting devices, such as the Roman *polyspaston*, but the treadmill crane became iconic in the medieval period due to the rise of Gothic architecture.

By the 12th century, projects like Notre-Dame de Paris (started 1163) required lifting heavy stones to great heights. The treadmill crane, or *magna rota*, met this need. It featured a large wheel powered by workers walking inside, winding a rope around an axle to lift loads via a jib arm. Many cranes were rotatable, allowing precise placement of materials. This design provided a mechanical advantage, enabling a single worker to lift loads that would otherwise need many laborers.

Treadmill cranes were widespread by the 13th century, used in sites like Chartres Cathedral (1194–1220) and Krak des Chevaliers. Illustrations in the *Sketchbook of Villard de Honnecourt* (c. 1230) show their design, typically made of wood with rope and iron fittings. They reflected medieval empirical engineering, building on ancient mechanics through practical innovation.

These cranes were crucial for medieval architecture, enabling feats like tall spires and sturdy fortifications. They remained in use until the 16th century, when more advanced designs emerged. The treadmill crane’s legacy influenced later machinery, highlighting the ingenuity of medieval builders in shaping history’s architectural wonders.

In this Instructable, we’ll design and build a working model of a medieval mechanical crane using Fusion 360 for 3D design and a 3D printer to create the parts. The crane will feature a thread-based lifting mechanism and a rotatable structure, just like the one in the reference image. We’ll break the crane into separate parts, print them, and glue them together for assembly. Let’s get started!

Materials Needed

1. Fusion 360 software (free for personal use)
2. 3D printer and filament (PLA recommended)
3. Super glue
4. 3 x M3 x 20mm bolt and nut.
5. Thread or thin string (for the lifting mechanism)
6. Small weight
7. Sandpaper (optional, for smoothing parts)

The crane consists of several key components: a base, a frame, a rotating treadmill wheel, a jib arm, and a thread-based lifting mechanism with a hook. To make assembly easier, we’ll design each part separately in Fusion 360 and ensure they can be glued together.

Here’s the breakdown of the parts:

1. Base: A sturdy platform to hold the crane.
2. Vertical Frame: Four vertical beams and cross-supports to form the main structure.
3. Treadmill Wheel: A large wheel with a central axle for the lifting mechanism.
4. Jib Arm: The angled arm at the top to hold the thread and hook.
5. Axle and Spindle: To connect the wheel to the frame and wind the thread.
6. Hook: A small hook to lift the weight.

Let’s design each part in Fusion 360. I’ll provide a description of the design process for Few major component.

1. Base:
2. Create a rectangular sketch (120 mm x 120 mm) with a thickness of 10 mm.
3. Add four small cylindrical holes (5 mm diameter) near the corners to slot in the vertical beams.
4. Extrude the sketch to create a solid base.
5. Vertical Frame:
6. Design four vertical beams (165 mm tall, 10 mm x 10 mm cross-section).
7. Add cylindrical pegs at the bottom of each beam to fit into the base holes.
8. Create two cross-supports to connect the beams at the top and middle.
9. Treadmill Wheel:
10. Sketch two large circular disks (98 mm diameter with a central hole (7 mm diameter) for the axle.
11. Add 8 evenly spaced slats between the disks to form the wheel’s structure.
12. Ensure the wheel can rotate freely around the axle.
13. Jib Arm:
14. Sketch a arms of frame to make Jib arm .
15. Add a small hole (3 mm diameter) for pully for thread to pass through and connect to axel..
16. Include a peg at the base to attach it to the top of the frame.
17. Axle and Spindle:
18. Design a cylindrical axle (60 mm long, 7 mm diameter) to pass through the wheel and frame.
19. Add a smaller square section for thread winding.
20. Hook:
21. Create a small hook (10 mm tall, 5 mm wide) with a loop at the top for the thread.

Whole design procedure is Long and get more details, please check design attached .

For more details check the actual Fusion 360 design preview available.

In Fusion 360, export each part as an STL file:

1. Select each component, go to the "Make" tab, and choose "3D Print."
2. Export as STL with high resolution for better detail.

You should have 20 STL files: Please check files below with the Number of prints written in name.

Check the assembly video for proper assembly.

Load the STL files into your 3D printer’s slicer software (e.g., Cura or PrusaSlicer).

Use the following print settings:

1. Material: PLA
2. Layer Height: 0.2 mm
3. Infill: 20%
4. Supports: Yes, for the jib arm and hook

Print each part separately. The total print time will depend on your printer, but it should take a few hours.

Now that all parts are printed, let’s assemble the crane using glue.

1. Attach the Vertical Frame to the Base:
2. Insert the pegs of the four vertical beams into the holes on the base.
3. Apply a small amount of glue to each peg to secure the beams in place.
4. Add the Cross-Supports:
5. Glue the cross-supports between the vertical beams at the top and middle to form a sturdy frame.
6. Install the Treadmill Wheel:
7. Assemble the treadmill wheel by gluing the slats between the two disks.
8. Pass the axle through the central holes of the wheel and frame, ensuring the wheel can rotate freely.
9. Glue the axle ends to the frame, leaving the wheel free to spin.
10. Attach the Jib Arm:
11. Glue the peg of the jib arm to the top of the frame, ensuring the arm extends outward.
12. Set Up the Lifting Mechanism:
13. Tie one end of the thread to the spindle on the wheel.
14. Pass the other end of the thread over the jib arm and through the hole at the tip.
15. Tie the hook to the end of the thread.

Rotate the treadmill wheel to wind the thread around the spindle, lifting the hook.

Attach a small weight (e.g., a metal nut) to the hook and test the lifting mechanism.

The entire frame should rotate on the base if gently turned, thanks to the loose fit of the beams in the base holes.

Sand any rough edges on the 3D-printed parts for a smoother finish.

If desired, paint the crane with acrylic paint to give it a more medieval wooden look.

You’ve now built a working model of a medieval mechanical crane! This model demonstrates the principles of historical engineering with a thread-based lifting mechanism and a rotatable structure. Share your build with the community, and let me know if you make any improvements!

https://www.npr.org/2023/10/01/1200546214/france-medieval-guedelon-castle-burgundy

Youtube Link for Crane

WIKIPEDIA Link