STL Files for Simple Machines: Gears, Levers, and Pulleys
Gears, levers, and pulleys are examples of basic machinery, yet they can be difficult to understand when presented solely in diagrams or textbooks. It can be tough for students and hobbyists to understand the practical applications of ideas like motion, force, and balance when there is no physical means to engage with them. When it comes to classroom or home use, traditional tools or kits can be prohibitively expensive, difficult to modify, or just not accessible.
3D printing is useful for that. You may build basic devices on your computer using free or cheap printed files. For an engaging, low-cost, and hands-on approach to learning about mechanics, we have compiled a list of the top 3D-printable models of pulleys, gears, and levers.
1. Simple Planetary Gears
A great way to demonstrate the inner workings of gear ratios to students is with this 3D-printed planetary gear set. Parts include a sun gear, planet gears, an outer annulus ring, and a support arm for the planet gears. Reduced to its bare essentials, the model is based on OpenSCAD code and is therefore considerably simpler to print and assemble. Depending on whatever component you keep stable, you may generate different gear ratios—a 1:6 ratio with a fixed sun or annulus and a 1:5 ratio with a fixed planet carrier—thanks to the ingenious construction of the gears.
The user gains an intuitive understanding of rotational direction and torque distribution due to the gears' seamless contact. Standard PLA works fine for printing, and supports aren't necessary. For anyone seeking a practical approach to understanding planetary physics and compound gear systems, this set is ideal for use in classes, makerspaces, or with inquisitive students.
Download file: Thingiverse.
2. Elliptical Gear with No Center Pivot
Here we have an interesting take on conventional gear systems with this one-of-a-kind 3D-printed elliptical gear. With its open design and lack of a central pivot ring, this model enhances the aesthetic value of any mechanical project while providing greater mobility. This version takes PerryT's original elliptical gear design and replaces the middle section with a spiral pattern, which, when paired with a matching gear, creates a smooth motion. The gears' off-center interlocking creates interesting, erratic motion, ideal for illustrating ideas related to non-circular gearing.
You can save time and filament by printing this model neatly without supports or rafts at a resolution of 0.2-0.3 mm. Smoothing the holes and carefully snapping in the pins are the only post-processing steps required. The uneven positioning of the teeth necessitates that the user turn one gear full circle to align their teeth correctly.
Download file: Thingiverse.
3. Bicycle Tire Lever
Cyclists who need to make quick repairs or maintenance will appreciate this small, durable multipurpose bicycle tire lever. Its ergonomically curved handle makes it easy to hold and use when removing tires, demonstrating its well-thought-out design. In addition to a spoke hook to secure the tool in place during repairs, the lever features an integrated 10 mm wrench, which is helpful for adjusting traditional tensioners. The model has been fine-tuned for the Prusa MK3/S/S+ with a layer height of 0.15 mm and 20% infill, ensuring long-term printing in PETG, which boasts exceptional durability and stress resistance.
A flawless finish is possible with the help of ironing and support material. It takes around one hour and thirty-five minutes and 3.59 meters of filament to print one object. This lever is perfect for weekend warriors and commuters alike; it's lightweight, adaptable, and dependable, making it an essential part of every biker's toolbox.
Download file: Printables.
4. Mini Minecraft Lever
An entertaining and practical 3D-printed device that integrates the physics of the popular video game Minecraft into the actual world is the Mini Minecraft Lever. Like in the game, this lever "snaps" into two positions thanks to its spring-loaded compliance mechanism. The model consists of two SpringRotors, two SpringLoaders, two SpringBoxes, a LeverBase, a LeverHandle, and a LeverTip.
Printed with a 1.5 mm layer height, these components fit together perfectly, even when printing intricate texturing. A little oil on the SpringRotor makes it run more smoothly, and a little super glue holds the finishing touches in place. The assembled lever has a wonderful snap motion that is both sharp and tactile. Anyone looking for a great resource for teaching compliant mechanisms, children studying mechanical systems, or Minecraft enthusiasts will find it.
Download file: Cults.
5. Ascent Zero 3 - Triple Pulley with 608 Bearings
The Ascent Zero 3 is a small, triple-wheel pulley system that manages to be both sturdy and aesthetically pleasing. You may choose between two different assembly methods—one that uses printed axles and another that uses M5 x 16 mm bolts and nuts—and both are designed to fit 608 bearings.
Tight tolerances may necessitate tapping with a gentle mallet, particularly when working with PLA or PETG, despite the compression-fit design's robust grip. Once fitted, the keyed axles minimize wobbling and guarantee proper orientation.
You may need to give the pulley wheels a gentle tap with a hammer to get them to sit firmly on the bearings. When combined, the two sections of the body form a robust pulley system that can withstand light lifting loads or mechanical demonstrations. Tests on Bambu printers with high-density profiles guarantee the model's solid part strength.
Download file: Makerworld.
6. Strong Pulley – 100% 3D Printable, Scalable & Durable
Three separate variants of this fully 3D-printable pulley system by Meister Edel provide maximum flexibility: one for fast printing, one for improved strength, and one for eyelets. The use of printed components in each iteration eliminates the need for any supplementary hardware. The sturdy pulley's two interlocking sections and central roller pin—which may be fastened for extra reinforcement—provide exceptional longevity.
When it comes to fixed systems, such as clotheslines or tension ropes, the eyelet version is ideal, while the easy-print version is ideal for quick prototyping. Simply adjust the measurements while maintaining the perimeters and tolerances, so any version works for your project.
While PLA is sufficient for smaller loads, PETG is better suited for more demanding applications. The integrated oiling ports reduce friction when in use, and printing at 100% infill with six perimeters enhances the structure.
Download file: Makerworld.
7. Pulley Generator – Parametric Timing Belt Pulleys
Using OpenSCAD and the parametric design tool Pulley Generator developed by Koolm, you can make timing belt pulleys that are uniquely yours. This tool is compatible with all the main pulley profiles, including GT2, HTD, MXL, XL, and T-series, so it's excellent for mechanical assemblies, automation systems, and robots. To meet your unique needs, you have the option to fine-tune the teeth count, flange arrangement, hub size, and bore types (keyed, hex, D-bore, or cylindrical).
Teeth clearance has been fine-tuned to ensure smooth operation with conventional timing belts, and the design contains teardrop-shaped screw holes to enhance printability. This model is perfect for Bambu Studio or Handy since it can be quickly and easily edited online and then downloaded for quick slicing. You can rest assured that your printing will fit and perform properly, as the modeling logic incorporates real-world pulley standards. Engineers and precise craftsmen who want complete control over their designs will find this tool invaluable.
Download file: Makerworld.
8. Lever Principle and Equilibrium
An instructional tool for engineering teachers and students, this 3D-printed model illustrates the operation and balance of levers in a hands-on manner. Participants in the MakerEd Project Challenge used this model to experiment with different lever lengths and weights, thereby learning about torque (force × distance).
With their straightforward designs, these parts print effortlessly at a resolution of 0.2 mm, eliminating the need for supports or rafts. The components require only 20% infill and are compatible with popular desktop 3D printers, such as the BCN3D+. For classroom use or self-directed discovery learning, the final assembly demonstrates how varying weight placements affect the balance of a lever. The ability to visualize concepts such as rotating forces, moment arms, and fulcrum placement helps students grasp the fundamentals of physics.
Download file: Thingiverse.
Best 3D Modeling Software for Education
There are many 3D design software available, but we recommend using SelfCAD. It is helpful here because it lets users easily design, customize, and modify simple machine models like gears, levers, and pulleys in the program. With built-in tools like the gear generator, measurements, and boolean operations, freehand drawing and sketching, and 3D sculpting tools, without the need for additional software. The video below shows the overview of the software.
It also comes with many interactive tutorials that make it easy to learn how the software works. It also comes with an in-built online slicer useful for slicing designs and generating the G-code to send to your 3D printer.