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Tutorial: How to Design a Rack-and-Pinion in Blender

A Rack-and-Pinion refers to a gear mechanism which converts rotational motion into linear motion. It consists of an involute gear wheel (pinion) and a mating toothed bar (rack). The teeth of a rack-and-pinion pair can be straight or helical. A rack-and-pinion is found in the steering mechanism of vehicles and many other places.

In this tutorial, you will learn how to design a rack-and-pinion mechanism in Blender and test it with Blender's rigid body physics engine. Both straight-toothed and helical gears are covered.

Updated 2017-03-22

3D Model: 3D-Printable Automotive Differential

Every automobile's got one, and this motorized model gives you a sneak peek of what's inside that large round housing where the drive shaft and the two wheel shafts meet.

The automotive differential transmits power from the engine to the driving wheels while allowing them to rotate at different speeds. There are four bevel gears in the center of a differential, and the pinion and ring gears (shown here in yellow) are usually of the bevel kind too, but this particular model uses a hypoid gear pair instead. The model is powered by a 6V electric motor equipped with a speed reducer.

Updated 2017-02-16

Tutorial: How to Design and Test the Automotive Differential in Blender

When a car turns, its driven wheels operate at different speeds as the inner wheel has to travel a shorter distance to complete the turn. This is made possible with the help of the automotive differential, an ingenious mechanism which splits the engine's torque between the two wheel shafts and enables one of the wheels to revolve faster than the other when the driving conditions call for it, such as during a turn.

In this tutorial you will learn how to design an automotive differential mechanism in Blender, and also test it in both the straight-motion and turning modes of operation using Blender's rigid body physics engine.

Updated 2017-01-30

3D Model: 3D-Printable Walking Gear Bot

This mechanism, through the clever use of planetary gearing, converts simple rotation to a walking motion. The Walking Gear Bot is driven by a single electric motor powered by four AA batteries. This robot is built around 11 meshing involute gears, and there are 36 printable parts overall

The Walking Gear Bot is an all-around fun and educational mechanical toy enjoyable by adults and kids alike.

Updated 2017-01-14

3D Model: 3D-Printable Eccentrically Cycloidal (EC) Model

Most gearing mechanisms known today were invented decades or even centuries ago. Not so with the Eccentrically Cycloidal (EC) drive: it is so new the ink is still not dry on its patents! This 3D-printable model is made available to the public with the explicit permission of the patent holder. Print your own EC model and become one of a very few human beings to ever lay hands on this new and remarkable invention.

This futuristically looking mechanism is very efficient and extremely compact. The gear ratio in this particular EC drive model is 1:9, an almost impossible feat for a standard involute gear pair.

Updated 2016-12-16

Tutorial: How to Design an Eccentrically Cycloidal (EC) Drive

The recently invented Eccentrically Cycloidal (EC) drive is closely related to the hypocycloid drive described in our Tutorial #5. From the modeling point of view, these two mechanisms are very similar as they are built around the same basic shape - the cycloid disk. In fact, both tutorials use the same online calculator. With the help of this calculator, designing a functional EC drive will only take a few minutes. This tutorial also tests the EC gear pair for compatibility using Blender's Rigid Body Physics engine.

Be aware that the EC drive is covered by a number of US and international patents. This tutorial was created with the explicit permission of the patent holder.

Updated 2016-12-16

3D Model: 3D-Printable Hypoid Gear Drive Model

Hypoid gears are similar to bevel gears but the pinion and wheel in a hypoid pair have non-intersecting axes. Unlike our bevel gear model, where the gears are overhang-mounted, the pinion in this model is straddle-mounted (i.e sandwiched between two bearings) for a much sturdier assembly. Click here to see the video of this model in action, and download the .stl files.

Updated 2016-11-11

Tutorial: How to Design a Hypoid Gear Drive in Blender

A hypoid gear drive is similar to a bevel gear drive, but the axes of the pinion and wheel in a hypoid drive do not intersect. Hypoid gears are widely used in automotive and other industries. They offer high gear ratios, good efficiency and sturdiness of the assembly.

The math behind hypoid gears is daunting, but thanks to the online hypoid gear calculator we have developed, you don't need to worry about it at all. This concise tutorial shows you how to design your own hypoid gear pair in Blender easily.

Updated 2016-11-11

3D Model: 3D-Printable Hypocycloid Speed Reducer

The hypocycloid speed reducer is truly an amazing invention. We have designed a 3D-printable model of the hypocycloid drive in such a way that you can actually see the inner workings of this remarkable mechanism. Click here to see the video of this model in action, and download the .stl files.

Updated 2016-10-13

Tutorial: How to Design a Hypocycloid Drive in Blender

In a hypocycloid (or simply cycloid) speed reducer, a flower-shaped gear called cycloid disk moves around a stationary ring of round pins in a cycloidal motion, driven by an eccentric bearing or cam connected to the input shaft. Radial holes on the face of the cycloid disk in turn drive the pins of the output shaft. Hypocycloid drives are widely used in the industry due to their excellent characteristics, such as wide range of gear ratios, compact size, smooth transmission, high efficiency, high overload capacity, low noise, long service life, and compact design.

With the help of our tutorial, you can design your own hypocycloid drive in Blender in a matter of minutes.

Updated 2016-10-12

3D Model: 3D-Printable "Perpetual" Flip Calendar (.STL format)

Inspired by vintage flip calendars of the 60s, this 3D-printed "perpetual" desktop calendar needs no batteries. You flip it every day to advance the date and gravity does the rest. Click here to see the video of this calendar in action, and download the .stl files.

Updated 2016-09-22

Tutorial: How to Design a Planetary Gear Mechanism in Blender

The Planetary, or Epicyclic, gear mechanism consists of one or more planet gears revolving around a central, or sun gear. Typically, the planet gears are mounted on a carrier which itself rotates relative to the sun gear. A planetary system also incorporates an outer ring gear which meshes with the planet gears. The teeth of the ring gear point inwards. Gears like that are often referred to as internal. The planet and sun gears are regular, or external, gears, and the design process for those was covered in our Tutorial #1. However, the design of an internal/external gear pair requires its own set of formulas and its own calculator. This tutorial covers the modeling of a profile-shifted ring/planet gear pair, and sun gear.

Updated 2016-08-16

3D Model: 3D-Printable Planetary Gear Model (.STL format)

This stackable model allows for an unlimited number of stages. Even with 3 stages shown here, this planetary gear reducer packs an impressive 1:216 gear ratio. Designing planetary gears in Blender 3D is described in detail in our Tutorial #04.

Updated 2016-08-16

Tutorial: How to Design a Bevel Gear Drive in Blender

Bevel gears, also sometimes called conical gears, are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped. Bevel gears are usually mounted on shafts intersecting at 90°, but can be designed to work at other angles as well. In fact, in this tutorial we are designing a bevel gear pair with the shaft angle of 100°. Also, the gear wheels designed in this tutorial feature curved teeth and an involute tooth profile. At the end of the tutorial, the gears' compatibility is successfully tested with Blender's Rigid Body Physics engine.

Updated 2016-07-06

3D Model: 3D-Printable Model of Bevel Gear Drive (.STL format)

Add this functional bevel gear drive model to your collection of 3D-printable mechanisms! The model features bevel gears with involute tooth profiles, curved teeth and a non-right angle between the shafts. Designing bevel gears in Blender 3D is described in detail in our Tutorial #03.

Updated 2016-07-06

Tutorial: How to Design Globoid Worm Drive in Blender

Worm drives are ubiquitous! They can be found literally everywhere, from heavy machinery to acoustic guitars. Designing a simple cylindrical worm drive is not hard: just apply the Screw modifier to a trapezoidal tooth profile and you get the worm, then throw in a standard involute gear wheel with slanted teeth and you are done. The globoid (also known as throated) worm drive is far more involved. Its backbone is not a cylinder but an hourglass-like shape cut out of a torus. The globoid worm shaft is as beautiful as it is picky: finding a mating gear for it is not a trivial task. In this tutorial, you will learn how to create both a worm shaft and mating gear wheel in Blender, and test their compatibility using Blender's Rigid Body Physics engine.

Updated 2016-06-10

3D Model: 3D-Printable Model of Globoid Worm Drive (.STL format)

Nothing validates a mechanical design better than a functioning, physical model! The globoid gear drive, the subject of Tutorial #02, is now available as a collection of 3D-printable parts in STL format that assemble into a perfectly operational and aesthetically appealing hand-cranked desktop mechanism. The model makes a great conversation piece, and a fun and educational toy for your kids!

Updated 2016-05-25

Tutorial: How to Model Geometrically Correct (Involute) Gears in Blender

Cogwheels are often depicted with straight and boxy teeth. However if you take a close look at a real-world gear wheel, you will notice that the sides of its teeth are not straight at all, and for a good reason. Two mating gears must stay in tight contact at all times, and most importantly, the direction of pressure one gear exerts on the other must remain constant to prevent vibration and noise. Leonhard Euler, a great mathematician of the 18th century, designed a gear profile satisfying these requirements with the help of the involute, a mathematical curve that can be described with a pair of simple parametric equations. In this tutorial, you will learn how to design a pair of perfectly meshing involute gear wheels in Blender in just a few minutes.

Updated 2016-03-20