This wonderful mechanism is similar in principle to the planetary reducer, but instead of the regular spur gears it employs bevel ones, and the gears in the middle are tilted. When projecting the pitch cones of these bevel gears on a vertical plane, their triangular outlines combine to create an isosceles trapezoid that is completely filled.

The gear ratio for this particular model is 4:1. The model's diameter in its widest part is 20 cm (7 7/8").

Updated 2023-08-28

Who can resist the pleasure of driving a radio-control car? And now you can raise the enjoyment a few notches by building your own car completely from scratch, and learn along the way what an RC toy is like under the hood, both the electronics and mechanics of it.

This RC vehicle is fully 3D-printed, with the exception of motors, electronics, a pencil and a few bolts and nuts. The electronic parts are readily available and relatively inexpensive. Absolutely no soldering is required to put it all together. The vehicle is designed with an "open" architecture in mind -- the power train and steering mechanism are intentionally exposed for all to see.

Updated 2022-09-21

Wherever our Fully 3D-Printed Rubik’s Cube Solving Robot is shown off, it always generates lots of excitement and curiosity, be it a classroom full of kids, an office full of co-workers, or a trade show floor full of attendees.

Now there is a way to bring about even more excitement and curiosity, even before the robot is unveiled. Just carry it into the room in a briefcase that is also fully 3D-printed!

This carrying case was designed specifically with the robot’s dimensions in mind. The robot will fit in it perfectly with plenty of room for accessories. By no means a small project, the case requires a printer with a large print platform, such as Creality CR-10, as some of its parts are outright massive. There are 44 parts overall, and you will need a big bag of bolts and nuts to hold them together.

Updated 2019-11-05

This fully 3D-printed mechanical spinning top is not only a fun toy, but quite educational too, and in more ways than one. Just like any spinning top, it demonstrates a fascinating physics phenomenon known as the gyroscopic effect, which prevents the toy from falling over while spinning. Also, nestled inside is a neat little mechanism which converts the reciprocal motion of the spiral rod to the one-way rotational motion of the spinning top's body. It is called the overrunning clutch, and we have managed to make it fully 3D-printed, even the torsion springs!

This fairly massive toy measures 20cm in its widest section, and not exactly a small project. However, the parts are designed in such a way that they are very easy to print and, with one exception, require almost no support.

Updated 2018-12-31

This fully 3D-printed clock is probably unlike any other digital clock you have seen. While in a regular LCD or LED-based digital clock the 7 segments for each of the four digits are switched on and off, the segments of this clock physically pivot in and out of view with the help of 28 individually controlled servo motors. The servos are connected to an array of servo controllers operated by a Raspberry PI application.

This huge clock (23" x 8") is sure to be an attention grabber and a great conversation piece in a crowd of computer and robotics nerds. And it shows precise time too!

Updated 2018-12-02

This gear model is full to the brim with mathematics, and it works well, too. The reference surface of each of these two gears is the one-sheet hyperboloid, which is formally defined as a "surface of revolution obtained by rotating a hyperbola about the perpendicular bisector to the line between the foci." The gears have an involute tooth profile. Also, the bearings for the top gear are shaped as parabolas, and the base is a plain circle.

This model transmits rotation between shafts crossed at 45°.

Updated 2018-05-01

This Rubik's Cube solving robot is fully 3D-printed. Other than the servos, servo horns, electronics and a few dozen bolts and nuts, it does not have a single traditionally manufactured part. If you have a 3D printer, less than $200 to spare, and some patience, this smart and beautiful machine can be adorning your own desk for everyone's enjoyment.

This robot has everything any serious robot does -- arms, servos, gears, vision, artificial intelligence and a task to complete. If you want to introduce robotics to your kids or your students, this is the perfect machine for it.

Updated 2017-08-15

Our collection of 3D-printable gear mechanisms would be incomplete without the model of a screw gear drive. Screw gears are regular helical gears mounted on non-parallel, non-intersecting shafts. They are also known as crossed helical gears.

The shape of this screw gear drive was inspired by the DNA molecule. In this particular model, there are three gears mounted at 45° to each other, but the shaft angle can be any number between 0 and 90°. Our screw gear calculator allows you to model the outlines of two meshing screw gears in Blender instantly.

Updated 2017-05-25

This tank does not require a single bolt or nut. You just print the parts, put them together, connect the motors and electronics, and it is ready for battle. It shows excellent off-road capabilities, and turns on a dime. Each of this tank's two tracks is printed in a single piece, thus eliminating the need for assembly hardware.

The machine shown here is powered with a Picaxe 20M2 microcontroller installed on a 300-hole mini-breadboard. There is also an H-bridge motor driver, an IR sensor, a couple of resistors and capacitors, and a whole bunch of jump cables. The entire set of electronic components used here can be bought on eBay for just a few dollars. The tank is operated with a regular Sony TV remote control.

Updated 2017-05-14

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

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

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

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

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

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

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

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

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