Pogo-Bot Goes All Terrain With Compliant Foot

September 30, 2026 by Tyler August 19 Comments

What do you get when you combine a pogo stick, a quadcopter, and engineering students from the University of Toronto? This thing, apparently– a “monopedal hopping robot” that uses a spikey, pivoting foot pad tensioned by what look like elastic bands to keep it upright on all terrain from soft sand to hard ice.

It’s an interesting concept. The thrust from the four propellers is what gives the energy to get the robot moving, but its pogo-like hopping is entirely down to the spring-loaded single legged “landing gear”. Early iterations just used a spike on the end of that leg, but that failed in ways that some might find humorous, which you will see if you watch the video embedded below. Giving the monopod an actual foot with some traction and the ability to pivot and match the terrain works much better– now not only can this robot leap tall fences in a single bound, an errant ice patch won’t send it skittering away.

This isn’t the first one-legged robot we’ve seen; some only use their leg while others have wings, but this odd quadcopter is the first we’ve seen to brave Canadian winter. Continue reading “Pogo-Bot Goes All Terrain With Compliant Foot” →

A grey box surrounding a circular red component is mounted on an aluminium extrusion frame. The circular red face has a protrusion extending from it with a white ball bearing at the tip.

Building A Micrometer-Level Displacement Sensor With 3D Printed Parts

June 30, 2026 by Aaron Beckendorf 8 Comments

Every experienced machinist knows the value of taking regular measurements. If one works carefully and checks dimensions frequently, it’s possible to make a part much more precise than could be made by relying on the machine’s accuracy alone. In a similar vein, it’s possible to make a measuring device out of comparatively crude parts, as long as their behavior is well understood. Related to both principles is [BubsBuilds]’s displacement sensor, which uses a 3D printed frame but reaches precision better than two micrometers.

Admittedly the printed parts aren’t the source of the sensor’s precision, that comes from an opto-interrupter. This design has a central stylus, one end of which contacts the object under measurement. The other end flattens to a knife-edge blade, which fits between the diodes of the opto-interrupter. As the stylus point is pressed in, the blade blocks off more light from reaching the photodiode, creating an output signal proportional to displacement. To keep the stylus from twisting or moving side-to-side, two flat, circular flexures hold the stylus in the center of a cylindrical housing.

[Bubs] printed several flexure variations to see how well they resisted and permitted various torques and forces, and a symmetrical flexure design proved best for his purposes. Once the sensor was assembled, he tested it against the measurements recorded by a laser confocal displacement sensor. This design was an update from a previous version, and it improved in a few regards: the non-linearity had decreased, and the repeatability was now better than two microns, though the range had been halved. Significantly, though, it’s now much easier to mount, making this an actually practical tool.

If, however, this doesn’t fit your needs, there are many other ways to build a linear displacement sensor, ranging from capacitive to magnetostrictive. On the manual side of things, we’ve also covered a comparison of calipers.

Continue reading “Building A Micrometer-Level Displacement Sensor With 3D Printed Parts” →

The Challenges Of 3D Printing Reliable Springs

April 27, 2026 by Maya Posch 19 Comments

Springs are great, but making them out of plastic tends to come with some downsides, for fairly obvious reasons. Creating a compliant mechanism that can be 3D printed and yet which doesn’t permanently deform or wear out after a few uses is therefore a bit of a struggle. The compliant toggle mechanism that [neotoy] designed is said to have addressed those issues, with the model available on Printables for anyone to give a shake.

The model in question is a toggle, which is the commonly seen plastic or metal device that clamps down on e.g. rope or cord and requires you to push on it to have it release said clamping force. Normally these use a metal spring inside, but this version is fully 3D printable and thus forms a practical way to test this particular compliant mechanism with a variety of materials.

The internal spring is a printed spiral spring, with the example in the video printed in PETG. You can of course also print it in other materials for different durability and springiness properties. As noted in the video, PLA makes for a very poor spring material, so you probably want to skip that one.

We covered compliant mechanisms in the past for purposes like blasters, including some that you can only see under a microscope.

Continue reading “The Challenges Of 3D Printing Reliable Springs” →

Origami On Another Level With 3D Printing

December 21, 2025 by Ian Bos 14 Comments

Origami has become known as a miracle technique for designers. Elegant compliant mechanisms can leverage the material properties of a single geometry in ways that are sometimes stronger than those of more complicated designs. However, we don’t generally see origami used directly in 3D printed parts. [matthew lim] decided to explore this uncharted realm with various clever designs. You can check out the video below.

Continue reading “Origami On Another Level With 3D Printing” →

A human hand is shown in the bottom right corner of the picture, holding one end of a pencil. A white, segmented, mechanical tentacle extends from the bottom left corner of the image and wraps around the other end of the pencil.

3D Printed Cable-Driven Mechanisms – Some Strings Attached

May 3, 2025 by Aaron Beckendorf 10 Comments

One of the most basic problems with robotic arms and similar systems is keeping the weight down, as more weight requires a more rigid frame and stronger actuators. Cable-driven systems are a classic solution, and a team of researchers from MIT and Zhejiang University recently shared some techniques for designing fully 3D printed cable-driven mechanisms.

The researchers developed a set of four primitive motion components: a bending component, a coil, screw-like, and a compressive component. These components can work together in series or parallel to make much more complicated structures. To demonstrate, the researchers designed a gripping tentacle, a bird’s claw, and a lizard-like walking robot, but much more complicated structures are certainly possible. Additionally, since the cable itself is printed, it can have extra features, such as a one-way ratcheting mechanism or bumps for haptic feedback.

These printed cables are the most novel aspect of the project, and required significant fine-tuning to work properly. To have an advantage over manually-assembled cable-driven systems, they needed to be print-in-place. This required special printer settings to avoid delamination between layers of the cable, cables sticking to other components, or cables getting stuck in the mechanism’s joints. After some experiments, the researchers found that nylon filament gives the best balance between cable strength and flexibility, while not adhering tightly to the PLA structure.

We’ve seen cable-driven systems here a few times before. If you’re interested in a deeper dive, we’ve covered that too.

Continue reading “3D Printed Cable-Driven Mechanisms – Some Strings Attached” →

3D Printed Blaster Does It With Compliant Components

December 17, 2024 by Donald Papp 20 Comments

The ease of integrating bendy parts into designs is one of 3D printing’s strengths. A great example of this is [uhltimate]’s six-shot blaster which integrates several compliant mechanisms. The main blaster even prints in one piece, so there’s not even any assembly required.

The ergonomics are unconventional, but the design is pretty clever.

The blaster itself has three main parts: the trigger, the sear, and the striker. Each of them rely on compliant mechanisms in order to function. The user pulls back the trigger, which hooks into and pulls back the striker. When the trigger is pulled back far enough, the sear releases the striker. This zips forward and slams into a waiting projectile, sending it flying.

The other interesting part is the projectiles and magazine in which they sit. The magazine fits onto the front of the blaster and pulling the trigger allows the magazine to drop down, putting the next projectile into firing position. After the final round is fired, the empty magazine falls away. It’s a pretty clever design, even if the ergonomics are a little unusual and it relies on gravity in order to feed. Tilt it too far sideways or upside down, and it won’t load properly.

We’ve seen compliant mechanisms used for projectile firing before, but this design really raises the bar in the way it does more than just firing the striker.

3D printing allows rapid iteration of designs, which makes devices that rely on compliant mechanisms much easier to develop and fine-tune.

Continue reading “3D Printed Blaster Does It With Compliant Components” →

Flexures Make Robotic Fingers Simpler To Print

July 16, 2024 by Dan Maloney 7 Comments

Designing an anthropomorphic robotic hand seems to make a lot of sense — right up until the point that you realize just how complex the human hand is. What works well in bone and sinew often doesn’t translate well to servos and sensors, and even building a single mechanical finger can require dozens of parts.

Or, if you’re as clever about things as [Adrian Perez] is, only one part. His print-in-place robotic finger, adorably dubbed “Fingie,” is a huge step toward simplifying anthropomorphic manipulators. Fingie is printed in PLA and uses flexures for the three main joints of the finger, each of which consists of two separate and opposed coil springs. The flexures allow the phalanges to bend relative to each other in response to the motion of three separate tendons that extend through a channel on the palmar aspect of the finger, very much like the real thing.

The flexures eliminate the need for bearings at each joint and greatly decrease the complexity of the finger, but the model isn’t perfect. As [Adrian] points out, the off-center attachment for the tendons makes the finger tend to curl when the joints are in flexion, which isn’t how real fingers work. That should be a pretty easy fix, though. And while we appreciate the “one and done” nature of this print, we’d almost like to see the strap-like print-in-place tendons replaced with pieces of PLA filament added as a post-processing step, to make the finger more compact and perhaps easier to control.

Despite the shortcomings, and keeping in mind that this is clearly a proof of concept, we really like where [Adrian] is going with this, and we’re looking forward to seeing a hand with five Fingies, or four Fingies and a Thumbie. It stands to be vastly simpler than something like [Will Cogley]’s biomimetic hand, which while an absolute masterpiece of design, is pretty daunting for most of us to reproduce.

Continue reading “Flexures Make Robotic Fingers Simpler To Print” →