Casting Silicone Parts With 3D-Printed Inserts For Stiffness

August 17, 2021 by Donald Papp 8 Comments

Prolific maker [Jan Mrázek] shared his process for casting soft silicone parts that nevertheless have some added stiffness, which he accomplished by embedding porous, 3D-printed “ribs” into the pieces during the casting process. The 3D-printed inserts act as a sort of skeleton, and as a result, the parts have a soft silicone surface but gain structure and rigidity that simply wouldn’t be obtained if the part were cast entirely in silicone. The nice thing is that no new materials or tools were needed; [Jan] 3D printed both the molds for the parts as well as the structural inserts. It’s always nice when one can use the same tool and materials to accomplish different functions.

The parts [Jan] is making are interesting, as well. He observed that the process of swapping resin in his printer’s build tank was an unpleasant experience for a number of reasons, chief among them being that resin is sticky and messy, and the shape of the build tank doesn’t make pouring resin from it a clean job.

His solution was to design a pour spout that could be pressed onto the build tank, and some specially-designed squeegees to allow scraping the tank clean with ease. Silicone is the ideal material for the parts because it turns out that sticky resin beads nicely on silicone’s surface. Anywhere else, resin tends to spread out and form a sticky mess, but on silicone resin it forms tidy drops and is much easier to clean up.

It’s a technique worth keeping in mind, because one never knows when it could come in handy. Fabricating soft robots for example tends to involve silicone casting and clever techniques. See [Jan]’s parts in action in the video, embedded below.

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Practical Print Makes IPad A Magnificent Eye Piece

August 11, 2021 by Ryan Flowers 9 Comments

Be it the ever shrinking size of components, the miniscule size of the printing on such pieces, or the steady march of time that makes visits to the optometrist an annual ritual, many of us could use some assistance when things start getting fuzzy at the workbench. Arm-mounted LED magnifying lenses can be a handy helper. Zooming in on a macro photo on a smartphone is also a common option that we’ve used many times.

[Timo Birnschein] started down a similar path when he realized that his iPad Pro comes with an app called simply “Magnifier”. A 12” iPad isn’t exactly the most convenient device to hold while trying to solder small parts, so he spent some time designing and 3D printing a specialty iPad stand that he calls a “Quick and Dirty High Performance EE Microscope.” We call it a magnificent tool hack!

Rotating the iPad diagonally so that the camera is closest to the subject leaves plenty of room to work and makes great use of the available screen space. [Timo] reports that at 50% magnification the 12” screen makes even 0603 SMD parts easy to read. Now he rejoices to have more to do with his iPad than watching YouTube and reading Hackaday- although we don’t know why you couldn’t do both.

The STL files have been released on Thingverse for your experimentation. [Timo] notes that he’d like to add an LED ring to brighten things up, and a fume extractor to protect the delicate lens on the iPad. We have to wonder if some plastic wrap over the lens might produce the same effect at almost no cost. Whatever [Timo] decides to do, we’re sure it’ll be brilliant.

If you don’t have an iPad and a 3D printer, you might enjoy an earlier post that shows how you can use your phone as a microscope. If Lego and Raspberry Pi are your go-to parts, you can set your sights on this Lego/Pi/Arduino microscope.

Do you have your own preferred solution for seeing yourself through a hazy situation? Be sure to write it up, and then drop it in the Tip Line!

See This Hybrid Approach To Folded 3D Printed Mechanisms

July 27, 2021 by Donald Papp 6 Comments

3D printers are quite common nowadays, but we’re still far from exhausting new ideas to try with them. [Angus] of [Maker’s Muse] recently got interested in 3D printing small mechanical assemblies that can be put together by folding them up, and also depend on folding linkages for the moving parts. (Video, embedded below.) The result would be lightweight, functional assemblies that would be simple to manufacture and require very few parts; but how to make the hinges themselves is the tricky part. As a proof-of-concept, [Angus] designed a clever steering linkage that could be printed flat and folded together, and shows his work on trying to make it happen.

[Angus] points out that that 3D-printed hinges have a lot of limitations that make then less than ideal for small and lightweight assemblies. Printing hinge pieces separately and assembling after the fact increases labor and part count, and print-in-place hinges tend to have loose tolerances. A living hinge made from a thin section of material that folds would be best for a lightweight assembly, but how well it works depends a lot of the material used and how it is made.

[Angus] tries many different things, and ultimately decided on a hybrid approach, combining laser cutting with 3D printing to create an assembly that consists of a laser-cut bottom layer with 3D printed parts on top of it to create a durable and lightweight device. He hasn’t quite sorted it all out, but the results show promise, and his video is a fantastic peek at just how much work and careful experimentation can go into trying something new.

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Tardygrade Walker Is A Lesson In 3D Printed Design

July 23, 2021 by Danie Conradie 12 Comments

The ability to quickly create complex parts with 3D printers has created a platform to show off mechanical design skills. This is true in the case of [Dejan Ristic]’s capable little Tardygrade walking robot, which uses only two servos and a bunch of clever 3D printed parts.

The robot’s chassis is split into two subassemblies, each with a pair of feet on diagonal corners. As one pair of feet lifts the robot, the other section of the robot can rotate before coming back down, allowing the robot to turn. One servo handles the actuation of the feet, while the other rotates the body as required. An ESP32 based controller creates a web server user interface, and power comes from a lipo cell.

The interesting part of this robot is in how [Dejan] designed it for printing and assembly. All the parts can print without support, and in the correct orientation to optimize strength. There are only six screws in the assembly holding the servo and servo horns, while everything else uses snap fits or short pieces of filament. Take a look at the videos after the break to gain some appreciation of the design effort and attention to detail that went into this robot. Even the contact surfaces of the feet were carefully designed for optimum walking over flat surfaces and small obstacles.

This reminds us of [gzumwalt]’s little 3D printed creations, like the fridge crawler and mechanical edge-avoiding robot.

Rover Uses Different Kind Of Tracks

July 22, 2021 by Danie Conradie 7 Comments

Tracked robots usually require at least two wheels inside to work properly. However, [James Bruton] discovered a curious tractor design from the 1940s, the Fordson Rotaped, which only uses a single sprocket wheel inside each track. Being [James], he built a self-balancing robot around the rotaped concept.

Instead of a lot of short track sections, the Rotaped uses six long sections of track, about the same length as the wheel’s diameter. To keep the track on the wheel, a series of chains or an oval frame is used on the inside of the track.

As is usual for [James]’ projects, most of the mechanical parts are 3D printed. To hold the tracks in place, he stretches a bungee cord loop around three points on each side of the track. To make things more interesting, he made the robot balanced on the tracks. This took a bit of PID tuning to get working without oscillations, since the wheels experience a slight cogging effect inside the tracks. The wheels are driven by a pair of brushless motors with O-Drive controllers. The balancing is handled by an Arduino Mega, which reads processed position values from an Arduino Pro Mini connected to an MPU6050 IMU.

This might be a viable alternative to conventional tracks for certain applications, and the reduced part count is certainly an advantage. Let us know in the comments if it spawns any ideas. [James] has previously built another tracked rover, which uses flexible 3D printed track sections. By far, the biggest 3D printed tracked vehicle we’ve seen was [Ivan Miranda]’s ridable tank.

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ZeroBug: From Simulation To Smooth Walking

July 21, 2021 by Danie Conradie 9 Comments

Thanks to 3D printing and cheap hobby servos, building you’re own small walking robot is not particularly difficult, but getting them to walk smoothly can be an entirely different story. Knowing this from experience, [Max.K] tackled the software side first by creating a virtual simulation of his ZeroBug hexapod, before building it.

Learning from his previous experience building a quadruped, ZeroBug started life in Processing as a simple stick figure, which gradually increased in complexity as [Max.K] figured out how to make it walk properly. He first developed the required movement sequence for the tip of each leg, and then added joints and calculated the actuator movements using reverse kinematics. Using the results of the simulations, he designed the mechanics and pulled it back into the simulation for final validation.

Each leg uses three micro servos which are controlled by an STM32F103 on a custom PCB, which handles all the motion calculations. It receives commands over UART from a python script running on a Raspberry Pi Zero. This allows for user control over a web interface using WiFi, or from a gamepad using a Bluetooth connection. [Max.K] also added a pincer to the front to allow it to interact with its environment. Video after the break.

The final product moves a lot smoother than most other servo-driven hexapods we’ve seen, and the entire project is well documented. The electronics and software are available on GitHub and the mechanics on Thingiverse.

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DIY Camera Dolly Costs More Time Than Money

July 19, 2021 by Donald Papp 14 Comments

A camera dolly can be fantastic filmmaking tool, and [Cornelius] was determined to create his own version: the “Dope” DIY Dolly. The result not only upped his production quality, but was also entirely in line with his DIY approach to filmmaking in general.

A basic dolly design is straightforward enough: a flat platform with wheels, and some aluminum tubing upon which to roll. But while dolly assemblies are easy to purchase or rent, [Cornelius] found that his DIY version — which used easily sourced parts and about 80 hours worth of 3D printing — provided perfectly acceptable results, while opening the door to remixing and sharing with like-minded filmmakers.

Interested? Download the STL files to get started on your own version. As for the track, smooth metal pipe is best, but sometimes track made from PVC can do the job. [Cornelius] has a few additional STL files for those planning to make a base from 1″ PVC pipe, and those are on a separate download link near the bottom of the project page (here’s that link again.) Watch the Dope Dolly in action in the brief video embedded below.

On the other hand, if you prefer your DIY camera equipment to be on the smaller and more complicated end of the spectrum, be sure to check out this multi-axis camera slider.

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