Beautiful DIY Spot Welder Reminds Us We Love 3D Printing

[Jim Conner]’s DIY tab spot welder is the sweetest spot welder we’ve ever seen. And we’re not ashamed to admit that we’ve said that before.

The essence of a spot welder is nothing more than a microwave oven transformer rewound to produce low voltage and high current instead of vice-versa. Some people control the pulse-length during the weld with nothing more than their bare hands, while others feel that it’s better implemented with a 555 timer circuit. [Jim]’s version uses a NodeMCU board, which is desperately overkill, but it was on his desk at the time. His comments in GitHub about coding in Lua are all too familiar — how do arrays work again?

Using the fancier microcontroller means that he can do fancy things, like double-pulse welding and so on. He’s not even touching the WiFi features, but whatever. The OLED and rotary encoder system are sweet, but the star of the show here is the 3D printed case, complete with soft parts where [Jim]’s hand rests when he’s using the welder. It looks like he could have bought this thing.
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Hackaday Prize Entry: DIY 6-Axis Micro Manipulator

[David Brown]’s entry for The Hackaday Prize is a design for a tool that normally exists only as an expensive piece of industrial equipment; out of the reach of normal experimenters, in other words. That tool is a 6-axis micro manipulator and is essentially a small robotic actuator that is capable of very small, very precise movements. It uses 3D printed parts and low-cost components.

SLS Nylon Actuator Frame. Motor anchors to top right, moves the central pivot up and down to deflect the endpoints.

The manipulator consists of six identical actuators, each consisting of a single piece of SLS 3D printed nylon with a custom PCB to control a motor and read positional feedback. The motor moves the central pivot point of the 3D printed assembly, which in turn deflects the entire piece by a small amount. By anchoring one point and attaching the other, a small amount of highly controllable movement can be achieved. Six actuators in total form a Gough-Stewart Platform for moving the toolhead.

Interestingly, this 6-Axis Micro Manipulator is a sort of side project. [David] is interested in creating his own digital UV exposer, which requires using UV laser diodes with fiber optic pig tails attached. In an industrial setting these are created by empirically determining the optimal position of a fiber optic with regards to the laser diode by manipulating it with a micro manipulator, then holding it steady while it is cemented in place. Seeing a distinct lack of micro manipulators in anything outside of lab or industrial settings, and recognizing that there would be applications outside of his own needs, [David] resolved to build one.

Hackaday Prize Entry: 3D Printed Linear Actuator Does 2kg+

The rabbit hole of features and clever hacks in [chiprobot]’s NEMA17 3D Printed Linear Actuator is pretty deep. Not only can it lift 2kg+ of mass easily, it is mostly 3D printed, and uses commonplace hardware like a NEMA 17 stepper motor and a RAMPS board for motion control.

The main 3D printed leadscrew uses a plug-and-socket design so that the assembly can be extended easily to any length desired without needing to print the leadscrew as a single piece. The tip of the actuator even integrates a force sensor made from conductive foam, which changes resistance as it is compressed, allowing the actuator some degree of feedback. The force sensor is made from a 3M foam earplug which has been saturated with a conductive ink. [chiprobot] doesn’t go into many details about his specific method, but using conductive foam as a force sensor is a fairly well-known and effective hack. To top it all off, [chiprobot] added a web GUI served over WiFi with an ESP32. Watch the whole thing in action in the video embedded below.

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Annealing Plastic For Stronger Prints

Much fuss has been made over the strength of 3D printed parts. These parts are obviously stronger in one direction than another, and post processing can increase that strength. What we’re lacking is real data. Luckily, [Justin Lam] has just the thing for us: he’s tested annealed printed plastics, and the results are encouraging.

The current research of annealing 3D printed parts is a lot like metallurgy. If you put a printed part under low heat — below the plastic’s glass transition temperature — larger crystals of plastic are formed. This research is direct from the Society of Plastics Engineers, and we’re assuming they know more about material science than your average joe. These findings measured the crystallinity of a sample in relation to both heat and time, and the results were promising. Plastic parts annealed at a lower temperature can attain the same crystallinity, and therefore the same strength, if they’re annealed for a longer time. The solution is simple: low and slow is the best way to do this, which sounds a lot like sous vide.

A while back, [Justin] built a sous vide controller for the latest cooking fad. The idea behind a sous vide controller is to heat food in a water bath at a lower temperature, but for a longer time. The result here is the most tender steaks you’ll ever have, and also stronger 3D printed parts. In his test, [Justin] printed several rectangular samples of PLA, set the temperature to 70°C, and walked away for a few hours. The samples annealed in the water bath were either cooled quickly or slowly. The test protocol also included measuring the strength in relation to layer height. The test jig consisted of a bathroom scale, a drill press, and a slot head screwdriver bit.

Although the test protocol is slightly questionable, the results are clear: annealing works, but only if the part is printed at a low layer height. However, parts with larger layer heights had a higher maximum stress. Is this helpful for the home prototyper? That depends. The consensus seems to be that if you’re at the mechanical limits of a 3D printed part, you might want to think about more traditional manufacturing. That’s just common sense, but there’s always room to push the envelope of 3D printing.

Controlling a Robot Over the Internet Grows Up

Since the beginning of the Internet people have been controlling robots over it, peering at grainy gifs of faraway rec rooms as the robot trundles around. RunMyRobot.com has taken that idea and brought it fully into the teens. These robots use wifi or mobile connections, are 3D printed, and run Python.

The site aims to provide everything to anyone who wants to participate. If you’re just an anonymous visitor, you can still play with the robots, but anyone can also play with the same one, and sometimes a whole bunch of visitors create a cacophony of commands that makes it not fun—but you can always move to a different robot. Logged-in members of the site have the option to take over a robot and not allow anyone else to use it.

If you want to build a robot and add it to the site, the creators show how to do that as well, with a Github code repository and 3D-printable designs available for download, as well as YouTube instructions on how to build either the printed robot or one made with off-the shelf parts. They’re also looking for patrons to help with development, with the first item on their list being a mobile app.

Thanks to [Sim] for the link.

 

ESP32 Mini Robot Packs Sensors and 4WD

[Stefan]’s Mini WiFi/BLE 4WD robot platform (seen next to a matchbox above) packs an impressive capability into a tiny rover. It’s based on a SparkFun ESP32 Thing, a very compact way to add wireless control to your project. Compare it to some giant old UNO with a WiFi shield, these boards are small but powerful, as well as an easy adoption for Arduino fans.

[Stefan] beefed up the robot with a BNO055 module to determine orientation, an APDS-9930 proximity sensor, as well as four CNY70 IR proximity sensors on the bottom, used for line-following. A pair of 6 V motors move the robot, with a DC-DC step up converter boosting the LiPo’s 3.7 V. It’s impressive how many components [Stefan] crammed inside the shell; they’re all packed in there snugly.

The concept behind the robot is that it’s a generic platform that could be customized as needed, and [Stefan] has versions with a LEGO dart gun as well as a camera. The robot’s code resides on GitHub and the custom 3D-printed chassis is up on Thingiverse.

If you like ESP32 projects you should be sure to check out the Monster Board and the Hamster Tracker we posted recently.

TORLO is a Beautiful 3D Printed Clock

What if you could build a clock that displays time in the usual analog format, but with the hands moving around the outside of the dial instead of rotating from a central point? This is the idea behind TORLO, a beautiful clock built from 3D printed parts.

The clock is the work of [ekaggrat singh kalsi], who wanted to build a clock using a self-oscillating motor. Initial experiments had some success, however [ekaggrat] encountered problems with the motors holding consistent time, and contacts wearing out. This is common in many electromechanical systems — mechanics who had to work with points ignition will not remember them fondly. After pushing on through several revisions, it was decided instead to switch to an ATtiny-controlled motor which was pulsed once every two seconds. This had the benefit of keeping accurate time as well as making it much easier to set the clock.

The stunning part of the clock, however, is the mechanical design. The smooth, sweeping form is very pleasing to the eye, and it’s combined with a beautiful two-tone colour scheme that makes the exposed gears and indicators pop against the white frame. The minute and hour hands form the most striking part of the design — the indicators are attached to a large ring gear that is turned by the gear train built into the frame. The video below the break shows the development process, but we’d love to see a close-up of how the gear train meshes with the large ring gears which are such an elegant part of the clock.

A great benefit of 3D printing is that it makes designing custom gear trains very accessible. We’ve seen other unconventional 3D printed clock builds before. 

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