Here’s some interesting work shared by [Ben Kromhout] and [Lukas Lambrichts] on making flexible 3D prints, but not by using flexible filament. After seeing a project where a sheet of plywood was rendered pliable by cutting a pattern out of it – essentially turning the material into a giant kerf bend – they got interested in whether one could 3D print such a thing directly.
The original project used plywood and a laser cutter and went through many iterations before settling on a rectangular spiral pattern. The results were striking, but the details regarding why the chosen pattern was best were unclear. [Ben] and [Lukas] were interested not just in whether a 3D printer could be used to get a similar result, but also wanted to find out what factors separated success from failure when doing so.
After converting the original project’s rectangular spiral pattern into a 3D model, a quick proof-of-concept showed that three things influenced the flexibility of the end result: the scale of the pattern, the size of the open spaces, and the thickness of the print itself. Early results indicated that the size of the open spaces between the solid elements of the pattern was one of the most important factors; the larger the spacing the better the flexibility. A smaller and denser pattern also helps flexibility, but when 3D printing there is a limit to how small features can be made. If the scale of the pattern is reduced too much, open spaces tend to bridge which is counter-productive.
Kerf bending with laser-cut materials gets some clever results, and it’s interesting to see evidence that the method could cross over to 3D printing, at least in concept.
For the uninitiated, the Curta is a mechanical calculator designed around the time of World War II. It is still often seen used in time-speed-distance (TSD) rallies to aid in the computation of times to checkpoints, distances off-course and so on. Many of these rallies don’t allow electronic calculators, so the Curta is perfect. The complex inner workings of the contraption were a key feature and point of interest among enthusiasts and the device itself is a highly popular collectible.
As for the 3D printed design, the attention to detail is impeccable. The current version has around 80 parts that need to 3D printed and a requires a few other screws and springs. Some parts like the reversing lever and selector knobs have been painted and digits added to complete the visual detail. The assembly took [Marcus Wu] around 40 minutes to complete and is one of the most satisfying builds we have ever seen.
What is even more amazing is that [Markus Wu], who is a software engineer by profession has shared all the files including the original design files free of cost on Thingiverse. A blog with written instructions is also available along with details of the iterations and original builds. We already did a post on a previous version so check it out for a little more background info.
How strong can you make a 3D-printed gearbox. Would you believe strong enough to lift an anvil? [Gear Down For What?] likes testing the limits of 3D printed gearboxes. Honestly, we’re amazed.
3D printing has revolutionized DIY fabrication. But one problem normally associated with 3D printed parts is they can be quite weak unless designed and printed carefully.
Using a whole roll of filament, minus a few grams, [Gear Down For What?] printed out a big planetary gear box with a ratio of 160:1 and added some ball bearings and using a drill as a crank. Setting it up on a hoist, he started testing what it could lift. First it lifted a 70 lb truck tire and then another without any issues. It then went on to lift a 120 lb anvil. So then the truck tires were added back on, lifting a combined weight of 260 lb without the gearbox breaking a sweat.
This is pretty amazing! There have been things like functional 3D-printed car jacks made in the past, however 3D-printed gear teeth are notoriously easily broken unless designed properly. We wonder what it would take to bring this gearbox to the breaking point. If you have a spare roll of filament and some ball bearings, why not give it go yourself? STL files can be found here on Thingiverse.
[James Bruton] built an electric skateboard out of oversized LEGO bricks he printed himself, and equipped the board with an excellent re-creation of a classic motor.
He began by downloading brick, gear, and pulley designs from Thingiverse and printing them up five times their normal size, taking 600 hours. The deck consists of 8M Technic bricks lengthwise and 4M bricks crosswise, with plates covering top. There’s even a monster 5×6 plate that’s clearly courtesy of a parametric brick design because you won’t find that configuration among LEGO’s official parts.
The coolest part of the project is probably [James]’ re-creation of an old school LEGO motor. He sized up a 6216M Technic motor originally rated for 4.5V swapping in a 1.5 kW, 24V motor controlled by a 120A ESC and powered pair of Turnigy 5000mAh LiPos wired in series.
[James] had to design his own casing in Blender because couldn’t find a file for the original LEGO part—pro tip for the future, LDraw has the 6216 design and it can be dropped into Blender.
Another nice touch are the wheels, with hubs based off upsized 40-tooth Technic gears with Ninjaflex tires that weigh half-a-kilo each and took 32 hours apiece to print.
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. Continue reading “Beautiful DIY Spot Welder Reminds Us We Love 3D Printing”→
[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.
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.
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.