Finite Element Analysis Results In Smart Infill

February 6, 2019 by Brian Benchoff 16 Comments

If you would like to make a 3D print stronger, just add more material. Increase the density of the infill, or add more perimeters. The problem you’ll encounter though is that you don’t need to add more plastic everywhere, only in the weak areas of the part that will be subjected to the most stress. Studying where parts will be the weakest is the domain of finite element analysis, and yes, you can do it in Fusion 360. With the right techniques, you can make a stronger part on your 3D printer, and [Stefan] is here to show you how to do it.

The inspiration for this build comes from [Adrian Bowyer]’s blog, where he talks about adding ‘fibers’ to the interior of 3D printed objects to increase strength. These ‘fibers’ aren’t really fibers at all, but long, thin, cylindrical voids. The theory of this is that the slicer will interpret this as a hole and place perimeters around these voids, effectively increasing the density of the infill in a local area in the print. Combine this with finite element analysis, and you get a part that is stronger where it needs to be, and doesn’t waste plastic.

However, there is an easier way. Fusion 360 and ANSYS Finite Element Simulation are both free-ish tools that allow for some amount of finite element analysis on an imported 3D object. This can be used to find the weakest part of any 3D print, and it can this can be exported as a 3D mesh. Slic3r has a modifier mesh function, and combining this finite element analysis mesh (printed at 100% infill) with the original part (printed at 10% or so infill) results in something that’s strong where it needs to be, doesn’t waste plastic, and is much easier to set up than [Adrian Bowyer]’s ‘fiber’ technique.

After printing a few 3D printed hooks with varying degrees and techniques of infill, [Stefan] found the baseline of 2 perimeters failed in a test hook at about 50kg load. The Smart Infill hook failed at about 100kg. Not bad, and the fancy-pants hook only weighs about 30% more.

You can check out a video of the entire toolchain and testing below. Thanks [Keith] for sending this one in.

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Hackaday Podcast 004: Taking The Blue Pill, Abusing Resistors, And Not Finding Drones

February 1, 2019 by Mike Szczys 17 Comments

Catch up on your Hackaday with this week’s podcast. Mike and Elliot riff on the Bluepill (ST32F103 boards), blackest of black paints, hand-crafted sorting machines, a 3D printer bed leveling system that abuses some 2512 resistors, how cyborgs are going mainstream, and the need for more evidence around airport drone sightings.

Stream or download Episode 4 here, and subscribe to Hackaday on your favorite podcasting platform! You’ll find show notes after the break.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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3D Print That Charging Dock For Your 3DS

January 31, 2019 by Brian Benchoff 15 Comments

The Switch is the new hotness and everyone wants Nintendo’s new portable gaming rig nestled in a dock next to their TV, but what about Nintendo’s other portable gaming system? Yes, the New Nintendo 3DS can get a charging dock, and you can 3D print it with swappable plates that make it look like something straight out of the Nintendo store.

[Hobby Hoarder] created this charging dock for the New Nintendo 3DS as a 3D printing project, with the goal of having everything printable without supports, and able to be constructed without any special tools. Printing a box is easy enough, but the real trick is how to charge the 3DS without any special tools. For this, [Hobby Hoarder] turned to the small charging contacts on the side of the console. All you do is apply power and ground to these contacts, and the 3DS charges.

Normally, adding contacts requires pogo pins or hilariously expensive connectors, but [Hobby Hoarder] has an interesting solution: just add some metal contacts constructed from LED leads or paper clips, and mount it on a spring-loaded slider. A regular ‘ol USB cable is scavenged, the wires stripped, and the red and black lines are attached to the spring-loaded slider.

There is a slight issue with the charging voltage in this setup; the 3DS charges at 4.6 Volts, and USB provides 5 Volts. If you want to keep everything within exacting specs, you could add an LDO linear regulator, but there might be issues with heat dissipation. You could use a buck converter, but at 0.4 Volts, you’re probably better off going with the ‘aaay yolo’ theory of engineering.

[Hobby Hoarder] produced a few great videos detailing this build, and one awesome video detailing how to print multicolored faceplates for this charging dock. It’s an excellent project, and a great example of what can be done with 3D printing and simple tools.

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This 3D Printer Is Soft On Robots

January 30, 2019 by Al Williams No comments

It always seems to us that the best robots mimic things that are alive. For an example look no further than the 3D printed mesh structures from researchers at North Carolina State University. External magnetic fields make the mesh-like “robot” flex and move while floating in water. The mechanism can grab small objects and carry something as delicate as a water droplet.

The key is a viscous toothpaste-like ink made from silicone microbeads, iron carbonyl particles, and liquid silicone. The resulting paste is amenable to 3D printing before being cured in an oven. Of course, the iron is the element that makes the thing sensitive to magnetic fields. You can see several videos of it in action, below.

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Plastics: PETG

January 29, 2019 by Dan Maloney 30 Comments

You’d be hard-pressed to walk down nearly any aisle of a modern food store without coming across something made of plastic. From jars of peanut butter to bottles of soda, along with the trays that hold cookies firmly in place to prevent breakage or let a meal go directly from freezer to microwave, food is often in very close contact with a plastic that is specifically engineered for the job: polyethylene terephthalate, or PET.

For makers of non-food objects, PET and more importantly its derivative, PETG, also happen to have excellent properties that make them the superior choice for 3D-printing filament for some applications. Here’s a look at the chemistry of polyester resins, and how just one slight change can turn a synthetic fiber into a rather useful 3D-printing filament.

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Casting Concrete With 3D Printed Molds

January 27, 2019 by Al Williams 13 Comments

[Thomas Sanladerer] wanted to create some molds using 3D printing for concrete and plaster. He used a delta printer with flexible filament and documented his process in the video below.

If you’ve printed with flexible filaments before, you know you need an extruder that has a contained path. [Tom] borrowed a printer, but it didn’t have that kind of set up. The first step was to swap extruders with another printer.

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WiFi Controlled Finger Dims Lights Over UDP

January 26, 2019 by Eric Evenchick 10 Comments

While WiFi controlled lights are readily available, replacing your lighting fixtures or switches isn’t always an option. [Thomas] ran into this issue with his office lights. For the developers in the office, these lights always seemed to run a little too bright. The solution? A 3D printed, WiFi controlled finger to poke the dimmer switch.

This little hack consists of a servo, a 3D printed arm and finger assembly, and a Wemos D1 Mini development board. The Wemos is a low cost, Arduino compatible development board based on the ESP8266. We’ve seen it used for a wide variety of hacks here on Hackaday.

For this device, the Wemos is used to listen for UDP packets on the company’s WiFi network. When it receives a packet, it tells the servo to push the dimming button for a specified amount of time. [Thomas] wrote a Slack bot to automatically send these packets. Now, when the lights are too bright, a simple message to the bot allows anyone to dim the lights without ever leaving the comfort of their desk. Sure, it’s not the most secure or reliable method of controlling lights, but if something goes wrong, the user can always get up and flip the switch the old fashioned way.