3D Printering: When An STL File Is Not Quite Right

STL files are everywhere. When there’s something to 3D print, it’s probably going to be an STL. Which, as long as the model is good just as it is, is no trouble at all. But sooner or later there will be a model that isn’t quite right in some way and suddenly project progress hits a snag.

When models interface with other physical things, those other components may not always be exactly as the designer expected. Being mindful about such potential inconsistencies during the design phase can help prevent problems, but it’s not always avoidable. The reason it’s a problem is because an STL file represents a solid model as a finished unit; it is not really intended to be rolled back into CAD programs for additional design changes.

STL files can be edited, but just like re-modeling a component from scratch, it can be a tricky process for those who don’t live and breathe this stuff. I’ll describe a few common issues related to STLs that can hold up getting that new project together, along with ways to deal with them. Thanks to 3D printing becoming much more commonplace, basic tools are within reach of even the least CAD-aware among us.

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IKEA Lamp With Raspberry Pi As The Smartest Bulb In The House

We love to hack IKEA products, marvel at Raspberry Pi creations, and bask in the glow of video projection. [Nord Projects] combined these favorite things of ours into Lantern, a name as minimalist as the IKEA lamp it uses. But the result is nearly magic.

The key component in this build is a compact laser-illuminated video projector whose image is always in focus. Lantern’s primary user interface is moving the lamp around to switch between different channels of information projected on different surfaces. It would be a hassle if the user had to refocus after every move, but the focus-free laser projector eliminates that friction.

A user physically changing the lamp’s orientation is detected by Lantern’s software via an accelerometer. Certain channels project an information overlay on top of a real world object. Rather than expecting its human user to perform precise alignment, Lantern gets feedback from a Raspberry Pi camera to position the overlay.

Speaking of software, Lantern as presented by [Nord Projects] is a showcase project under Google’s Android Things umbrella that we’ve mentioned before. But there is nothing tying the hardware directly to Google. Since the project is open source with information on Hackster.io and GitHub, the choice is yours. Build one with Google as they did, or write your own software to tie into a different infrastructure (MQTT?), or a standalone unit with no connectivity at all.

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Gentle Electric Eel

It’s no shock that electric eels get a bad rap for being scary creatures. They are slithery fleshy water snakes who can call down lightning. Biologists and engineers at the University of California had something else in mind when they designed their electric eel. Instead of hunting fish, this one swims harmlessly alongside them.

Traditional remotely operated vehicles have relied on hard shells and spinning propellers. To marine life, this is noisy and unnatural. A silent swimmer doesn’t raise any eyebrows, not that fish have eyebrows. The most innovative feature is the artificial muscles, and although the details are scarce, they seem to use a medium on the inside to conduct a charge, and on the outside, the saltwater environment conducts an opposite charge which causes a contraction in the membrane between to the inside and outside. Some swimming action can be seen below the break, and maybe one of our astute readers can shed some light on this underwater adventurer’s bill of materials.

One of our favorite submarines is the 2017 Hackaday Prize winner, The Open Source Underwater Glider. For a more artistic twist on submersibles, the Curv II is one of the most elegant we have seen.

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