Prusa Launches Their Own 3D Model Repository

If you own a 3D printer, you’ve heard of Thingiverse. The MakerBot-operated site has been the de facto model repository for 3D printable models since the dawn of desktop 3D printing, but over the years it’s fallen into a state of disrepair. Dated and plagued with performance issues, many in the community have been wondering how long MakerBot is still going to pay to keep the lights on. Alternatives have popped up occasionally, but so far none of them have been able to amass a large enough userbase to offer any sort of real competition.

Sorting models by print time and material required.

But that might soon change. [Josef Průša] has announced a revamped community for owners of his 3D printers which includes a brand-new model repository. While clearly geared towards owners of Prusa FDM printers (support for the new SLA printer is coming at a later date), the repository is not exclusive to them. The immense popularity of Prusa’s products, plus the fact that the repository launched with a selection of models created by well known designers, might be enough to finally give Thingiverse a run for its money. Even if it just convinces MakerBot to make some improvements to their own service, it would be a win for the community.

The pessimists out there will say a Prusa-run model database is ultimately not far off from one where MakerBot is pulling the strings; and indeed, a model repository that wasn’t tied to a particular 3D printer manufacturer would be ideal. But given the passion for open development demonstrated by [Josef] and his eponymous company, we’re willing to bet that the site is never going to keep owners of other printers from joining in on the fun.

That being said, knowing that the users of your repository have the same printer (or a variant, at least) as those providing the designs does have its benefits. It allows for some neat tricks like being able to sort designs by their estimated print time, and even offers the ability to upload and download pre-sliced GCode files in place of traditional STLs. In fact, [Josef] boasts that this is the world’s only repository for ready-to-print GCode that you can just drop onto an SD card and print.

Regular Hackaday readers will know that we’ve been rather critical of the decisions made by MakerBot over the last few years, but to be fair we aren’t exactly alone in that respect. The community desperately needs a repository for printable models that’s in somebody else’s hands, and frankly we’re thrilled with the idea it could be [Josef Průša] leading the charge. His printers might not be perfect, and they certainly aren’t cheap, but they definitely don’t fail to impress. Here’s hoping this latest venture will be the same.

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When Unfolding An STL In Software, Math Isn’t The Tricky Part

Some time ago, [Trammell Hudson] took a shot at creating a tool that unfolds 3D models in STL format and outputs a color-coded 2D pattern that can be cut out using a laser cutter. With a little bending and gluing, the 3D model can be re-created out of paper or cardboard.

There are of course other and more full-featured tools for unfolding 3D models: Pepakura is used by many, but is not free and is Windows only. There is also a Blender extension called Paper Model that exists to export 3D shapes as paper models.

What’s interesting about [Trammell]’s project are the things he discovered while making it. The process of unfolding an STL may be conceptually simple, but the actual implementation is a bit tricky in ways that have little to do with number crunching.

For example, in a logical sense it doesn’t matter much where the software chooses to start the unfolding process, but in practice some start points yield much tighter groups of shapes that are easier to work with. Also, his software doesn’t optimize folding patterns, so sometimes the software will split a shape along a perfectly logical (but non-intuitive to a human) line and it can be difficult to figure out which pieces are supposed to attach where. The software remains in beta, but those who are interested can find it hosted on GitHub. It turns out that it’s actually quite challenging to turn a 3D model into an unfolded shape that still carries visual cues or resemblances to the original. Adding things like glue tabs in sensible places isn’t trivial, either.

Tools to unfold 3D models feature prominently in the prop-making world, and it’s only one of the several reasons an economical desktop cutter might be a useful addition to one’s workshop.

Walking Through MRIs With A Vive

If you were to make a list of the most important technological achievements of the last 100 years, advanced medical imaging would probably have to rank right up near the top. The ability to see inside the body in exquisite detail is nearly miraculous, and in some cases life-saving.

Navigating through the virtual bodies generated by the torrents of data streaming out of something like a magnetic resonance imager (MRI) can be a challenge, though. This intuitive MRI slicer aims to change that and makes 3D walkthroughs of the human body trivially easy. [Shachar “Vice” Weis] doesn’t provide a great deal of detail about the system, but from what we can glean, the controller is based on a tablet and Vive tracker. The Vive is attached to the back of the tablet and detects its position in space. The plane of the tablet is then interpreted as the slicing plane for the 3D reconstruction of the structure undergoing study. The video below shows it exploring a human head scan; the update speed is incredible, with no visible lag. [Vice] says this is version 0.1, so we expect more to come from this. Obvious features would be the ability to zoom in and out with tablet gestures, and a way to spin the 3D model in space to look at the model from other angles.

Interested in how the machine that made those images works? We’ve covered the basics of MRI scanners before. And if you want to go further, you could always build your own.

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Make Use Of Your Drone Video With WebODM

If you ever watch the original Star Trek, Captain Kirk and crew spend a lot of time mapping new parts of the galaxy. In fact, at least one episode centered on them taking images of some new part of space. It might not be new, but if you have a drone, you probably have accumulated a lot of frames of aerial imagery from around your house (or wherever you fly).

WebODM allows you to create georeferenced maps, point clouds and textured 3D models from your drone footage. The software is really an integration and workflow manager for Open Drone Map, which does most of the heavy lifting.

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Using Photogrammetry To Design 3D Printed Parts

[Stefan] is building a fixed wing drone, and with that comes the need for special mounts and adapters for a GoPro. The usual way of creating an adapter is pulling out a ruler, caliper, measuring everything, making a 3D model, and sending it off to a 3D printer. Instead of doing things the usual way, [Stefan] is using photogrammetric 3D reconstruction to build a camera adapter that fits perfectly in his plane and holds a camera securely.

ScanPhotogrammetry requires taking a few dozen pictures with a camera, using software to turn these 2D images into a 3D model, and building the new part from that model. The software [Stefan] is using is Pix4D, a piece of software that is coincidentally used to create large-scale 3D models from drone footage.

With the 2D images turned into a 3D model, [Stefan] imported the .obj file into MeshLab where the model could be cropped, smoothed, and the file size reduced. From there, creating the adapter was as simple as a little bit of OpenSCAD and sending the adapter model off to a 3D printer.

Just last week we saw photogrammetry used in another 3D object scanner. The results from both of these projects show real promise for modeling, especially with objects that are difficult to measure by hand.

Rigging Your 3D Models In The Real-World

Computer animation is a task both delicate and tedious, requiring the manipulation of a computer model into a series of poses over time saved as keyframes, further refined by adjusting how the computer interpolates between each frame. You need a rig (a kind of digital skeleton) to accurately control that model, and researcher [Alec Jacobson] and his team have developed a hands-on alternative to pushing pixels around.

3D Rig with Control Curves
Control curves (the blue circles) allow for easier character manipulation.

The skeletal systems of computer animated characters consists of kinematic chains—joints that sprout from a root node out to the smallest extremity. Manipulating those joints usually requires the addition of easy-to-select control curves, which simplify the way joints rotate down the chain. Control curves do some behind-the-curtain math that allows the animator to move a character by grabbing a natural end-node, such as a hand or a foot. Lifting a character’s foot to place it on chair requires manipulating one control curve: grab foot control, move foot. Without these curves, an animator’s work is usually tripled: she has to first rotate the joint where the leg meets the hip, sticking the leg straight out, then rotate the knee back down, then rotate the ankle. A nightmare.

[Alec] and his team’s unique alternative is a system of interchangeable, 3D-printed mechanical pieces used to drive an on-screen character. The effect is that of digital puppetry, but with an eye toward precision. Their device consists of a central controller, joints, splitters, extensions, and endcaps. Joints connected to the controller appear in the 3D environment in real-time as they are assembled, and differences between the real-world rig and the model’s proportions can be adjusted in the software or through plastic extension pieces.

The plastic joints spin in all 3 directions (X,Y,Z), and record measurements via embedded Hall sensors and permanent magnets. Check out the accompanying article here (PDF) for specifics on the articulation device, then hang around after the break for a demonstration video.

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MAME Cabinet 3D Modeled And CNC Milled

[Entropia] is just putting the final touches on his bar-top MAME cabinet (translated). The project started out as a 3D model to get the case dimensions just right. An old laptop is being, so the enclosure was designed to fit the bare LCD assembly and hide the rest of the computer. [Entropia] had access to a CNC mill through an education program and used it to cut most of the parts for the case out of MDF.

From there the build proceeds as normal. Mounting holes for the controls were cut with a drill and hole saws. We think it’s a bit easier to lay this design out once you have the control panel itself milled, rather than try to get it right in the 3D model. The image above is part way through the build. Since it was taken the case has been painted and a sound system was added but it looks like it’s still waiting for a bezel over the LCD and a marquee for the masthead.

You can see a demo of the game selection UI after the break.

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