Ditch OpenSCAD for C++

There’s an old saying that a picture is worth a thousand words. If you’ve ever tried to build furniture or a toy with one of those instructions sheets that contains nothing but pictures, you might disagree. 3D design is much the same for a lot of people. You think you want to draw things graphically, but once you start doing complex things and making changes, parametric modeling is the way to go. Some CAD tools let you do both, but many 3D printer users wind up using OpenSCAD which is fully parametric.

If you’ve used OpenSCAD you know that it is like a simple programming language, but with some significant differences from what you normally use. It is a good bet that most Hackaday readers can program in at least one language. So why learn something new? A real programming language is likely to have features you won’t find readily in OpenSCAD that, in theory, ought to help with reuse and managing complex designs.

I considered OpenJSCAD. It is more or less OpenSCAD for JavaScript. However, JavaScript is a bit of a scripting language itself. Sure, it has objects and some other features, but I’m more comfortable with C++. I thought about using the OpenCSG library that OpenSCAD uses, but that exposes a lot of detail.

Instead, I turned to a project that uses C++ code to generate OpenSCAD output, OOML (the Object Oriented Mechanics Language)). OpenSCAD does the rendering, exporting, and other functions. Unfortunately, the project seems to have stalled a few years back and the primary web-based documentation for it seems to be absent. However, it is very usable and if you know how to find it, there is plenty of documentation available.

Why not OpenSCAD?

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Wireless Robotic Gripper With Haptic Feedback

We’re not sure what kind of, “High School,” [Sam Baumgarten] and [Graham Hughes] go to that gave them the tools to execute their robotic gripper so well. We do know that it was not like ours. Apparently some high schools have SLS 3D printers and Solidworks. Rather than a grumpy shop teacher with three fingers who, despite that, kept taking the safety off the table saws and taught drafting on boards with so many phalluses and names carved into the linoleum, half the challenge was not transferring them to the line work.

Our bitterness aside, [Sam] and [Graham] built a pretty dang impressive robotic gripper. In fact, after stalking [Sam]’s linkedin to figure out if he was the teacher or the student, (student) we decided they’re bright enough they could probably have built it out of scraps in a cave. Just like [HomoFaciens], and Ironman.

The gripper itself is three large hobby servos joined to the fingers with a linkage, all 3D printed. The mechanical fingers have force sensors at the contact points and the control glove has tiny vibrating motors at the fingertips. When the force of the grip goes up the motors vibrate more strongly, providing useful feedback. In the video below you can see them performing quite a bunch of fairly fine motor skills with the gripper.

The gripper is mounted on a pole with some abrasive tape, the kind found on skateboard decks. At the back of the pole, the electronics and batteries live inside a project box. This provides a counterbalance to the weight of the hand.

The control glove has flexible resistors on the backs of the fingers. The signal from these are processed by an Arduino which transmits to its  partner arduino in the gipper via an Xbee module.

[Sam] and [Graham] did a great job. They worked through all the design stages seen in professional work today. Starting with a napkin sketch they moved onto digital prototyping and finally ended up with an assembly that worked as planned. A video after the break explaining how it works along with a demo video.

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ImplicitCAD: Programmatic CAD Built with 3D Printing in Mind

Cornerstone of many useful things: This Prusa i3 part was modeled in OpenSCAD.

Programmatic CAD, in particular the OpenSCAD language and IDE, has accompanied the maker movement for a while now. After its introduction in 2009, it quickly found its way into the 3D printing toolbox of many makers and eventually became what could be called an Industry Standard among open hardware labs, makerspaces and tinkerers. The Prusa i3, one of the most popular DIY 3D printers, was designed in OpenSCAD, and even Makerbot, the company that sold 100.000 3D printers, uses the language for its “Customizer” – an online tool that allows users to customize 3D printable models with minimal effort.

OpenSCAD is indeed a wonderful tool, and we have been using it a lot. We have become used to its quirks and accepted working with polygon mesh approximations of the models we are trying to design. We have made our peace with excessive rendering times, scripting workarounds and the pain of creating fillets, and we have learned to keep our aesthetic expectations low. We are happy with the fact that there is a way to programmatically create and share virtually any object, but sometimes we wish there was a better way in the open source world. Hint: there is.

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Ask Hackaday: Selling CAD Prints That Are Not Yours

[Louise] tried out her new E3D Cyclops dual extrusion system by printing a superb model dragon. The piece was sculpted in Blender, stands 13cm tall and can be made without supports. It’s an impressive piece of artwork that reflects the maker’s skill, dedication and hard work. She shared her creation on the popular Thingiverse website which allows others to download the file for use on their own 3D printer. You can imagine her surprise when she stumbled upon her work being sold on eBay.

It turns out that the owner of the eBay store is not just selling [Louise]’s work, he’s selling thousands of other models taken from the Thingiverse site. This sketchy and highly unethical business model has not gone unnoticed, and several people have launched complaints to both Thingiverse and eBay. Now, there are lots of things to talk about here, but the 800 pound high voltage transformer in the room is the legality of the whole thing. What he’s doing might be unethical, but is it illegal?

When [Louise] politely asked the eBay store owner to remove her work, he responded with:

“When you uploaded your items onto Thingiverse for mass distribution, you lost all rights to them whatsoever. They entered what is known in the legal world as “public domain”. The single exception to public domain rules are original works of art. No court in the USA has yet ruled a CAD model an original work or art.”

Most of the uploaded CAD models on Thingiverse are done under the Creative Commons license, which is pretty clear in its assertion that anyone can profit from the work. This would seem to put the eBay store owner in the clear for selling the work, but it should be noted that he’s not properly attributing the work to the original creator. There are other derivatives of the license, some of which prohibit commercial use of the work. In these cases, the eBay store owner would seem to be involved in an obvious violation of the license.

There are also questions stirring with his use of images.  He’s not taking the CAD model and making his own prints for images. He lifting the images of the prints from the Thingiverse site along with the CAD files. It’s a literal copy/paste business model.

With that said,  the eBay store owner makes a fairly solid argument in the comments section of the post that broke the news. Search for the poster named “JPL” and the giant brick of text to read it. He argues that the Thingiverse non-commercial license is just lip service and has no legal authority. One example of this is how they often provide links to companies that will print a CAD design on the same page of a design that’s marked as non-commercial. He sums up one of many good points with the quote below:

“While we could list several other ways Thingiverse makes (money), any creator should get the picture by now-Thingiverse exists to make Stratasys (money) off of creators’ designs in direct violation of its very own “non-commercial” license. If a creator is OK with a billion-dollar Israeli company monetizing his/her designs, but hates on a Philly startup trying to make ends-meet, then they have a very strange position indeed.”

OK Hackaday readers, you have heard both sides of the issue. Here’s the question(s):

1.  Is the eBay seller involved in illegal activity?

2. Can he change his approach to stay within the limits of the license? For instance, what if he credits the                      original maker on the sale page?

3. How would you feel if you found your CAD file for sale on his eBay store?

KiCad Script Hack for Better Mechanical CAD Export

Open source EDA software KiCad has been gaining a lot of traction recently. CERN has been devoting resources to introduce many new advanced features such as differential pair tracks, push and shove routing and this plenty more scheduled in the pipeline. One important requirement of EDA packages is a seamless interface with mechanical CAD packages by exporting 3D models in industry common formats. This improves collaboration and allows further engineering designs such as enclosures and panels to be produced.

KiCad has had a 3D viewer available for quite a long time. But it uses the VRML mesh format (.wrl files) and there are compatibility issues which prevent it from rendering certain versions of VRML files. Moreover, the VRML mesh export is not particularly useful since it cannot be easily manipulated in mechanical CAD software. Recent versions of KiCad now offer IDFv3 format export – the Intermediate Data Format, a mechanical data exchange specification for the design and analysis of printed wiring assemblies. Taking advantage of this new feature, [Maurice] created KiCad StepUp – an export script that allows collaborative exchange between KiCad and FreeCAD.

A FreeCAD macro and a corresponding configuration file are added to the KiCad project folder. You start with .STEP files for all the components used in the KiCad design. The next step is to convert and save all .STEP files as .WRL format using FreeCAD. On the KiCad side, you use the .WRL files as usual. When you want to export the board, use the IDFv3 option in KiCad. When [Maurice]’s StepUp script is run (outside of KiCad) it replaces all instances of .WRL files with the equivalent .STEP versions and imports the board as well as the components in to FreeCAD as .STEP models. The result is a board and its populated components which can be manipulated as regular 3D objects.

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