3D Finger Joints For Your Laser Cutter

A laser cutter is an incredibly useful tool and they are often found in maker spaces all over. They’re quite good at creating large two-dimensional objects and by cutting multiple flat shapes that connect together you can assemble a three-dimensional object. This is easier when creating something like a box with regular 90-degree angles but quickly becomes quite tricky when you are trying to construct any sort of irregular surface. [Tuomas Lukka] set out to create a dollhouse for his daughter using the laser cutter at his local hackerspace and the idea of creating all the joints manually was discouraging.

The solution that he landed on was writing a python script called Plycutter that can take in an STL file and output a series of DXF files needed by the cutter. It does the hard work of deciding how to cut out all those oddball joints.

At its core, the system is just a 3D slicer like you’d find for a 3D printer, but not all the slices are horizontal. Things get tricky if more than two pieces meet. [Tuomas] ran into a few issues along the way with floating-point round-off and after a few rewrites, he had a fantastic system that reliably produced great results. The dollhouse was constructed much to his daughter’s delight.

All the code for Plycutter is on GitHub. We’ve seen a similar technique that adds slots, finger-joints, and t-slots to boxes, but Plycutter really offers some unique capabilities.

FreeCAD Debugging

Powerful software programs often have macro programming languages that you can use, and if you know how to program, you probably appreciate them. However, sometimes the program’s built-in debugging facilities are lacking or even nonexistent If it were just the language, that wouldn’t be such a problem, but you can’t just grab a, for example, VBA macro from Microsoft Word and run it in a normal Basic interpreter. Your program will depend on all sorts of facilities provided by Word and its supporting libraries. [CrazyRobMiles] was frustrated with trying to debug Python running inside FreeCAD, so he decided to do something about it.

[Rob’s] simple library, FakeFreeCad, gives enough support that you can run a FreeCAD script in your normal Python development environment. It only provides a rude view of what you are drawing, but it lets you explore the flow of the macro, examine variables, and more.

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Digital Preservation For Old Batteries

The times they are a-changin’. It used to be that no household was complete without a drawer filled with an assortment of different sizes and types of batteries, but today more and more of our gadgets are using integrated rechargeable cells. Whether or not that’s necessarily an improvement is probably up for debate, but the fact of the matter is that some of these old batteries are becoming harder to find as time goes on.

Which is why [Stephen Arsenault] wants to preserve as many of them as possible. Not in some kind of physical battery museum (though that does sound like the sort of place we’d like to visit), but digitally in the form of 3D models and spec sheets. The idea being that if you find yourself in need of an oddball, say the PRAM battery for a Macintosh SE/30, you could devise your own stand-in with a printed shell.

The rather brilliantly named Battery Backups project currently takes the form of a Thingiverse Group, which allows other alkaline aficionados to submit their own digitized cells. The cells that [Stephen] has modeled so far include not only the STL files for 3D printing, but the CAD source files in several different flavors so you can import them into your tool of choice.

Like the efforts to digitally preserve vintage input devices, it’s not immediately clear how many others out there are willing to spend their afternoons modeling up antiquated batteries. But then again, we’ve long since learned not to underestimate the obscure interests of the hacker community.

FreeCAD Parametrics Made Simple

Simple drafting programs just let you draw like you’d use a pencil. But modern programs use parametric models to provide several benefits. One is that you can use parameters to change parts of your design and other parts will alter to take account of your changes. The other advantage is you can use one model for many similar but different designs. [Brodie Fairhall] has a nice video about how to use parameters in FreeCAD.

The nice thing about parameters is they don’t have to be just constants. You can put in formulae as well. For example, you could define one line as being twice as big as another line. You provide various constraints and parameters and FreeCAD works out the shape for you, keeping all the constraints and formulae satisfied.

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Hyper Links And Hyperfunctional Text CAD

Strong opinions exist on both sides about OpenSCAD. The lightweight program takes megabytes of space, not gigabytes, so many people have a copy, even if they’ve never written a shape. Some people adore the text-only modeling language, and some people abhor the minimal function list. [Johnathon ‘Zalo’ Selstad] appreciates the idea but wants to see something more robust, and he wants to see it in your browser. His project CascadeStudio has a GitHub repo and a live link so you can start tinkering in a new window straight away.

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Autodesk Blinks, Keeps STEP File Export In Free Version Of Fusion 360

Good news, Fusion 360 fans — Autodesk just announced that they won’t be removing support for STEP file exports for personal use licensees of the popular CAD/CAM platform after all.

As we noted last week, Autodesk had announced major changes to the free-to-use license for Fusion 360. Most of the changes, like the elimination of simulations, rolling back of some CAM features, and removal of generative design tools didn’t amount to major workflow disruptions for many hobbyists who have embraced the platform. But the loss of certain export formats, most notably STEP files, was a bone of contention and the topic of heated discussion in the makerverse. Autodesk summed up the situation succinctly in their announcement, stating that the reversal was due to “unintended consequences for the hobbyist community.”

While this is great news, bear in mind that the other changes to the personal use license are still scheduled to go into effect on October 1, while the planned change to limit the number of active projects will go into effect in January 2021. So while Fusion 360 personal use licensees will still have STEP files, the loss of other export file formats like IGES and SAT are still planned.

Figuro Draws 3D In Browser

We would have never guessed there would be so many browser-based CAD packages. While TinkerCAD is great for simple things, there are also packages such as OnShape that rival commercial CAD programs. A site calle Figuro claims to occupy the space between TinkerCAD and Blender. We aren’t so sure, but it is an interesting entry into the field. Apparently, Figuro has been around for some time, but has recently had a major face lift. The new interface looks good, but it has invalidated a number of video tutorials on their YouTube channel.

One of the things we like about TinkerCAD is it is highly discoverable. That is, you can fire it up, play with it a bit, and probably do quite a few things. Maybe it is just us, but Figuro didn’t give us the same experience. It is easy enough to draw simple shapes. But trying to multiselect was unreliable. Panning and rotating the view was very sensitive too, so we found we were occasionally lost in the work view with no easy way to reset the view. Even something as simple as subtracting one shape from another was painful.

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