What is Mastery Based Grading, why would you use it, and what’s the LEAST you can do to implement something effective? In this post we'll share how we implement this technique in a college calculus course with a very controlled retake policy built into class time and randomly generated multiple-choice quizzes with hidden coded answer keys entirely in LaTeX... // Hacktastic

Spring semester is coming and we'll be teaching a introductory class on 3D printing and design. As usual, our first-day 3D print will be a Penny Trap. In this article we'll walk through how to create this model in Tinkercad, Fusion 360, OpenSCAD, and the Thingiverse Customizer. Those happen to be exactly the same four design tools our students will learn about... // Hacktastic

Companies come and go, especially online. Data gets lost, start-ups don't get past start, and businesses get bought out or go belly-up. Your online content could go out the window without warning. So, if you post or publish your work online, forget New Year's resolutions... instead we have an end-of-year resolution: Back up your online content before New Year's Eve!... // Hacktastic

A few years ago we created a spiky knot model to show off the power of dissolvable supports: our Giant Spiky Perko Knot. It took six days and lots of failed starts to print... but alas, a few weeks ago one of our cats knocked it down and broke it! In this post we'll walk through reprinting this giant 3D model, and compare the virtues and pitfalls of dissolvable and breakaways supports... // Hacktastic

Need a last-minute gift for a special person? You can create a unique, custom 3D-printed clock with just a little bit of design knowledge and an inexpensive battery-powered clock kit. In this post we’ll show you how you can create a custom 3D-printable clock face with three different software programs, or by customizing a clock with our Sunburst Clock Maker. // Shapeways Magazine

The Snowflake Machine uses random numbers, mathematical algorithms, computer code, and SCIENCE to create well over a billion unique and beautiful snowflakes. It's a customizable design available for free on Thingiverse, and people around the world have already used it to generate almost four thousand unique snowflake models! Choose a random seed value and then set various style parameters... // Hacktastic

This week we created a special collection of 3D knot models based on some old projects we did with students a few years ago. To recreate these knots we used our old data to recode each of the models in a consistent way in OpenSCAD. This year's version of the knots are scaled and sized to form a matching set suitable for printing on SLS printers like the ones at Shapeways... // Hacktastic

One of our favorite 3D designs is a model of Dudeney's famous hinged dissection of a triangle to a square, also known as the Haberdasher's Puzzle. Today we'll revisit this design and update it for printing on SLS machines. We designed our original triangle-square model a few years ago with OpenSCAD, using data from an article by Mark Meyerson... // Hacktastic

This is a joint work by Edmund Harriss (gelada) and Laura Taalman (mathgrrl), made at the #0things Hackathon at Construct3d 2018, run by the unstoppable DesignMakeTeach. We were inspired by British constructivist artist Mary Martin, whose artwork "Inversions", now in the Tate Gallery in London, is based on the mathematical idea of permutations... // Hacktastic

This is the fourth post in our series about machine knitting and our goal of using a Silhouette Cameo 3 craft cutter to create custom punch cards for vintage knitting machines. In this post we'll discuss how to design the patterns for the cards and then get those designs into the Silhouette Studio software. We'll start with a simple solution to the problem, using the easy-to-use online design program Stitch Fiddle... // Hacktastic

Sometimes a digital 3D design looks great in software, but just can’t make it in reality. Here in the real world, models with very skinny wires or delicate parts might break after printing, or worse, not be able to 3D print at all. In this post, we’ll examine how auto-checks, human checks, and prototyping can help you design models that print successfully and are sturdy enough to handle repeated use... // Shapeways Magazine

Does the world need yet another filament sampler model? Probably not. But we made one anyway. Along the way we tested out Thingiverse's new "Send to Fusion 360" feature for adding fillets and revisited our "Blender Bake" method for enabling OpenSCAD to add text to an existing STL file in a way that can be used in the Thingiverse Customizer. Our elegant tombstone design... // Hacktastic

Not every polyhedron is tetrahedralizable. The simplest example is the Schönhardt polyhedron, which is a twisted triangular prism constructed in such a way that all tetrahedra that share vertices with the polyhedron fall into the exterior. This means that the Shönhardt polyhedron can't be subdivided into tetrahedra using only its original set of vertices... // Hacktastic

What do you do when your 3D model is broken? I mean really broken, like “can’t even upload it” broken, or “half of my triangles are disappearing” broken? In this post we’ll talk about what to do when your usual mesh-repairing strategies fail and you need to bring out the big guns. So we can follow exactly what’s going wrong, we’ll create a bad mesh by modifying an existing 3D model... // Shapeways Magazine

In this post we'll use 3D printing to solve the micro-problem of keeping an ultra-fine point Sharpie marker aligned in a Silhouette craft cutter. This is a tiny part of our long saga of learning how to create punch cards for a Brother KH-881 knitting machine. To keep the Sharpie aligned in the cutter we used a commercial maker holder and a 3D-printed spacer made with OpenSCAD... // Hacktastic

There's a new shape in town! In a new article "Scutoids are a geometrical solution to three-dimensional packing of epithelia" in the journal Nature, a group of scientists just introduced a new shape that they have dubbed a "Scutoid". To make a 3D model of this new shape, we created a simple polyloft module in OpenSCAD that lofts from one polygon to another... // Hacktastic

I brought nearly 1000 research papers and over 200 books with me to Peru this spring. Not in heavy stacks and stapled packets, but on a SONY Digital Paper, a large-format e-reader that is basically the size of a thick piece of standard 8.5 x 11 paper. The Paper is the first electronic device I've used that is suitable for reading technical mathematics research papers... // Hacktastic

A saddle surface is one of the few things I think is really worth 3D printing for Calculus students. There’s something important able to feel the two competing curvatures with your actual hands, instead of just looking at a picture. Since I always like to use the simplest design tools possible, this is a model that I export from Mathematica and then process in the much easier to use design software Tinkercad... // Hacktastic

This month I had the opportunity to speak about mathematics and 3D printing in Johannesburg, Pretoria, Cape Town, and Kimberley as part of the U.S. Embassy Speaker's Program. For this visit I made a special 3D-printed keychain to give away at events, which highlights the nine provinces of South Africa. By running a loop through the landlocked country of Lesotho, you can make a keychain... // Hacktastic 

We're finally getting back to our Brother KH-881 punch card knitting machine project... and it's time to make some punch cards! The KH-881 reads 24-stitch repeat punch cards, and uses the punched holes to determine where stitches are slipped, tucked, or knit in a differerent color, depending on the settings on the machine. Some punch cards come standard with the machine, but you can also hand-punch custom cards... // Hacktastic