Class Cut Up
Cheaper, safer subtractive machining tools let students leap quickly from designs to prototypes and products.
By Chris Rogers
While 3D printing seems to get the most press on revolutionizing the engineering classroom, I have been most excited by the growth of smart subtractive machining. At the top of the list is the laser cutter, with its ability to rapidly and accurately cut out complicated shapes with ease. No other tool has had more of an effect on our students’ projects. While it is still relatively expensive, the price continues to drop and air handling systems continue to improve. The great part is that it is pretty difficult for students to get hurt using laser cutters—unless they disable the interlocks, in which case anything is possible, or attempt to cut materials that catch on fire or release toxic gas. Impressively, these tools rarely break down, despite being used by a few hundred students a year. Finally, they are fast. Students can iterate a design multiple times in an hour (unlike with 3D printers), and some of the new ones, like Glowforge (glowforge.com) will cut along any lines you draw, removing the need to learn CAD. As a result, design classes are no longer limited to drawing on paper and can proceed to cutting out prototypes.
My favorite part is the variety of what students can produce using laser cutters, from etchings of their favorite photos on Christmas tree ornaments to jewelry, puzzle pieces, or even bottle openers. I’ve watched students cut long, parallel grooves to make hinged joints, cut multiple iterations of ever shrinking airfoils to make a glider wing, and fashion a small ukulele out of chipboard (using the hinge technique to build the sides that need to bend in the shape of the top and bottom). They make a lot of boxes—boxes that are glued together, bolted together (screws and nuts), or simply flanged together; boxes for robot bodies, for gardens, including one for a totally automated hydroponic garden, for a musical instrument, or simply to store stuff (all with engraved walls, of course).
Other subtractive machining tools, such as milling machines, lathes, and routers, have in the past been dangerous and required oversight and training. Recently, however, companies like Othermill (othermachine.co), Roland (MDX line), Nomad (Carbide3D.com), and Carvey (inventables.com) have begun making small mills in which a computer provides much of the oversight and training. Those are the names I’m familiar with from our lab, but a number of companies are jumping into this market. The Othermill even has handles, making it easy to carry, and intuitive driver software. The Carvey uses Easel, one of the easiest CAD/CAM programs I have encountered. These devices require a little more setup and make a little more of a mess than the laser cutter, but the software is continually improving and I was told there is no reason you cannot have your Othermill cutting horizontally while placed on a trash can.
For woodworkers, including me (it’s my favorite material for making musical instruments), routers, too, are now connected to computers, ranging from the Shopbot and Handibot (shopbottools.com) to the Shapeoko (carbide3d.com) to the VCarve (inventables.com) or to the rather inventive Shaper Origin (shapertools.com). They are not quite as portable as some of the small mills and are a lot messier. They also tend not to have safety interlocks—although many have protective housings if you want to spend a bit more money, or you can just make your own.
So how far are we from students simply checking out a mill for the night to cut their own part or circuit board, or dorm rooms that come with a Glowforge laser cutter? Imagine what classes will look like when tool safety is really no longer a concern. It won’t be too long before these tools will have full torque control (no need to calculate feeds and speeds) and safety stops—from the lids with interlocks to the always amazing SawStop (sawstop.com) table saw. (Take a look at the Discovery Channel video in which an inventor puts his finger in the saw.) There even are some Kickstarter companies (like Pocket NC) that offer computer control over a five-degrees-of-freedom cutting tool.
The things we can make in class are becoming ever more complex, with less worry about students hurting themselves. Imagine what the 2025 student will be able to do for a weekend project.
Chris Rogers is a professor of mechanical engineering at Tufts University. firstname.lastname@example.org