Our first installment of using the arduino Uno in the STEM classroom centered on programming basics and wiring, with a simple bit of code to make a series of LEDs cascade back and forth like a scanning eye. With that accomplished, we next bring the lights to life by taking advantage of CNC machining capabilities available to increasing numbers of teachers around the country. We will create a robot face that resembles a cross between villains on two different but popular science fiction series, placing the LEDs inside for a realistic effect (jump to the video below if you want a preview). This makes for an excellent  project-based learning experience that integrates CAD and CAM skills, design, programming and many other key STEM disciplines.

Summary

With the arduino code and basic wiring behind us, we will begin by taking our CAD design file and convert it to a series of toolpaths with a CAM program (we use SprutCAM, available at low cost for teachers). Next we cut the part out on the Tormach PCNC1100 mill from 6061 aluminum. Once the part has been deburred of any sharp edges, we will use perf board to mount the LEDs on the robot and connect them back to the arduino. Then sit back and let the scanning begin!

 Tools and Materials for Part II

CNC Mill and Tooling

6x6x.25  aluminum plate

3mm o-rings

perfboard

extension wires (we used pwm cable)

soldering iron and solder (optional for permanent installations)

Step One: CAM

Import the design as an .igs file into SprutCAM. Transform the stock as needed to orient the coordinates with Z at the top of the part. Set up a drilling operation first to make the holes for the LEDs. We used a .25 in drill bit for this task. The holes are space .4 in apart for alignment to the holes in the perfboard later.

.4 in Spacing works well

We will cut out the detail features of the model using two pocketing operations. Select the edges of each pocket (make sure the edge tool is activated) and set the depth to leave a bit of material under the holes for the LEDs to remain in place. Tip: use ‘project on plane’ if students are unable to find the edges of the pockets.

Pockets Take Shape

Next we will give the face some depth with a roughing waterline operation. This reduces the height of the main part of the face, allowing for a protruding forehead so common to villainous robots. Select the face under job assignment and Sprutcam does the rest.

Waterline helps give robot depth

To cleanly define the forehead we next do a 2D contour around it with a 9/64 endmill. This is followed by a final contour around the edges of the part to separate it from our stock. To prevent the part from moving during the cut, we leave .01 inches on the bottom level and knock it out with a mallet.

And of course students love the final simulation at the end of the CAM programming set up.

All operations check out on the simulation

Step Two: Cutting the Part

We use a standard set of clamps to fixture the stock to the machine table. Always place a piece of flat sacrificial material under the stock to avoid expensive damage to the machine should anything go awry.

Pocketing

Waterline gives depth to the robot

Face milling top surface

Final Contour Complete

Step Three: Assembly

The most difficult parts of this project are now complete. The final assembly can be accomplished in a variety of ways. In order to line up the LEDs, we will use perfboard to hold them together. The perfboard sits behind the robot, with the LEDs visible from the front. Because aluminum is conductive, it is very important to make sure there is no contact with the legs of the LEDs to avoid a short circuit.

Start by verifying that the LEDs and the holes are sized compatibly. Trim and deburr if necessary. To keep the LEDs in place, we use 3mm o-rings slipped around them from the front side of the robot. They are visible in their temporary location in the photo below, used just for checking the hold sizes.

Ensure that LEDs are sized correctly for holes

Verify the perfboard spacing is correct for your holes. Trim the perfboard as needed.

Perf Board and LED holes line up just right

Checking again for alignment

At this point there are two options for wiring. One is to trim the legs of the LEDs to length after soldering them to the perfboard for a permanent installation. In that case, a set of third hands with a magnifier is handy for students to see their work better. Polarity of the LEDs is critical, so whether soldering or not, check that the LEDs light up before diving too deep.

Since we are planning to reuse our LEDs the use of spare PWM cables makes for a sturdy but easy to disassemble option.

PWM cables were a good fit

Only two of the three lines on the PWM cables were used.  They are not the ideal solution for tight space management, but with careful wire wrapping it looks just fine.

Test fire the whole assembly and troubleshoot as needed. If you use the program from part one of this project, everything should look like this:

Click here to view the video on YouTube.

With this project-based learning activity, students have been given a mandate to acquire a wide variety of STEM skills and demonstrate their competencies in them. They have engaged in genuine engineering practices, from programming and design all the way to advanced manufacturing. Students can be assessed in a wide variety of state and national standards, all in one project that culminates in a fun product that showcases student skills. These are the skills that are in such short supply in today’s job market.  Keeping kids motivated encourages them to push themselves harder, enables them to collaborate with one another and bring to bear problem solving abilities they didn’t know they had.

Keep helping kids find that STEM career waiting for them in the world ahead.

The Arduino microcontroller is an inexpensive, robust and easy to program microcontroller that can easily be used in any STEM classroom. The Arduino platform has tremendous support from hundreds of vendors that offer customized products for just about any task imaginable. Sensors, motors, breakout boards, lighting, and more can be used by students to engage in real science and engineering practices safely and inexpensively.

Even if you are just getting started with STEM activities, consider taking this path. Using microcontrollers such as the Arduino involve multidisciplinary skills from computer science to mechanical engineering, making this a very high value item for project-based learning curricula. Students stay engaged, focused and learn by doing while you facilitate as they move along at their own pace. Working with microcontrollers forces students to demonstrate proficiencies in a wide variety of science and engineering standards, making meeting the Next Generation Science standards a breeze for every teacher.

Summary

This project-based learning activity introduces students to programming the Arduino microcontroller by creating a series of cascading LED lights resembling an evil race of robots from a popular science fiction series. In the second half of this activity, students will use CAD and CAM to create a replica of the robot using the Tormach PCNC 1100 mill from aluminum, and incoporate their programmed LEDs to add a final touch of realism to the model.

Part One: Light ‘Em Up

Materials

Arduino Uno (or nearly any Arduino platform with at least 9 I/O pins)

9 Resistors( use values from 100ohms to 2200 ohms)

9 Red LEDs

Breadboard

Programming Cable(use a usb printer cable)

Jumper Cables (2

Arduino IDE program (download at arduino.cc)

Arduino Uno, Breadboard, Resistors, LEDs, and Jumper Cables

Preliminary Steps:

Download and install the Arduino IDE. It works on virtually all operating systems, so be sure and choose the correct version to install on your computer(s). It is very important to install the driver correctly. Do not have Windows search for the driver, you will need to install it from the downloaded IDE into the correct folder.

Verify that Arduino is communicating to the computer. The best way to do this is to plug it in and run the ‘blink’ example program (arduino programs are also referred to as ‘sketches’). It uses the built-in LED on pin 13 so no additional hardware is needed. Remember this tip for future troubleshooting on any connection issues later. Pass it on to students to give them some self sufficiency with troubleshooting. I remind them this way: If it’s blinking, it’s thinking.

Use the blink code example for troubleshooting

If the yellow LED on P13 is blinking, all is well.

Getting Started

Let’s run a simple led program that calls for a bit of extra hardware. Instead of using the on board LED we will add connect an LED remotely using the breadboard. Students need the breadboard, a resistor, LED and some jumper wires.

1. Energize the breadboard by connecting a red wire to the positive rail and black to the negative rail on the breadboard. Next connect the red wire to the 5V pin and the black to the GND pin on the arduino. Your breadboard now has a 5 volt power source.

Power Up the Breadboard

2. The process of creating the robot eye begins with a single LED mounted on the breadboard.  LEDs do not survive long with excessive voltage, so a resistor is necessary for each. Don’t waste the opportunity to remind students of  this application of Ohm’s Law. You might want to give them a quick quiz on the relationship between voltage, current and resistance as a requirement to move on with this activity. In any case, a resistor of anywhere between 100 and 2500 ohms will do. We will use 2200 ohm resistors in our example, which are colored red-red-red.

3. Because LEDs have  a cathode and anode (+/- ) it is essential that they be connected in the right orientation. This is one of the most common failure points for students because it is difficult to tell sometimes which side is which. Generally the longer leg of the LED is (+). The bottom line for students is that if it doesn’t light up, try reversing the polarity of the LED.

4. Thankfully resistors are not polar, so they can be fitted in any orientation. Resistors can be a bit fiddly to fit on the breadboard. They tend to take up a fair amount of space, and if you are creating a circuit with many components things get crowded fast. In order to help save space, we bend the resistors as shown below. Simply cut one of the leads to half size, bend it over and you save about 50 percent of the space otherwise used.

How to save space

Well Worth the Effort

5. Insert the LED into the breadboard, with one leg in the same row as the resistor. Add a jumper to the row as well, terminating the other end in P13 of the arduino. On the other leg of the LED insert a jumper that is connected to the ground rail on the breadboard.

6. The final step is to run the ‘blink’ example sketch again. Since we connected the LED to pin 13, we don’t need to change anything on the program. The LED should blink once per second.

On

Off.   Simple!

 More Is Better

Okay, now comes the fun part. In order to make our roving robot eye, we will need to create a sequence of 9 flashing LEDs.  You can use more or less, but 9 seems to be a minimum for authentic effect. This means 9 resistors, and another 18 wires. If possible keep consistent with the wire colors. You can purchase sets of these jumper wires very inexpensively at a variety of vendors.

1. Begin by wiring up just three of the LEDs as a test. Since you are using P13, just continue down and use pins 12 and 11 for the other two LEDs. Keep them lined up as closely together as possible. Consider proper wire management a priority when evaluating student work here. Students should strive to keep things tidy and consistent in terms of spacing and colors.

Wire Management

2. There are an unlimited number of ways to write a program to accomplish this task. Later we will explore more advanced techniques to include fading and differential timing. For the moment, our sketch will build on the default ‘blink’ program. This program lights up the LEDs on pins 13, 12, 11 back and forth in an infinite loop. Download the file ‘blink3roboteye’ or copy and paste it into your arduino IDE. Students should adjust the timing (delay) value until they are satisfied with what they see.

3. At this point both the hardware and software need to be adjusted to accomodate the 9 LEDs. Students should add the remaining 6 LEDs, 6 resistors, and 12 wires to the breadboard and arduino. As before, the pins are on the digital side of the board, and will go from P13-P5.  Remember the polarity of the LEDs.

The  ’BlinkCylon’ sketch builds upon the previous ‘blink3′ program, adding the additional pins and command lines for each LED.  Download it and edit to your liking.

Click here to view the video on YouTube.

In this tutorial, STEM students have learned about the Arduino microcontroller and some of its capabilities. They have applied Ohm’s law, developed wire management techniques, and learned to program. Students have developed troubleshooting skills and learned to optimize a program to make it their own. In the next installment of the Roaming Robot Eyes tutorial, we will machine a replica of a Cylon Warrior with the Tormach CNC machine and install our LEDs. Stay tuned.

Because the Arduino is a bare PCB, some protection is a good idea for storage and/or during use, particularly in a classroom environment. In this STEM lesson, we will be making an aluminum enclosure for the Arduino Uno using the Tormach PCNC and SprutCAM software. This is a simple starter project for the CNC that will help the user gain skills and confidence for more advanced projects later.

This enclosure is designed to be used with or without the cover in place. The slots provide access to the I/O pins, but if a tall shield will be used you can remove the cover-or modify the design for additional height. Because the enclosure is electrically conductive, be sure and cover the bottom floor with some non-conductive material (we use mesh shelf liner).

CNC Tools

Vise

Clamping Kit

Digital Probe/EdgeFinder

2 Flute .5 in HSS End Mill

2 Flute .125 in HSS End Mill

2 Flute .0625 in HSS End Mill

Bill of Materials

2 in x 5 in  6061 Aluminum Stock

.10 in x 6 in Aluminum Sheet

Summary of Procedure:

1. Square up the stock.
2. Mill pockets and slot on front face.
3. Flip part and mill slot on rear face.
4. Mill main pocket.
5. Mill cover.

Begin by importing the .IGES file into SprutCAM. Transform the axes to bring Z to the top of the piece. Add stock to the part based on what you will be using.

If the part is cut in the center first, the remaining walls will be too thin to support it securely in the vise. Therefore we will machine the front and back faces, leaving the center for last.

We will flip the part for machining the front face by rotating it on the SC desktop. Next we will create a local cs (coordinate system) that will reorient the CNC machine to recognize the new axes. In order to do this, create a new pocketing operation. Click on the face to be machined. Next click on ‘create CS sense look vector’. Now the most important part: choose machine setup and turn on local CS. Then change global CS to Local CS1.as shown.

That will reference the part and the machine to the new coordinate system.

Select the edges to be machined. Choose the .0625 EM.

Use a spiral plunge for less chance of tool breakage with these tiny EMs. When you select spiral in SprutCAM, the option doesn’t appear until you close out lead in/lead out and then reopen them. Just a small bug that may or may not be present in your version.

Be sure and account for the extra stock when choosing your final depth.  Run the simulation. Easy!

Now we will flip the part for the rear slot using the same procedure as before. This time the new coordinates will be called local CS2. In order to do this, create a new pocketing operation. Click on the face to be machined. Next click on ‘create CS sense look vector’ as before. Again choose machine setup and turn on local CS. Then change global CS to Local CS2 as shown to reference the part and machine to your new coordinate system.

Select the edges of the slot. Use the .0625 EM again with the spiral cut as before. Run the simulation.

Time to mill out the main pocket that holds the Arduino. Create a third pocketing operation and change the coordinate system back to the original Global. Be sure and change the machine setup parameters to global as well!

This part of the procedure will include two more pocketing operations. You can hog out most of the material with a .5 inch EM.

Run the pocket again with a .125 EM for a clean corner.

Now part 2, the top of the Arduino enclosure.

Load the part into SC, and set up the transformation as usual.

Add stock around the part as needed.

Use a pocketing operation to cut the two slots. Again we will use the .0625 EM.

Use a 2d contour to remove the part. Make sure the edge selection tool is activated. For best results use the .0625 EM to get those nice tight corners.

This part will be clamped to the CNC table rather than put in the vise. If want to, put a screw through the slots to hold the part in place. Alternatively, leave .02 inches off the final cut depth and knock out the part. That is what we generally do.

Here is the box in its final form. Insert Arduino and begin programming! In our next installment we will have some fun making a bank of LEDs behave like menacing robots from a certain science fiction show.

References

Squaring up the aluminum stock. You’ll find an excellent tutorial below.

Click here to view the video on YouTube.

Feeds and Speeds

Gwizard

Recognition of the reality that robots are here and their economic importance makes it obvious that the study of robotics is a crucial part of any STEM education program. Many STEM programs are centered around robotics because the field is so broad-based that it brings to bear every STEM discipline. The many opportunities for competitive robotics for secondary students can turn a science and engineering pursuit into a sport of the mind, motivating kids to stay engaged in the subject matter beyond the confines of a classroom period.

Robots come in many forms, but two main distinctions can easily be made for the educator: Remote-controlled and autonomous robots. Remote-controlled robots respond to commands from an external source, such as a radio transmitter or infra red remote. Autonomous robots have sensors and programming that gives them a degree of independence from external influence, such as a robot vacuum. Combining these two into a hybrid system is a  third type of robot, where autonomous routines can take place in conjunction with remote operations. This is seen in certain military robots such as drones and FIRST Robotics Competition ‘bots.

CNC (Computer Numeric Controlled) machines of various types can be considered robots as well. These semi-autonomous devices are programmed by the user to build things using processes that were once under human control, now machined with extreme precision under computer control. Thanks to efficiencies in manufacturing the cost of CNC machines for the classroom has been reduced to a realistic level for many school environments. The creation of robots using other robots brings the experience full circle for STEM students who are provided with this opportunity.

Making use of CNC machines to create robots will be the focus of a new series of project-based STEM lessons over the next several weeks on TeachSTEMNow. We will take advantage of the ubiquity of the Arduino microcontroller that has found its way into thousands of classrooms to do a number of projects that will incorporate all of the latest developments in content delivery, hardware and software for educators. Students will learn to program the Arduino as well as the CNC mill to manufacture components for robotic mechanical systems.  They will learn how robots interact with their environment, how to control robot behavior, and create components they need to build a complete autonomous robot. These lessons are guaranteed to help drive your classroom toward the ’100 percent engagement, 100 percent of the time’ model that makes the most of student potential. Stay tuned.

The time has come to move your student experiments from the classroom into outer space. With the advent of inexpensive electronics that can monitor everything from ambient temperature to magnetic fields, it is possible to conduct real science outside the confines of earth’s atmosphere. The most practical method to reach the ‘outer limits’ is to use a weather balloon that lofts the experimental payload into the stratospshere. Doing this in an advanced level course is an excellent STEM project that can take the entire year to complete. It involves students in everything from obtaining permits from the FAA to release the balloon to calculating trajectories, forecasting weather and using telemetry. This is a project in and of itself, and creating the on board science experiments is another layer of challenges to complete.

For those teachers who are not able to devote the time or resources to conduct the launch themselves, there is an alternative known as the PongSat from JP Aerospace. Billing itself as “America’s Other Space Program’, the organization is focused on DIY space exploration. Regular launches allow for teachers to get on a list to get their student’s experiments on board.  Best of all, it’s free! What sorts of experiments fit in a ping pong ball? Some ideas include:

-sending seeds to determine the effect of space on germination and growth

-measuring atmospheric changes with altitude

-measuring charge output of a photovoltaic cell in space

-magnetic field changes

The sky’s the limit with what can be done within the confines of a ping pong ball.  Whether your students send up a  packet of seeds or an arduino nano with a sophisticated array of sensors, real science and engineering can be done for very little costs other than time. And since spending time doing STEM is the way to get students engaged, getting on board the next available mission to space is worth the wait.

Ironically, jobs in the biotech sector are projected to increase up to seventy percent in the immediate future. What options do biology teachers have that specifically addresses this need? How can a teacher transform life science- focused activities into engineering practice?

In this article we will take an overview look at transforming a few traditional life science activities into more biotech focused activities with some simple alterations that encourage engineering practices. We will see that the application of cross cutting STEM concepts can be made without completely gutting what biology teachers already do.

One of the roadblocks to complete implementation of these changes is a lack of available technology. In order to practice engineering, students will need access to technology, and some specialized equipment that may be under the domain of other courses. For example, you may need soldering irons, batteries, motors, CAD software, even CNC machines in some cases to really do this right.

Bear in mind that it doesn’t all need to be done at once. This is a transition period as we get accustomed to the Next Generation Science Standards. So pick a few things to change that will get the ball rolling, choosing the easiest activities first.

-Make it known to custodians, colleagues, administrators and parents that you want technology in your classroom. Explain exactly what you will be doing with it using examples such as those in this article.

-Borrow from other departments or supply areas. If there is a set of soldering irons in the back room that haven’t been used for years, see if you can get them. If the vocational program has been severely cut back or is non existent look for mothballed equipment you can bring back to life.

-Ask about equipment that is being or has recently been discarded. Computers that can’t run in a graphics arts environment will work just fine for programming or simple modeling.

-Look ahead at materials and equipment purchases. Try to buy things with multiple uses. That includes pooling your resources with others in your building.

-Create an inventory of parts and equipment by salvaging used and/or broken items as described in this article.
Food Web

Food web dynamics are quite complex, but some simple algorithms that determine relationships between consumers and producers can make for some very interesting modeling. This can be a challenge if you don’t have any programmers in class, but you can spend a week with Scratch which has a very gentle learning curve. Since they will be learning Scratch within a well defined context, it is time well invested. As a place to start, students can take a look at the ready made food web simulation here and get an idea of what algorithms are being used. They can then reverse engineer it with some simple relationships between producers and consumers to create their own simulations.

Animal Behavior

Swarm theory and Robots

Insects are often described as simple biological robots. Until recently it was unknown how organisms with relatively few neurons could exhibit complex behaviors. Using simple autonomous robots, swarm theory has emerged as one explanation. Robots that can not function alone take on new dimensions of behavior when grouped together, including division of labor and moving objects. Students can build small robots using a variety of methods to explore this fascinating topic further, doing genuine research in the process. Here are some links to get started:

Super Simple BEAM robots

link to a leading research group’s methods and results.

Body Structure

Students gain a unique appreciation for appendages when they create their own. Building artificial devices that mimic body structure and functions brings many facets of science, engineering and manufacturing together. It also invites the exploration of topics on artificial limbs, organs and biomedical ethics in general (Common Core, anyone?). The robot arm is an excellent introduction, and they can be built from cardboard, 3D printed or CNC machined from metal. Movement can be achieved through pressurized gas, servo motors or simple pulleys. Here are some variations that would work well in many classrooms:

Cardboard Robot Arm

Duct Tape and Syringe Arm

CNC Milled Robotic Arm

Genetics

Punnet squares are great, and so is reading about Mendel and his pea plants. Students can have the computer generate the effects of mutation and sexual reproduction by looking at this scratch simulation. Once they download the code, they can use it as a template to run their own studies, then discuss the results with the class. Diving deeper into DNA replication means manipulating DNA itself. So how do students use gel electrophoresis and polymerase chain reactions in the biology classroom without a budget borrowed from the Pentagon? This is quite possible thanks to some pioneering work done by open source science advocates. To get your students started, here are some links:

Gel Eletrophoresis for under $100

Arduino PCR Thermal Cycler

Evolution and Natural Selection

The forces of natural selection are very difficult to model. There are too many variables to account for, and their interdependency makes it that much more complex. However, taking a few relatively simple selective pressures and modeling them yields a better understanding of how species may change over time. The best way to start modeling their own simulations is to look at a couple of examples. Control for as many variables as possible

Here’s one in scratch

http://www.agner.org/evolution/

And here is the classic Peppered Moth, in interactive form.

http://www.techapps.net/interactives/mothproject.htm

Students can write a simple program in scratch, python or java to simulate the famous peppered moth in every biology textbook. They can use the above link to examine what parameters work best for selection and see what happens, then apply this to their own algorithms. This presents an opportunity for advanced students to create their own selective pressures and see how they effect organisms over time.

The common theme here is that these projects have well-defined parameters but they are very much open ended in terms of results. Learning to model, simulate, create and innovate using technology as a tool brings a whole new level of proficiencies to a standard biology curriculum. Biology teachers now have the means to have students probe complex topics in depth with their own research. Today’s technology makes it inexpensive to make real engineering practice something that biology students can expect to add to their repertoire of skills as they enter the workforce. The jobs are waiting.

The Fab Lab concept was first institutionalized by MIT through what is known as the Center for Bits and Atoms, and the bill specifically recognizes this as its model. The program has worked for several years to create Fab Labs across the globe, with the goal of enabling innovative thinkers with tools to make their ideas a reality.  The bill falls lock step into this mold, as it recognizes that  ”a coordinated public-private partnership will be the most effective way to accelerate the provision of infrastructure for learning skills, developing inventions, creating businesses, and producing personalized products.”

This bill is a good start, but just a beginning. It is not particularly ambitious in terms of distributing the Fab Labs.  The bill  recommends a minimum of one Fab Lab for every 700,000 people in the first ten years after its implementation. How did they get at this number? Divide the population of the United States by 435 Congressional Districts, and that gives every Congressperson one Fab Lab.  Which sounds fair, but look at it this way: California would get 53 Fab Labs, and Montana gets 1.  So people in rural areas are destined to be underserved by the NFLN, although momentum has been building on a parallel track through Makerspaces and Hackerspaces. There are also for-profit enterprises such as TechShop.

It is noteworthy that the above terms do are not found anywhere in the bill. Yet the Makerspaces and Hackerspaces are the result of a true grassroots effort by local individuals with many of the same goals as the Fab Lab Network. Can these facilities exist in parallel? No doubt there will be regulations that govern Fab Labs that would not sit well with many in the Maker/Hackerspace community. On the other hand, the potential for federal funds and instant nonprofit status may mean that locals get absorbed by the National Network over time.

Either way, in terms of STEM education the existence of a digital fabrication facility within reach of students is a good thing. Many schools do have a limited digital manufacturing capability, but many do not. A possible corollary effect of this legislation may be that schools themselves become part of the Fab Lab Network. Why not?  If a state of the art facility were available to educators, the possibilities are endless.  What if students became just as familiar with advanced manufacturing technology as they are with advanced communication devices today?  Imagine the innovative technological solutions they will create to solve problems that are meaningful to them.  They will have the knowledge and the tools to build what they imagine.  They will take their personal interest in what they are learning at school to products they can design and manufacture as young entrepeneurs in the marketplace.

Let’s encourage the establishment of the NFLN. Chances are your  students and community need an injection of empowerment through digital fabrication.

Next have them chart out the values of the circumference and diameter of each circle. The circles should have a wide variation in size. At the end, when they have taken all their measurements and recorded them, the aha! moment should occur. The final column in the chart should be the ratio of the two values, calculated to several decimal places. All will be close to 3.14, the value of pi. It won’t matter what units they used, or the size of the circle. Pi is pi. There will be some discrepancies due to measurement errors and calculator rounding, and those subjects are worthy of discussion because anticipating these sorts of errors will help in any further experiments and data collection long term.

For other resources on Pi Day, visit:

http://www.piday.org/

Pi Day At The Exploratorium

There are three basic iterations of design in terms of dimension. 3-D objects can be printed directly or cut out on the mill or lathe. Two dimensional objects can be cut on a laser, CNC plasma cutter, or they can be milled as well (technically this can be considered 2.5-D since there is some accounting for height). Finally, 2-D shapes can be designed to be assembled into 3-D objects. This is commonly seen when acrylic or wood is assembled from flat pieces cut on a laser cutter, or metal cut on a CNC plasma is welded into a 3-D part.

As we teach STEM students about the concept of design for manufacture, we ask them to consider time as a cost factor. The time it takes to assemble a 3D object from a set of 2-D parts can be significant. The assembly process can also introduce errors into the final product. We analyze the number of T-slots in an acrylic project box, or count the number of holes that need to be tapped,  all with the notion of reducing sources of various costs.

Recent research in Germany has provided an ingenious solution to some of these cost factors for those using acrylic to manufacture parts on a laser. Rather than cutting the parts, laying them out and assembling them, some of the joints are actually bent by applying selective laser heat and drawn down by gravity. What this means is that the creation of 3-D parts is possible using 2-D materials, reducing costs dramatically. It is an extreme example of rethinking the design for manufacture process itself, and should be a great inspiration to students. Extending this inspiration into the classroom as part of student engineering practice is highly recommended, and here is the connection to make it happen. The challenge is to make the process of 2-D laser cutting into a selective bending process that works for your machine. This will engage the students in genuine science and engineering because the process has not been adapted to standard inexpensive laser machines.  Watching the video (and reading the research paper) will provide some insight as to what needs to be done. The key is to reduce the intensity of the laser beam and broaden its path in specific locations that will permit bending in the desired area. One possibility is to apply a material or color band on the material that will diffuse the laser and reduce its power. Another is to program the laser to adjust speed and/or power level in different areas along the tool path.  The other important factor is the platform and its height must be configured to allow movement of the piece toward the ground. Pay particular attention to the use of a servo motor to rotate the material shown in the video.

This is a project for a team of advanced students. They will need to be familiar with the properties of acrylic as well as the machine and its software. Remember that lasers are dangerous if used carelessly, and the protective cover should always be used. In some cases eye protection should be worn. Whether or not your students perfect this process, they will be engaged in genuine research.  If they are successful, they should take every opportunity to share their findings at science fairs, social media and maker web sites. Students who are given the opportunity innovate and experiment in this way are modeling STEM education the way it should be whenever possible. Try it or something similar in your classroom.

Click here to view the video on YouTube.