Monthly Archives: October 2014

3dprinter, engineering

Getting Started with 3D Printing – Lets make something

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OK, it’s been a couple of weeks since my last post. I’ve decided to do an instructional post to break things up a little. One of the projects I had my physics students work on last year was an engineering/design problem. I simply asked them to create an accessory for their cell phones. This idea was not original to me, but I honestly can’t remember where I got it from.


In order to actually make their own accessories my students needed some sort of program to create a 3D model. Our school doesn’t currently have drafting or CAD classes, so I was left with only a few options. We have no CAD software and even if we did, my students wouldn’t know how to use it.


I settled on cloud based solution, Tinkercad, for my students. Tinkercad is very simple, which also means it lacks many functions you’d expect in a traditional CAD program. It is also run in the cloud so it can be slow at times, but on the plus side if your computers have Chrome there is also nothing to install. This can be a huge plus in an educational environment. I use Tinkercad at least in part for almost all my 3D printing projects.


The basic idea behind Tinkercad involves building models by joining together simple shapes. Shapes can either be solids or holes. It seems like this would be a difficult way to create anything, but as it turns out you can create some very useful models with this very simple idea.

I originally found this phone stand on Thingiverse. I like it because it holds the phone up a little higher than most of the ones I’ve seen. I’ll show you how easy Tinkercad is to work with by recreating it. We’ll talk about the phone case in a future post.

If you have students create accounts for Tinkercad please steer them away from using their Facebook or Twitter accounts. In the past I’ve had a few students create accounts at home using their Facebook credentials. We block Facebook, so they were unable to access their accounts at school.



Go Back to earlier parts in the series: Part 1, Part 2, or go on to Part 4

3dprinter

Getting Started with 3D Printing – Part 2

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This is part two in my ongoing series of articles on 3D printers for the classroom. Click here for part one.

I don’t know about you, but I have virtually no training in 3D modeling software. How should a classroom teacher start with their new 3D printer? Personally, when my printer arrived I spent a lot of time looking for cool designs online. The main repository I used and still use is the Thingiverse.1

The best way to start with your new printer is to find some models that other people have created and printed successfully and print them your self. There are lots of great ones to choose from. Some of which are simply models for demonstration while others may be tools or puzzles. My printer came with two spools of plastic. I burned through them and called it professional development. I really did learn a lot from this. You should probably do the same thing. Print stuff because you think it might be fun, useful, or you just want to see how it prints. I think the nerd word for this is experiential learning.

The bottom line is, it doesn’t really matter what you print. Print small stuff, big stuff, stuff with lots of small details, stuff with overhangs. Start with the default settings on your machine, then change them to see how it affects the final print. This will begin to give you a sense for what you can print and what you can’t. I also kept a small scale handy so I could determine the mass of my prints and then figure out the material costs. If I buy a 1 kg spool of plastic for $48, then each gram of plastic used is 4.8 cents. So a 20 gram part costs about $1 in materials.

Don’t worry if you’ll never use these early prints in your classes. One of the first things I ever printed was a replacement cup holder for my Ford Focus. While it had nothing to do with teaching it did begin to show me the power of having access to a 3D printer. I also got my first experience with warping2, a problem that plagued a lot of my early 3D printing.

During my learning process I did manage to print a few tools to be used for teaching, including a Macro Extension tube for my camera so I can take extreme closeups without having to buy a $400+ lens, an adapter to hold my iPhone to a telescope, an adapter for my Canon camera that works both with our telescope and our instructor microscope. But mostly I printed random stuff like an iPad sound reflector, games to play with my son, Higgs-Bosons, Pan Tail Duck call, and a bunch of other stuff.

If you feel you must print something useful try these:

  • Triangle “Missing Square” Puzzle: It’s a good critical thinking exercise. Print one and play. You may have to do a little sanding to make it fit perfectly.
  • Wind Puzzle: Not sure if this one is a Bernoulli effect demonstration or some other fluid dynamics principal. Either way it’s fun and my students love it.
  • Microscope Mount for iPhone 5: I modified an iPhone telescope adapter to work with our student microscopes. If it doesn’t fit yours I’ll teach you how to modify it in a future post.
  • One Small Step: Cool desk placard showing the first footstep on the moon on one side and the moon in relief on the reverse.
  • Lincoln Life Mask: The Smithsonian is starting to publish 3D models of their artifacts online. You can see how the presidency aged one of our greatest leaders.
  • Air Powered Rocket Car: This one presents good learning opportunities. It’s the first one I printed that required “supports”3.

Back to Part 1 or Continue to Part 3.

Footnotes:
1. Now I should say that many people have philosophical objections to the Thingiverse. Thingiverse was started by Makerbot. Makerbot had it’s origins in the Open Source Hardware movement. At some point Makerbot moved away from Open Source and was later bought by Stratasys, a large traditional 3D printing company. However you feel about Makerbot’s abandonment of Open Source or their later acquisition, the Thingiverse is a great place to find cool models to make.

2. Warping can happen with larger prints. The corners of the print lift off the build platform. Sometimes the part will still be usable, but more often it will not and sometimes can lead to the whole print coming unstuck resulting in a completely failed print job. I’ll talk about what to do to deal with warping in a future post.

3. FDM printers build from the bottom up. For some prints you will have parts that can not be printed because there is nothing below them to hold them up. Supports are typically a series of thin “walls” added below these areas, designed to be easily broken off the final print.

make and take, physics

LED Color Mixer – Make and Take

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Tomorrow, Saturday 10/4/14, is the fall meeting of the Michigan Section of the American Association of Physics Teachers. If you’re interested, it will be at the University of Michigan, Flint. For more information you should check out the meeting page.

Anyway, Jim Gell and I will be running a Make and Take in the afternoon. One of the things we will be doing again is the ever popular LED Color Mixer. We’ve done this before as a modified version of the LED mixer presented by Chris Chiaverina in the Physics Teacher. This is a pretty cheap demo device, but in the past we ordered $1-2 LED, $1 battery holder, $0.50 ping pong ball, and 2 AA batteries. Cost for each one was between $3 and $4. This was a bit costly to run as a Make and Take. It also involved soldering, which while not particularly difficult did require the direct supervision of someone.
We will be doing the same project on Saturday at a cost of less than $0.20/device with no soldering required. This project is cheap enough that you can have participants make one on site and then send them home with a couple extras to make with their classes. They’re so cheap that a teacher could have each of their students make one to take them home and explain how they work to their families.

The parts list:

I should note that while both the batteries and LEDs are sourced from Amazon, the LEDs come from China and will take a few weeks to arrive. While the LEDs are cheaper than we’ve been able to get them in the past the real savings is from the batteries. In order to make things extra cheap I replaced the ping pong ball with a paper cube.
Simply bend the leads on the LED as shown. The shorter of the two leads goes to the negative side of the battery with the longer going to the positive. Use a little electrical tape to hold the leads to the battery. If needed, slip a small strip of overhead transparency in between one lead and the battery to act as an “off switch”.
Print out a copy of the 2.25″ Cube Template and assemble. Before closing the last flap put 1/2 a Kleenex in to help diffuse the light and cut a hole in one side. The simply slip your LED and battery in and bask in the color changing goodness you have created.
How would you use this with your students? Share your thoughts in the comments.
3dprinter, makerbot

Getting Started with 3D Printing – Part 1

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I’ve had a 3D printer in my classroom for a couple of years now and it is totally awesome. Last year I wrote a blogpost answering a question I received as a tweet. The question was, “What resources or designs do you wish existed for teachers/students when you got your printer?” I’ve decided to do a series of posts from an educator’s point of view to create the resource I wish I’d had when I first got my 3D printer.

There are a lot of emerging technologies that are capturing attention today. Of all of these, I think 3D printing has the most power to inspire students. I managed to get the first generation MakerBot Replicator a couple years ago and every time it’s running in the back of my classroom it acts as a student magnet. Some would just stand and watch a print run from start to finish if I’d let them. I have to say it is pretty awesome to watch an object get made seemingly out of nothingness.

When I got my printer, it cost just under $2,000. Today you can get a pretty respectable machine for under $500 and if you want to go into the $2,000 to $3,000 range you can get a really nice printer. If you’re in the market for one I would highly recommend picking up a copy of Make: Ultimate Guide to 3D Printing. The last two years Make Magazine has done a great rundown on the consumer grade 3D printers that are available. If I was going to buy a new printer, this is where I’d start.

The main thing you need to know, is there are two broad categories of 3D printers you might consider for your classroom, Fused Deposition Modeling (FDM) and Stereolithography (SL). My printer does FDM so that’s what I’m familiar with and able to speak to. I really want to try SL, because it’s totally cool. The most common printers in classrooms today use FDM, but this may change in the future.

In a nutshell, Fused Deposition Modeling printers melt plastic and push it out through a nozzle like a hot glue gun. The nozzle in this case is much smaller and hotter than a glue gun, however. The printer builds the object up one layer at a time.

Stereolithography printers use a liquid resin. The resin solidifies when a light is shined on it. These printers also build an object one layer at a time, but the do so a bit differently. The light source in an SL printer will either be a laser that traces a path similar to an FDM printer or a DLP projector that will simply project an image of the whole layer at one time. Once the layer at the top of the liquid solidifies, the printer lifts the growing object and the next layer is illuminated.

If you’re looking for more resources to get you started I’d recommend:

Continue to Part 2 in the series.