Category: Experiments

3D Printers as Construction Toy Factories

The 3D printer is the hottest tool to bring into classrooms these days. They are the talk of the town. In lots of ways, they are amazing machines. It possibly more ways, they are tricky classroom tools. Most of them take plenty of tinkering and tuning, print times are long (a 1 hour print for all 50 students in a grade can be a week or more in the making), upkeep is time consuming. Lots of little quarks.

However, where they have excelled in my classroom is in printing construction brackets. If we aim to print small parts to be used to let students build bigger structures you can kill a few birds with one stone. Print times are reduced, and you have a build to pull students away from the computer screen.

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I wanted to share a few examples, and how I use them in my classroom. First up, the simplest. Brackets to join straws at different angles. I took inspiration from Makerbot’s Speedy Architect project for this one. These pieces are tiny, taking less than 10 minutes on our Printrbot Simple Metals using my super-duper fast printing profile. Currently, the 6th grade is designing architectural models using these brackets. They will be adhering to uniform proportional scale for the structure (about 1″ to 10′), and will be closely monitoring a the cost of production. Straws cost $100 per inch, and 3D prints cost their real life cost, times a thousand, or about $20 per basic bracket.

straws

I’m super excited to see how this project turns out. There are lots of great math connections to the 6th grade curriculum using the scaling and the economy system. The structures are bit innocuous from the structural engineering perspective, but the amount of iterative design & 3D printing we can pull off while printing such small parts will make this project worth while. We are lucky enough that each of our groups of 4 will have their own 3D printer to operate during class time, keeping the project rolling at a fast pace.

Up next, there are the balsa wood brackets, that came from the Zazouck project on Thingiverse. These parts are a bit different than the straws in that I use them exclusively as construction tool. The parts are all printed ahead of time, sorted into different types and they are used to do rapid fire construction challenges. Most recently students were tasked with building a 12″ bridge, while controlling for the cost of parts and materials used to build the bridges.

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These pieces are great for rapid construction. They lack in the structural consistency that using glued joints might give you, but they let students build quickly. Often, balsa breaks in the brackets, but a drill bit reams them out pretty easily. These are great bits, and took about 30 mins to print a set of each piece. To get a classroom set of about 20 of each part, I had the machines running constantly for a few days. But now they are done and we have our own custom construction set…in colors that match the labs floors!

Last up, we’ve got the most complicated component yet. The craft stick brackets. These pose the most difficult design process of the three, but I think it gives the most rewarding final product. Requiring constantly being aware of stick orientation in regards to slot location on the brackets. I think the challenge of the design makes these an awesome candidate for creating a lesson on using Fusion 360 assemblies to virtual design structures before printing them. This is something I’ve got in the pipe for the 7th grade next semester.
1025160920All of these follow a basic principle. Find a material that is cheap and plentiful in you lab, and design brackets to join them at different angles. Have students design the parts, even model the whole structure in CAD before printing. Cut down print times, end up with bigger and cooler parts…its a win win all around. Have you done any construction projects like this? Let me know!

Experimenting with OnShape

I recently became aware of OnShape during MakerCon coverage on the Make Magazine blog. It looked great. It had alot of the bells and whistles of things like Autodesk Inventor and Solidworks, with sketch based modeling and assemblies. And, it runs in the browser. It looks promising, so I signed up for the beta. Sure enough, only a few hours later, I was given access.

I hadn’t gotten too much time to play with it recently, but I decided to give it a shot today. I wasn’t feeling super inspired to make anything interesting, but I was annoyed about losing whiteboard markers constantly. So, I decided to design a little holster.

firstSketch

 

It has been a long while since I used a more technical 3D CAD tool like this. I find myself banging out little 2D brackets in Inkscape or simple  3D models in 123D Design, or even Tinkercad more often then needing the toolset of something like Solidworks. That being said, I was a bit rusty, but it followed what I expected with my use of Inventor and Solidworks in the past. On the left, I could see a history of my recent actions, organized by sketch and related feature applied to the features.

 

For such an extensive toolset, the interface never felt over complicated or scary. I was quickly able to find my tools based on the icons and just natural placement of tools. It was an intuitive little environment. The speed with which the design rendered changes was pretty satisfying as well. I was worried the bandwidth needed for this sort of app could choke it up with complex features, but it seemed to handle everything with ease.

curaIn about a half an hour, I had the model produced and into Cura, ready to be sliced and printed on the Printrbot Simple Metal. STL Exporting from OnShape wasn’t too obvious, but I figured it out with some Googling and guessing. I was disappointed to find out that there is currently no assembly STL export when I was Googling. It wasn’t something I needed for this model, but it would be one of the reasons I’d turn to this tool in the future if I needed to do a complex assembly.

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Sure enough I messed up three times. First, I made the holes for the markers too small. Then I made the stopper holes too small. Then, the next print messed up with about 5 minutes to go. But, thanks to 3D printing, I was able to print and check and print again quickly.

 

Overall, I am solidly surprised. I didn’t think it would be easy to slam functionality of massive tools like Solidworks into a browser based app, but OnShape seems to do it pretty well. I think that the interface is clever and modern, and it can serve as a great step past 123D Design for students in my classroom. It especially serves as a valuable tool for Chromebook based classrooms that lost 123D Design in the browser not long ago.

 

 

3D Printing Rockets

Recently, I was given the chance to run a series of all day projects with some of my students. This gave us all day to focus on big projects, start to finish. Following the theme of ‘Aerial Explorations’, we took to the sky to explore flight.

Perhaps the most interesting project to come out of these experiments was the 3D printed model rockets. The idea was simple…print basic rockets that would accept a small model rocket engine, and see if they’d fly. I took inspiration from the ‘disposable rocket‘ by Thingiverse user kebes22. I was worried that this minimal two piece design was the consequence that the small engines couldn’t launch solid plastic rockets. Presumably the off the shelf rockets are made of thin cardboard for a reason…

Disposable Rocket by kebes22 on Thingiverse.

 

However, after some back-of-the-napkin calculations, I decided that the rockets would launch just fine. Likely the additional mass would act pretty significantly against the thrust, but we weren’t attempting to go into orbit, simply trying to take flight!

We turned to Tinkercad as our design tool of choice. This was mostly because my students had the greatest experience with it. If I were using this project to introduce students to 3D design and printing, I likely would have used 123D Design instead. 123D Design has features that make designing with specific dimensions much easier. And, the cylindrical model of a rocket lends this to a perfect example case for the revolve tool, that is often times a bit confusing to students new to CAD.

Designing in Tinkercad

We used 1/2A3-4T rocket engines from Estes (who has some great teacher resources), from Amazon in a bulk pack. Using the 13mm dimension for the diameter, we left a cavity in our design to accept the rocket engines. In Tinkercad, I instructed students to make a cylinder with the same dimensions of the engine, then had them define it as a hole and instructed them to make sure to place the component in the center of the rocket. Students also design ringlets for the launch pad guide rod to connect to. However, in the long term, adding the guide after the print would be easier. Perhaps as simple as a drinking straw, or even a stirring straw from the breakroom would work better.

The instructions were very limited, as I wanted to allow the students to be creative with this project. However, any level of aerodynamics, or rocketry lessons would be easy to attach. The lesson can even be expanded to attach to Kerbal Space Program and KerbalEdu for interactive video game based simulations. (I found the demo of Kerbal Space Program supplied plenty of content for our one day lesson.)

Finally, we printed the rockets on the Printrbot Simple Metal. The prints took no more then 30 mins each printing at 0.25mm layers at 65mm/sec speed. The prints weren’t beautiful at that speed and resolution, but they were functional!

All of our rockets ready to go!

The launches were all successful! They all took off to a height of around 100-150′ before returning to earth. For safety, I kept all students a good 50′ from the pad unless they were at the pad launching their rocket. I connected the leads to the engine, then gave the nod to the rocketeer, stood back and allowed them to launch. Launching at a sleight angle downwind ensured no rockets returned back onto anyone’s head.

Ready for take off…

 

We have take off!

 

 

 

 

 

Home brewing on the small scale

This year I’ve decided to dive head first into home brewing. To get back on the horse, I’ve built a new small scale 1 gallon all grain system. This has a ton of pros; its small enough for my tiny kitchen, it is quicker and cleaner, cheaper per batch and makes it easier to brew lots of batches. That being said, I’m still working out the system, but it is coming along pretty well.

3 Vessels

The system isn’t a brew in a bag setup, but sort of a miniature all grain set up. I built the mash tun out of a 2 gallon beverage cooler with a stainless mesh bottom made from a hose. Nothing crazy, but I haven’t had any stuck mashes, and I can hold temp pretty well (+/-2 degrees) during an hour mash (as long as I preheat the tun). I’ve got two 30 qt kettles, one liquor tank and one for the boil. I want to add valves to these kettles at some point in the future, but for the time being, this works perfectly. The mash comes out looking great, and hitting preboil volumes and gravity no problem thanks to Beer Smith.

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The 3 vessels.

 

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The mini mash tun, fitted with a ball valve holding steady at 154F.

 

Recirculating Chiller

My sink is hopelessly small. I couldn’t fit a bucket, let alone a kettle. I decided to build a wort chiller nice and simple. Some 3/8″ copper hose very loosely wrapped and connected into a small Harbor Freight submersible pump. I load up a bucket with about 2 gallon of the coldest tap I can get, and I’m usually around 75F in 15 minutes. I’m really happy with how this came out, it was a fun little thing to build.

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The chiller set up, sitting in the boil and sanitizing.

 

 

1 Gallon Jug Fermenters

I’ve been fermenting each batch in 1 gallon jugs, and have had no issues getting into a strong ferment. Everything after that has been the struggle. At first, I built a little temp controlled water bath with an aquarium heater and left that to keep the temps around what I thought was 68F, but turns out was way too warm, more like 75. The first two batches came out wonderfully vegetal. The next two batches were pulled mid ferment from this hot bath, but I think the damage was done. Now, the temps are rising and it is easy to maintain 64F ambient in the house. I’m likely going to move into 2 gallon buckets shortly. I worry that the 1 gallon jugs don’t supply enough head room, both for krausen and for aeration. I’m still experimenting with the fermentation, but hopefully I’ll have that locked down soon.

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The product, just after pitching. Lots of cold break still settling.

Moving Forward

Getting this new system up and running has been a blast. I’m still getting the hang of it, but it has been easy and not heartbreaking to ruin a few batches as I figure out what the hell I am doing. I love the approach of brewing often, and brewing experimentally. I’ve been trying anything and everything, meticulously controlling variables, digesting as much reading material as possible and getting absorbed into the hobby like never before.

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Keeping track of all the numbers.

 

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Experimenting with these new southern hemisphere hops. The galaxy’s look and smell wonderful.

 

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Brew buddy Poppy, ensuring no squirrels mess with the brew day.

 

 

Experiments with Bare Paint Conductive Paint

I got my hands on a tube of Bare Paint the other day, and decided to give it a try. I aimed to make an LED loop around an acrylic sign holder, but quickly ran into issues. The paint is not terribly conductive, and running the length of the 8.5×11″ sign holder proved to be too much. The paint itself was super easy to work with, and worked perfectly in small, short amounts, but running more than a few inches creates a resistance issue.

I didn’t get to do to much digging into the restiveness properties, and truthfully, it would be a difficult task to tackle. It seems that the surface of the paint, once dry, looses a great deal of conductivity. The most conductive was encased in the dry outer shell. Perhaps sometime soon I can use the remaining amount to try to come up with the resistance over a unit of volume and use it to my advantage next time I use it!