Month: May 2015

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.

IMG_3364

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.

 

 

Experiments with the ESP8266

IMG_3363

I’ve been meaning to jump on the Internet of Things bandwagon, but I’ve just been a bit turned off by the price point. I built a simple temperature logger for my fermentation fridge using a Spark Core, but the experience was not that straightforward…or as straightforward as I wanted it to be for using in the classroom.

Then the ESP8266 came around, and then it got Arduino support and then I couldn’t keep away. I’ve been tinkering with the idea of creating a super easy to use Wifi connected device that would allow my students to more or less flip a switch and start collecting sensor data wirelessly. The lesson would result in creating active data visualizations, not the details of creating this wireless data streaming device. The ESP8266 looked like it could provide a cost effective solution to this little challenge.

So I snagged a few ESP8266s from eBay and got them out of the bag yesterday. I tried to use the little ‘carrier board’ that came in the $7 eBay kit, but couldn’t get code over. Tracing the board back, I found I wasn’t able to manipulate a few pins I’d need to ground for programming then disconnect…so I soldered up a pretty shoddy little protoboard and connected it to a breadboard. A big thanks to Alasdair Allan on the Make Magazine blog for an article that got me through building this board and programming the board.

I got the data pushing out to data.sparkfun.com easily enough using some example code by Liam Marshall on Hackaday.io. The code went over in no time, and connected directly to the network instantly. I was super surprised…I expected a bigger struggle. I actually has less trouble with the ESP8266 then the Spark Core. (Which I still have configured to pump data directly in to Google Sheets instead of a service like Phant.)

Now that the data is streaming, it is time to start creating the ease of use component…which is the hard part for sure. I’m going to aim to create a simple Python front end that will pipe the SSID and password into the code and reprogram the board. Alternatively, I might simple try to pump the data over serial into precompiled code to avoid running into programmer issues. Once I can get it to a ‘plug it in and tell it the SSID and password’ point, I’ll start thinking about where to collect the data. Likely I’ll set up a Phant.io install and collect the data that way.

Check out the data stream here.

See the code below.

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!