I found a design for a Diesel engine on Thingiverse by Nick Randall – I decided that his trucks and wheels would make an excellent base for my train, as he had a tested design with the right dimensions.
The Toronto Public Library has a 2 hour limit on 3D print jobs. To work within this limitation, I printed the design at low resolution over three sessions. The body was printed in two sessions, and glued together with Krazy Glue (cyanoacrylate). In one of the sessions, a different filament was used. The final toy was painted and assembled with screws.
I learned a few more things about 3D printing, design in general, and sharing online.
Parts printed with PLA material can be glued together with Krazy Glue
In this instance, there is a visible gap. The parts were printed with different filament, and as a result, the parts didn’t align exactly. The output from one of the print jobs warped. When laid flat, the middle was probably 2 to 3 mm above the surface
As would be expected, detail is lost when printing at low resolution
When designing a model for printing on 3D printers, the limitation of not being able to print in mid-air must be considered. Although printing with supports is a solution, it leaves a less-than-perfect surface. It would be interesting to learn how more experienced designers work around this issue. It would also be interesting to try a 3D printer capable of using a dissolvable support filament.
A model printed with PLA can be painted with Testor’s Enamel
The library is a great place to learn about 3D printing, and print small parts. It is less expensive than other places – a two hour print job costs about $6. For my next project, however, I would probably look at other alternatives without these limitations. I think the library has probably achieved a good compromise, making a technology available to anyone with interest to learn and a library card, but definitely not offering a service which would compete with commercial offerings.
When I thought about 3D printing, I though about the physical realization of an object. In reality, there are many things that must be considered when designing anything physical, and 3D printing is not the solution to all of them. This is evident even in the simplest of designs, such as this one, where metal screws are used to fasten parts and enable movement.
This model was designed to scale – this might be appropriate for a scale model, but the train looks very long relative to the other wooden trains on the track. Many of the features, such as the lights, windows, and doors, are very small. If I were to design another toy train, I would exaggerate features, and would not design to scale. George’s Trains, a local model rail hobby store, apparently stocks a wooden subway train that follows these principles and appears to be a much better toy.
Finally, it has been fun posting and sharing my designs on Thingiverse. Although I have accounts on other sites with social-network type features, this is the first time I’ve posted anything. It is fun to have an forum to share my work, and it’s great feeling to see that people have looked at my design and clicked “like” – recognition for someone having fun with basic skills, practising a hobby.
I haven’t worked in 3D at all before, and I was looking for a simple project.
As with the Brio/Duplo wagon, I was thinking about what was within my ability, and not commercially available. I decided I would try to build a custom tire valve stem cap with my daughters’ school logo (a polar bear).
Looking at freely available 3D modelling tools, I checked out Blender and OpenSCAD. OpenSCAD seemed to be simple for someone starting out with designs built out of basic shapes.
I converted the bitmap logo I had to a vector drawing using Inkscape‘s “Trace Bitmap” feature. Following an Instructables tutorial, I exported the bear’s outline and features to a DXF file, which can be imported into OpenSCAD. I encountered number of difficulties (it has been a while since I completed the design – I can’t remember which issues, specifically, I encountered). I tried again, with great results, using the Inkscape OpenSCAD export plug-in.
I merged the bear with a cap designed by Dan Ujvari, and printed it at the Toronto Public Library’s innovation lab. I used a black permanent marker to highlight the bear’s details after printing.
It was interesting to learn that even with a simple project as this one, there are limitations to 3D printing. It was almost impossible to remove the support material on the reverse side, as the bear is narrower than the cap. If I were to refine the design, I would make the bear the same width as the cap. I definitely have more to learn about successfully designing an object around the limitations of current 3D printers.
I have been excited about the potential for 3D printing for quite some time.
Shortly after our local library acquired a couple 3D printers, I took the mandatory course, where we were taught the two primary rules of printing at the library:
Rule #1) Don’t touch the heating element
Rule #2) Don’t print guns
Course completed, I started to think about applications. What can’t you just buy, what makes sense to print?
The idea of combining Duplo and Brio seemed like a great idea – I was thinking of an elaborate track with bridges over bridges, and Duplo seemed almost perfect for the job. What I really wanted was a piece with a wooden train (Brio) top, and Duplo bottom.
A quick search revealed that I wasn’t the first person to think about this, someone had already designed a Duplo/Brio bridge support system. Looking into this further, and loading these parts into 3D printing software revealed that each segment would take about 2 hours to print – the maximum time allowed on the library’s printer. Given that a simple bridge would require at least four segments, I looked for alternate ideas and stumbled across the Duplo/Brio wagon.
I downloaded the file, went to the library, and printed it out. 83 minutes later, my train was completed. I attached the wheels to the body with paper clips, and glued fridge magnets to the ends for the couplings. I was quite pleased with the end product (see photo). The library charged just under $5 for the printing time, which is about what a train car costs from a local toy store.
Taking this idea further, I thought I may try to design my own toy 3D printed TTC subway or street car for wooden train tracks. I have occasionally seen them available commercially, but they are generally hard to come by.
After lunch, the girls and I hopped on the subway and headed to the Canada Day events hosted at Queen’s Park. We ended up having a great time – there were free bouncy castles, live music, hula hoops, and more.
But I thought the coolest activity was the build and test your own air rocket, hosted by Makerkids.
The children were given pipe insulation for the rocket’s body, and duck tape, scissors, cardboard, streamers, and everything else you would need to complete an air rocket.
With occasional help from Rachel, Tegan built her rocket.
The Makerkids team had several launching stations setup on University Avenue, which appeared to be similar to the Make design.
As scotch tape was used for some of the cosmetic touches, I warned Tegan that the rocket may not survive its first test flight intact. She decided to launch it anyway.
Shortly after breakfast on July 1st, Tegan picked up a recently discarded brown cardboard box sitting beside our recycle bin. She had a vision in mind: she wanted to build a rocket ship. She needed some assistance – the cardboard box was too thick to cut with her scissors. So she created a design.
First, I was assigned the window. With a utility knife, I cut a circle out of the box. A clear plastic lid, also sourced from the recycle bin, was installed. Tegan then made the fins from the box’s former flaps, and installed them using packing tape.
Next came the nose cone. Rachel was a proponent of using the two remaining box flaps, and building an A-frame, triangular nose cone. Tegan had her heart set on a true conical design, but couldn’t quite figure out how to achieve it with the materials at hand. In the end, we taped 9 sheets of construction paper together, and rolled the now super-sized sheet into a cone, and installed it on the top of the rocket.
Together, the girls painted the rocket red. To this day, it sits in a corner of their room.
I do. Even in an era of smartphones and data plans, every once in a while, I find myself searching for open WiFi hotspots.
Who else does? I set out to find out. I built a WiFi hotspot that served up an open-to-everyone community wall.
To build it, I set up my Raspberry Pi with a WiFi USB dongle, and configured it as a WiFi hotspot (with WPA security disabled). I needed a name that would encourage people to choose my hotspot over the others in the area – “CommunityWiFi” seemed like a suitable name.
I chose to use my Raspberry Pi because:
its cheap enough I could leave it anywhere without worrying about it getting stolen
it can run off a USB battery pack, so it can be taken anywhere
But there’s nothing special about this hardware setup – you could set this up with any laptop, a hacked Android phone, or home router.
The system is setup with a DHCP server, a DNS server (dnsmasq) configured to redirect all dns requests to the Pi, and a webserver configured to send all requests to the Community Wall page. The Community Wall consists of a couple PHP pages backed by SQLite.
Once the user attempts to visit any web page while connected to the hotspot, the system will direct them to the Community Wall, where they can read and post messages.
I took the system to our local library one morning. I tested it out with my smartphone, and everything worked great, but I received no posts over the hour or so I had it running. This is likely because most library users will have already saved the connection to the library’s own WiFi. I will be trying this out in other busy areas, without free wifi, and report back.
Some people have taken this idea much further than myself – check out PirateBox by David Darts. A PirateBox is a mobile WiFi hotspot that allows any user to connect, chat with other connected users, and share files.
It’s been a long winter. I love taking the kids outdoors, even when it’s cold, but sometimes, it can be fun to play indoors too. I haven’t acquired a game machine, the kids haven’t expressed much interest in playing video games, but we DID have fun playing a Dance Dance Revolution (DDR) type game at an arcade in hotel we stayed at once. What would it take to play at home?
Searching around, I came across StepMania, an open-source, DDR type game. I thought I’d look for a used mat on Craigslist, but when I started researching dance mats, I was surprised to see that many people actually preferred homemade mats over the cheap roll-up mats.
The simplest designs I came across measured the capacitance of the body on aluminium foil to detect steps. I took a cardboard box from our closet, some sheets of aluminium foil, connected the foil to some resistors, connected to an Arduino. I covered the aluminium foil with packing tape. What’s cool with this design is I had everything in the house already, except suitably sized resistors, so the whole thing cost me $1 (plus tax).
There’s an Arduino library (CapSense) that makes measuring capacitance really easy, and I found firmware called “Big Joystick” that makes the Arduino UNO appear as a regular, USB, HID joystick. Detecting steps works really well, and the whole thing works flawlessly with Stepmania.
What I didn’t get right was the positioning of the pads – it seems harder to get the steps/combinations right than I remember it being at the arcade. Lisa thinks they are too far apart. But other than that, the sensors work really well.
I’m trying to think of other applications where a large “switch” like this one would be useful. With the right configuration, these sensors will also sense proximity – not just touch.
Although this book is targeted at older children, and my children aren’t particularly interested in robotics, we still had fun completing a couple of the simpler projects at home.
First, we built a mechanical hand with cardboard, drinking straws, string, and a glue gun. This was a great craft, because my six year old could complete all the assembly steps (given guidance) and the completed project was unanticipated, functional and fun.
Next, we built a drawing robot, which consisted of a plastic cup, tape, an electric motor with an added weight (like a mobile phone or pager vibrator), batteries, and markers. This craft required more assistance – I connected the batteries, and the weight to the motor. My six year old assembled the cup and the markers, and shot video footage.
Last summer, I built a pop-bottle sailboat with my (then) four year old. After trying a couple of designs with keels in our bathtub, we settled on a catamaran style design with two pop bottles. We tied a string to it, threw it into the pond, let the wind carry it away, and then pulled it back to shore.
And I thought, wouldn’t it be cool to add remote control functionality?
So I did. I finished my smartphone controlled, WiFi sailboat on Saturday.
I configured the Raspberry Pi to act as a WiFi hot spot. Using any smart phone, you can connect to the boat, and visit its web page.
The page has two jQuery slider controls.
When re-positioned, the slider controls drive a PHP page which sends commands over the USB interface to the Arduino, which then controls the servos.
It seems like overkill – an Arduino AND a Raspberry Pi for such a simple task? I’d considered alternatives – using only an Arduino with Bluetooth or another wireless interface, or using the Raspberry Pi to directly control the servos – but in then end, I just used the parts I had on hand.
My initial design used a 7805 IC to supply the 5V for power – that didn’t work… Everything would boot, the 7805 would get super-hot, and the Raspberry Pi would crash after moving a servo a few times. A little reading lead me to pick up a switching regulator (I happened to pick up one from Castle Creations at my local hobby store).
I tested the design out with my assistant in our bathtub, and everything worked!
But, by the time everything was built, the city drained the reflecting pool I had intended to use for trials for the fall – I had to try it out in a nearby pond. And, of course, there was no wind. I’ll post more photos following a windy day test.
With a little more money, and a little more time, I think it would be fun to build a boat I could launch in lake Ontario, at the foot of Yonge St., to sail autonomously down the St. Lawrence to Brockville, where friends in Ottawa could retrieve it.