Simplifying my pull-back racer

Simplifying my pull-back racer

I wrote in a previous post about my first attempt at designing a pull-back racer. Being the over-engineered design it was, I took a shot at simplifying it for use in workshops and educational purposes.

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I removed the vast majority of the pressure-fit components, and reduced them to 3. It isn’t nearly as elegant to the eye, but it is far easier for kids to assemble. There is the base that holds the elastic in place, and the sides to hold the axles.


I went with skewers for the axles, and the wheels can be laser cut as well, or cut from dowel. In the pictures below, they are laser cut.


Overall assembly is pretty straightforward: push the sides onto the base, slide the axles through the holes in the sides, add the wheels, and strap on the elastic. The elastic then needs to be taped to the rear axle so it can wind up around it and provide the drive for the car. The rear wheels, ideally, should pressure-fit onto the axle as well, but often they don’t, and this is a trade-off for using skewers. Skewers tend to vary in diameter significantly, so while sometimes they will pressure-fit well, other skewers from the same pack may be way too small. It is nothing a little bit of masking tape can’t fix.



Different sized wheels can also be cut and swapped out so kids can experiment with the effect of wheel size on the car. You can also add elastics around the outside of the wheels, or tape, or foam tape, to experiment with the effect of friction on the car’s wheels and its overall performance.

I have been working on removing the elastic and replacing it with a 3D printed spring, so that kids can be exposed to differing kinds of modern manufacturing (additive manufacturing with 3D printing and subtractive manufacturing with laser cutting). This will also remove another fiddly bit to the project: taping the elastic to the rear axle. It doesn’t always work out on the first try, not that is a bad thing, it’s good to have a deliberate failure point in a project so you can create a learning opportunity out of it, but sometimes, due to circumstances, having a fail-proof project is beneficial as well.


Designing a pull-back racer

Designing a pull-back racer

I recently offered a workshop at WPL for kids where we made wind-up, or pull-back, racers. Instead of the standard cardboard bodies, which in testing I felt bent far too easily, I opted to quickly design and laser-cut some basic frames made out of 6mm MDF the kids could attach their parts onto.

This led me to thinking: could I design a whole pull-back racer, save for the elastic, to be cut on one sheet of MDF?

After some internet sleuthing for ideas, I did see one, similar example to what I had in mind, and with that as a source of inspiration, I fired up Inkscape and went to work designing.


After designing, I needed a quick trip to Kwartzlab for 20 minutes on the laser cutter to cut the design, and move closer to turning my idea into reality. I dry-fitted the components, and it started to look like a car.


30 minutes of gluing later, and I had a fully-functioning pull-back car. My design is far from perfect: the rear wheels wander too much due to me over-worrying about tolerances, and the car is probably 2-3 times larger than it needs to be, but it feels solid and reliably works. See for yourself:

One thing I did learn, and will try to apply to the next time I offer this activity to kids, is the friction between the wheels and the floor is very important. In the video above you can see I wrapped one of the wheels in an elastic to increase friction. Otherwise, the car wasted too much energy spinning its wheels and didn’t go too far. I think cheap, adhesive-backed craft foam might be an effective and economical solution to that problem.

I am going to try a new design that balances between the cheapness of the crafty cardboard designs and my over-engineered single-sheet MDF one. A basic body, with side supports for skewer axles, and large wheels, all laser cut.

Organizing the Waterloo Mini Maker Faire

Organizing the Waterloo Mini Maker Faire


June 15 at Kitchener City Hall, a large group of folks (including myself) organized and ran the region’s first ever Maker Faire, the Waterloo Mini Maker Faire. For those of you unaware of the Maker Faire phenomena, they are basically large, creative, do-it-yourself festivals, where folks come together to show off their creations, share their passion for their hobbies and interests, and for some, to sell things and make some money. A quick Google image search shows just how crazy and imaginative Maker Faires can be.

Aside from the generosity and support received from the sponsors, volunteers, makers, and general public, the other thing that blows me away was that all of this started as a result of a tweet I sent out a year ago today:

From that tweet, and in less than a year, myself, many of the hardworking folks at Kwartzlab, Diyode, and many other individuals from the #kwawesome community came together and pulled off a Maker Faire.

We had almost 50 tables as well as talks, workshops, demonstrations and live music. We had press coverage from The Record, The Kitchener Post, CBC KW, CTV News, to name a few. We had politicians come out and tour. Most importantly, we had 4-5,000 members of our amazing community come to Kitchener City Hall to tour the Maker Faire and interact with the exhibits.

Organizing it was a tiring, sometimes frustrating, but ultimately exhilarating experience. And I am crazy enough to try and do it again next year, but with two caveats: it will be bigger and better.

My favourite homemade salsa recipe

My favourite homemade salsa recipe

Once upon a time, back when my wife and I lived on our own together, we used to cook a lot. Not that we don’t cook a lot now, but back then we took courses to expand our abilities and tried new things. Today, due to having three young kids, our cooking is usually on the simple, “kid-friendly” side of the spectrum.

Back then, I once tried to make my own salsa. I found a recipe on the internet that sounded good enough so I made it. Uninitiated in the use of jalapeños in cooking, my first mistake was touching my eyes while coring the jalapeños. After crying for two hours, during which I finished making the recipe, I got desperate and I went to the internet for advice and decided to pour milk in my eyes. My second mistake was adding the dozen cored jalapeños uncooked to the salsa. I know now that cooking jalapeños is kind of key to controlling the hotness of the salsa. Regardless of whether you like your salsa hot or not, you should cook the jalapeños at least a little bit, otherwise you will pay for it not only when you eat it, but… later as well.

One day, after regaling her co-workers about my salsa-making exploits, my wife stumbled upon this homemade salsa recipe, shared with her by a co-worker. This recipe has become a staple in our household. When we finish eating the last batch made, we make another. It’s become a condiment in our house, both my wife and I can’t eat eggs anymore without adding this to them. It’s addictive, and I gave it out as gifts this past Christmas season. In the past year alone, I’ve made about 30 litres of the stuff. And, I am a pro at canning now, too.

So now, here is my favourite, addictive-as-crack salsa recipe:

Saute for 15-30 minutes:

  • 1/2 cup olive oil
  • 2 cups chopped peppers (use green, red, orange and yellow peppers, it makes it look really fun)
  • 4 cups chopped onion
  • 16 jalapeño deseeded and chopped
  • 4 bulbs garlic finely chopped (that’s right! 4 whole bulbs! the most time-consuming part of this recipe is peeling all the individual cloves)

Add, cook and cover ~ 1hr:

  • 14 chopped/peeled tomatoes (we do not peel the tomatoes!)
  • 1 1/2 cups vinegar
  • 2 small cans tomato paste
  • 3 tbsp coarse salt (kosher is the only way to go)
  • 1 bunch chopped cilantro ~1 cup (we often skip this one)

The length of time you cook the salsa will affect its hotness. Cooking for the full times shown above will result in mild salsa, and shortening the cooking time just a bit (to 45 minutes instead of an hour) will get you medium heat.

Makes about 3.5 to 4 L depending volume of tomatoes

Neat Engineering Competition

Neat Engineering Competition

Working at the University of Waterloo affords me some pretty neat opportunities. One of them is being able to occasionally view student project competitions for the Faculty of Engineering. This one I was interested in because I replied to a late-night plea for an ultrasound sensor that went out to the Kwartzlab mailing list. I guess a student group making a self-navigating boat damaged their ultrasound sensor and needed a spare for a competition the following day, and I happened to have one I could spare. After hearing the details of the competition, I decided to go have a look:

It was a fairly simple setup and the boats weren’t overly complicated. They used polystyrene insulation for the hull, a servo to steer, a drive motor for the propeller, usually three ultrasound sensors for wall detection, and many had arduinos for the brains. It is amazing what sort of complicated behaviours you can see emerge from such a simple physical/electrical setup.

Harmony Lunch

Harmony Lunch


This past weekend I took my son to Harmony Lunch for the first time. He had a playdate who bailed on him and I decided to do something nice with him to cheer him up.

Suffice to say, I love that restaurant. From the pork burgers, to the weathered, contoured hardwood floors, to the still-functioning shake machine right out of the 50’s, to how you stink like grease and hamburgers when you leave, everything about that place is comforting to me.

As I sat beside my son, eating, we talked about how others can let you down, how to be strong, and how sometimes it is important to sometimes take the time to do something that makes you happy. Our conversation drifted to other things, and I told him about how the restaurant was his Great-great-Uncle’s favourite restaurant. Apparently it is now his favourite restaurant, too. He suggested we bring mom there for lunch on Mother’s Day.

With his little brother still a crawler the thought of taking the whole family there, with Isaac shuffling around on those floors, makes my skin crawl. Still, it warms my heart to think that there may be a new tradition started on that Saturday afternoon.

My own CNC mill – Shapeoko construction so far

My own CNC mill – Shapeoko construction so far


I consider myself a Maker, and have been looking to expand the tool set that I have available to create projects at home. One of my main focuses was to put together a small CNC mill. Ideally, a mill good enough for small wood/hardboard projects that I could also re-purpose as a circuit mill. The Shapeoko seemed to fit that bill.


A little while ago I purchased the Shapeoko mechanical kit. I eagerly tore it open, impressed with the packaging it was shipped in. I spent a few evenings meticulously assembling it, and soon got distracted by other projects around the house. The past few evenings, I have felt a strong push to finish the project.


The instructions are admittedly a little vague, but not too bad if you are comfortable making some assumptions. This is a credit to the design of the Shapeoko: it is designed well enough that it is hard to screw up the assembly. Tapping the few holes that needed to be tapped was probably the least enjoyable part of the experience so far. It became a little tiresome as it relied upon more endurance in my forearm muscles than what I already have.


Overall, assembly is relatively quick and straightforward. I am curious as to how it will operate once complete. The kit itself isn’t designed with any sort of end stop sensors, so I bet there is a lot of focus on proper set up and hope that the project won’t overrun the physical limits of the mill. I am hoping it’ll be fully operational with a few test runs under it’s belt by the end of the weekend.


Then, on to my Prusa.

KW Awesome Foundation

KW Awesome Foundation


So for almost a year now I have been involved with the Kitchener-Waterloo chapter of the Awesome Foundation. I love it. I love every part of it. It can be stressful, difficult to find time for, and at times calls for a lot of effort, but it is worth it.

The Awesome Foundation is a random collection of 10 folks who get together once a month to pool $100 each to give away $1000 to local projects for which the money would make a huge impact in their community. Chapters are popping up all around the world. As of writing, officially there are 64 chapters in 12 countries, with over $380,000 given away worldwide so far.

I am a Co-Conspirator with Gabrielle Clermont, or what the larger Awesome Foundation would call a Dean. We basically pull the whole thing together. We find 10 people willing to give away $100 each to upcoming projects. We book a location to host us, solicit pitches and organize it so that everyone shows up and the money gets given away.

I’ve learned a lot about how the how charitable process works behind the scenes, and have gained an understanding as to why things can seem bureaucratic sometimes. The Awesome Foundation is pretty much the opposite of bureaucracy; it is a very loosely organized group of folks who do things very differently from chapter to chapter. Here in KW, we only give the money away every second month, have a $200 “People’s Choice” award if there are enough trustees that month, and we are big on having the Pitch Night to vet projects. Other cities operate entirely independently, for example, some chapter have Pitch Nights, others use only the content a web form only to decide who receives the money. Networking to find trustees to generously give away their own money, being thankful for any help received and maintaining those relationships, no matter how small, and always talking with others about the cool ideas in your head are a few of the things I’ve learned.

As the Foundation grows, both the bigger Awesome Foundation as well as our chapter here in KW, there has to be some change as well. Bureaucracy is creeping in. We’re working toward being more professional, advertizing more, doing press releases, and reaching out to people to encourage them to apply.

Personally, I’ve also designed posters, business cards, and I’ve even silk-screened t-shirts for the foundation. I spent a day last week distributing posters and just talking to random strangers about their cool ideas that could make our community even greater.

However, the best part of the Foundation are the people. The Trustees are some of the coolest people I’ve had the opportunity to work with. And the projects! I love them all. Even the ones who don’t get the grant are all awesome. When deciding that month’s prize winner we often have several we’d love to give the money to and there’s never been a clear winner.

Also, I tend to try to support anyone who pitches. My social calendar is basically dictated by the Awesome Foundation. I’ll volunteer for projects that need help or go to the shows and performances of the artists who pitch. That, in a nutshell, is what made me fall in love with the Foundation. I have met so many amazing people in this community and done and seen so much since I started putting more into it a year ago. The Awesome Foundation has made me a better, happier, more engaged person.

Silk Screen Printing

Silk Screen Printing

I was up late last night/this morning doing my first ever run of silk screen printed t-shirts.

It was fun. I can see how it can be addicting.

Two nights ago I mixed up the chemicals and treated the silk screen with the photo sensitive solution so it would be dry and ready to use.

First, I started off with a design I made for the KW Awesome Foundation Logo. I printed it onto three layers of acetate, lined them up, and taped it together. My toner is currently bleeding on my printer, so I took it to Fed Ex Kinko’s to print.

Once together, I set up the low-cost 150-watt incandescent bulb and pie plate method to burn the image into the silk screen, so the image could be washed away to make the negative.

I left it alone for 45 minutes to return to this:

You can see the image burned into the screen ever so slightly, in yellow.

Next part was to wash out the negative in lukewarm water and then let it dry. Washing it out was fun, and once you were done it was very satisfying to see the negative as clear as day on your screen.

While the screen dried, I ironed out the shirts, and got the set up ready to go.

Once the screen was dried, I covered the back with green painter’s tape everywhere except for the negative. During the washing-out process with the negative, a few pinhole-size holes appeared in the screen, so instead of having random colour dots on the finished shirt, I decided to just cover it all with tape to be safe.

Then, I dumped some ink on the screen and squeegeed. First shirt:

I learned three things from the squeegee process:

  1. If you used a backer, make sure it is flat and smooth. Initially I used a flat piece of cardboard from a crate of spaghetti sauce my wife had recently purchased, and its surface was slightly bumpy and textured. The first shirt shows where the circles were in embedded in the cardboard from the weight of the jars.
  2. Ink is best transferred if it is spread out evenly on the negative before it even put onto the shirt. I thought you could put the screen down first, apply ink in a line, then squeegee it across, but this method doesn’t transfer ink well on toward the bottom of the print.
  3. When you squeegee, use a little more pressure than the weight of your hands, and press evenly across the length of the squeegee, ideally with two hands. I was pressing so hard the ink was going through the shirt and onto the backer I had put in to support the shirt.

End results:

In the end, I was very happy with the result. In the picture with the 8 shirts all in a row you can see my technique progress. I am pretty confident now that I could do a run of shirts of any quantity successfully from the start now.

Start to finish, it took me about 4 hours to go through everything. It could have been shorter if I made the negative the night before, which I would probably do in the future. Basically, 1 night to prepare the screen and let it dry, a second night to expose, wash out and dry the negative, and another night to print. I guess you’d also need a fourth night to iron the shirts once the ink is dry as well. You’re supposed to iron them to help the ink set in permanently.

I look forward to doing this again in the future. My oldest son has a drawing he recently did that my wife and I adore. I’m thinking of scanning it on our computer and making a negative from that to print on some shirts. It should make for a great gift.

Stay-at-home dad

Stay-at-home dad

My third child, Isaac, is almost nine months old, and for the next three months I am on parental leave while I wife returns to work. I take some parental leave for two reasons: to maximize the limited top-up both of our employers give us on top of the government EI payments we receive for parental leave, and so my wife and I can see how it is to be on the “other side” of the fence.

Working while one parent is at home with the kids is a blessing since you leave the mess and craziness behind for 8 hours a day to deal with a different sort of mess and craziness at work. You get to have a break from the kids.

When you come home, often your spouse needs a break after being with the kids for those eight hours. Meanwhile, you just want to put your feet up after a long day at work. There is no rest for either parent, but both parents feel as though they deserve it.

Empathy starts to kick in. You enter a state of Zen-like bliss where craziness is the norm and rest is an impossible dream. And when it does happen, you feel strange being idle and not having anything to do.

Being a dad on parental leave is a great thing. I think it’s helped to make be a better father and husband. My wife gets jealous responses from co-workers when she tells them she came home to a clean house and dinner being made (although those two happening on the same day is a statistical oddity).

Sometimes I get mild ribbing from other (usually older) male co-workers when I tell them I am going on parental leave. “I’d never do that!” or “That’s mom’s job” are a few responses I’ve heard, which I find weird. Men are supposed to be the stereotypical “tough” members of the household. Fix the car, mow the lawn, burn the meat. If you’re such a tough guy, why are little children so intimidating? Real men raise their kids, have tea parties with their daughters, wipe their son’s boogers off their fingers. Real men are involved with their kids, dirty diapers and all.