3D Printing & Imaging Arduino Education Technology
Losing to My High School Class a Big Win

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Recently I switched careers from designing industrial food and dairy equipment to teaching industrial technology in a high school. While planning this move and taking night classes, I read quite a bit about authentic instruction where the students engage in real projects that end with something tangible and with real criteria for success. With the exception of the hero teachers from the stories I read like Underwater Dreams, high schools were apparently still full of worksheets, sitting still, being quiet, and pointless drudgery. I started this job with a commitment to myself that my classes wouldn’t be like that. Giving students the freedom to fail and grow on their own with an exciting project would motivate them to do great things, right?

I knew the school where I was going to start teaching had a 3D printer in my Computer Aided Drafting classroom, and having some previous experience with radio-controlled cars I decided that we should design and build our own cars, then race them. Who wouldn’t be into that? There is plenty of room for innovation but the idea is familiar enough that there is a bank of prior knowledge to help the students get started. Surely these students’ competitive nature would drive them to be the best they could be. It turns out that there were a lot of things I didn’t know about high schoolers though, and here’s how things went down for me.

Lessons Learned

Task Avoidance is engrained

One of the first realizations that I had was that high schoolers are mostly motivated by not working. Left to their own devices (pun intended), the vast majority will look at the internet given the option between that and any other thing that’s allowed in the classroom. Task avoidance is so engrained by high school that they will avoid things they would otherwise pay to do strictly out of habit. I played videos of R/C car races and hounded them for action on a daily basis, and very slowly we worked through this phase and as we approached race day the students were coming in before and after school to work on their cars. The takeaway from this is that the beginning of this lesson needs a sub-goal; a way of having a quick payoff for effort that is near-term and achievable. Additionally, even though the overall project is very open-ended, high school students need structure in terms of time management, file management, materials organization, and teamwork.

Tangible objects yield informed decisions

It also became clear that the students weren’t able to start thinking critically about design decisions until the first versions of their cars had been modeled and printed. By this time they may have been getting a little better at thinking about their car, but I believe it was the new ability to see something physical, to hold something in their hands and move it around that enabled them to start making informed decisions about their designs, and indeed at this point arguments started popping up about who had the best solutions to their various problems. As a teacher, this was the best part. I held my tongue and watched them debate the pros and cons of each other’s ideas, and enjoyed the process of watching them decide on a solution. High school students have a difficult time thinking in the abstract about ideas they have no experience with, and in the future I intend to have a variety of cheap radio-controlled cars for them to disassemble and play with before they begin their designs.

Decide constraints before design process starts

As a group they had a very hard time delegating tasks, and most teams gravitated towards one student doing most of the work while the other students watched or just looked at the internet. As the project wore on, the students who were not assertive were pushed to the sidelines and lost ownership of the design, and it was difficult to bring them back into the fold in an authentic way by the very end. Students who were good designers were not necessarily good leaders, but those students ended up being in leadership positions because few other students were willing or able to offer input on the design of the car. Students had trouble deciding on constraints so that two students could work on mating parts at the same time. I asked one idle student to work on a steering knuckle but he said he needed to know the wheel diameter before he could start. I asked the student who was working on the wheel what his diameter was going to be, but he informed me that he wouldn’t know until his design was complete. I never was able to get that student to commit to a diameter before the design was finished, and the steering knuckle kid had to wait. In the future I will make a design requirement that the cars must break apart in the middle, and divide the teams onto front half and rear half sub-teams. This will force more students to have ownership in the design of the car and require them to commit to design constraints before the design process even starts.

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Have a file structure and shared drive space

Some of the stumbling blocks in this lesson were me misjudging what high school students know and how they would handle this project, but others were just plain screw-ups on my part. I failed to have shared drive space available on our network so that students could create and edit Inventor files in one place. We used flash drives and Google Drive, but both were far from optimal. Also, when I was working in industry we made one drawing with multiple sheets for a project, so that is what I asked the students to do for their team’s final drawing turn-in package. However, one drawing means one file, which means only one student can open and dimension the drawings at a time. I also did not give these students as much structure as I should have, and a big part of that was that I really didn’t know what this lesson was going to look like until we were in the middle of it (like the student designing the wheel, I guess). As a drafter it would be a red flag if my employer told me that they didn’t have a file structure in place for drawing management and just do whatever works for me, but that is exactly what I told these kids, and they suffered for it.

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This project was a great learning exercise for both the students and me. Overall everything went as well as I had envisioned; I just ended up having to work a lot harder than I expected for it. My students generally had a great time once they were rolling, and this lesson was probably a better picture of what real life will look like after graduation than anything else they have done in high school. On race day we invited the principals down to watch, and even though I designed and built an awesome car myself, they crushed me on the track. They all had a good laugh that Mr. Z was the loser, but being soundly beaten by my students that day couldn’t have been a bigger win for me.

Knowing what I know now, in the future I plan to implement all of the improvements to this lesson that I’ve discussed and invite some regional high schools to compete against us in a race. My total cost per team was only $50 in supplies, and only $18 of that was consumables, so next time I teach this lesson I should be able to do it for $18 per team. This is a great competitive project for a school that has a 3D printer but can’t afford to take part in an organized robotics competition.

Rules:

  • Cars must be no more than 8″ long, 7″ wide, and 5″ tall.
  • Tires cannot be made of anything that was designed to be a tire.
  • Racetrack is on basketball court, and is made of long straights and short twisty curves.
  • Motor, radio, servo, battery holder, speed controller, brass bushings, 3mm threaded rod, 3mm nuts, 3mm washers, 4mm washers, ¼” aluminum tubing, and rubber bands are provided. Any additional materials must be purchased from the team’s $3 budget, except for parts printed on a 3D printer or resin casted.

What worked for us, and what didn’t:
Tires: We used mountain bike inner tubes cut into bands for tires, stretched over 3D printed wheels. This gives some traction, but it’s not awesome. Some students put rubber bands under or over their inner tubes. I would like to try Ninjaflex filament to see if we could print better tires with it. Ideally I would resin cast silicone tires, but time and budget didn’t allow it at this point.

Suspension: I pretty much banned suspension setups because my students were having a hard enough time just getting 4 wheels stuck together on a frame. Without exception though, our frames warped slightly on the printer, and there was always a wheel in the air, which made steering with our poor traction tires all the worse. Finding a way to keep all wheels on the ground is crucial, even on a flat basketball court. Cheap clicker pens have lightweight springs that just fit over 3mm rod, and this seems like a great resource.

Gearing: We bought some gears and planned on making resin casted copies of them, but it turns out that 3D printing small drive pulleys and using rubber bands works really well. It’s easy to make multiple pulleys on the same part and move the rubber band back and forth (like the speed control of a drill press) to fine tune the gearing too. I’m not sure how efficient they are, but they work great and are super easy. A good gear ratio starting point is to have nearly as small a pulley as you can print on the motor shaft and just under the same diameter as the wheels on the drive shaft.

Press fitting: We struggled with 3D printing parts that could be reliably and repeatedly press fit onto shafts. We ended up mostly making a light press fit, and feeding a small rubber band through the hole before we pushed the shaft through for friction, then cutting the rubber band that overhung the 3D part off with a blade.

Speed Controller: I made my own speed controller from scratch using a Picaxe microcontroller and a DRV8833 motor driver chip. You can buy “320 Amp” ESC speed controllers for less than $10 on eBay that would probably work just as well, but they are quite a bit heavier.

Differentials: I attempted to 3D print a ball differential for my car using BBs, but it was difficult and wasn’t very smooth. My students mostly made solid axle drives for their cars, driving both rear wheels at the same speed all the time. This made our poor traction situation even worse. Some teams drove just one of their two rear wheels, but this made the car difficult to turn towards the driven side, and their cars would easily spin out when turning to the non-driven side. My car had a single rear wheel in the middle, and this easily worked the best for turning and for not having a suspension, but it suffered in straight-line traction.

Bushings: We used K&S brass metric tubes for our bushings. The 4mm fits just inside the 5mm, and the 3mm fits just inside the 4mm. It worked really well, but the fit is so close that if you have two co-linear 5mm sections with a single 4mm shaft going through them they will bind and cause excessive friction. It’s almost impossible to get both 5mm sections perfectly in alignment. Every team struggled with this problem. I may buy cheap 4mm inner diameter bearings in bulk for the next time I teach this, but we were able to modify our designs so that our drive axles only passed through a single bushing tube, and it worked well.

Bolts: We used nylon insert 3mm nuts from McMaster Carr on both ends of a cut piece of threaded rod instead of bolts. We used red Loctite on one end. If you 3D print a hexagon recession into one of the two parts you are bolting together you won’t need a wrench on that side.

Motors: We used the Pololu 130 Size 3v brushed 17kRPM, 3.6A stall motor (Part number: 1592), and at $1.59 each (+5 quantity) they are a really good buy. We absolutely destroyed them though, running them at greater than 4.8v, and they had a life span of only a few days of abuse. You need to solder capacitors to the motor connections to prevent radio interference too, and I spent a lot of time desoldering capacitors from dead motors and soldering them back onto new motors. I would recommend spending a few more bucks on a carbon brushed motor, maybe a Tamiya Dash series 130 motor. I am currently trying to find cheap replacement carbon brushes for 130 size motors so I can upgrade the cheap ones I’m already using.

Servos: We used Hextronik HXT500 servos and they worked well until a hard crash when the steering linkage breaks the teeth off of the gears. This could have been prevented with bumpers or by bending an angle in the paperclip wire linkage so that the wire would bend before it damaged the servo.

Batteries: We used four NiMH AAA batteries per car because I already had a charger for them. The output voltage is perfect for the receiver and servo, and gives good power to our 3v motors, although with a shortened life.

Parts List:
zparts

As I think back, that $7 for the speed controller may be a bit optimistic. I may have $10 in that.

29 thoughts on “Losing to My High School Class a Big Win

  1. I myself am in my second year teaching Engineering courses in high school. I also came out of Industry. I had to laugh at your first realization because it’s so true. If your district hasn’t heard of Project Lead The Way I’d advise checking out the program, they have a full engineering path and the intro course is specifically learning the design process including setting down criteria.

    I hope you continue to share your observations because I know I’d love to hear them. I’ve found I sometimes give the students to much credit for basic computer knowledge. I’ve learned they are social media savvy which does not always truly translate to computers, especially Microsoft Office products.

    1. I also teach PLTW classes in addition to my CAD classes (and woodworking). Next year I’m going to add Digital Electronics, which I am stoked about.

      1. Which PLTW courses? I currently teach Intro Eng Design, Engineering Design and Development and Civil Engineering & Architecture. I taught Drafting last year but my schedule was modified this year for all PLTW courses.

  2. I’m curious as to some of the up’s and downs of getting into teaching. I’ve been a professional fabricator all my life, but I toy with the idea of getting into teaching shop. It’s definitely something I’m passionate about, and think there’s a hole in our education system for these classes.

    1. I went the Temporary Authorization Certificate route here in Missouri. If you have a BS in Industrial Technology (which I did) you can teach as you take your classes to become a teacher. Between being a professional equipment designer and my teaching job I worked at a science museum as an outreach educator for about 2 years, where I taught science to grade-schoolers in one-hour blocks. That experience, while taking teaching classes, was amazing and gave me a leg up when a position opened up.

      Teaching is crazy hard and time consuming. It is emotionally draining. I lay in bed and think about my students instead of sleeping. On the other hand, I don’t have customers trying to beat me up on price and delivery. I didn’t lose $150,000 of somebody else’s money today by screwing up the design of a cheese melter. I’m seeing a lot more of my family. I would totally do it again.

  3. Congratulations on your class and the positive outcome – it sounds like you aren’t the only one who enjoyed it. I love reading about projects like this, and can’t help but marvel at the tools and lessons that are available to kids today. I spent most of my high school years trudging through tedious group projects that never got much beyond measuring how much string was used to lift weight ‘x’ through distance ‘y’ using pulley ‘z’.
    My at-home electronic projects were far more interesting, practical, and educational, and my grades suffered for it – I spent too much time learning and not enough time doing classwork.
    Looking forward to hearing about how the next iteration of this project goes!

  4. Thanks for sharing, Brian. As a relatively new father, I’m curious about how engaged the female students were. R/C car racing sounds like a lot of fun to you and me, but I can imagine the nonplussed stare I might get for my daughter if I were to describe this project to her 15 years from now.

    1. You have 15 years to not limit your daughter’s options, there’s no reason she won’t be fascinated by this – I would have been! If she knows it’s ok to be interested then maybe she will be

      – female engineer who designs sanitary processing equipment for the food industry but would love to teach instead (seriously, this article called to me on many levels)

      1. No need to state the obvious or be condescending, Tuppet. My comment clearly implies that I am already thinking about how to get my daughter interested in the maths and sciences.

        1. Simon,
          The nice way to explain what you did there – while entirely not meaning to – was referring to the common element of you and the author (as guys) and then imagining you’d get a nonplussed stare from your daughter 15 years from now.

          Just stepping in (3 months after the fact) as a fellow dad of 3 daughters and I am concerned about the same stuff. It’s often hard to admit that even we ‘open minded’ dads occasionally carry with us a good bit of gender stereotyping.

          Just expose them to everything, share your excitement, make it clear they don’t have to be a dad to try/do/enjoy the things you do. That seems to be the best we can do.

          Abe

          P.S. I’d tend to avoid Disney kid shows. I’ve noticed a disappointing theme of them playing to the stereotypes about ‘nerds’ and then throwing out the occasional token, “but nerds are occasionally OK” story line as though that makes up for episodes of mocking them. [Sorry – different soapbox…]

    2. Many girls become interested when they realise it isn’t all that dirty! i also taught a jewellery making class which appealed to the girls rather more although a lot of boys took the class as well.

      There are so many aspects to design and engineering it would be hard not to find something that appeals.

      I would say that teaching is hard and frustrating. You spend a lot of time in planning and preparation then find the kids aren’t as enthusiastic as you are. Some things work some don’t.

      If you can cope with working surrounded by 20 or 30 people watching you and keep control of the situation then you should do OK.

      1. Take it from a girl; it
        has nothing to do with jewelry making or avoiding dirtiness. The key here is to
        present the projects in the light of solving problems. Mentors in the field are
        a great way to show students (boys and girls) all of the possibilities that
        engineering can hold. I taught engineering, 3 years at an all-boys school and 3
        years at an all-girls school, the major difference was exposure! The boys had
        used tools and knew the terminology more than the girls.

        Simon, I recommend
        exposing your daughter at a VERY young age – start with Duplos and move on to Legos.
        Let her help you when you fix things around the house. Talk about engineering! I
        really don’t think we need to change the content at all to appeal to girls. I
        never did and I had many students (boys and girls) go on to be successful
        engineers!

        Brian, I love what you are
        doing. Just keep doing it and making it accessible and more students will come!

    3. I only had one female in the class, and she was awesome. WAY more competitive than most of the boys, and came in caring about how the project turned out a lot more than most of the other people in the class too. I hadn’t thought about it before your comment, but really the lack of motivation on the classes part as a whole would easily equal any lack of motivation by what one might think of as a stereotypical girl based on general interest.

      1. Thanks, Brian. Sounds like the challenge is getting female students interested enough to enroll in your class. Any ideas on how this might be accomplished?

  5. My original post didn’t seem to get up:
    I also started out designing computer controlled food manufacturing equipment in the UK
    I moved into teaching in 1995 and taught for 15 years.
    Your totally right about motivation being low. Most classes and schools are not big on motivating students to think and be independent.

    I used to do a big project every year some can be seen here http://www.instructables.com/
    if you search for rickharris

    we built full sized racing cars and raced them, Dome buildings 30 feet across, computerised robots and lots of other things to get kids thinking that design and engineering wasn’t just making poor quality Micky mouse things.

    It worked with some, although there are always some who don’t get it.

    Quite a few of my students went into engineering, one works for a Formula 1 racing team. I considered it a success when they went on to study engineering at university far more than I saw exam results as a measure of success.

  6. Fantastic Post Brian! Thanks! I also appreciate the detail of the post. You are in good company with many of us educators who are learning along side our students and often times “getting schooled” by our students. I’m running a similar project-based effort for our school partners. http://www.cvtech.org/blog/
    godspeed

  7. Engrained should be ingrained. The former is not a word.

    Also, consider looking towards hobbyking for cheap components. If you order a month or two in advance shipping won’t be a problem and you can get some pretty good equipment extremely cheaply. An ESC/Motor combo is likely to be both cheaper and far more useful than what you used in the article.

  8. a couple of thoughts:
    1) On the tires, i have younger kids, elementary, and those rainbow looms are all the rage. Basically a bunch of interwoven silicone bands. Some of the patterns seem like they might work well around the wheels and provide both a “sticky” surface, and some give to help with the twisted frames. This also seems like it would provide some allowance for the wheels not being perfectly parallel with the ground.
    2) On press fit components; did you consider simply omitting or greatly under-sizing the hole and using a drill press to machine the hole to the correct size? I’ve always viewed 3D printers as programmable plastic casting machines. So if i need a precision part, it seems like a bit of post cast machining would be normal.
    3) i may be wrong here, but the car shown in the pictures doesn’t seem to have Ackermann steering geometry. I wonder if that would have helped the low traction turning of your cars.

    *edited for spelling.

    1. You’re right, those cars don’t have Ackermann geometry, even though I gave a lesson on it. I think it was just a bit more than they could absorb along with everything else. That’s a good idea about the rubber band bracelets.

  9. Hi Brian, this is an awesome write up and is very similar to the fun/work we are doing with some schools in the UK and the US. We have 3D printed line followers, tracks and a custom Arduino board (with BLE & a motor driver) called the BlueBrain. I’d like to get in touch over email if I may ? http://www.cannybots.com (my email is wayne at [that domain])

  10. Hi Brian, as a Secondary Technology teacher in West Australia who loved your post and project concept, I have two follow up questions: How many hours of class did you devote to the project? And what was the age-group you ran the project with? Oh, ok, a bonus question for the fun of it… do you have any video of race day? – because that would be fun to see!

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Brian Zweerink

Brian Zweerink is a first-year High School Industrial Technology teacher after his mid-life career switch. He used to design sanitary processing equipment in the food and pharmaceutical industries. His goal is to use awesome projects to motivate high school students to pursue engineering careers.

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