Hi, I’m Pete. I’m the quality control manager here at SparkFun. I’ve been at SparkFun since 2007, so I’ve helped take quite a few product ideas to market. In 2016, I was contacted by an engineering professor at CU Boulder, Jacob Segil. He asked me to do a guest lecture each semester focused on design for manufacturing and testing (DFM/DFT).
His class is called “Invention and Innovation,” and the junior-level undergraduate engineering students are challenged to build a commercial product. In addition to teaching the GEEN3400 class and others, Jacob is also doing some pretty awesome prosthetic robotic research. You can check that out here.
My presentation to the class mostly focuses on the hard lessons learned during our experience with product development at SparkFun, but it is also a celebration of all the solutions we eventually found. Here are some highlights:
Automated optical inspection machine finds a failure!
According to our automated optical inspection machine, there is something wrong with this resistor! I love sharing this slide. It gets people’s attention and highlights how very slight tweaks in a design can dramatically help a production team. It also highlights the fact that just a little bit of spider web can throw off a production process.
Early prototype of “locking footprints”
Above, you can see one of our header pins in a prototype circuit board. If you look closer, you will notice that the holes are actually staggered. This forms a brace on the part and holds it perfectly in place. Production can then do the finishing solder work in one easy step. Traditionally, these holes are aligned in a straight row, and allow for the part to fall out of position. You can read all about this in our Sneaky Footprints Tutorial.
Stress testing a revision to the IOIO
Above is a picture of my hand-wired stress-testing apparatus for the IOIO Andriod development board. This product did fine during prototyping and initial launch, but after a while, we kept hearing strange cases of customers destroying the power input circuit. After much investigation, we uncovered that the cause was using a 10-foot or longer power cable. This is a good lesson in trying longer cables, but also a good reminder that you need to really think outside the box to predict how some customers will use your product.
USB connector prototype
Parallel prototyping is another method that is very useful in product development (and DFM especially). Above, you can see that we were testing out some new footprint ideas for a USB connector. At first, we were not sure about how much solder paste to put on the pads, so we prototyped many varieties on the same PCB. I always encourage designers to have several prototypes running in parallel; there’s no need to wait and find out you didn’t nail it the first time. Odds are you won’t (sorry)!
So that highlights some of the big takeaways from my presentation. Feel free to check out all of my Google slides here, and don’t be afraid to comment below if you have questions.
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Now, onto the recap of my recent visit to the CU Engineering Expo. I interviewed seven teams, and it was great to hear about the creative solutions and challenges faced during prototyping.
1. Team Transitional Swivel Nozzle
These guys were designing a thrust vectoring system similar to what you find on Harrier Jet engines. Their project can make a straight tube transform into an right-angled tube.
By combining various angles on each rotational gear, they can adjust the end of the tube in any position, from 0-90 degrees. They used continuous rotation servos, and are therefore able to reposition the thrust in a range of directions.
Transitional Swivel Nozzle RedBoard and servo controller
I was pretty stoked to spot a RedBoard as their controller! But the DFM engineer in me saw those prototyping cables and was screaming for solder joints.
2. Team SCARY
This team had some electronics strapped to a rather old-school bicycle, so I had to stop and ask! Their project involved converting mechanical energy into heat energy. As you rode this beauty, it would warm up your jacket. They told me that during testing their jacket warmed up to 119 degrees Fahrenheit (living up to their name :). You control it by manually switching the power on and off.
I also learned that they were having a bit of trouble going straight from their coil system to heating wires, so they included a battery that would charge up while you rode. Here is their poster that shows some of their calculations.
Team SCARY’s project poster
3. Team Kikuyu Black and White Colobus
These guys were tackling a mechanical engineering project that is helping the Colobus monkeys at the Denver Zoo. Their finished product is made of plastic, and is being used to help the monkeys eat a more nutritious diet. Previously, the Colobus monkeys were eating mostly fruit, becoming overweight, and had bad dental health. With these new tube feeders, the monkeys enjoy the challenge of pulling out healthy vegetables and greens, all the while getting a great workout climbing on the ropes. They had some great data to back it up.
Kikuyu Project Poster
4. Team Stride Tech
Next up was a team interested in helping elderly and disabled people track data on walking ability. There is a lot of research showing that a decrease in stride length is linked to many other illnesses. They used Hall effect sensors and magnets on a wheel to record the speed and stride length of the person using the walker. They also had an IR sensor pointed across the bottom two wheels, so it could detect when each leg moves forward. Again, I was pretty stoked to see those red PCBs!
Team Stride Tech’s 3D-printed enclosure for sensors and controller
Engineering sketches of the Stride Techs concept
Stride Tech’s RedBoard and uSD shield for data logging
5. Team LAVA
Team LAVA was helping a disabled child stay engaged with exercise. Their souped-up shopping cart would play Disney tunes only when the cart was in motion.
Team LAVA’s controller and audio player
Another RedBoard spotting - wahoo!! Looks like an MP3 player shield and a mono audio amp in there too! They were also using an accelerometer to sense the motion of the cart.
Team LAVA’s project poster
6. Team Big Shopper
Team Big Shopper was more interested in the act of shopping than the carts themselves; they were collecting data on customers. They used a webcam and a Raspberry Pi to analyze shoppers' behavior, including facial recognition (crazy!). The data could then help stores better position product. It's always amazing to see what can be pulled off with a Raspberry Pi.
Team Big Shopper’s project poster
7. Team ELSA
Haley Basti from Team ELSA
This team used a Raspberry Pi, touchscreen and Python to make a nice interface for shopping. I was most excited about its ability to remember the order that you usually pick up your items at the grocery! They are working on a feature where you can email or text in a recipe and/or coupons to the device to keep them organized.
Team ELSA’s project poster
I actually talked with Team ELSA after my lecture in March. They were having trouble with their Python code and keyboard input feature, and I shared a project of mine: Engineering Checklists. The program interacts with Excel docs, and I thought it might be helpful. I put the bulk of the project here: Pete’s checklist GUI GitHub repo.
There were over 40 teams at this event; it’s a shame I was only able to interview a few. I’d highly recommend checking it out each semester. I’d also like to thank Jacob for the opportunity to come speak at his GEEN3400 class; it is wonderful to share our experience in DFM. Looking forward to the next semester!
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