3D printing adventures: A simple adaptor for lab equipment

Short version:

Needed an adaptor for our teaching lab’s spirometer, so I made a model using tinkercad and printed it on my 3D printer.  It’s a really, really simple model, but my first time designing then printing!  Awesome!

Long version:

In the 101 lab, students measure their lung capacity using a spirometer.  There are a few models of these, but basically students breathe into a tube, which displaces water and allows the air volume to be determined.

Both of the models we have rely on these disposable cardboard tubes, for students to breathe into.  The tubes are about 50-75 cents each! And it’s a lot of waste.

Kevin Lam, in another course, had made his own spirometer, and used big fat straws (for bubble tea or smoothies).  They’re a lot cheaper, and easier to come by.  They’re skinnier (1.2 cm diameter) than our cardboard tubes (2.2cm diameter), so we need an adapter.  Hurrah, opportunity for my shiny new 3D printer!ccbgtjuviaanbr
I wanted to make an adapter to fit the spirometer on one end, and the bubble tea straw on the other end.  So I did a some measurements and a bit of math to help me build the model, dusting off my trigonometry from many moons ago.

(A student noticed and said “That’s the first time I’ve seen someone use math to do anything useful!”)

Using these notes, here’s a screencapture of the model I came up with, made using TinkerCad (output is an stl file) and then sliced using Cura (output is a gcode file).

All the printing I’ve done before has been with pre-built models, so this was my first opportunity to use TinkerCad.  It is AWESOME – clean and simple interface, quite intuitive, and good functionality for basic shapes.  I tested out a few different diameters, to see what would fit best.



Took about 2 hours to print.  Worked out great.








And, trying it out – also a success!  Worked really well, despite my astro-boy hair this week.

IMG_0160 (1)

We found that the best adaptor worked with a short length of tygon tubing inside, and then the straw inside that — it keeps the best seal.  It took a couple tweaks to fit the straw, but that’s the value of rapid prototyping!

Now just have to print up 3 more for the other apparatuses (apparati?) and then go talk to our prototype sponsors SFU Bubble World to get more straws!

Also, for the hordes of people interested in my physiology, my lung (vital) capacity is 3.9L.  I picture that like I’m breathing the equivalent of a whole bag of milk (or for the non-Ontarians, a gallon-jug of milk).  Lungs are HUGE!






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