Ask an Engineer References

In case you didn’t know (and you probably didn’t, given how un-announced it was here), I was invited to be on the Adafruit Ask an Engineer webcast as a special guest.

Essentially it was aiming to be a quick highlight of what  someone could do in the realm of mechanical projects, since the usual target of the show is very much EEs and software folks. I gave a rundown of some of the projects (the entire build histories of which are to the left in the sidebar) and answered a few questions about EV technology. One thing that cropped up was where to start reading or joining if you want to build mechanical things, and I really couldn’t provide a good answer on the show.

I still can’t think of one – unlike the Ardusphere, there’s not really any well known big names that ‘unify’ the mechanical hobbies, such as what Sparkfun and Adafruit might do for the modern EE hobbyist, since the scope of these is so much larger than open-source electronics. You’d generally have to break it down further, like ‘modified electric bikes’, or ‘battlebots’ or something, which is why I suggested with only a bit of irony for people to google search the thing they want to build. For instance, there’s pretty much a community for every make and model of car in existence.

But here’s a classic-me onslaught of links which should help at least a few people get hooked and started:

General Knowledge

  • Instructables: search for your desired project. Here’s the ones I wrote.
  • Making Things Move is probably one of the best primers for basic mechanical concepts and parts I have seen. Highly recommended (a copy of this is in our shop library, by which I mean a pile on my desk)
  • Gizmology and RoyMech: Two of my favorites for some more in depth analysis of basic mechanical components
  • Fundamentals of Design: Still one of my all-time favorites despite the diabetes-inducing writing style, because it drills down deep into theory and concepts for many different machine components. Unfortunately, it seems the book is now behind a MIT certificate wall, so I’m hosting it locally here.



  • Big Blue Saw (custom waterjet and laser machining)
  • eMachineShop and FirstCut (custom 3D machining – $$$)
  • Shapeways (custom 3D printing) and its upmarket competitor Materialise
  • I don’t know enough about Ponoko to say anything about it besides Ponoko.
  • is for the more pro designers who want to hire out manufacturing of just about anything.


The part that we touched on the least, one of the issues limiting people from engaging in building mechanical things is the lack of a well known toolchain to do so – for example, Eagle or KICAD. Most CAD systems are proprietary and extremely expensive; $10,000 is considered quite cheap and there are a few recent systems that start at ‘only’ $1000 or so. The free ones tend to be gimmicky and limited in functionality. Given enough time and practice, of course, these limitations could be overcome.

  • Autodesk gives 1-3 year student licenses to those with a .edu or verifiable educational relation. This is how I keep running Inventor forever.
  • Autodesk 123D design seems to be the highest design software in terms of accessibility * usability product. Autodesk has been pushing hard into the hobbyist market recently, so this might explain that.
  • Alibre (now Geomagic) was a low cost CAD system which was bought by 3D Systems recently.
  • Sketchup (formerly Google) is popular with some folks, though I found the 2013 free version frustratingly limited.
  • Open Source CAD platforms: I haven’t kept up with these so much recently since they inevitably require you to be a Linux hacker to even run, but in case you are one already:
    • FreeCAD seems to be the most together in terms of a functional parametric CAD software (i.e. not just mashing cubes into spheres)
    • OpenSCAD: I am put off greatly by the thought of “programming” your shapes, but to each their own! Many of the models on Thingiverse seem to be made with this.
    • Some people do use Blender to design mechanical things.

Parts for Designing

  • Thingiverse, a repository of mostly 3D printable models
  • 3DContentCentral: Affiliated with Solidworks, many industrial suppliers
  • GrabCAD: Full of pretty design models, not so much useful individual parts.
  • One of the great things about McMaster is that they have basically every nut and bolt and sprocket and gear and everything else as downloadable solid models. 50% of any of my designs these days are just downloaded from McMaster, pursuant to the art of design-around-what-you-have-fu.

There’s also my own references page which I’ve gathered all my rather technical or design-heavy posts, or posts that use or demo one specific part. I also have some downloadable CAD models uploaded.



5 thoughts on “Ask an Engineer References”

  1. Sorry, stupid comment… I got to the part where you actually answered my question about your scar.

  2. I know Limor is an EE, and PT is a really smart guy too, but the whole interview rubbed me the wrong way. It seemed really condescending and came across like you were talking to some CIO/CTO of a big corporation who may have been an EE in college, but has been at the top with clean hands for too long. Maybe I just rushed to judgement, but, not to be completely offensive, their questions seemed really stupid. Then again, they may have been asking them for the sake of the audience, in which case I retract my statement.

    Either way, good job.

  3. Yeah, AaE is pretty “general audience” – I knew going in that there wasn’t going to be anything intensely technical. Still thinking of doing a “Monthly Mechanical Mayhem” or something…

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