Teardowns
The forensic exploration of how something was made and the deduction of any reasoning as to why.
Forensic Disassembly
Reverse Engineering is a fancy name for taking things apart. Taking something apart is the root of understanding, experience and deep engineering knowledge. But smashing it open and seeing what falls out is hardly “best practise”. Imagine instead you’re the investigator in a crime drama and are trying to work out exactly what has happened here.
Since everything in front of you has been made by someone, there must be a reason why it is there. It doesn’t have to be a good reason, but there was definitely a reason. Sometimes you’ll see spaces for batteries in a product that works off a cable, because they also sell a battery powered version and wanted to keep the components the same. Sometimes design features will be left over from an earlier iteration of the product and were never removed. Whatever it is, there is a reason to it being there. Your goal is to try and work out what those are.
For engineers this should be a natural mind-set, philosophy or guiding principle. (In my opinion it should be lesson 1).
Images from Todd McLellan’s fantastic book Things Come Apart
“Observation is a passive science, experimentation is an active science.”
Claude Bernard 1813-1878
The Process
Anyone can break something apart. But as engineers we’re doing it to learn as much as we can and then to use that knowledge sometime in the future. Perhaps for something unrelated. Therefore to get the most out of it, we need to be forensic in our approach.
The Three Simple Principles:
Observe (look, smell, touch, use etc… all your senses)
Measure
Experiment
Observation is shorthand for all of your senses… touch, smell, temperature, sound etc… (depending on what you’re taking apart, perhaps avoid taste! Use your common sense for this one). But everything that can be seen or experienced, should be seen…
Nothing is inconsequential, as you don’t know what will eventually be consequential! but in the words of Albert Einstein:
“Not everything that counts can be counted, and not everything that can be counted counts.”
So try and document everything that you see but not everything will be useful at the end of the day. But better to have over-documented the process than to have under-documented the process and not be able to go back. Take lots of photographs or even videos if there is a process to see.
Don’t jump to conclusions!
For conducting experiments in order to ascertain the function of a given component (making sure you do this safely of course!) a nice method is the “Subtract & Operate” procedure:
Step 1. Disassemble and remove a part
Step 2. Attempt to operate the altered product
Step 3. Analyse the effect of the subtraction
Step 4. Deduce the function of the part
Step 5. Replace the part and repeat with each other part… one by one
Step 6. Create a function model
“Measurement is the first step that leads to control and to improvement… If you can’t measure something, you can’t understand it. If you can’t understand it, you can’t control it. If you can’t control it, you can’t improve it.”
James Harrington 1979 IBM
Some Teardown Examples…
There are some brilliant videos on Youtube of people taking almost everything apart. One of my favourites (but by saying this I do not endorse some of his language or views, it’s not exactly politically correct in places) is that of AvE and the “Bored of Lame Tool Reviews” BOLTR channel. He’s taken a huge amount of stuff apart and his engineering knowledge and analysis is excellent. As an aside he’s also produced some fascinating videos on working out why some engineering disasters (in particular crane collapses) have happened. It’s a great example of reverse engineering failure analysis.
I also like the fact that he does not post-edit his videos to be correct all along, sometimes he sees things that he criticises until he realises the real reason why something has been done in a particular way. You’ll see this in Part 1 of the grinder teardown below as he demonstrates some great mental maths to work out the forces at work on a shaft and why they don’t have a keyway in this product.
Part 1:
Part 2:
Have a search through his videos, he’s done things on a huge variety of products, you might just find some cross-over knowledge with whatever you are taking apart.
One for a bit of fun:
Another good resource
One place that has some great advice on how to carefully take things apart (from a repairing point of view) is the IFIXIT website and their campaign to make everything repairable.
They have a huge database and guide list to products that they have dismantled to repair some common issues. It’s well worth a look.