You've probably used a clicky pen very recently.
Even if you've taken one apart, it's still hard to understand how it works.
Lucky for us, we've got 3D animation on our side.
The clicky pen consists of several different parts.
The lower barrel,
the ink cartridge,
the upper barrel,
the push button,
and the cam.
Push and release, and the pen tip is out.
Push and release again, and the tip is in.
Take a look at what happens when the ink cartridge is pressed downward.
The spring gets compressed
and provides resistance against the button press.
Most of the action happens up here.
Let's get a closer look.
The push button has eight notches on the side that guide it as it slides in and out.
Notice the jagged edges at the very end.
The cam has only four teeth at the end but they're pointed the other way.
This piece translates linear motion into rotational motion.
In fact, it's the only piece that's allowed to rotate.
The guides are molded into the upper barrel.
The notches in the push button slide up and down these guides.
The four white teeth on the cam slide up and down these edges.
Alright let's put all these pieces together.
Starting with the pen tip in.
You'll notice that the cam teeth are halfway along these edges.
If the guides weren't there, the spring resistance would cause the teeth to slide all the way in.
Instead we're kind of at an awkward halfway point.
The button is pushed and the cam begins to slide.
Once the cam teeth are free of the guides,
the cam rotates just a bit while they slide into the edges.
The contact is what creates the first click.
As the button is released, the cam teeth come in contact with the guide edges causing more rotation.
As soon as the teeth are free of the push button edges it slides all the way in again.
This is the second click.
The cam doesn't go back as far which is why the pen tip stays out.
To get the pen tip back in, we repeat this same process.
Push and release has two clicks but if it happens fast enough, it may sound like one click.
Now keep in mind that this is just one kind of pen mechanism,
not all clicky pens will work like this but they're probably similar.
If you're new to my channel,
my name is Jared Owen and I love to make 3D animations on how things work.
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Thank you for watching!