Ultra Thin Pen (Bistable Compliant Mechanism)

Hello,

this is my pen based on a bistable compliant mechnism.

It is very thin (3 to 5 mm) and works with a standard BIC refill (BIC Cristal). 

Its center of mass is located (approx.) on the first contact surface (seen from the actuating mechanism). This way it is nicely balanced when the pen rests in your hand and even though the actuating mechanism looks bulky you almost won't notice it while using the pen. I know it's not really aesthetically pleasing (yet) but maybe a nicer version will follow in the future :-)

Its dimensions are approx.  5 (3) x 148 x 30 mm

I hope you like it.

How does it work?

At the end of the pen sits the actuation unit, to which the BIC refill is attached. The BIC refill is then guided over three contact surfaces and one ring. You operate the actuation unit by pushing the rectangle (in which the refill is attached) downwards. This causes the entire refill to move forward so you can write. The actuation unit remains in its position until you change it again. To store the refill safely, move the actuating mechanism back again.

How do you insert the refill correctly?

You have to insert the refill from the front and from the bottom at an angle and then push it backwards so that it locks securely into the actuation unit.

What do you have to bear in mind when using it for the first time?

There are two things to do before using the pen for the first time. 
Firstly, when moving the actuating mechanism for the first time do it very slowly. This prevents the individual struts of the actuator from breaking (depending on the material you use - I use PLA). Once you have moved the actuator slowly once, you can use the pen normally.
The second thing to do is to adjust the position of the BIC refill. This is done by actuating the actuating mechanism and then pushing the refill forward until it touches the 0.5 mm thick spacer at the front. This ensures that the refill is fully extended when using the actuation unit.

What is the difference between the stl files?

The “Updated Pen (compliant mechanism) v1” stl file is an updated version of the original file. I updated it based on the feedback I got so far. The small clips at the actuating unit are twice the length now and I also added a small lever at the back which also works as a spacer. 

The "Pen (Improved Ergonomics)" stl file is also the updated version but with rounded corners and a larger support area at the front to rest your fingers. Overall this version is more comfortable to use, but the printing time is more than 1 hour.

Are there more versions planned?

Yes. I'm designing two future versions of the pen. One that's a bit smaller and more ergonomic. The other one will only be printable with a SLS 3d printer (which I do not have but the design will be more fun).

I hope you like it. If it does not work for you please leave a comment or shoot me a message instead of just posting a 1 star review, I'm sure there is no problem that can't be solved.