Cap Mounted Sun-monocle

You r all excited to go to the beach, you get your towel, swimsuit, the cooler and hat and leave to go to the ocean. Oh no, did you forgot your sunglasses ? No! there are integrated to your cap, Phew !

In this instructable, I will be sharing how I have made baseball-cap mounted sunglasses (there are more like monocles, but you can use 2 at a time) that can also be adjusted in opacity to adapt to any situation. In this instructable, I used 2 different types of 3D printer, resin (Elegoo Mars 2) & filament (Elegoo Neptune 2).

This instructable is divides into 3 different mechanism each with one specific task. In step 1, you find the description of cap mounting mechanism allowing to mount the on the cap in a non-permanent manner. Step 2 describes the mechanism used to hold the lenses into the 2 positions : in front of the eyes or away from the eyes. Finally, step 3 describes the mechanism used to control the amount of light going through the lens i.e. the opacity of the lens

You will find all 3D files here: https://github.com/Virgile-Colrat/sunmonocle/tree/main

·        3d printer , I used resin (Elegoo Mars 2) & filament (Elegoo Neptune 2)

·        Pliers

·        14x5mm extension spring

·        .5mm steel wire

·        8x3x3.5mm (ODxIDxh) ball bearing

·        Clothespin

·        Polarizing filter

·        6mm M3 screws (x2)

·        12mm M3 screw

·        Glue

·        Scissors (to cut the filter sheet in round “lenses”)

The goal of this 1^st mechanism is to provide a stable enough base to connect the cap to the rest of the system. The system used is simply a 3D printed clothespin mechanism, why 3D printed ? Because we are adding mounting point on the clothespin for the 2 positions holder mechanism described in the next step. Thos mounting points are only on one side of the clothespin, meaning that you could technically only print one clothespin half (the half that has the mounting points) and use the classic wood clothespin for the 2^nd part of the mechanism

The goal of this 2^nd mechanism is to be able to hold the lens arm position in 2 different position, it is a bistable mechanism.

First, the 2 ball bearings are pressed into position on the clothespin half that has the mounting points

Then the arm is slid in position in which the 6mm M3 screws can be inserted to catch the ball bearing, /!\ Make sure the screws to not go deeper than the ball bearing, we need to keep the path open for the extension spring to move.

The extension spring can be placed, it is pinned on side by a 12mm M3 screw, on the other side, make a extension of the spring with the steel wire looping around one side of the spring and around the 12mm M3 screw pin. When installing the wire, you should keep a constant tension on the spring to get the mechanism actually working

This 3^rd and last mechanism is here to provide a tunable luminosity filter to the lens. (you find for relatively cheap online polarizing filter sheets)

The lens are just 50mm circular filter cut out of a sheet of polarizing light filters (with scissors). On its own, the filter is not tunable, however, in conjunction with another one, turning one relative tunes the amount of light power able to go through. You can find a lot of examples, for instance here: https://www.youtube.com/watch?v=E9qpbt0v5Hw

This mechanism is an application of these filter and is just a filter that is kept steady relative to another one. Adjusting manually the rotation of the outer lens adjusts the luminosity of the system. Friction holds the moving lens in position when not deliberately rotated.

The mechanism is divided into 3 3D printable parts:

·        the stator lens holder (in pink on the pictures)

·        the outer lens holder (in teal on the pictures)

·        the link between the 2 lens holder (in orange on the picture)

(the orange and teal parts are forming the rotor part of the mechanism and are press assembled)

The assembly is described in the GIF and divided in 3 steps:

1.     Glue the disc filter in the pink part, glue the other disc filter to the teal part.

2.     Sandwich the pink part between the teal and orange parts (the orange part are press assembled). At this point, the pink part should be able to rotate around in the assembly.

The pink part stinking out is then pressed into the monocle arm.

And you are done !

You can build 2 monocle to get each eye covered (literally) as depicted on the picture

Note: I call this project a "sunmonocle" but can also be called "sunglass" for lack of a better term, if you have any better idea, please do not hesitate to post a comment !