My answer to What’s the best way to build prototypes for sunglasses?
Answer by Scott Tarcy:
What’s the best way to build prototypes for sunglasses?
Examples or guides would be awesome. I’m particularly interested in how lenses are made. I imagine the first step could be cutting out films to glue over them, but how do you move closer to real lenses?
There would be 2 main components to make a prototype. The frame and the lenses. I’ll discuss the frame first and then the lenses.
The first step is to create the general shape and look that you desire. This is called a concept sketch. This can be done with some rough sketches and hand renderings. This is an example of a concept sketch I made.
Often you will have many sketches before coming up with a final version. Once a concept is chosen, the next step is to move into a CAD file of this. The concept sketch is used as a reference but the actual CAD data must be manually generated. Dimensions are taken from an existing pair of sunglasses to make sure the size of the legs and frames is correct. The lenses size and dimensions must be known at this stage as well because of how they snap into the frame. Below are a few photos of the CAD file in progress from a past project.
Once the CAD is made, a prototype of the frame is possible. There are multiple ways to do this. One would be to CNC cut the plastic from a block. Another would be to 3D print the frames. In my opinion, 3D printing is the way to go. It takes less material and usually less time. Nylon is a great material for a prototype of sunglasses, because it is flexible. Here are some pictures of the 3D prints.
3D PRINTED SUNGLASSES
The next step is to get the lenses made. Remember that the lenses decision must be made up front before the frame is created since the lenses snap into the frame.
Lenses are very difficult to prototype, so generally it would be best to repossess lenses from an old set of sunglasses. But if you wanted to create your own original lenses, here is how you would do it.
First, you will need a CAD file made of the lens. If the CAD of the frame was already done, then the lens dimensions can be generated by using that file. Once the CAD file of the lenses is made, a mold will be needed to make the parts (assuming the lenses will be plastic, which the vast majority of sunglasses lens are). The most common materials for sunglass lenses are polycarbonate and SR-91.
An aluminum mold would be a good idea since it costs less than a steel mold and at the beginning stage of product development there will often be changes. A steel mold is better if you are planning on making the same part for years, since an aluminum mold will not last as long.
The lens plastic is made with a colored tint so that it has the color already. There are is also some post treatment of the plastic that is needed as well. This video shows a lot of the steps (fast forward to 4 minutes): https://www.youtube.com/w
All of these steps to create custom lenses require specialized equipment, best suited for a company already making lenses. This is why I recommend repossessing lenses from an existing set of sunglasses if possible.
Finally, once you have the frame prototype and the lenses made, the parts are assembled. Typically, the legs of the frame are held in using a hinge and small screws. The lenses snap into the frame.
If you are interested in my company’s assistance in creating your prototype, please email me at [email protected]
Scott Tarcy, President of http://CADdesignhelp.com