We recently put the finishing touches on our latest “just for fun” prototype project: a magnifying glass created from a single piece of plastic. Because so many of our client projects are protected by nondisclosure agreements we spend a portion of our free time creating products that synthesize creative design, engineering, and allow us to promote the unique capabilities of our team. One of our young engineers recently came up with the idea of a prototype magnifying glass which he brought to life by machining a single piece of acrylic plastic into a lens and then 3D printing the handle to go with it. The computer aided design as well as the pieces fabricated from it were all manufactured in-house at Creative Mechanisms.
So here’s a look at how you can produce an acrylic lens along with the accessories required to turn it into a magnifying glass from start to finish:
Step 1: Start with a single piece of acrylic plastic. Acrylic is a clear plastic commonly referred to as “plexiglass.” The material we used was the 1.5” thick cast acrylic block you can see below:
Step 2: Begin rough cutting the acrylic into the approximate shape of the lens. The desired specifications were to have a converging lens with a 3” diameter and a focal length of 3”.
The above image shows the single tool CNC machine cutting the acrylic plastic piece according the Computer Aided Design (CAD) files provided to it by our design engineer.
Above is an image of the acrylic plastic stock at various points in the machining process. The left-most plastic piece is the stock plastic from a supplier. The piece in the center is the lens halfway through the machining process and right-most plastic piece is the lens after the machining process is complete.
Step 3: Finish cutting the lens. We are able to precise finish the lens to an accuracy of 0.005” of its final desired dimensions using our CNC machine. The lens was machined to have a focal point 3 inches away from the middle of the lens and 3x magnification. You can see a close-up of the lens below:
Step 4: Wet sand the lens with #600 grit and then #1200 grit sandpaper. Finish polish the lens with an industrial plastic polishing compound (these products typically contain suspended particles of crystalline liquid silica that provide a wonderful finish for a plastic lens). Want to learn more about creating an acrylic lens from scratch? Watch this video. Finally, here are a few pictures that show the optical properties of the lens and how a laser reacts within it. Notice the bouncing and/or curving of the light:
Step 5: Design, 3D Print, and assemble a plastic handle. We felt creative when we put this together so we added a little flair to the handle. First you can see the 3D CAD design in Solidworks followed shortly by the real life product. Check it out:
And that’s it! A novel magnifying glass prototype designed and produced entirely from scratch using nothing but plastic! The entire project was designed and produced by the team at Creative Mechanisms using Solidworks CAD and our integrated software-hardware infrastructure. The lens is CNC machined from a single sheet of transparent acrylic stock and the handle is 3D printed using ABS plastic. For various reasons with a project like this it is actually impossible to create the handle using either injection molding or a CNC machine. As such we chose the manufacturing method most suited to the particular aspect of the project. In the case of the handle it was our state of the art 3D printer.