While last week was about hand prototyping in the PDL with raw materials, the most important highlights of this week were learning to prototype with the laser cutter and I even got a chance to learn about the 3D printer.
I had absolutely zero experience with these apparatuses until this week and am proud of the learning curve that took place in such a short period of time. What surprised me was how intricate these machines were to set up and how one little error can actually do a lot of damage. I probably learned more of what not to do than what to do, but both are equally valuable.
From a design standpoint, I became more familiar with some features in SolidWorks that I was unaware of after talking to Sam. Additionally, I learned how to link different aspects of a design so that it is more efficient to make changes; I figured this one out the hard way after having to break apart the whale-bone design to make in the 3D printer simply because of the structures that I wanted made. This is because if I had tried to print the design as one single piece, the prototype would have turned out wrong as the piece was asymmetrical and would have printed as a warped model. As a result, I made a new design with snap in parts so that I could assemble them into what I wanted. This part of my week is where I learned about the entire design process. For example, I learned about tolerances; this important aspect is something I completely forgot so when I tried to piece my model together it didn’t work. I then proceeded to use clamp a drill-bit to the table and turned the parts by hand to expand the holes to the proper size (I didn’t want to waste material plus I prefer to work with my hands anyways) so I wouldn’t crack the plastic. Although I ‘messed’ up making this model because rings were thicker than I had planned (measurement error), I made a new one using the laser cutter anyways and screwed the parts together. I am overall unhappy with how the ‘whale-bone’ design is coming along and may manipulate it around more next week.
Moving on to a different design though, I finally assembled the pin-wheel type design properly. Last week I simply had the wheels rotating on a nail with hot glue. Not surprisingly it constantly fell apart so I decided to find a better way to stabilize the model. Another problem was that once all of the wheels were stacked together, the wheels stuck together which will be a problem if the whole purpose of the wheels is to allow for single step transitions for lenses. Additionally the wheels rotated too freely on the nail- they could wobble back and forth and any imbalance in the weight caused them to rotate incorrectly.
To address these problems I planned to put the wheels on a larger diameter screw with washers in between. Since I made the holes too small in the design in SolidWorks for any of the longer screws to fit, I ended up using a drill to expand the holes. However, I had to drill halfway through each side to avoid cracking the wheels because of the brittleness of the material. Anyways, I made the changes to the prototype and secured the whole thing with a bolt on the end. Although the fit was far superior and more secure (not to mention safer without a sharp end) with the screw, the problem of the wheels sticking remained. I discovered the solution to the problem accidentally by playing with the extra bolts and the wheels during my lunch break. Although the bolts are thicker thus increasing the space between the lenses that will fit into the wheel, they allow the wheels to all rotate independently. Additionally since the fit is tight, there is some resistance to the wheels spinning to that once the lenses are in place, there will be no problems with them falling to balance the weight of the lenses (what I mean by this is if there is one lens which is more massive than the others in the wheel due to the curvature and the resultant additional volume, there is no worries of the wheel rotating freely down on its own so that the most massive one can only sit on the bottom). This means that the diagnostician will not have to hold to wheels in place as they cycle through the lenses. This was my original intent for this design so I am content with the prototype thus far.
This week I also looked into other diagnostic alternatives after Professor Kim approached me with the idea of the focus-able cross hair described in a few other posts. There will be more on this to work on next week and will serve as my focus for the first part of the upcoming week.
One other thing that happened this week is that I was able to contact Dr. Bob Lipski and arranged to visit his office this week to learn retinoscopy and observe what he does/how he performs his job. I am definitely looking forward to it.