DAY ONE:
Brainstorming Ideas
The first step was to brainstorm ideas for our bottle cap. I don't really have experience with bottles or with bottle caps. I mean, I only last year even saw a glass coca cola bottle with a cap. I thought those were history. And I must not have opened more than 5 bottle caps in my entire life. That being said, I do remember the action of a bottle cap opener and at least one design of a bottle cap opener.
The general action of a bottle cap opener is thus: one part(the lifting edge) of a bottle cap opener gets underneath the pleats of the metal bottle cap and pushes up, while another part (the stabilising part) of the bottle cap opener rests on the far side of the metal bottle cap and pushes down. The lifting edge pushes the bottle cap away from the bottle. the curve of the bottle rim and the pleats of the cap means that an upward force on the cap is partially translated into outward force that slightly expands the pleats of the cap so that the cap becomes wide enough to pass over the rim of the bottle cap. The stabilizing part does two things, it provides you with leverage, and it stabilised the cap. The far side can act as a pivot for the lever that is the bottle cap opener multiplying the force applied on end of the lever away from the pivot so that more force is applied in the middle of the lever where the lever is pushing up on the bottom of the bottle cap. And the stabilizing part pushes down on the far side while you push up on the near side to your hand, helps even out the translational force so that the cap or the bottle doesn't go up so much, and kind of pins the cap to the bottle rim so that the cap doesn't go flying off as it would if you just jabbed it on the underside.
During the brainstorming session, my partner Meba and I immediately thought of cutting a J shape active area into what would otherwise be a wrench. While that would have been strong at supporting the stress of opening a metal bottle cap, we both agreed that cutting it out of a thin sheet, and then requiring a person to push and pull on the thin edge to open a bottle cap wouldn't be so pleasant.
So then, we thought of moving that around such that the user could apply comfortably pressure on the flat end of the material.
This required a replacement of the lifting and stabilization surfaces. Finally we came up with the idea to have a hole, where one end could get underneath the pleats and the other end would rest on the cap on the far side from where the opener touched the pleats.
If I were to brainstorm again, I would have brainstormed for longer. I think we only addressed general ideas for 5 minutes before moving on details. My thought is that we could have afforded to go longer and go crazier. I know another group that came up with a sleek design that reminded me of a miniaturized batman masquerade mask.
bottle with bottle cap attached
brainstormed rough ideas
Measuring
Taking into consideration the general action of a bottle opener in mind, it was the most important that we get the distance from the lifting edge and the stabilization correct so that there was enough leverage, so that when the lifting edge was placed under the pleats, the stabilizing end was near the far end of the cap top. It needed to be far enough so as not to interfere with the lifting action, but not so far enough as to miss the cap entirely, which would mean no pivot for our lever action to work against.
Thus, the second step was to measure the width of the bottle cap and guesstimate how big the opening of our bottle cap opener had to be in order for the levering action to work properly.
The diameter of a bottle cap at the top where it is the smallest is 2.5cm. the diameter of a bottle cap at the bottom where the flaired rills are, is around 3cm. I figured that since our bottle opener had to span a bottle cap diagonally, where the lifting end is at the rills, and the stabilizing end is
We came up with a circle of diameter 3 cm and a little semicircle protrusion to catch the underside of the bottle cap.
initial dimensions:
Making Model: checking dimensions
We transferred our idea onto some cheap foam to verify that our guesstimated distances correctly spanned the distance and could theoretically lift the bottle cap off the bottle, were the opener not made of flimsy foam.
We first cut the hole, and we never bothered much with the aesthetics of the outside border, saving that consideration for later, after we had reached a working version.
I liked that approach, because we first put most of our effort on the most vital part of a functioning bottle cap opener.
Just checking hole fit. Not bad
DAY TWO:
On the second day, a third person joined my group. In addition to Meba, I now counted Callie as a member. As she had not come to the first day of class, she had some catching up to do. We quickly caught her up on what we had done the on the first day and then we were off.
First SolidWorks Model ever!
what is Solidworks?
Solidworks is a powerful software that allows one to design and test things before building them. One can design parts, test parts, assemble them together, and convert them in to precisely detailed diagrams that a machinist, or in our case, a laser cutting machine should be able to follow.
To be honest, I think we were supposed to train ourselves on Solidworks parts and drawings before
I was trained and had some experience designing parts (but not assembling them or FEA them) in Autodesk Cad, which is a similar program that tries to do the same thing as SolidWorks. That was late 2009, or just around 6 years ago. As I am 20 at the moment, that was 30% of my life ago. Generally, I knew I had to sketch, specify dimension, and extrude, and beyond that, I didn't really know how SolidWorks worked.
I didn't know where the buttons lived or what exactly the different buttons did, but somehow I managed to whip up a sketch and figure out extrude before my partners(who had also not gone through the tutorial) even had a chance to struggle with Solidworks.
I went through it again more carefully to make sure I understood the steps of sketching, dimensioning, and extruding and where the buttons for those lived.
I also learned about the skins function and how to edit sketches after you've extruded.
I also learned to fillet something that is not fish.
Sadly ,the author does not have pictures of Solidworks in operation at the moment the author is writing this.
On the second day, as we were really getting ready to finalize the dimensions on our SolidWorks model, we wanted to verify our measurements. Meba made a foam version with a diameter of just over 2.5 cm. That hole proved to be too small. I re-cut the hole to be larger. We readjusted the hole size and we were ready to go.
After we had a model that we were satisfied with, we created a drawing out of it and saved it into the DXF file format.
selecting material
We were ready to make our bottle opener cutout!
but before we did we needed to select the thickness of Delrin.
What is Delrin? Delrin is the product name for Polyoxymethylene, otherwise more commonly known as Acetal. It feels like sturdy plastic. Its milky white with about the opacity of curdled milk. Its pretty rigid and it has a low coefficient of friction.
We wanted it to be rigid, but not to thick, or otherwise we would have difficulty crowbarring the lifting end under the cap, in the space between the cap and the bottle.
We ended up using3/8ths Delrin which we thought was the best compromise.
Laser Cutting
What is a laser cutter? Its a machine that precicely directs a powerful, controlled and precise beam of light (laser) that melts, burns, vaporizes away the material that the laser is pointed at. Not all materials are suitable for laser cutters. Those that create toxic fumes when vaporised are not meant for Laser cutters.
We moved the DXF file containing the drawing for our bottle opener, and then our tutor helped us setup and laser cut our piece.
Before the machine could be used, the drawing had to be defined in Corel, so that the machine would know how to use its laser.
video of laser cutter cutting our bottle cap opener
Filing
because the material was far too thick to fit in between the cap and the bottle at the lift point, we filed down the lifting edge to fit it underneath the cap.
Testing
it works!
Video of our bottle opener opening bottles!
My teammates uncapped 7 bottle caps on the second day.
Thankfully, we did have a bottle capping device to recap bottles so we didn't have to open new bottles wit each time
we did have some concerns: the edge was sharp.
The bottle opener was 10 cm long by 5 cm wide and was just long enough for me, with my long thumbs to reach around the long end to hold it at stabilization point.
Improvements
Of course, just because we got a working sample, this is not the end. In the future we will be considering aesthetics and cost of production. we are thinking of trying out a thinner Delrin, which Delrin, which is expensive, but would require less filing time. I've already put fillets to smooth out the edges of the bottle opener, and we were considering decorating the bottle opener as an old cell phone. I'm fascinated by the spline feature in solid works, and
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