Making parts and assemblies, driven by a set of parameters has always fascinated me. The post is an attempt at showing, how we can leverage a set of a few commands / features and make the part easily modifiable by associating these features with the desired, predefined and well-known parameters. The concept applies to assemblies too. However, for the sake of simplicity, I have used part as an example and not used many features to avoid complication and challenges that may arise with explaining the example itself. So, my main focus is on demonstrating the concept and how you may do such a thing. The example itself, that I have demonstrated may not have any practical utility as such, however the concept itself can of course be applied, and is applied to vast range of problems.
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| Beer bottle cap |
When a part is modeled in such a way, that you can modify it quickly, it gives you the chance to test many cases quickly without spending much time on re-designing. However, making a model in this way takes up some forethought and may not always be ideal. So depending on situation, it may or may not be desirable to take this route.
How did I create the bottle cap?
The cap of the glass bottle is manufactured with sheet metal bent into desired shape and pinched around the bottle's mouth. It's my assumption, that the cap functions by creating a seal between the inner side of the cap (which has thin rubber lining) and the top part of the bottle's mouth. The relative movement of the cap is arrested since it's formed into shape around the lip of the bottle's mouth, likely by pinching sheet metal. Since the cap is manufactured with sheet metal, I used the shell command at the end, after solid modeling the geometry as desired.
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| Hockey puck like shape created |
I started with a circle and modeled a hockey puck shape solid by using the Pad command. I approximated the circle diameter to be around 25mm, and pad length was 5mm. Subsequently, equally spaced points were created on the edge of surface using point and planes repetition option to have a set of 36 points on the periphery. These are the points that served as locations for applying variable draft angle, you can also see it below.
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| Applying variable draft using equidistant points |
The draft is applied such that odd points are driven by a draft angle parameter called 'inside angle', while even set of points are driven by another draft angle parameter called 'outside angle'. By varying the values of these angles we can create quite a lot of variations. One of the option can be seen below.
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| Applying draft using different parameters for odd and even set of points. |
The crown like cap is not complete yet, we need to apply the fillet value at the top, subsequently, we can apply shell with the value that we want. This will yield us the cap like shape we desire. Below you can see this cap.
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| Complete bottle cap - Outside angle 0 deg, inside angle -20deg |
Modeling the cap in this way, I can easily modify the design and test many cases. For the sake of simplicity, I have not taken into account the exact geometry required for the bottle cap. However, this you can easily overcome by creating additional features as you desire and applying boolean operations just before shell. Below you can see some of the test cases generated simply by modifying the inner angle and outer angle parameters. All possible value combinations can be tried if needed to create numerous possible solutions.
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| Some of the possible solutions shown along with corresponding values |
