Discover the art of creating window symbols using polygons in CAD software. Understand the difference between inscribed and circumscribed polygons to draw precise symbols.
Key Insights
- The article provides a step-by-step explanation of creating a window symbol using polygons in CAD, focusing on hexagons inscribed in a 1 1/4 inch diameter circle.
- It highlights the importance of understanding the distinction between inscribed and circumscribed polygons. An inscribed polygon is located inside a circle, whereas a circumscribed polygon surrounds the circumference of a circle.
- Correctly using the polygon tool in CAD requires some elementary mathematical understanding, such as knowing that a diameter is twice the size of a radius, as these values are necessary when specifying the size of the polygon.
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In this video we will talk about polygons while we work on the window symbol. So let's go File, New, choose our template.
Let's go File, Save. This will be called window-symbol and I'll save and I will go to Layer Properties, make my new layer, A-SIMS, change my color to 120, Enter to lock it in, and double-click to activate my layer. Let's close Layer Properties and Control-S to save.
If we check our handout, we can see that our window symbol is a hexagon, which is a six-sided polygon, and it is inscribed in a 1 1⁄4 inch diameter. In order to understand what that means, I'm going to first draw a circle at 1 1⁄4 inch and then we can use the polygon tool to understand what inscribed or circumscribed mean. So to begin, let's draw this circle together.
Let's go up to Circle. I'm going to choose 0, 0 for my center point, Enter to lock it in, D, Enter to choose diameter, and I will go 1 over 4, Enter. Let's zoom extents, roll out just a little bit, and Control-S to save.
Remember, what we're seeing is a quarter inch diameter circle. Now, in order to find the polygon tool, we will need to go into the flyout for the rectangle tool. After all, a rectangle is a form of polygon where the top and bottom edges are parallel and the left and right edges are parallel.
The polygon tool creates a regular polygon where all of the sides are equal and all of the end points of those sides align on a circle. Let's start using the polygon tool to learn a little more. So I'll choose polygon, Enter the number of sides is the first question asked on our command prompt, so I will do 6, Enter, and now it says specify the center.
This is 0, 0, so I can type 0, 0, Enter, and now it is asking for inscribed or circumscribed. If we choose inscribed, we can hit I, Enter, and now we can see our polygon beginning to be drawn. In this case, we can see that it is important to point the cursor in the right direction.
Checking the handout, I see that my hexagon is organized in this direction, so I will find my zero degree polar direction, and by checking the command prompt, I see that it says specify radius. Now, we did this on purpose. It is not possible to specify a diameter for a polygon.
In this case, we have to do a little bit of mental math, and this will happen pretty often when you're working in CAD. A diameter is twice the size of a radius, and 1 quarter inch is twice the size of 1 eighth inch, so in this case, I will type 1 over 8, Enter. That is my inscribed polygon.
Let's do it one more time circumscribed. I'm going to leave the geometry on my screen. Let's go back to the polygon tool.
Number of sides is 6, and notice it's in the greater than, lesser than symbols. That means use this as a suggested option. If I want to use 6 again, all I have to do is hit ENTER.
The center of this polygon is 0 comma 0, Enter, and this time, let's do C for circumscribed, Enter. Now, in this case, if I wanted to draw this polygon at the same angle, I cannot use the 0 degree. Instead, I need to find 90 or 270 degrees to show that distance.
Now, I will do 1 over 8, Enter, and we can see that the circumscribed polygon is much larger. This is because the distance in circumscribed polygons is represented by the distance from the center of the circle to the midpoint of the line, while an inscribed polygon is the center of the circle to the endpoint of the line. A circumscribed polygon will go around the circumference of a circle.
An inscribed polygon will be inside of the circle, and that's why I had the circle here for the example. Because the handout asks for an inscribed polygon, we can choose the circle and the circumscribed polygon, which will be larger, and I can use the Delete key to delete both of those geometries. Let's zoom extents and CTRL S to save.
Once again, we will add in our attributes towards the end of the course.
