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In this lesson we are going to learn how to clean up our geometry. We are going to look at the Trim and Extend commands. Trim and Extend help us correct our line work after we have made changes. On my screen I have some simple geometry. Let's say I'd like to remove this line work on the inside of this small circle. To do that, I will launch the Trim command. Trim is located in the Modify panel of the Ribbon. The icon is right here. Now that I have launched the tool, take a look at the command line. AutoCAD is asking me to select a cutting edge. When we use the Trim command, we are essentially using one object to cut another.
So I am going to select this circle as my cutting edge and then I will right-click. Then I will click the objects I'd like to Trim, and when I am finished, I will hit my Esc key. Notice AutoCAD trimmed those entities back to meet that cutting edge. Let's take a look at the exact opposite situation. Maybe I have had a design change. I am going to select this circle and then I will come over to my Property Changer, and I will change its radius to 5. I will hit Enter, and then I will move outside the palette and I will hit Esc to deselect the circle. Now, instead of my lines being too long, they are too short.
I would like to project my lines to meet this circle. To do that, I will use the Extend command. Extend is also located in the Modify panel. I am going to click this fly-out. Notice that Trim and Extend share the same menu. I will select the command and if we look at the command line again, this time AutoCAD is asking us for a boundary edge. Now, Trim and Extend work the exact same way, except instead of this edge cutting my objects, this edge will be used as the stopping point for my projected geometry.
I am going to select this circle as my boundary edge and I will right-click, and then I will click on each of these entities to project it to meet my boundary edge. When I am finished, I will hit Esc. Now, I'd like to show you a shortcut, because the Trim and the Extend commands are so similar that we can launch one from within the other. Let's pan this over a little bit. On my screen I have some simple line work. Let's see if we can convert this geometry into the shape of the ladder. To do that, I am obviously going to have to extend some of these lines and I will have to trim some of the others.
I am going to start by launching the Extend command since that was the one we used last, and then I will select this edge, and this edge as my boundary edges, and I will right-click. I will then click to extend this entity, and this one, this one, and this one. And instead of getting out of the command and launching Trim to finish this up, take a look at my cursor. If I hold my Shift key, I can toggle to the Trim command. By holding down Shift, the boundary edges become cutting edges. So I can click this entity, this one, I can trim this one, and this one.
When I am finished, I will hit Esc. So by holding down the Shift key, we can easily toggle from one command to the other. Alright! Now that we understand how to use Trim and Extend, let's try it out in a practical example. I am going to pan my drawing over. On my screen, I have a pair of windows. let's see if we can modify this window, such that it looks like the one on the right. First thing I am going to do is create the arched top. To do that, I will use the Circle command and I'd like to create my circle from the Shift+Right-click, mid-point of this line, and the circle dimension, I can get right down here.
the diameter of the circle must be 39. So I am going to right-click to access the Diameter sub-option, and then I will type 39, and hit Enter. Now, I am going to create the circle for this arc on the inside. We can get the dimension right here. I can see the radius of that circle is an inch-and-a-half less than the previous one. So I am going to re-launch the Circle command, I'd like to create my circle from the center of this one, and take a look at the command line. I can see the radius of the previous circle was 19.5.
If I take one-and-half away from that, the radius of this circle must be 18, Enter. Let's zoom-in a little bit. Now, I can start cleaning up my geometry. I am going to launch the Trim command, and I will select this line as my cutting edge, and I will right-click, and I would like to remove the bottom half of these circles, and then I will hit the Esc key. Now, I don't need these little ends out here. So I am going to launch the Trim command again. I will select this arc as my cutting edge and I will right-click and now I will click to remove these ends.
Now, before I exit the command, I am going to hold down my Shift key, and then I will click each of these lines to project them up to meet that edge. Now that I am finished, I will hit Esc. Okay, the only thing I have left to do is remove a whole bunch of little tiny pieces. Once again, I will launch the Trim command, and instead of selecting a whole bunch of cutting edges, take a look at my cursor. I can either select objects or if I hit Enter, everything in this drawing becomes a cutting edge. Now, it's very easy. I can just come around here and click all the pieces that I'd like to remove and when I am finished, I will hit Esc.
As you can see the Trim and Extend commands have essentially the same workflow, jumping from one to the other is as simple as pressing your Shift key. Knowing how to use both of these commands will allow you to quickly and accurately clean up your geometry.
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