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Have you ever experienced a time when you had difficulty joining two entities together? Well, joining multiple objects into a single polyline can sometimes be a frustrating experience. It seems that AutoCAD is not very forgiving if your geometry doesn't meet exactly end to end. In this lesson we are going to look at some strategies to use to help us join together almost any geometry. On my screen, I have a drawing of a large wooded lot. To the east of the property, I have an existing 10 foot wide bike path. I have also designed the centerline for a proposed bike path that will run through this lot.
Currently my centerline geometry is made up of Polyline segments. I've got some lines and some marks. I would like to join all of this linework together into a single Polyline such that I can offset it to either side to define the edges of my bike path. The first thing I am going to do is turn off my tree layer so that this geometry isn't in the way. I'll do that by clicking the Layer Off icon and will select one of my trees, and I will press Escape. Now a good practice says before I join the stuff together, I should select the first entity and then force this to be a color.
I am going to select Magenta, and I will press Escape. This way, if there's a problem joining things together, the problem will be easy to find, because it will be located wherever this color stops. Now I am going to open the Modify panel and launch the PEDIT command. I will then select my first object and press Enter to turn this into a Polyline, I will select Join and then I will window all of my centerline geometry, and press Enter.
Then I will press Escape. As you can see, AutoCAD joined everything up to here. Let's zoom in and it appears I have a problem with my geometry. This line work does not meet end to end. Let's fix this. I am going to zoom out a little. Now if this arc is tangent to this straight segment, I should be able to draw a line from the center of the arc, perpendicular to this segment to find the point of tangency.
Let's zoom in again. It looks like the straight segment is a little bit too long, so I'm going to launch the Trim command. I will grab my line and press Enter and I will trim back this geometry and press Escape. Finally I will erase my straight line and we'll try and join this together again. Now at this point, the first half of the centerline is a Polyline, so I can relaunch the PEDIT command by simply double-clicking this entity.
I'll select Join and I will window the remaining geometry and press Enter and then I will press Escape. Okay, it looks like I have another problem. Let's zoom in and take a closer look at this. Now these entities appear to meet end to end. Let's take a measurement to verify that. I'm going to launch the Distance command and we will find the distance from the end of this line to the end of this one. And AutoCAD is coming up with a distance of 2, which doesn't seem possible unless one of these objects is at an elevation. Let's check that.
I'm going to select the Polyline and then I will move over to the Properties palette and I can see this geometry has an elevation of 0. I will press Escape. I will then select this line segment. I'll go back to the Properties palette and I can see that this geometry has a start and end Z value of 2. So in both cases, I'm going to set this to 0 to flatten that line out.
And I will press Escape to deselect the entity. Okay, let's zoom out and we will continue joining. And we will double-click my Polyline, select Join, and I will window the remaining geometry. I will press Enter and Escape. Okay. It looks like I have another problem right here. Let's zoom in and take a look. Once again this geometry appears to meet end to end. I am going to take a measurement to be sure. I will find the distance from the endpoint here to the endpoint here.
Now in this case, the distance is 0, so in fact this geometry does meet end to end. Now why won't these join? Well, this object is a Polyline. Maybe this point isn't the endpoint of the Polyline. Let's find out. I am going to zoom out, I will double- click this Polyline to launch the PEDIT command, and I will select Edit Vertex. And when I do, AutoCAD is going to display a small X at the endpoint of the Polyline.
Notice where the X is located. I am going to select Move and I will move this point over here and then I will press Escape. So, these objects wouldn't join, because I was trying to join an end point to a corner. I am going to launch the Trim command. I will select my Polyline and press Enter. And I will trim off this end of the Polyline and I will press Escape. I will then zoom out and we will continue joining. I will double-click the Polyline and launch Join.
And I'll window the remaining geometry and press Enter. Then I will press Escape. All right, this looks good. The centerline of my proposed bike path is now a single Polyline. I'm going to select this and I will change its color property back to ByLayer. And I will press Escape. Now, all we have to do is offset this geometry to either side to define the edges of the bike path. I will launch the Offset command. My distance is going to be 5 and I will press Enter. I will then offset my centerline to this side.
I will zoom in and select it again and I will offset it to this side. When I am finished, I will press Escape. Finally, I will select each of these edges. I will place them on the proposed edge of Pavement layer and I will press Escape. Let's double-click the scroll wheel to do a Zoom Extents. And I'm going to click Layer Previous to bring back the trees. When it comes right down to it, if you have geometry that won't join together, there's always a good reason. You just have to find it.
If you check the accuracy of your line work, verify the elevations and ensure you're working with end points, you should be able to join together any line work in your drawing.
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