Get the Right Offset Gap in AutoCAD

27 Oct, 2014

When offsetting a polyline to the outside, AutoCAD has three different techniques it can use to deliver the perfect offset. This video from Cadalyst and Lynn Allen explains the three different settings of the OFFSETGAPTYPE variable. With Lynn’s guidance, you can be sure you'll get the exact offset you are after!

Video Transcript

Hello there, this is Lynn Allen, coming to you with another AutoCAD tip, courtesy of Cadalyst magazine. Thank you so much for joining me. Today I'm coming to you from Dublin, very excited about attending the Revit Technology conference this week. But back to you.

Today we are going to be talking about a system variable that is very important if you do a lot of offsets. I'm sure many of you do. The system variable is called the OFFSETGAPTYPE. I know, easy for you to say -- OFFSETGAPTYPE. Let's start off by just doing a simple offset on this closed polyline. So I already have a distance set -- and I'm going to select this object to offset. Love this preview, right? So if I come to the outside, in order to offset that, AutoCAD is going to extend the polylines where it needs to get it to meet, to do that offset. Okay? OFFSETGAPTYPE right now is set to zero, and it will simply extend those polylines to get the desired offset.

Let's see what happens if we change the OFFSETGAPTYPE system variable to 1. I know you can hardly wait. Let's see -- OFFSETGAPTYPE, let's set it to 1. Let's try that again. Erase that last one that I did. Let's go back into Offset, and I'll only use one character that time. I'm going to select this. Look at that! Can you see that? When I offset it to the outside, it puts a fillet in on those corners. Rumor has it that the radius of that fillet is equal to the same value as the offset distance. Pretty crazy. If you have OFFSETGAPTYPE set to 1 because we know that it starts at zero, then it's going to fillet that particular situation, those corners. Let's undo that.

Let's see what happens if we set OFFSETGAPTYPE to 2. Oh my goodness, what's going to happen now? Let's go back into the Offset command. We have a setting for the distance. I'm going to select my closed polyline, and -- if you move it to the inside, you aren't going to notice anything because it doesn't have to do anything complicated, but if I move it to the outside, can you see that in this case, it chamfered the angles up there, those lines that extend have champfers now.

So if you set OFFSETGAPTYPE to zero, it just simply extends it and does the offset that most of us expect. If you set it to 1, it's going to add a fillet radius in equal to the distance that you have for the offset. If you set it to 2, it's going to champfer it. Crazy! So the setting that you have for OFFSETGAPTYPE makes a big difference.

So, I hope that you will take that into consideration the next time that you go into the Offset command. I hope you have a great week, and I'll see you back here in two more weeks. Thank you for joining me.

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