Workaround – Drawing Arcs To Length

A CAD-a-Blog reader sent me this e-mail asking how to draw an arc to a particular length. Here is Saqib’s question:

“If we have a curve or arc, we know its length and radius. If we want to divide or mark some points on given length so what is way of it. One way to do this use "DIVIDE" command then enter how many parts you need. But what I want is that we don’t need exact parts like 10,20,23,50 etc. How can I divide arc into desire length like 12.33,44.77,20.83 like so on.”

These tow methods are how I do it. If anyone has a different method of doing this please e-mail me or comment to this post.

Method one:

Use the ARC, Center, Start, Length command. You can find it in the DRAW, ARC pulldown menu. Or start the ARC command, select the CENTER option (type in C at the prompt-then press enter), select the arc’s center point, then select your starting point, and finally type in the desired length. You have just drawn an arc of a known center point and radius to a specific length. Keep in mind that AutoCAD defaults the direction of an arc as going counter clockwise. That means that when you select your starting point that the arc will be drawn from that point and extend out in a clockwise manner. If I start at the top of the arc, then it will be drawn to the left of that point. If I start at the bottom of a circle, then my arc will start at the bottom and go to the right.

Method Two:

Use the lengthen command to change the length of an arc. Start the LENGTHEN command (type in LENGTHEN). Choose the TOTAL option (type in T). Now you have the choice to change the arc to a certain angle (or delta) or to a certain length. Type in the length desired and select the arc (you can select multiple arcs if you want to). Make sure that you know which end is your starting point. In this case, the starting point will be the first end point drawn.

I hope this helps. Happy CADDING.