How to make an arc meet another curve perpendicular


I am trying to make Arc1 meet the Circle (or could be any type of curve) perpendicular, but I can´t figure out how to do that. Any suggestions?


The center of the Arc would be on a line tangent tot he circle where the arc touches it.
Also a line tangent to the end of the arc would pass through the center of your circle.

If you know the arc radius you want, you have everything you need to position the arc.

1 Like

Well, there is my problem. I don´t know the radius of my arc. In the problem shown in the picture, I know my outer and inner diameter and the angle. The arc radius however is unknown.

So what specifically is the problem you’re trying to solve?

Well… kind of a kludgy workaround, until I or someone much smarter actually figures out a proper solution:

ArcBlendWorkaround.3dm (49.4 KB)

Set up your angled line and a radius line and set up an ArcBlend between the two with History. Then rotate the end of the radius around until CurvatureGraph on the blend shows a constant radius. You can get pretty close that way.

Measure the radius and make a new arc…


I am trying to create the geometry in the previous post. I have an outer diameter of 10, and inner diameter of 7, and an angle of 30 degrees.

Thank you for the suggestion. I could perform an iterative procedure like this, however I prefer a more precise method since I will be making several different variations of the geometry.


Circle TTR should do it, with the points option.


1 Like

Brilliant, This is perfect!