Error Message meaning and rectification

I keep on getting an error message “Niumber of segments is too large for a given angle and radius”. I am using one of the arc tools, trying to draw a small arc. What does the error message mean, and what do I have to do to rectify what I am doing to 1 - get rid of the message, and 2 -draw a small arc.

It means that the number of segments selected to create the arc is too large and if it allowed you to create the arc, you would have problems down the line. You can avoid the message and get the small arc by reducing the number of sides before you start drawing the arc. Activate the Arc tool and type a new, smaller number in the Measurements window.

You might also consider using the Dave method (do a search for Box’s tutorial) or maybe you could just model at a larger size. When I am modeling for 3D printing I general use Meters for the units and treat either millimeters or inches as meters. If the slicer software will let you specify the units of the imported .stl file, you can leave the model at the meters size. Or if your slicer won’t let you set the units, you can scale the model down after you’ve created it so you can export the .stl.

I tried reducing the number of segments with no luck. I took it to the extreme with 1 segment and still got the same message. In the end, I realized I was working with too small a distance for the arc to fit in. Made it twice as wide, and it finally accepted my arc.
On a related topic, with the arc tool, if the arc turns magenta, it is tangent at both ends. If it is a light blue, does that mean it is tangent on one end only (and if so, what end?).
I am not doing any 3d work here. I am trying to develop a profile to use with the follow-me tool see what a turned box would like with a specific profile. Will look at the Dave method soon!

How small is the arc?

Yes. A cyan arc is tangent only at one end. Generally that will be the first end. It’s usually pretty obvious if you look.

Still, if it’s quite small, working at a larger scale would be beneficial.

Scale your model by a factor of 10 or 100. Then work on the arc or circle. SU doesn’t like really small arcs or circles.
Once you’ve drawn the curve, scale it back up.

Or draw just the arc at 10x then scale it back down. This works for very small objects as well.