Sphere tangent to 3d curves won't accept a radius input

Rhino
,
1

The picture is the sphere tangent command without a radius value input after selecting the first and second curve, just eyeballing close to the radius I want. However, if I instead input ANY radius value, the command results in nothing, no sphere, no feedback or error. Scratching my head here… Thought of making a sphere with the radius I want separately before moving it tangent to the curves, but couldn’t accomplish that for a workaround. Hope theres an obvious issue with my process and it’s not a bug.

Sphere-tan-tan-radius
Sphere-tan-tan-radius640×480 14.1 KB

Sphere-tan-tan-radius.3dm (39.4 KB)

2

Because your curves are not planar, I think there is no exact answer
For the same reason, with those curves a Circle Tan, Tan, Radius will not give you a result, nor will Fillet work on these curves.

That being said, I think what might help is to take the middle of the intersection curve of two pipes around the curves and draw a sphere at that point, to get you a close enough result

Sphere-tan-tan-radius.3dm (190.0 KB)