Internal corner INVERSE chamfers around a tube?

how are INVERSE chamfers created for internal corners around a tube? “help” and all of the YouTube videos I’ve found only show the use of the fillet command on external corners on rectangular solids. see attached image. the internal corner shown in the image is 1/32" high and I’d like to add an “inverse chamfer” completely around the circumference of the tube; image a TIG weld joining the two pieces of tubing.


stepped primary tube.3dm (2.4 MB)

Not sure what you mean by inverse chamfer - is it this?

That was done with the FilletEdge command on the Solid menu. Run the command, set NextRadius a tad smaller than the height of the step (0.025" in this case) and pick the edge within the angle.

If, however, you mean a bead something like this:

Then you need to trim the lower surface back a short distance (extract an isocurve to use for the trim), remove the vertical face, create an arc between the two and use Sweep 2 Rails with the surface edges to create the bead.

As an observation, you may struggle to produce either of the above with your model as a) the construction has somehow resulted in an invalid polysurface, b) the surfaces are unnecessarily complicated and c) because your tolerance is far too tight. I reduced the tolerance to 0.001 and recreated the tubes from simple extrusions and revolves in order to produce the examples shown.

stepped primary tube 002.3dm (3.9 MB)


Maybe this ?

thanks guys for your posts; looks like I should have included a diagram! the included diagram shows what I was attempting to describe. normally I’d simply describe them as internal fillets but Rhino’s nomenclature seems to restrict the use of “fillets” to external corners. part of the subtlety I’m hoping to implement is equal length fillet legs on the inside and the outside of the tube’s bend radius. if not already handled by Rhino, suspect that means a 2 rail sweep with a circle on one side and an ellipse

Pipe command
Select ChainEdges option
Select appropriate edges to use the Rail (centerline for Pipe command)
Radius as desired
Complete command
BooleanDifference to remove unwanted portion of the object just created.

thanks for your post! I don’t see how to get equal length fillets with “pipe’s” center line driven solution. Jeremy’s Sweep 2 Rails approach seems like it will get there; I just don’t know how to create the construction plane (the 3 points isn’t the problem) in Rhino 7 to get the required ellipse.

Artinternal corner bend radius consideration

messy but doable! does Rhino support creating an object on one layer and subsequently copying or moving that object to a different layer in the same file as an independent object?


messy but doable

Hi @artesmith,

After trimming back the tube and removing the end face, use Circle Around Curve on the tube edge to create a circle overlapping the raised section:

Then use PlanarSrf with the circle selected to create a plane perpendicular to the edge:

Then use Intersect to get the intersection between the circular plane and the raised tube:

(You will get a second intersection with the inner surfaces but you can ignore that.)

Use BlendCrv to blend from the intersection line to a point at the centre of the circle:

Delete the temporary plane, circle and intersection curves and sweep the arc around the two edges. If you don’t get a good sweep you may need to create two or three more arcs at intervals around the joint.