A polyline and a spline don't fillet, with the fillet tool?

[Giovannino60]

A polyline and a spline don't fillet, with the fillet tool? Thank you

[Cad64]

You can't fillet a spline and a polyline, but if you FLATTEN the spline, it will convert the spline to a polyline and then you can run the Fillet command. But, it depends on how the spline was created. If you drew the spline from left to right or right to left, it will affect whether the Fillet works correctly or not. Also, after you fillet the two polylines and then you run the PEDIT command to Spline the polyline, the curvature of the line will change. So there are some issues related to this procedure.

[lrm]

As noted, the fillet command will not add an arc from a line to a spline.  If your goal is to make a smooth transition from the line to the spline such that the spline is tangent to the line near where they meet you could modify the spline.  This process would not create an arc from the line to the spline but may give acceptable results. 

 

Assume that we have a line (white)  and a spline (red).  The spline was created with fit points as can be seen in the image below.

 

Make a copy of the spline on top of itself (copy [Enter] 0,0,0 [Enter][Enter]).  Change the color of the copy to green.  Also make a copy of the line and place it at the end of the line.

Give the splinedit command and select one of the splines then enter E (Edit vertex) and M (move). Position the first CV (Control Vertex) on the line but away from its original end.  Hit Enter (which should bring you to the next CV if the spline is going in the right direction) and move the second CV onto the line using osnap nearest. Choose a location for the second CV that yields an acceptable curvature.  The results may look something like the following.  If the second CV is on the line (or its extension) the spline will be tangent to the line at its end.

Adjust the location of the first 3 or 4 CVs so that the new spline follows the shape of the old spline except as it forms a radius near the line.

Here's the final result with the old spline (red) still present so you can compare the before and after splines.

Note, if the spline is going in the wrong direction you can use splinedit to reverse it.

[mhupp]

Building on what Cad64 said. the file sizes after you convert splines to polylines can be massive sometimes. I had a file that was cross sections of a step file converting from spline (35mb) to polylines i think it was less than 2mb.

 

;;----------------------------------------------------------------------------;;
;; Converts Spline to Polyline
(defun C:S2P (/ cnt SS)
  (if (setq SS (ssget "X" '((0 . "SPLINE"))))
    (progn
      (foreach e (vl-remove-if 'listp (mapcar 'cadr (ssnamex ss)))
        (vl-cmdf "_.Flatten" e "")
      )
      (prompt (strcat "\n"(itoa (sslength SS)) " Spline(s) Converted"))
    )
    (prompt "\nNo Splines Found in Drawing")
  )  
  (princ)
)