You can use the Autocad Express tool ‘ FLATTEN’ to convert a Spline into a Polyline.Į. Of course we want a polyline – not a spline so we have another process to go through.ĭ. You can offset the original ellipse, delete the original Ellipse and then offset the spline back by the same amount to create a spline version of the Ellipse. If you offset an Ellipse, you get a spline (this makes sense, from a geometry point of view, All points on the curve are no longer equidistant from the Foci). This will instruct Autocad to draw all Ellipses as polyline approximations ( My preferred option).Ĭ. Firstly, you can set the Autocad variable ‘ PELLIPSE’ to 1 (just type ‘PELLIPSE’ at the command line and follow the prompts). Your CNC Programmer may be able to convert AutoCAD ellipses to Polylines using a program such as Alphacam – but if it falls to you to provide an elliptical Polyline then there are a number of simple techniques you can use.ī. However, most CNC machines won’t accept ellipses. The Focus points are where the Arc crosses the Major AxisĮllipses can easily be drawn with AutoCAD’s ‘ ELLIPSE’ Tool. You can find the Focus points of an Ellipse by drawing and Arc equal to the Major radius O to a from the end point of the Minor radius b. Points F1 and F2 are called the Focus points (or Foci). The distance from F1 to PTn to F2 is always equal to the Major diameter a to – a What is an Ellipse?Īn ellipse is the locus of all points of the plane whose distances to two fixed points add to the same constant. That is when these old tips from the drawing board really come in useful.Įdit: I picked up one more technique for spline to polyline conversion from my good buddy Kevin Ellingson of Mechanical – check out the link at the end of the post.
However, sometimes the best method is to redraw the offending geometry yourself. If you are in this situation, there are a few AutoCAD tricks you can use to convert an Ellipse (or any Spline) into Polylines.
We’ve all been in that situation ) Our Boss thinks we can use the Designer’s file as it is, but we know that the CNC machine won’t take the geometry. Sometimes it falls to Us to convert one to another. Unfortunately fabricators like defined geometry.
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