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Unfortunately, the "Edit/Trim-Extend/Fillet Edge" function won't work on complex edges like this. So I had to use some other method to "fillet" the edges. I had to create a series of arcs along the edges of the solid that could be used as template curves for the "Draw/Surface Connect" function. This is easier said than done.

First I traced the edges of the work solid. You can see these blue curves in "surface lines 2.jpg. I used the "Draw/Tickmark" function to generate many evenly spaced marks along each curve. Then I created a circular plane with a 0.25" radius and set two handles, one at the center and the second at a point on a line passing through the center and perpendicular to the plane.

I copied the circular plane at each tickmark, with the center handle on the edge curve at a tickmark and the second handle on the curve at the next tickmark. This placed the circular plane copies about perpendicular to the curve at each point (close enough for modeling government work). Then I used "Draw/Lines/Surface Intersection" to generate lines 0.25" long on the surface of the work solid that intersected at the blue curve. You can see these in the "surface lines 2.jpg" image.

Next I created arcs with a 0.25" radius that were tangent to these intersecting lines. Unfortunately, DesignCAD doesn't have an "Arc Tangent to 2 Lines" function. To create the arcs I used "Draw/Circles/Circle Tangent to 2 Lines) to create circles tangent to the pairs of lines. Then I used "Draw/Lines/Perpendicular to a Line" to create perpendiculars from each circle center to the two tangent lines. Then I used "Draw/Arcs/Arc (center, begin, end)" to draw an arc with the center at the center of the circle and ends at the ends of the perpendiculars. After creating about 230 arcs this way I deleted all of the 500+ circles and perpendiculars. The resulting (red) arcs can be seen in "surface lines 3.jpg."

I cleaned up the intersections where the curved edges come together by generating template lines common to both surfaces. I used these arcs as template lines for "Surface Connect" to produce the blue grids shown in the "surface lines 4.jpg" picture.

The two green surfaces between the blue grids and the back plane were easy. I just drew perpendicular lines from the end of each arc closest to the back plane of the cushion. First I drew a large rectangular plane for the back surface. Then I started the "Draw/Lines/Line" (V) function and gravity snapped to the end of the arc. Then I pressed F7 to execute "Point/Plane Snap" to set the second point of the line on the plane. This created a perpendicular from the end of the arc to the back plane. After drawing all of these perpendicular lines I used "Surface Connect" to create the green surfaces. I did have to draw separate polygons at the bottom sides where the blue grids curve around and back to the back surface.

The front red surfaces were drawn one polygon at a time. Each of the three and four sided polygons was hand drawn with the "Draw/Planes/Plane" (P) function. Then the back plane for the cushion was drawn with the plane function. This completed all of the surfaces. All template lines and arcs were then moved to a separate junk layer for safe keeping in case I screwed something up and had to try again.

I should say that I had to experiment a bit with the hand drawn polygons (red) on the vertical surface. If you put too many triangles together with a single common apex point - fan shaped - they don't render very well, and each polygon is visible in a different shade of gray when rendered. By alternating three and four sided polygons I got a better result, but you can still see some unevenness in the shaded surface.

All panes and grids were selected and then combined into a single solid with "Solids/Solid Define." The result can be seen in "surface shape 3.jpg." This is a lot smoother than the first attempt. After several days of drawing hundreds of template lines/arcs and circles and a few dozen grids I had the result I wanted.

CONTINUED IN NEXT POST

Phil

Phil