wave drawing

Hi guys, I have a drawing, see attached where I have to create a wave shaped bench for someone. I have managed to do it using a spline, but they want it as arcs sso that they can send it to a CNC machine for production. Is there a way of computing how to intertwine the arcs smoothly?

Thanks

Dave

Wave bench.dwg

How set are you on exactly the same curve? If you can slightly adjust it, draw a circle that approximates either the left or right curve. Mirror it across the center then draw a circle TAN-TAN-TAN to the 2 circles and the center brace. Trim away and you're good to go.

There are some LISP routines that attempt to convert splines to polylines, you may find some of them referenced in the related threads links below... I tried one of them and the results were not as good as doing it manually.

Good luck

Glen

The way the seat is now, the left and right curves are different than the center and they droop and flatten out toward the ends.

The only way to get smooth tangent points with arcs, without having the seat be at different heights is to use equal radius arc's to begin the construction of the drawing. After you have that result, you can tangent on a couple of smaller arcs at the ends with flatter radii, or lines, then trim to them.

This is the way I began to construct your seat surface using equal arcs.

Divide the seat length by three and mark the thirds by offsetting vertical lines at that distance to get the exact tangent points.

Trace the center curve with a polyline arc.

Mirror that arc upside down and copy/move the mirror image out to the center arc end snaps, over each end curve of the spline.

Join the polyline arcs of the seat surface, then offset the result to the seat underside surface.

Trim/extend the arcs and end lines of the seat.

Erase the splines.

Adjust the height of the support balls on the top spreader rail, and Bob's yer Uncle.

Now the seat height does not quite match the side elevation, so you will have to change that too.

See attached drawing.

Wave bench.dwg