Hi Alice,
Welcome to the forum. I understand you want to produce something like this:
That approximates the red helical form:
Create a new layer to hold construction lines and select it. Working in the Right viewport, start by placing a point at the centre of the helix. Draw circles around the point and passing through the inner and outer edges of the helix, and one midway between them.
Draw a line from the centre and passing through the mid point of the lower end of the helix. Create a polar array of 24 lines around the centre, starting from that line and subtending an angle ending at the mid point of the upper end of the spiral. Bisect the first and last pairs of lines, giving you this:
Draw vertical lines from where the bisectors intersect the middle circle:
Then get the intersections of those lines with the top face of the helix:
Delete the vertical lines. Draw lines perpendicular to the first bisector to delineate where you want the inner and outer faces of the facet to fall. I’ve chose to place them where they just fully encompass the red helix, but you may have different criteria. They need to extend well past the radiating lines:
Now reintroduce the red helix and draw a line normal to the upper surface, starting from the marked intersection point:
Using Circle Around Curve, draw a circle around the normal line, centred on the marked intersection and large enough to encompass the facet boundary with space to spare:
Extrude that downward along the normal line by the thickness you want for your facet. I used 16mm, per your layer name. This gives you a solid disc. In the Right viewport, use Wirecut with the two radial lines and the inner and outer face lines to split the disc and delete the unwanted sections, leaving the first facet:
Select the two marked intersection points only, then use the boxedit panel to determine the x-dimension size (i.e. the distance between them parallel to the helical axis). Divide that distance by 22 to get the offset between facets. Create a polar array of 23 facets about the centre point, setting the ZOffset option to the calculated value and using the ends of the bisector lines as the reference points for the angle to fill, giving you a full set of facets, as shown above.
Because we have used wirecut to trim our facet perpendicular to the viewport, the chamfered faces are already there. If you plan to build this, you need to think about designing some additional pieces to hold the facets precisely in place during glue up.
HelixPlanarFacetsHelp 001.3dm (895.3 KB)
HTH
Jeremy
