Written Feb. 16th, 2017 by Johannis Likos (Mech. Eng. & IT Consultant) [likosjo@yahoo.com]
CoffeeSCAD is one of several free web-based environments for programmatically designed 3D objects. The general purpose of using scripts inside a browser is to visualize the virtually created objects before exporting them as STL files for 3D printing.
The Tested 3D Object As test object we take a nut, a fastener element for mechanical engineering, which consists of concentric cylindrical and conic shapes to be merged, subtracted and intersected in order to get the desired result. All below mentioned shapes should be concentric with common Z-axis. Practically should be executed several grouped steps as follows: 1. create the initial main body by merging a. one conic shape on top b. one cylindrical shape in the middle c. one conic shape upside-down at the bottom 2. merge multiple conic shapes for the inner face of the final object a. every cone in odd order (1st, 3rd, 5th) should be upside-down b. add special cones for the entry/exit area of the bolt 3. extrude a 2D hexagonal shape for the outer face of the final object a. in this example are use pre-calculated coordinates b. alternatively could be used a circle with extra parameter $fn:6 4. do the final inner shape a. subtract the threads from the cylindrical main body 5. do the final outer shape a. intersect the extruded hexagonal shape with the cylindrical main body 6. remove all unused shapes