Modelisation recommendations

A few recommendation when using CAD -> convert program(ex:stl2dat) to modelise parts:

The tesselation parameter should be set so that a regular cylinder is output with 16 facets. In Solidworks, this is done by setting the minimum angle to 22.5 deg and by setting the maximum deviation to a high value. It is difficult to set this option in interactive dialog, so the best is to use the following files :
stl2000.reg file (Solidworks 2000)
stl99.reg file (Solidworks 99)
stl98.reg (Solidworks 98+ or before)
Create only partial cylinders that are multiple of 22.5 deg. When this is not possible, modify the design to replace portion of the cylinder by line segments.

Example:


Part with a cylinder not multiple of 22.5°	Part modified to use a cylinder of 90°

Resulting tessalation. Notice the odd number of facets of the cylinder.	Resulting tessalation. The cylinder can be modelised with a standard primitive.

	Sketch of the part

Sometimes, when the cylinder intersects with another surface, the tessalation is not well done by the CAD program. To avoid that, use a polygon instead of a cylinder.


Intersection of two cylinders.	Cylinder made with polygons instead of circles.

Resulting tessalation. Notice the number of unwanted triangles.	Resulting tessalation. The facets defining the cylinder are exactly matching the polygons.

	Sketch of a polygone