Curves from beginning to endPresentation Transcript
Curves from Beginning to End Mark Biasotti SolidWorks Corporation Product Definition – New Concepts January 22 nd 2008
2D sketch vs. 3D sketch
Current curve types in SW
The basics of the 2D sketch spline
The basics of the 3D sketch spline
Using Relationships with 2D sketch spline
Using Relationships with 3D sketch spline
Using 2D and 3D splines in Surface construction
Splines: Can live with them, can live without them! What are they good for and why do we use them?
Splines: Can live with them, can live without them My Goal: By the end of this presentation I hope to transform your feelings about splines from this… To This
Why use Splines? When shape can not be described by line, arc, ellipse etc. (or it takes many of them in series to accomplish) Series of arcs Single Spline
Why use Splines? Single Spline results in smoother overall edge verses series of arcs. Series of arcs Single Spline C1 C2
Why are splines so important to consumer product design?
Many products, although they look prismatic, are not.
Explanation of C0 thru C3
Surface matching conditions explained
C0 Condition – Surface boundaries share Common edge but no tangency C1 Condition – Surface boundaries share Common edge with tangency but rate of curvature does not match at boundary C2 Condition – Surface boundaries share Common edge with curvature matching C3 Condition – Surface boundaries share Common edge with curvature matching to greater degree than C2
2D verses 3D Sketch 4 degrees of freedom vs. Six Degrees of freedom
Types of Curves in SolidWorks
2D Sketch Spline
2 sketch Projection – 3D Curve via 2ea. 2D sketches
3D sketch spline
Spline on Surface (SOS)
Curve thru XYZ/reference points
Convert and offset entities – composite curves
Fit Spline: using analytical (arcs, lines, splines etc.) and fitting a spline over it
Curve by intersection (of two surfaces)
Helix and Parabola
The 2D spline Curvature Comb (Show Curvature) point of inflection Control Polygon Handle Spline point handle widgets Shadow Spline position
The 2D spline Spline point Asymmetrical Tangent Magnitude Vector Angle Widget Combined Asymmetrical Vector + Tangent
Spline Tip – Hold down <Alt> key when dragging Vector/Tangency Widget to get symmetrical control.
The 2D spline PropertyManager checked
Spline Tip – When using Control Polygon, use Relax Spline when continuing to edit spline via spline points and make sure Tangent driving is off.
un-checked C3 Continuity possible* when 2 point spline with equal curvature Current spline point’s values Reset current or all spline handles Relax (Re-parameterize – i.e. smooth) the spline Allows for Spline end points to be dragged while maintaining previous tangency keeps all points porportional to each other (will illustrate later)
Lets review with a SolidWorks example
Creating and re-shaping splines
Asymmetrical control of spline handles
Example of using Spline control widgets for tracing complex shape objects.