Curves from Beginning to End

Mark BiasottiSolidWorks CorporationProduct Definition – New ConceptsJanuary 22nd 2008

Outline

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

C0 Condition – Surface boundaries shareCommon edge but no tangencyC1 Condition – Surface boundaries shareCommon edge with tangency but rate of curvature does not match at boundary

C2 Condition – Surface boundaries shareCommon edge with curvature matchingC3 Condition – Surface boundaries shareCommon edge with curvature matching to greater degree than C2

Surface matching conditions explained

2D verses 3D Sketch

4 degrees of freedom vs. Six Degrees of freedom

Types of Curves in SolidWorks

2D Sketch Spline

Projected Curves

2 sketch Projection – 3D Curve via 2ea. 2D sketches

3D sketch spline

Spline on Surface (SOS)

Curve thru XYZ/reference points

Face Curves

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.

Asymmetrical Tangent Magnitude Widget

Vector Angle Widget

Vector + Tangent MagnitudeTo pull asymmetrically

Degree raising

You can make a C3 spline with the following requirements:– 2 point spline only

– C= relationships on both ends

Standard Degree Raising

Applying a Face Tangency Constraint

*Play Video to show

Using Face Tangency Constraint& Equal Curvature

Using the Proportional Option

3D curve by 2ea. – 2D sketch spline curves

Curve thru X,Y,Z Points

Curve thru Reference Points

Face Curves

Curve by intersection of surfaces (or planes)

Fit Spline Function

Higher Tolerance

SolidWorks Tip: Which is more smooth – the lower or higher tolerance?

Convert, Offset & Composite Curves

In the 2D sketch – “Convert Entities” and “Offset

Entities” Allows user to copy or offset external (outside the

sketch) model edges

In the 3D sketch – “Convert Entities” Allows user to copy external model edges

Outside the sketcher – “Composite Curve” Allows the user to gather model edges into one

single curve entity

Helix Curves

Built from single 2D sketch circle. Can control: Pitch Variable Pitch No. of Revolutions Can make tapered

Application of 2D Sketch Spline “Bridge Spline”

Getting around problem with constraining to projected curve

Play Video to show

Initial over constraint

3D Sketches – how do they work?

Editing 3D sketch splines in 3D space

Getting around in 3D space

When creating multiple point 3D sketch splines two helps to controlling them are:– The Sketch Triad

– Multiple windows

Using curves in Surface features

Curves in surfacing, can affect and correct flow of surface

3 Curves in 2nd direction 4 Curves in 2nd direction

22

3

43

11

Play Video to show*

Using reference surfaces with 3D Sketch

Using curves in Surface features

Reference surface example

Boundary SurfaceFill Surface

Reference Surface

Reference Surface

Using curves in Surface features

Fill Surface with Curve Example

3D sketch splines and surfaces

Andy and I will now take your questions