Design & Tech CAD
Reference geometry
Variable Section Sweep
Layers & visibility
Adv. Rounds
Mathematical control
Advanced Patterns
Draft & Split plane Trim
Geometry from 2D graphics
Model analysis
Accuracy
Skeleton based surfacing:
Model Analysis
Section Curvature
Splines
Boundary Blend
Construction and manipulation
Trim, Merge & Solidify
3sided surfaces
Offset Surfaces
Construction and manipulation
Golden Rule No.1: All curves or edges to be used as your surface boundaries must be robustly related to each other at the same level required in your surface boundaries.
Chain selection and trimming
Your surface boundary should consist of four boundary chains. It may then have internal cross curve chains. Each chain could be a single curve/edge or a number of curves/edges chained together.
Selection Techniques.
RMB [right mouse button] - when hovering over an element to pick it you can use the RMB [momentary press, not press and hold] to toggle through all the selectable elements under the cursor. This will also highlight part of a curve.
CRTL key - hold whilst collecting curves in one direction
SHIFT key - if one of the boundaries needs to be a chain of edge/curve elements then:
- select the initial 'anchor' curve/edge
- release the CRTL key and hold the SHIFT key
- hover over the segment you you are working on to see the pop-up hint 'one-by-one' - left click the curve again to change the selection method - keep hold of the shift key.
- select the segments you need for the chain. Remember you can right click to toggle through the selectable segments
- return to the CRTL key to
select the next curve in that direction
This seems a bit awkward when written down but is quite easy and quick once your
used to it.
Curve end handles - The right click menu under the end chain handle allows you to trim the chain length.
Boundary conditions
To set the boundary conditions where two surfaces meet, simply right click the condition marker and choose the appropriate level.
If your boundary uses the curve rather than the edge then you will have to select the surface to which you want to create the relationship.
Remember, a boundary relationship can only be as high as the level of the curves which form that boundary.
Boundary influence
This example looks at the result of using multiple or single patches and the resulting boundary influence
Click the image below to enlarge
The above images show three different constructions - the first two have the bulge constructed using two patches and the third has the bulge constructed as one patch with one internal curve.
Two types of analysis are shown for each method - Gaussian and curvature spines.
In the first two models we have alternate 'leader' [parent] and 'follower' [child] surfaces. The follower surface is constructed to satisfy the curvature continuity condition across the boundary while the leader remains unchanged. You can see a sudden peak in curvature just passed the boundary.
The third model is a single surface with an internal curve. The curvature flows smoothly across the internal curve.
Therefore, create a quilt with as few individual surfaces as possible - the example at the beginning of this page should be created as a single feature.
But.....do not take this too far.
Unlike freeform surfaces, where you will see large quilts with lots of
dramatic changes in surface and boundary direction and curvature, with
ProE you are better splitting your quilts into areas which naturally
group together.
Mesh the surface to make sure the UV lines aren't
'working too hard' - have dramatic changes of direction/curvature.
Leader/follower Workaround
If you have to have a leader follower situation across a boundary and it cause a poor continuity section across the boundary [as in first and second image above] then you might try creating a ribbon surface on the boundary before creating the two surfaces and then using this as the reference for the boundary condition.