General Build Startegies

  • try and keep features for a form close together in the model tree – use the insert arrow
  • combine datum points where possible – better organised and creates a more concise model tree
  • planar curves should default to sketches not curve thru’ points
  • don’t build surfaces in their final form if overbuilding and trimming is more appropriate
  • extrude/surface/cut is generally the simplest method for trimming
  • manage your symmetry appropriately

 

Golden Rule 1: Curves forming the surface corners must be connected.  Internal curves must be connected if they cross.

Golden Rule 2: 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 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  – 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.

Ctrl 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 Ctrl key and hold the Shift key
  • select the segments you need for the chain.  Remember you can RMB toggle to work through the selectable segments
  • return to the Ctrl key to select the next curve in that direction

Curve end handles – the RMB 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

enlarge image

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.