Geometry Pattern

Let’s start off with making a simple box. Make a rectangular sketch on Front Plane and extrude it to 50 mm.

Create another rectangular sketch on the top face of the box. Use it to perform an Extruded Cut offset by 5 mm from the bottom face of the box.  

Finish off with a Linear Pattern of the Extruded Cut. Make 8 instances of the feature along the length of the box. Set spacing at 10 mm.  

Easy enough. Now let’s run diagnostics on this part to check the rebuild times. Select Tools->Feature Statistics. A window will pop up listing the rebuild times for each feature. At this point Linear Pattern is taking 61% of the time to rebuild the model.  

We can reduce this in just a few mouse clicks by simply editing the Linear Pattern feature and ticking the box where it says “Geometry Pattern” under the “Options” tab.

Accept changes and run Feature Statistics once again.

Nothing has changed geometrically yet rebuild time is now reduced by 20 milliseconds. Although not a massive improvement in this simple case, such a change would significantly cut the rebuild times for complex geometry.

So what’s the catch? – Geometry pattern reduces calculations by simply copying the geometry of the seed part. Having that option disabled would pass on all of the seed feature references and relations to pattern instances.

The part below was made exactly the same way as the first one except the bottom face is now curved. Note how surface offset relation is retained for the pattern instances in the first case. This is all lost when Geometry Pattern is enabled.  

Second case is faster to rebuild however does not meet the design intent.