Page 313 - Mastering SolidWorks

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PAtterning in A Sketch 285

including the sketch pattern and a single Extrude feature, using the sketch with the pattern to do
an extruded cut. The sample parts are in the download materials for this chapter for reference.
Look for the filenames beginning with Reference1 through Reference7.
The most shocking data here is the difference between a sketch pattern of a hex when a
patterned sketch cuts into a flat plate compared to a feature pattern of a single extruded hex with
each using the Verification on Rebuild option—0.36 seconds compared to 126 seconds.

Table 9.1: Pattern rebuild times in Seconds
Pattern Type Default Geometry Pattern Verification on Rebuild
20 × 20 sketch circle .87 n/a 5.52

20 × 20 sketch square 4.5 n/a 60
20 × 20 sketch hex 9.6 n/a 126
20 × 20 feature circle 0.06 0.53 0.08

20 × 20 feature square 0.23 0.53 0.23
20 × 20 feature hex 0.36 0.55 0.36

NOTE it is true that using a multicontour sketch for the cut is a slow process, but that might not be
because of the pattern. delete the sketch pattern relation, do a ctrl+Q, and check the statistics. in my
test, the results were very close. A big feature (with many resulting faces) will be slow, regardless what
relations are in the sketch, sketch patterns or not.

Always keep this general information about sketch patterns in mind:
◆ Sketch patterns are bad for rebuild speed.
◆ The more faces created by any pattern, the longer it takes to rebuild.

◆ The more sketch relations a sketch pattern has, the longer it takes to rebuild.
◆ Geometry Pattern does not improve rebuild speed unless a special end condition like Up
To Surface has been used.
◆ Verification On Rebuild dramatically increases rebuild time with the number of faces but
is far less affected by feature patterns than extruded sketch patterns.
Figure 9.1 shows one of the parts used for this simple test.
One interesting finding of this test was that if a patterned extruded feature creates a situation
where the end faces of the extruded features have to merge into a single face, the feature could
take 10 times the amount of time to rebuild as a pattern with unmerged end faces. This was an
inadvertent discovery. I’m sure you will make your own discoveries if you investigate rebuild
speeds for end conditions for cuts such as Through All, Up To Face, Up To Next, and so on, as
well as the difference between cuts and boss features. Further, using Instant 3D can be an
impediment when you’re editing very large sketches simply due to the effects of the preview.