Patterns
Repeat geometry so a bolt pattern stays a bolt pattern when the plate changes size.
By the end you can
- Create linear and circular patterns of features and of whole parts
- Choose between patterning a feature and patterning geometry in the sketch
- Drive a pattern count from the part it belongs to instead of a fixed number
On this page · 4 sections
FTC structure is built on repeating hole patterns. Modelling them one at a time is slow the first time and unmaintainable every time after.
Pattern the feature, not the sketch
You can repeat geometry two ways: copy the circles inside the sketch, or pattern the hole feature itself. Pattern the feature.
A sketch full of copied circles is a sketch with dozens of extra entities to constrain, and no single place to change the count. A feature pattern has one count field and one spacing field.
Patterns of parts, not just features
The pattern tools work on whole parts too. A row of standoffs between two plates is one standoff, patterned — which means changing the standoff length changes all of them.
Make the count follow the part
The most useful habit here: drive the pattern from the thing it belongs to rather than from a number you typed.
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Sketch the first hole and dimension it from the plate edge.
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Pattern it along the plate with the spacing your extrusion actually uses — 8 mm for goBILDA, 0.5 in for older kit systems.
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Set the count using a variable rather than a literal. Onshape variables are declared with
#— for example#holeCount. -
Change the plate length and update the variable. One edit, and the pattern still terminates where it should.
Why not just over-pattern and cut?
Some people pattern far more holes than needed and let the plate boundary trim them. It works, and it is genuinely faster to set up. It also means the model no longer says how many holes there are — so the drawing, the bill of materials, and the person at the drill press all have to count.
Circular patterns
Same idea, different axis. The two FTC cases worth knowing:
- Wheel hubs and sprockets — bolt circles are circular patterns about the bore axis.
- Turret and pivot plates — an arc of holes that lets a mechanism be indexed to several positions.
For both, pattern about an axis derived from the bore, not about the origin. When the bore moves, the pattern should move with it.
Next
Several parts, designed together, in one studio.
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