Designing parts together
Model a whole mechanism in one studio so mating parts stay mated when one of them changes.
By the end you can
- Model several parts in one Part Studio and keep them deliberately related
- Trace a dependency from one part to another and predict what a change will do
- Decide what belongs in the same studio and what does not
On this page · 3 sections
This is the idea that makes Onshape worth learning properly, and it is the one most teams skip.
Design in context, not in isolation
Two plates hold a shaft. In a file-per-part workflow you model plate A, write down where the bore is, open plate B, and type the same number. The two are related only by your memory.
In one Part Studio you sketch the bore once and both plates use it. Move the shaft and both bores follow, because they were never two separate decisions.
The master sketch pattern
Put the geometry that defines the mechanism — shaft centres, plate spacing, the envelope it must fit in — into a single sketch, and build every part from it. That sketch becomes the one place the mechanism's layout lives, and changing it changes the whole mechanism coherently.
Dependencies cut both ways
Relating parts is powerful and it is not free. A dependency means a change propagates — which is the point, and also the risk. A studio where everything depends on everything becomes one where no change is safe.
The test for whether two parts belong together
Ask: if this part changes, must that one change too? If yes, same studio. If it is merely convenient, separate studios and let the assembly relate them.
Good groupings for an FTC robot:
- One studio per mechanism — intake, lift, drivetrain each get their own.
- Shared hardware in its own studio — standoffs and spacers used everywhere depend on nothing.
- Purchased parts imported, never modelled — a goBILDA motor is a fixed reference, not something your design drives.
The whole-robot-in-one-studio trap
It is tempting, and it works until about the third mechanism. Then every rebuild takes thirty seconds, one broken sketch fails features in unrelated subsystems, and two people can no longer work at once without colliding.
Check yourself
Your intake side plates and the robot's main drivetrain rails are both aluminium and both bolt to the chassis. Should they live in the same Part Studio?
Next
Parts exist. Time to put them together and make them move.
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