Four questions a spindle catalogue cannot answer on its own.

A catalogue stiffness value is only actionable when its definition and operating state are known. Central, differential, secant, nominal and maximum stiffness are not interchangeable labels for the same quantity.

The Architecture Screen keeps the coefficient definition explicit and asks where the shaft actually runs: load, clearance, supply state and support condition.

Published capacity is a reference point, not automatically the remaining machine margin. Process load, supply state, unbalance, tolerances and service condition can all change the operating corner.

No universal derating is assumed here. The screening question is whether the selected candidate remains feasible across the actual envelope once those states are defined together.

Shaft temperature, housing temperature, material selection and cooling path can move the operating clearance. The direction and magnitude depend on the actual geometry and thermal state; they cannot be inferred from a room-temperature clearance alone.

Gas-film behaviour is strongly clearance-sensitive, so the thermal state belongs in the same controlled operating-state definition rather than being treated as a separate afterthought.

When the same support architecture carries several load components, separate catalogue values do not automatically mean separate machine budgets. Actual coupling depends on the bearing arrangement, load path and tool or process overhang.

The Architecture Screen therefore resolves the combined machine load path instead of treating axial, radial and moment figures as isolated pass/fail checks.