The present disclosure provides a method of manufacturing a turbomachinery component for a gas turbine engine, comprising: receiving an ideal design of the turbomachinery component, the turbomachinery component comprising: an aerofoil portion comprising an aerofoil surface and having an ideal aerofoil wall thickness; and a platform portion comprising a platform surface coterminous with the aerofoil surface, the platform portion having an ideal radial platform thickness along a radial direction; determining an intermediate design of the turbomachinery component comprising an intermediate platform portion having an intermediate platform surface and an intermediate radial platform thickness which is greater than the ideal radial platform thickness; forming, by an investment casting process, an intermediate turbomachinery component based on the intermediate design, wherein the intermediate turbomachinery component comprises at least one detectable reference feature formed by an internal core element during the investment casting process; defining a datum system for machining the intermediate turbomachinery component comprising detecting the at least one reference feature and defining a radial datum based on the at least one reference feature; and machining the intermediate turbomachinery component using the datum system to remove material from at least the intermediate platform portion of the intermediate turbomachinery component to create a machined turbomachinery component.