Post by ND Engineering and Maintenance Services (Pty) Ltd

With a component like the RDA, accuracy isn't just about tight tolerances on paper. It's about understanding what happens to a welded structure the moment you start machining it.​ ​ Every weld and its heat-affected zone carries residual stress. When you remove material during machining, those stresses redistribute, and the part begins to move. If you haven't left sufficient material in the right orientation before you start, there's nothing the machinist can do to recover it.​ ​ This is one of the more nuanced challenges in fabricating welded components: allowing for the movement that's already built into the material, before the cutting begins.​ ​ The right approach involves: ​ — Leaving adequate green material before machining ​ — Orienting the component correctly for stability during and after cutting ​ — Performing detailed dimensional inspections before final machining, so the machinist can reset the workpiece and still achieve the final dimensions.​ ​ This is particularly critical on longer components, where even small cumulative deviations become significant.​ ​ This is one stage in the RDA fabrication process. We'll continue sharing the machining, assembly, and inspection stages as the build progresses.​