A pressure die cast set of parts was first tried. NCR were unable to tolerate draft angles in the side detail so this had to be cast solid and machined in later. The machining uncovered internal defects, typical in pressure die castings, which prevented the units from sliding efficiently. Micro Metalsmiths has provided the ideal combination of strength, finish and economy, using investment castings from multi-impression tooling. No draft angles are required.
All detail is cast, and a further sizing operation gives flatness to close tolerances.