Davenport Model B

The Davenport Model B uses a single main camshaft that rotates once per part cycle. Cams machined on this shaft control: (1) the 5 cross-slides (one per station); (2) the end working (back working) unit; and (3) the spindle carrier indexing. As the camshaft rotates, the cam profiles push and retract each cross-slide at programmed positions and rates. The spindle carrier indexes at the end of each cam rotation, advancing all 5 spindles simultaneously to the next station. Cycle time is determined by how fast the camshaft rotates - faster rotation enables shorter cycle times but requires all operations to complete within the faster cycle. Programming a new part requires machining new cam profiles to match the required feed rates, dwell positions, and operation sequence - this is the cam design and cutting process.

The Davenport CNC replaces the mechanical cam cross-slides with CNC servo axes, while retaining the mechanical spindle drive and indexing system. In the CNC version: cross-slide movements are programmed via G-code rather than cam profiles, dramatically reducing changeover time from 8-24 hours to 1-4 hours for a new part. Complex part geometries (tapers, radii, multiple diameter cuts) are programmed easily rather than requiring complex cam design. The mechanical spindle drive retains the Model B speed advantage for cycle time. Shops converting from mechanical to CNC Davenport can often maintain the same tooling and setters, reducing retraining. The CNC upgrade is applied to new machines or as a retrofit to existing Model B machines.

Best economic fit for the Model B: (1) Simple turned parts with 1-3 diameters in 6-25 mm bar at 500,000+ pieces/year (machine screws, shoulder bolts, pivot pins); (2) Hexagonal and square head hardware in brass and low-carbon steel (connectors, standoffs, threaded inserts); (3) Small knobs, bushings, and spacers with minimal profile complexity; (4) High-volume brass electronics hardware (terminals, contacts, spacers in 4-15 mm). Less suitable: complex parts requiring multiple drill angles, back operations on 3+ surfaces, or tight tolerances below 0.025 mm (0.001 in) which are better handled by CNC Swiss or CNC multi-spindle.

Davenport setters (the skilled operators who design and cut cams and set up machines) are an increasingly scarce specialty. The peak Davenport workforce trained in the 1960s-1980s; current setters are typically 50-70 years old with limited new workforce entering the craft. Finding experienced setters is the single largest challenge for new Davenport operators. Tooling: Davenport tooling (holders, collets, tool bodies) is actively manufactured by Davenport Machine and by third-party suppliers (Leland Gifford, Elgin National). Cams are machined to order by Davenport or by specialty cam cutting shops. The secondary market for Davenport machines, cams, and tooling is active nationally through machinery dealers.

For a simple 4-diameter turned part in 10 mm brass at 1,000,000 pieces/year: Davenport Model B at 3,600 parts/hour (1-second cycle) needs 280 machine-hours per million parts. CNC Swiss lathe at 240 parts/hour (15-second cycle per part on a typical 5-operation Swiss) needs 4,167 machine-hours per million parts. Machine cost ratio: Davenport $200K new vs Swiss $250-400K new. At 1M pieces/year, the Davenport provides 15x the throughput of a single Swiss on this part - the economics strongly favor the Davenport at this volume. Below 100,000 pieces/year, the CNC Swiss flexibility for smaller batch quantities and faster setup justifies its higher cost per part vs the Davenport cam setup cost.