Billet Steel: When a high quality camshaft or low volume production is required, engine builders and camshaft manufacturers choose steel billet.
This is a much more time consuming process, and is generally more expensive than other methods. CNC lathes, CNC milling machines, and CNC camshaft grinders will be used during production.
An alternative used in the early days of OHC engines was to drive the camshaft(s) via a vertical shaft with bevel gears at each end.
This system was, for example, used on the pre-World War I Peugeot and Mercedes Grand Prix cars.
Fibre gears have a short life span and must be replaced regularly, much like a timing belt.
In a four-stroke engine, the valves are opened only half as often; thus, two full rotations of the crankshaft occur for each rotation of the camshaft.
The timing of the camshaft can be advanced to produce better low RPM torque, or retarded for better high RPM power.
The cam lobes force the valves open by pressing on the valve, or on some intermediate mechanism, as they rotate.
Camshafts can be made out of several types of material.