In a mass production environment the Plek Pro machine is supplemented by an STS  (String Tension Simulation) module that is capable of simulating the tension of guitar and bass strings, so that the guitar and bass necks can be processed without strings.

With the aid of headstock and body adapters the instrument is placed into the sts adapter cradle. With a computer controlled pneumatic procedure a predefined string tension is produced for each individual neck. The truss rod and guitar neck react as if under normal string tension. An interesting advantage of using the sts is the possibility of just processing guitar necks, i.e. the the body of the instrument is not required.

STS internal type

The internal STS is controlled by the software of the Plek Pro machine and is inserted into the machine in place of the service door. Depending on the chosen guitar / bass model all the relevant process parameters are loaded with a preassigned template, including the required sts air pressure.

STS external type

The external sts is a stand-alone device with an independent numerical control unit. With it the desired neck relief can be obtained by adjusting the truss rod under simulated string tension prior to processing. When working simultaneously with the internal and external sts production-time is optimized.

A typical operation sequence with the Plek Pro/STS

The operator fixes the adapters on the instrument, inserts it into the external sts and activates the string tension simulation via the touchpad. The truss rod is adjusted until the “dial indicator neck relief gauge” shows the desired result. This procedure takes about one minute.

The pre-adjusted guitar is taken out of the external sts and placed into the internal sts. If the saddle is to be cut as well, it should be fixed into a special vice located in the machine. The appropriate template is selected, the parameters in the “Virtual Fret Dress” menu are set and processing starts. Under simulated string tension the frets are cut including all other process functions (nut or saddle cutting, etc.) that have been selected in the template.

While the machine is processing, pre-adjustment and finishing work can be carried out, such as:

  • Taking off the adapters of the processed guitar.
  • Polishing the frets of the processed guitar.
  • Fixing adapters to the next guitar to be processed and adjusting the neck relief with the truss rod using the external sts.