Guitar Neck Fretter (ME 560 - Machine Design)
The standard process for fretting a guitar neck requires a luthier to cut each fret from a spool of wire, press the fret into grooves, and grind down the frets until they are flush with the neck. Our team was tasked with designing a machine that would automate this process.
This project involved team management, refinement of specifications, down-selection through Pugh charts, motor selection, large CAD assemblies, PDR and FDR, and financial justification.
Design Specifications
Automate the installation of frets on guitar necks stored in racks of 10.
“Cut” slots in neck, press frets into slots, trim and finish sides of frets.
Max automated cycle time: 5 sec per fret + 60 for trimming.
Must accommodate a variety of neck shapes.
Project Contributions**
Overall assembly design, including main compartments.
Torque calculations for motor and linear drive selection.
Input/output racks and piston (moves guitar necks from rack to main drive).
CNC slot cutter and fret presser.
** All CAD modeled in SolidWorks 2019
Process - Top level
Piston and Neck Rack
Pneumatic piston pushes neck from rack to linear drive with .053 N force.
Guide rails align rack for installation; rack locks into mounting plate.
1500mm stroke linear drive moves compartment to next guitar neck.
Fret Slot Cutting: CNC Mill
2 axis + spindle rotation — neck fixture pre-adjusted to appropriate cut depth.
2 axis cross-cut motion reduces milling time and allows multiple processes to occur simultaneously.
“Air cooled” spindle: Sawdust management without wood damage.
Fret Wire Presser
Electric actuator moves presser apparatus down toward the neck, pressing fret wire into the milled slot.
Arms rotate out due to downward pressure, conforming to the neck radius.
Spring constant calculated to balance downward force with rotation of presser arms.
Main Compartments
Four separate compartments → Easier to install, move, and maintain.
All machinery with safety risk factors contained behind safety glass to protect operator.
Sliding doors allow maintenance access.
Swivel vibration-damping leveling mount have 2000 lb capacity per foot.
