Set current to roughly the motor's rated amps (a hair under is fine — foam cutters barely load the motors, so you can run conservatively and stay cool and quiet). For A4988: I = Vref / (8 × Rsense); for DRV8825: I = Vref / (5 × Rsense), which on common 0.1 Ω boards is the well-known Vref ≈ amps ÷ 2. Always check your board's sense resistors before trusting any chart.
Measure Vref with a multimeter between the pot and ground, adjust with a ceramic screwdriver, and confirm the motor runs cool. For TMC2209 the clean method is UART — set the run current digitally in your FluidNC config and skip the pot entirely.
Measure Vref with a multimeter between the pot and ground, adjust with a ceramic screwdriver, and confirm the motor runs cool. For TMC2209 the clean method is UART — set the run current digitally in your FluidNC config and skip the pot entirely.