drillgcode.cs

using System.Globalization;
using System.IO;
using System.Text;

namespace DrillBoardGcode
{
    class Program
    {
        static double DRILLDEPTH = -4;
        static double DRILLFEED = 5 * 60;
        static double MOVEFEED = 20 * 60;
        static double MAGIC = 2.54;

        static void Main()
        {
            var builder = new StringBuilder();
            builder.AppendLine("M3 S1000"); // Spindle ON
            builder.AppendLine("G90");

            for (double i = 0; i < 85.5; i += MAGIC)
            {
                for (double j = 0; j < 54; j += MAGIC)
                {
                    builder.AppendLine(MoveTo(i, j));
                    builder.AppendLine(DrillInto());
                    builder.AppendLine(DrillOut());
                }
            }

            builder.AppendLine(MoveTo(0, 0));
            builder.AppendLine("M5"); // Spindle OFF
            using var w = new StreamWriter("output_2_54.gcode");
            w.Write(builder);
        }

        static string MoveTo(double X, double Y) => $"G01 X{Format(X)} Y{Format(Y)} F{MOVEFEED}";

        private static string Format(double value) => value.ToString("0.00", CultureInfo.InvariantCulture.NumberFormat);

        static string DrillInto() => $"G01 Z{DRILLDEPTH} F{DRILLFEED}";

        static string DrillOut() => $"G01 Z0 F{MOVEFEED}";

    }
}