MECHANICAL CAD & FASTENER ENGINEERING

Laser & CNC Fastener Countersink & Counterbore Calculator

Calculate standard ISO 273 clearance hole diameters, 90°/82°/100° countersink depths, and DIN 974-1 Socket Head Cap Screw (SHCS) counterbore pockets with CAM toolpaths.

1. Fastener Standard & Size

Thread Size

Head Style & Chamfer Standard

ISO 273 Clearance Fit Class

2. Plate & Machine Stock

Plate Thickness (T_plate) [mm]

Hole Feature Dimensions (CAM Vectors)

Through Hole (d_h)

3.40 mm

ISO 273 clearance diameter

Head Pocket Dia (D_cs)

6.72 mm

Top chamfer / pocket diameter

Pocket Depth (H_depth)

1.86 mm

Z-depth from top face

Remaining Web (T_web)

4.14 mm

Material thickness under head

HOLE CROSS-SECTION & VECTOR CUT CONTOUR:

Geometry Formula:

                            H_cs = (D_cs - d_h) / (2 × tan(α / 2))
                        

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SpotItLive separates clearance holes, pilot circles, and counterbore profiles into discrete DXF layers with pre-calculated lead-ins for laser cutters and CNC mills.

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