COUNTERBORE HOLE DIMENSIONS CHART (METRIC)


Counterbore hole dimensions chart for metric socket head cap screws.

Counterbore Hole Dimensions Chart
Counter Bore Hole Dimensions
Nom. Size or Basic Screw Dia.  Normal Drill Size, A H X Y
Close Fit Normal Fit
M1.6 1.80 1.95 1.60 3.50 2.0
M2 2.20 2.40 2.00 4.40 2.6
M2.5 2.70 3.00 2.50 5.40 3.1
M3 3.40 3.70 3.00 6.50 3.6
M4 4.40 4.80 4.00 8.25 4.7
M5 5.40 5.80 5.00 9.75 5.7
M6 6.40 6.80 6.00 11.25 6.8
M8 8.40 8.80 8.00 14.25 9.2
M10 10.50 10.80 10.00 17.25 11.2
Nom. Size or Basic Screw Dia.  Normal Drill Size, A H X Y
Close Fit Normal Fit
M12 12.50 12.80 12.00 19.25 14.2
M14 14.50 14.75 14.00 22.25 16.2
M16 16.50 16.75 16.00 25.50 18.2
M20 20.50 20.75 20.00 31.50 22.4
M24 24.50 24.75 24.00 37.50 26.4
M30 30.75 31.75 30.00 47.50 33.4
M36 37.00 37.50 36.00 56.50 39.4
M42 43.00 44.00 42.00 66.00 45.6
M48 49.00 50.00 48.00 75.00 52.6

Note 1: X - Counterbore Diameter, Y - Countersink Diameter, H - Counterbore Depth / Max. Head Height for Socket Head Cap Screw

Note 2: All dimensions are in mm.

Supplements:

Reference:

  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc.
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) . Machinery's Handbook . 29th edition.  Industrial Press Inc.