# COUNTERBORE HOLE DIMENSIONS FOR METRIC SOCKET HEAD CAP SCREWS

Counterbore Hole Dimensions for Metric Socket Head Cap Screws Calculator was developed to show recommended clearance and counterbore hole sizes for metric socket head cap screws from M1.6 through M48. There are two classes of fit category; close- and normal-fit category. The recommended drill size for each class of clearance hole is shown in calculation results.

Counterbore Hole Dimensions for Metric Socket Head Cap Screws Calculator is working in line with the charts given in the Machinery's Handbook, 29th page 1612.

##### Calculator:

 INPUT PARAMETERS Nominal Screw Size M1.6 M2 M2.5 M3 M4 M5 M6 M8 M10 M12 M14 M16 M20 M24 M30 M36 M42 M48 Fit Class1,2 Normal Close

###### Note 2: Normal Fit: The normal fit is intended for screws of relatively long length or for assemblies involving two or more screws where the mating holes are to be produced by conventional tolerancing methods.

 RESULTS Parameter Symbol Value Unit Nominal Screw Size --- --- --- Max. Body Diameter Dmax --- mm Fit Class --- --- -- Nominal Metric Drill Size A --- mm Counterbore Diameter X --- mm Countersink Diameter 1 Y --- Max. Head Height Hmax --- Max. Transition Diameter Bmax ---

##### Definitions:

Clearance hole: A hole on a part where threaded section of a bolt can pass.

Counterbore: A hole used when the head of the socket head cap screw is needed to be flushed with or below the level of the workpiece's surface.

Countersink: A hole with conical shape. In this case, it's used to remove the burr left from a drilling operation thereby removing any sharp edges.

Drill bit: A cutting tool used in drilling machines to drill a hole.

##### 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.