Fasteners / Useful knowledge / Our knowledges & what we worked on

The proposed table specifies the diameters of the passage holes for screws & bolts in the general case.

The values proposed are recommended by ISO 273 (NF EN 20273)

D = Nominal screw diameter

Dh = Passage hole diameter

The following table gives the dimensions of the recesses intended to serve as a bearing surface for the screws.

For certain applications and depending on the type of tool provided, it is possible to increase or decrease the counterbore diameter proposed.