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Westfield Fasteners Product Specification:

Flat Point Grub Screws, to ISO 4026 / DIN 913

This product guide contains the specification for metric threaded flat point grub screws, available from Westfield Fasteners. The basis of this specification is the ISO standard ISO 4026 and the older DIN 913.

Product Description
Also known as a set screw, these headless types of screws have many uses. This particular type has a hex socket drive, and a flat on the opposite end.
Scope of the ISO standard.
ISO 4026 specifies the tolerances and the variation in form of metric threaded flat point grub screws, for sizes from M1.6 up to and including M24. Table 1 below defines the overall dimensions and tolerances of this screw type. Table 2 defines the tolerance on the shank length.

Grub screws in general are graded by hardness rather than by tensile strength. The relevant DIN and ISO standards specify a 45H hardness grade for non stainless steel grub screws and 21H for stainless steel grub screws.

Although the DIN 913 standard has been superceded by ISO 4026, the dimensions are the same and off-the-shelf parts could be marked with either standard.

technical drawing of Flat Point Grub Screws, to ISO 4026 / DIN 913

Figure 1: Flat Point Grub Screw


Notes to figure 1:



Table 1: Dimensions & Tolerances according to ISO 4026 / DIN 913

Thread, dM1.6M2M2.5M3M4M5M6M8M10M12M16M20M24
thread pitch (standard metric coarse)0.350.40.450.50.70.811.251.51.7522.53
diameter of the flatdp max.0.801.001.502.002.503.504.005.507.008.5012.0015.0018.00
dp min.0.550.751.251.752.253.203.705.206.648.1411.5714.5717.57
diameter of the facedf≈ (approx.) Minor thread diameter
socket width across cornerse min.0.8091.0111.4541.7332.3032.8733.4434.5835.7236.8639.14911.42913.716
socket width across flatss nom.0.70.91.31.522.5345681012
s max.0.7240.9131.3001.582.082.583.084.0955.146.148.17510.17512.212
s min.0.7100.8871.2751.5202.0202.5203.0204.0205.0206.0208.02510.02512.032
socket depth t min. (shortest lengths)0.70.81.21.21.522344.86.4810
t min. (other lengths)1.51.7222.533.5568101215



Table 2: Shank Length Tolerance according to ISO 4026 / DIN 913

thread length (mm)+/- (mm)
20.3max 0.2min
2.5-30.2
4-60.24
8-100.29
12-160.35
20-300.42
35-500.5
55-600.6


For further details, please refer to the original ISO/DIN standard document for this item.