DIN 371 is the standard cited for machine taps (din 371 / din 376). This page sets out what the standard controls for this part, reproduces the dimensional table supplied against it, and notes the related designations referenced on drawings.
DIN 371 — Scope
DIN 371 specifies the dimensional requirements for machine taps (din 371 / din 376).
Material, surface condition and any performance rating are set by separate documents specific to this part family — ISO 898-1 and ISO 898-2, which govern bolt and nut property classes, do not apply here.
Tolerance & Product Grades
Tolerances for machine taps (din 371 / din 376) are given as limits on the individual dimensions in the table rather than as a fastener product grade.
Where a general-tolerance class is cited on the drawing instead, it applies to the dimensions not otherwise toleranced.
Dimensions Specified by DIN 371
| Tap form | Chip behaviour | Hole type | Suited to |
|---|---|---|---|
| spiral point (gun nose) | pushes chips ahead of the tap | through holes only | steel, stainless, general production |
| spiral flute | pulls chips back out of the hole | blind holes | steel, aluminium, blind tapping |
| straight flute | chips break and collect in the flute | short through or blind holes | cast iron, brass, hand and machine use |
| thread-forming (fluteless) | no chips at all | through or blind | aluminium, copper, mild steel, thin sections |
| DIN 371 shank | n/a | n/a | M1 to M10, short shank |
| DIN 376 shank | n/a | n/a | M10 to M30, long shank |
Companion Standards
DIN 371 controls only the geometry of machine taps (din 371 / din 376). Surface finish is governed by separate finish standards (for example ISO 4042 for electroplating), and corrosion testing by ISO 9227 (neutral salt spray). Mechanical performance is set by the standards specific to this part family, not by ISO 898-1 or ISO 898-2, which apply to bolts, screws and nuts.
When to Specify DIN 371
DIN 371 is still widely used in European mechanical engineering and as a cross-reference on legacy drawings; its ISO equivalent is preferred for new designs.
