Specification summary of GB T 1804 M as applied to custom machined component: the dimensions the standard fixes, the full size range supplied, and the related designations commonly cross-referenced.
GB T 1804 M — Scope
The table below lists the dimensions catalogued for custom machined component — iso / din (series 115) under GB T 1804 M. The scope of GB T 1804 M itself is not summarised here — where a figure matters, confirm it against the published document.
Tolerance & Product Grades
Product grade is a concept from dimensional fastener standards and does not apply to GB T 1804 M. Tolerances for this part are the limits shown against each dimension in the table.
Dimensions Specified by GB T 1804 M
| Size designation | Outer diameter / width (mm) | Length / height (mm) | Bore / thread (mm) | Material | Reference standard |
|---|---|---|---|---|---|
| Size 1 | 10 | 20 | 6 | C45 carbon steel | GB/T 1804-m |
| Size 2 | 12 | 25 | 8 | C45 carbon steel | GB/T 1804-m |
| Size 3 | 16 | 32 | 10 | C45 carbon steel | GB/T 1804-m |
| Size 4 | 20 | 40 | 12 | C45 carbon steel | GB/T 1804-m |
| Size 5 | 25 | 50 | 16 | C45 carbon steel | GB/T 1804-m |
| Size 6 | 32 | 63 | 20 | C45 carbon steel | GB/T 1804-m |
| Size 7 | 40 | 80 | 25 | C45 carbon steel | GB/T 1804-m |
| Size 8 | 50 | 100 | 30 | C45 carbon steel | GB/T 1804-m |
Equivalent Standards
Where direct equivalents exist (ISO ↔ DIN, ISO ↔ ASME), they are listed on the parent Custom Machined Component — ISO / DIN (Series 115) page.
Always confirm against the dimensions on this page, since some "equivalent" standards differ in tolerances and head geometry.
Companion Standards
A complete specification for custom machined component — iso / din (series 115) normally cites several documents: one for the geometry, one for the material or mechanical properties, and one for the finish. GB T 1804 M is one of them, not all of them.
Custom manufacturing · Made to drawing
Need a machined component to this standard in a non-standard size?
Parts built to GB T 1804 M are already in the catalog, so a special is usually a variation on existing tooling rather than a new design — which is what keeps the cost down. Made by warm forging or thread turning.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.


