Allen Grub Screw (Inch)
Inch-series headless set screws with internal hex drive and cup point per ASME B18.3. Designed for shaft locking in US-specification and legacy equipment. Alloy steel Rc 45-53, UNC threads, class 3A tolerance, sizes #4 to 1-1/2 inch.
Specification
#
Standard
ASME B18.3
Material
Alloy Steel
Thread
UNC (Coarse)
Grade
12.9
Coating
Black oxide
Head Type
Headless (no head)
Drive Type
Hexagon socket (Allen key/hex wrench)
Point Type
Cup point (concave depression)
Dimension
#
Size
Thread Dia (d)
Pitch (TPI)
Length(L)
Thread Length (b)
3/16
0.1887-0.1900
24
3/16" - 1"
Full
1/4
0.2489-0.2500
20
1/4" - 1
Full
5/16
0.3113-0.3125
18
5/16" - 1 1/2"
Full
3/8
0.3737-0.3750
16
3/8" - 1 1/2"
Full
1/2
0.4985-0.5000
13
1/2" - 1 1/2"
Full
5/8
0.6232-0.6250
11
5/8" - 1 1/2"
Full
- All dimensions in inches, tolerance +/- 0.001 in. Additional dimensions available on request.
Benefits
#
Inch-series grub screws address shaft-locking requirements in US-specification machinery, legacy equipment, and aerospace assemblies where inch-dimensioned fasteners are standard. The cup point produces a controlled indentation on the shaft surface, providing a mechanical lock against rotational slip and axial movement without the complexity of keyed connections.
The headless design installs entirely within the threaded bore, eliminating protrusions that interfere with adjacent components in tight assemblies. Alloy steel hardness Rc 45-53 ensures effective indentation across common shaft materials. ASME B18.3 provides documented seating torque values by size, enabling predictable and repeatable installation. Coarse threads (UNC) provide reliable locking for general-purpose applications.
Common Applications
#
Inch-series grub screws are specified in US-dimensioned assemblies requiring headless shaft locking and component fixation.
- Legacy US-specification machinery and equipment
- Shaft-to-collar and shaft-to-gear locking (inch shafts)
- Pulley and sprocket fixation on inch-diameter shafts
- Aerospace and defense equipment (inch specifications)
- Automotive powertrain components (US specifications)
- Industrial valve and actuator assemblies
- Door handle and lockset hardware (inch bore)
- Electrical terminal and bus bar connections
- Hydraulic cylinder and manifold assemblies
- Conveyor roller and idler fixation
Read Me
| Standard | ASME B18.3 |
| Material | Alloy Steel |
| Thread | UNC (Coarse) |
| Grade | 12.9 |
| Coating | Black oxide |
| Head Type | Headless (no head) |
| Drive Type | Hexagon socket (Allen key/hex wrench) |
| Point Type | Cup point (concave depression) |
| Size | Thread Dia (d) | Pitch (TPI) | Length(L) | Thread Length (b) |
|---|---|---|---|---|
| 3/16 | 0.1887-0.1900 | 24 | 3/16" - 1" | Full |
| 1/4 | 0.2489-0.2500 | 20 | 1/4" - 1 | Full |
| 5/16 | 0.3113-0.3125 | 18 | 5/16" - 1 1/2" | Full |
| 3/8 | 0.3737-0.3750 | 16 | 3/8" - 1 1/2" | Full |
| 1/2 | 0.4985-0.5000 | 13 | 1/2" - 1 1/2" | Full |
| 5/8 | 0.6232-0.6250 | 11 | 5/8" - 1 1/2" | Full |
