PARAMETRIC · 3D · STEP / STL / 3MF
Socket Head Cap Screw M8 × 20SOCKET HEAD CAP SCREW
Free STEP, STL and 3MF download of a socket head cap screw M8 × 20 with live 3D preview. Key dimensions: Pitch 1.25 mm, Pitch diameter 7.188 mm, Minor diameter 6.466 mm, Tap drill 6.80 mm. Every parameter stays adjustable, and you can send it straight to Orinovate for printing.
- StandardISO 4762
- SizesM2–M16
- ThreadSimplified / modeled / print
- OutputSTEP · STL · 3MF · DXF
LIVE · SOCKET HEAD CAP SCREW
M8 × 20
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CALCULATED · SPEC
AUTO-COMPUTED
P
1.25mm
Pitch
d2
7.188mm
Pitch diameter
d3
6.466mm
Minor diameter
⌀
6.80mm
Tap drill
dh
8.4 / 9mm
Clearance hole (fine / medium)
dk
13.00mm
Head diameter
k
8.00mm
Head height
s
6.0mm
Hex key size
t
4.00mm
Socket depth
b
20.0mm
Thread length
L
28.00mm
Overall length (incl. head)
As
36.61mm²
Tensile stress area
Fm
29.3kN
Min. tensile load (class 8.8)
HOW-TO
How to generate a socket head cap screw STEP / STL file
- 1Pick the thread size — head dimensions follow the standard automatically.
- 2Enter the length or tap a common length.
- 3Choose the thread mode: simplified for assemblies, modeled to see the thread, 3D-print for printing.
- 4Check the spec cards and any warnings.
- 5Download STEP, STL or 3MF — or send it to Orinovate for a quote.
What is a socket head cap screw (ISO 4762)?
A socket head cap screw has a cylindrical head with a hexagon socket driven by an Allen key. The compact head sinks fully into a counterbore, which makes it the standard screw for machines, fixtures, aluminium extrusions and 3D printers. ISO 4762 sets the head diameter dk ≈ 1.5d and head height k = d; longer screws are partially threaded with b = 2d + 12 mm (reference).
ISO metric thread formulas
The ISO 68-1 basic profile is a 60° triangle with fundamental height H = 0.866P. Pitch diameter d2 = d − 0.6495P, internal minor D1 = d − 1.0825P, external minor d3 = d − 1.2269P, tensile stress area As = π/4 × ((d2 + d3)/2)². For M8 (P = 1.25): d2 = 7.188, D1 = 6.647, d3 = 6.466 mm, As = 36.6 mm². Modeled threads are right-handed and faceted into 36 planar segments per turn (error < 0.4 % of the diameter).
Specs at default parameters
| Parameter | Value | Range |
|---|---|---|
| Thread size (d) | M8 | M2 / M2.5 / M3 / M4 / M5 / M6 / M8 / M10 / M12 / M14 / M16 |
| Length (l) | 20 mm | 1–200 |
| Thread mode | Simplified (no thread) | Simplified (no thread) / Modeled thread / 3D-print thread |
| Print clearance (c) | 0.15 mm | 0.05–0.5 |
| Pitch (P) | 1.25 mm | — |
| Pitch diameter (d2) | 7.188 mm | — |
| Minor diameter (d3) | 6.466 mm | — |
| Tap drill (⌀) | 6.80 mm | — |
| Clearance hole (fine / medium) (dh) | 8.4 / 9 mm | — |
| Head diameter (dk) | 13.00 mm | — |
| Head height (k) | 8.00 mm | — |
| Hex key size (s) | 6.0 mm | — |
| Socket depth (t) | 4.00 mm | — |
| Thread length (b) | 20.0 mm | — |
| Overall length (incl. head) (L) | 28.00 mm | — |
| Tensile stress area (As) | 36.61 mm² | — |
| Min. tensile load (class 8.8) (Fm) | 29.3 kN | — |
Popular socket head cap screw sizes
FAQ
What hex key fits an M5 socket head cap screw?
The key size equals the socket across-flats s: M2 1.5, M2.5 2, M3 2.5, M4 3, M5 4, M6 5, M8 6, M10 8, M12 10, M16 14 mm. Button head (ISO 7380) and countersunk socket screws use one size smaller.
How big should the counterbore be?
Make the counterbore about dk + 1 mm in diameter and k + 0.5 mm deep. For M5 (dk 8.5, k 5): ⌀9.5 × 5.5 mm deep, with a ⌀5.5 mm clearance hole.
What size hole for an M3 screw? Which tap drill?
Tap drill ≈ nominal diameter − pitch: M3 → 2.5 mm, M4 → 3.3, M5 → 4.2, M6 → 5.0, M8 → 6.8, M10 → 8.5, M12 → 10.2 mm. For a clearance hole (ISO 273): M3 3.2 (fine) / 3.4 (medium), M4 4.3 / 4.5, M5 5.3 / 5.5, M6 6.4 / 6.6, M8 8.4 / 9 mm. The spec cards list both for the selected size.
What do property classes 8.8, 10.9 and 12.9 mean?
Per ISO 898-1 the first number × 100 is the nominal tensile strength in MPa and the product of both numbers × 10 the nominal yield strength. The specified minimums are slightly higher: 8.8 (d ≤ 16) = 800 / 640 MPa, 10.9 = 1040 / 940 MPa, 12.9 = 1220 / 1100 MPa. Socket cap screws are usually 12.9, general hex bolts 8.8. Minimum breaking load = tensile strength × stress area As; the spec cards show it for class 8.8.
Do 3D-printed threads work?
Yes, from about M6 up — a 0.4 mm FDM nozzle can barely resolve an M3 thread (0.5 mm pitch). Use the 3D-print mode (external thread shrunk 0.15 mm, internal enlarged 0.2 mm, adjustable), print screws standing up with ≤ 0.12 mm layers. For parts that are assembled often or loaded, heat-set inserts or a captive hex-nut pocket last far longer than printed threads.
Which software opens the socket head cap screw STEP file?
STEP (AP214) opens in Fusion 360, SolidWorks, FreeCAD, Onshape and Rhino. STL / 3MF import directly into Bambu Studio, PrusaSlicer or Cura.
Is it free?
Yes — no sign-up, no fees. Need a physical part? Send it to Orinovate for an instant quote in FDM, SLA, SLS, MJF or CNC.
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About STEP / STL / 3MF / DXF
- STEP (.step / .stp, AP214) keeps exact dimensions and surfaces for editing in Fusion 360, SolidWorks or FreeCAD.
- STL and 3MF are triangle meshes that import directly into Bambu Studio, PrusaSlicer or Cura.
- DXF is the top-view 2D outline, ready for laser cutting, waterjet or CNC routing.
- All models are in millimetres at true scale.