PARAMETRIC · 3D · STEP / STL / 3MF
Hex Cap Screw (UNC) 5/16-18 × 1"HEX CAP SCREW UNC
Free STEP, STL and 3MF download of a hex cap screw (unc) 5/16-18 × 1" with live 3D preview. Key dimensions: Threads per inch 18 TPI, Pitch 1.411 mm, Major diameter 5/16" (7.94 mm), Minor diameter 6.410 mm. Every parameter stays adjustable, and you can send it straight to Orinovate for printing.
- StandardASME B18.2.1
- ThreadUNC 1/4–3/4"
- Unitsinch / mm
- OutputSTEP · STL · 3MF · DXF
LIVE · HEX CAP SCREW UNC
5/16-18 × 1"
SCALE 1:1 · mm
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CALCULATED · SPEC
AUTO-COMPUTED
n
18TPI
Threads per inch
P
1.411mm
Pitch
D
5/16" (7.94 mm)
Major diameter
D1
6.410mm
Minor diameter
⌀
F (6.53 mm)
Tap drill
dh
0.332" (8.43 mm)
Clearance hole (fine / medium)
F
1/2" (12.70 mm)
Width across flats
G
14.66mm
Width across corners
H
13/64" (5.16 mm)
Head height
LT
7/8" (22.22 mm)
Thread length
L+H
30.56mm
Overall length (incl. head)
As
34.35mm²
Tensile stress area
HOW-TO
How to generate a hex cap screw (unc) STEP / STL file
- 1Pick the UNC size — width across flats F and head height H follow ASME B18.2.1.
- 2Pick the length in inches (mm shown).
- 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 UNC hex cap screw?
ASME B18.2.1 hex cap screws with Unified coarse (UNC) threads are found in US machinery, automotive parts and camera gear. Thread length is 2D + 1/4" for L ≤ 6"; shorter screws are threaded full length. Width across flats is e.g. 7/16" for 1/4" and 3/4" for 1/2".
UNC thread dimensions
ASME B1.1 Unified threads share the 60° ISO profile; pitch P = 25.4 / TPI mm, internal minor D1 = D − 1.0825P, pitch diameter D2 = D − 0.6495P. The model is built in millimetres and the STEP file is in mm — switch units in your CAD to read inches.
Specs at default parameters
| Parameter | Value | Range |
|---|---|---|
| Size (diameter-TPI) | 5/16-18 | 1/4-20 / 5/16-18 / 3/8-16 / 7/16-14 / 1/2-13 / 5/8-11 / 3/4-10 |
| Length (L) | 1" (25.40 mm) | 1/2" (12.70 mm) / 5/8" (15.88 mm) / 3/4" (19.05 mm) / 1" (25.40 mm) / 1-1/4" (31.75 mm) / 1-1/2" (38.10 mm) / 1-3/4" (44.45 mm) / 2" (50.80 mm) / 2-1/2" (63.50 mm) / 3" (76.20 mm) / 3-1/2" (88.90 mm) / 4" (101.60 mm) |
| Thread mode | Simplified (no thread) | Simplified (no thread) / Modeled thread / 3D-print thread |
| Print clearance (c) | 0.15 mm | 0.05–0.5 |
| Threads per inch (n) | 18 TPI | — |
| Pitch (P) | 1.411 mm | — |
| Major diameter (D) | 5/16" (7.94 mm) | — |
| Minor diameter (D1) | 6.410 mm | — |
| Tap drill (⌀) | F (6.53 mm) | — |
| Clearance hole (fine / medium) (dh) | 0.332" (8.43 mm) | — |
| Width across flats (F) | 1/2" (12.70 mm) | — |
| Width across corners (G) | 14.66 mm | — |
| Head height (H) | 13/64" (5.16 mm) | — |
| Thread length (LT) | 7/8" (22.22 mm) | — |
| Overall length (incl. head) (L+H) | 30.56 mm | — |
| Tensile stress area (As) | 34.35 mm² | — |
Popular hex cap screw (unc) sizes
FAQ
Can UNC and metric screws be mixed? What does 1/4-20 mean?
No. UNC sizes are inch diameter and threads per inch: 1/4-20 = 1/4" (6.35 mm) diameter with 20 TPI (1.27 mm pitch). It is close to M6 (1.0 mm pitch) in diameter but the pitch differs, so forcing one into the other strips the thread. Both use a 60° profile, so the same formulas apply. Camera tripod screws are 1/4-20 UNC.
What tap drill for 1/4-20?
Common UNC tap drills (≈ 75 % thread): 1/4-20 #7 (5.1 mm), 5/16-18 F (6.5 mm), 3/8-16 5/16" (7.9 mm), 7/16-14 U (9.3 mm), 1/2-13 27/64" (10.7 mm), 5/8-11 17/32" (13.5 mm), 3/4-10 21/32" (16.7 mm). Metric substitutes: 5.1 mm for 1/4-20, 8.0 mm for 3/8-16.
How do SAE Grade 5 and Grade 8 compare to metric classes?
SAE J429 Grade 5 has 120 ksi (≈ 830 MPa) tensile strength — roughly metric class 8.8; Grade 8 has 150 ksi (≈ 1030 MPa), about class 10.9. Three radial lines on the head mark Grade 5, six mark Grade 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 hex cap screw (unc) 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.
Related generators
Need a physical part?
Send the model straight to Orinovate's instant quote: FDM, SLA, SLS, MJF, metal printing and CNC, made in Hsinchu, Taiwan.
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.