Machine Screw Hex Nuts
Small-pattern hex nuts for machine screw sizes.
Machine-screw hex nuts in steel, stainless and brass for instrument and panel work.
Specifications & technical data.
Machine screw hex nuts to ASME B18.2.2 — the small-series nuts from #0 through 3/8″ that mate with machine screws in panels, controls and instrumentation.
Download our machine screw hex nut dimensioning table (PDF)
| Nominal Size (Basic Major Diameter) | F | G | H | FIM | |||||
|---|---|---|---|---|---|---|---|---|---|
| Width Across Flats | Width Across Corners | Thickness | |||||||
| Basic | Min. | Max. | Min. | Max. | Min. | Max. | Max. | ||
| #0 | 0.060 | 5/32 | 0.150 | 0.156 | 0.171 | 0.180 | 0.043 | 0.050 | 0.005 |
| #1 | 0.073 | 5/32 | 0.150 | 0.156 | 0.171 | 0.180 | 0.043 | 0.050 | 0.005 |
| #2 | 0.086 | 3/16 | 0.180 | 0.188 | 0.205 | 0.217 | 0.057 | 0.066 | 0.006 |
| #3 | 0.099 | 3/16 | 0.180 | 0.188 | 0.205 | 0.217 | 0.057 | 0.066 | 0.006 |
| #4 | 0.112 | 1/4 | 0.241 | 0.250 | 0.275 | 0.289 | 0.087 | 0.098 | 0.009 |
| #5 | 0.125 | 5/16 | 0.302 | 0.312 | 0.344 | 0.361 | 0.102 | 0.114 | 0.011 |
| #6 | 0.138 | 5/16 | 0.302 | 0.312 | 0.344 | 0.361 | 0.102 | 0.114 | 0.011 |
| #8 | 0.164 | 11/32 | 0.332 | 0.344 | 0.378 | 0.397 | 0.117 | 0.130 | 0.012 |
| #10 | 0.190 | 3/8 | 0.362 | 0.375 | 0.413 | 0.433 | 0.117 | 0.130 | 0.013 |
| #12 | 0.216 | 7/16 | 0.423 | 0.438 | 0.482 | 0.505 | 0.148 | 0.161 | 0.015 |
| 1/4" | 0.250 | 7/16 | 0.423 | 0.438 | 0.482 | 0.505 | 0.178 | 0.193 | 0.015 |
| 5/16" | 0.312 | 9/16 | 0.545 | 0.562 | 0.621 | 0.650 | 0.208 | 0.225 | 0.020 |
| 3/8" | 0.375 | 5/8 | 0.607 | 0.625 | 0.692 | 0.722 | 0.239 | 0.257 | 0.021 |
All dimensions in inches, per ASME B18.2.2. FIM = bearing-surface runout to thread axis. Confirm requirements with our estimating team.
Standards.
What are machine screw hex nuts?
Machine screw nuts are the small end of the hex nut family — numbered sizes #0 through 3/8″, proportioned thinner than full nuts, chamfered on both faces. They make up with machine screws in panel and equipment work.
- #0 through 3/8″
- Double-chamfered faces
- UNC and UNF, class 2B
- 18-8 and 316 stainless as standard
Other names
- Machine nuts
- Small pattern hex nuts
- Panel nuts (loosely)
Tips for purchasing
- These run thinner than finished nuts of the same flat size — check H if stack height matters.
- Stainless dominates this size class for corrosion service.
- Match the screw's thread series — UNC and UNF do not mix.
- Certs available on request.
Materials.
Representative capabilities — every item is manufactured or certified to your specification. Confirm requirements with our estimating team.
