Materials and Finish for Wing Nuts
Material Options by Type
| Wing Nut Type | Primary Material | Alternative Materials |
|---|---|---|
| Type A | Carbon steel (user-specified) | Brass, corrosion resistant steel |
| Type B | Carbon steel (user-specified) | Brass, corrosion resistant steel |
| Type C | Die cast zinc alloy (only) | None — zinc alloy is the only option |
| Type D | Carbon steel (user-specified) | Brass, corrosion resistant steel |
Default Finish
Unless otherwise specified, all wing nuts are supplied with a plain (unplated or uncoated) finish.
Material Selection Guide
- Carbon steel — Default choice for indoor, non-corrosive environments. Strongest option for Types A, B, and D. Should be specified with protective plating (zinc, cadmium, etc.) for any exposure to moisture.
- Brass — Naturally corrosion resistant. Non-sparking (critical in explosive atmospheres). Lower strength than steel. Excellent for marine, electrical, and food-processing applications.
- Corrosion resistant steel (stainless) — Best all-around corrosion resistance with high strength. Higher cost than carbon steel or brass. Specify for outdoor, chemical, marine, or wash-down environments.
- Die cast zinc alloy (Type C only) — Good for high-volume consumer products. Excellent dimensional consistency. Poor strength-to-weight ratio compared to steel. Subject to creep under sustained load at elevated temperatures.
Wing Screws: The Screw Side of the Equation
A wing screw is a screw with a wing-shaped head designed for manual turning without a driver or wrench. Where wing nuts pair with separate bolts or studs, wing screws are self-contained fasteners—the wings are built into the head.
Wing screws follow the same ANSI B18.17-1968 (R1983) standard and are classified by type (manufacturing method) and style (design characteristics).
The Four Wing Screw Types
Type A — Two-piece construction with cold formed or cold forged wing portions of moderate height. Available in Light, Regular, and Heavy series. The wing portion is assembled onto a separate screw shank.
Type B — Hot forged one-piece construction. Two styles: Style 1 (moderate height wings) and Style 2 (high wings). Strongest wing screw type due to one-piece forging.
Type C — Two styles: Style 1 is one-piece die cast construction with moderate height wings (zinc alloy only). Style 2 is two-piece construction with a die cast wing portion and a separate steel shank.
Type D — Two-piece welded construction with stamped sheet metal wing portions. The wings are stamped and then welded to the screw shank.
Type A Wing Screws — Dimensions
All dimensions in inches. Plain point standard unless alternate specified.
| Nominal Size | TPI | Series | Blank | A (Wing Spread) | B (Wing Height) | C (Wing Thick.) | E (Boss Dia.) | G (Boss Hgt.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|---|---|---|
| #4 (0.112) | 40 | Hvy. | AA | 0.59–0.72 | 0.28–0.41 | 0.07–0.11 | 0.29–0.33 | 0.10–0.14 | 0.25–0.75 |
| #6 (0.138) | 32 | Lgt. | AA | 0.59–0.72 | 0.28–0.41 | 0.07–0.11 | 0.29–0.33 | 0.10–0.14 | 0.25–0.75 |
| Hvy. | A | 0.78–0.91 | 0.34–0.47 | 0.10–0.14 | 0.39–0.43 | 0.14–0.18 | |||
| #8 (0.164) | 32 | Lgt. | A | 0.78–0.91 | 0.34–0.47 | 0.10–0.14 | 0.39–0.43 | 0.14–0.18 | 0.38–0.75 |
| Hvy. | B | 0.97–1.10 | 0.43–0.57 | 0.14–0.18 | 0.45–0.50 | 0.17–0.22 | |||
| #10 (0.190) | 24, 32 | Lgt. | A | 0.78–0.91 | 0.34–0.47 | 0.10–0.14 | 0.39–0.43 | 0.14–0.18 | 0.38–1.00 |
| Hvy. | B | 0.97–1.10 | 0.43–0.57 | 0.14–0.18 | 0.45–0.50 | 0.17–0.22 | |||
| #12 (0.216) | 24 | Lgt. | B | 0.97–1.10 | 0.43–0.57 | 0.14–0.18 | 0.45–0.50 | 0.17–0.22 | 0.38–1.00 |
| Hvy. | C | 1.12–1.25 | 0.53–0.66 | 0.17–0.21 | 0.51–0.58 | 0.20–0.25 | |||
| ¼ (0.250) | 20 | Lgt. | B | 0.97–1.10 | 0.43–0.57 | 0.14–0.18 | 0.45–0.50 | 0.17–0.22 | 0.50–1.50 |
| Reg. | C | 1.12–1.25 | 0.53–0.66 | 0.17–0.21 | 0.51–0.58 | 0.20–0.25 | |||
| Hvy. | D | 1.31–1.44 | 0.65–0.79 | 0.20–0.24 | 0.64–0.70 | 0.26–0.30 | |||
| 5⁄16 (0.3125) | 18 | Lgt. | C | 1.12–1.25 | 0.53–0.66 | 0.17–0.21 | 0.51–0.58 | 0.20–0.25 | 0.50–1.50 |
| Reg. | D | 1.31–1.44 | 0.65–0.79 | 0.20–0.24 | 0.64–0.70 | 0.26–0.30 | |||
| Hvy. | E | 1.81–1.94 | 0.87–1.00 | 0.26–0.33 | 0.86–0.93 | 0.35–0.39 | |||
| ⅜ (0.375) | 16 | Lgt. | D | 1.31–1.44 | 0.65–0.79 | 0.20–0.24 | 0.64–0.70 | 0.26–0.30 | 0.75–2.00 |
| Reg. | E | 1.81–1.94 | 0.87–1.00 | 0.26–0.33 | 0.86–0.93 | 0.35–0.39 | |||
| Hvy. | F | 2.62–2.76 | 1.31–1.44 | 0.34–0.40 | 1.13–1.19 | 0.51–0.55 | |||
| 7⁄16 (0.4375) | 14 | Lgt. | E | 1.81–1.94 | 0.87–1.00 | 0.26–0.33 | 0.86–0.93 | 0.35–0.39 | 1.00–4.00 |
| Hvy. | F | 2.62–2.76 | 1.31–1.44 | 0.34–0.40 | 1.13–1.19 | 0.51–0.55 | |||
| ½ (0.500) | 13 | Lgt. | E | 1.81–1.94 | 0.87–1.00 | 0.26–0.33 | 0.86–0.93 | 0.35–0.39 | 1.00–4.00 |
| Hvy. | F | 2.62–2.76 | 1.31–1.44 | 0.34–0.40 | 1.13–1.19 | 0.51–0.55 | |||
| ⅝ (0.625) | 11 | Hvy. | F | 2.62–2.76 | 1.31–1.44 | 0.34–0.40 | 1.13–1.19 | 0.51–0.55 | 1.25–4.00 |
Type B Wing Screws — Dimensions
Style 1 (Moderate Height Wings)
| Nominal Size | TPI | A (Wing Spread) | B (Wing Height) | C (Wing Thick.) | E (Boss Dia.) | G (Boss Hgt.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|---|
| #10 (0.190) | 24 | 0.91–0.97 | 0.39–0.45 | 0.12–0.15 | 0.36–0.39 | 0.22–0.28 | 0.50–2.00 |
| ¼ (0.250) | 20 | 1.09–1.16 | 0.50–0.56 | 0.14–0.17 | 0.44–0.47 | 0.28–0.34 | 0.50–3.00 |
| 5⁄16 (0.3125) | 18 | 1.38–1.44 | 0.61–0.67 | 0.15–0.18 | 0.52–0.55 | 0.34–0.41 | 0.50–3.00 |
| ⅜ (0.375) | 16 | 1.66–1.72 | 0.73–0.80 | 0.17–0.20 | 0.60–0.63 | 0.41–0.47 | 0.50–4.00 |
| 7⁄16 (0.4375) | 14 | 1.94–2.00 | 0.84–0.91 | 0.18–0.21 | 0.68–0.71 | 0.47–0.53 | 1.00–3.00 |
| ½ (0.500) | 13 | 2.22–2.31 | 0.94–1.06 | 0.20–0.23 | 0.76–0.79 | 0.50–0.62 | 1.00–3.00 |
| ⅝ (0.625) | 11 | 2.72–2.84 | 1.19–1.31 | 0.23–0.27 | 0.92–0.96 | 0.62–0.75 | 1.00–2.50 |
Style 2 (High Wings)
| Nominal Size | TPI | A (Wing Spread) | B (Wing Height) | C (Wing Thick.) | E (Boss Dia.) | G (Boss Hgt.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|---|
| #10 (0.190) | 24 | 0.95–1.01 | 0.72–0.78 | 0.11–0.14 | 0.36–0.39 | 0.22–0.28 | 0.50–1.25 |
| ¼ (0.250) | 20 | 1.16–1.22 | 0.88–0.94 | 0.13–0.16 | 0.44–0.47 | 0.28–0.34 | 0.50–2.00 |
| 5⁄16 (0.3125) | 18 | 1.37–1.43 | 1.03–1.09 | 0.14–0.17 | 0.52–0.55 | 0.34–0.41 | 0.50–2.00 |
| ⅜ (0.375) | 16 | 1.57–1.63 | 1.19–1.25 | 0.15–0.18 | 0.60–0.63 | 0.41–0.47 | 0.50–2.00 |
Type C Wing Screws — Dimensions
Style 1 (One-Piece Die Cast, Zinc Alloy)
| Nominal Size | TPI | A (Wing Spread) | B (Wing Height) | C (Wing Thick.) | E (Boss Dia.) | G (Boss Hgt.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|---|
| #6 (0.138) | 32 | 0.83–0.85 | 0.43–0.45 | 0.12–0.15 | 0.39–0.41 | 0.07–0.12 | 0.25–0.75 |
| #8 (0.164) | 32 | 0.83–0.85 | 0.43–0.45 | 0.12–0.15 | 0.39–0.41 | 0.07–0.12 | 0.38–1.00 |
| #10 (0.190) | 24, 32 | 0.83–0.85 | 0.43–0.45 | 0.12–0.15 | 0.39–0.41 | 0.07–0.12 | 0.38–1.25 |
| ¼ (0.250) | 20 | 1.05–1.08 | 0.53–0.56 | 0.14–0.17 | 0.44–0.46 | 0.07–0.12 | 0.50–1.50 |
| 5⁄16 (0.3125) | 18 | 1.20–1.23 | 0.62–0.64 | 0.19–0.22 | 0.49–0.51 | 0.10–0.14 | 0.50–1.50 |
| ⅜ (0.375) | 16 | 1.42–1.45 | 0.72–0.74 | 0.21–0.24 | 0.62–0.63 | 0.12–0.15 | 0.50–1.50 |
Style 2 (Two-Piece, Die Cast Wings + Steel Shank)
| Nominal Size | TPI | A (Wing Spread) | B (Wing Height) | C (Wing Thick.) | E-F (Boss Dia.) | G (Boss Hgt.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|---|
| #6 (0.138) | 32 | 0.83–0.85 | 0.42–0.43 | 0.12–0.14 | 0.36–0.41 | 0.18–0.20 | 0.25–1.00 |
| #8 (0.164) | 32 | 0.83–0.85 | 0.42–0.43 | 0.12–0.14 | 0.36–0.41 | 0.18–0.20 | 0.38–1.00 |
| #10 (0.190) | 24, 32 | 0.83–0.85 | 0.42–0.43 | 0.12–0.14 | 0.36–0.41 | 0.18–0.20 | 0.38–2.00 |
| ¼ (0.250) | 20 | 1.05–1.08 | 0.53–0.57 | 0.14–0.16 | 0.42–0.48 | 0.21–0.23 | 0.50–2.50 |
| 5⁄16 (0.3125) | 18 | 1.20–1.23 | 0.62–0.64 | 0.18–0.20 | 0.49–0.57 | 0.24–0.26 | 0.50–3.00 |
| ⅜ (0.375) | 16 | 1.42–1.45 | 0.72–0.74 | 0.21–0.23 | 0.60–0.69 | 0.27–0.29 | 0.75–3.00 |
| 7⁄16 (0.4375) | 14 | 1.86–1.89 | 0.90–0.91 | 0.28–0.29 | 0.73–0.83 | 0.37–0.38 | 1.00–4.00 |
| ½ (0.500) | 13 | 1.86–1.89 | 0.90–0.91 | 0.28–0.29 | 0.73–0.83 | 0.37–0.38 | 1.00–4.00 |
Type D Wing Screws — Dimensions
| Nominal Size | TPI | A (Wing Spread) | B (Wing Height) | C (Wing Thick.) | E-F (Boss Dia.) | G (Boss Hgt.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|---|
| #6 (0.138) | 32 | 0.72–0.78 | 0.34–0.40 | 0.12–0.18 | 0.31–0.40 | 0.14–0.21 | 0.25–0.75 |
| #8 (0.164) | 32 | 0.72–0.78 | 0.34–0.40 | 0.12–0.18 | 0.31–0.40 | 0.14–0.21 | 0.38–0.75 |
| #10 (0.190) | 24 | 0.84–0.90 | 0.40–0.46 | 0.15–0.21 | 0.31–0.53 | 0.16–0.22 | 0.38–1.00 |
| #12 (0.216) | 24 | 1.03–1.09 | 0.40–0.46 | 0.20–0.26 | 0.39–0.61 | 0.18–0.24 | 0.38–1.00 |
| ¼ (0.250) | 20 | 1.03–1.09 | 0.40–0.46 | 0.20–0.26 | 0.43–0.61 | 0.18–0.24 | 0.50–1.50 |
| 5⁄16 (0.3125) | 18 | 1.25–1.31 | 0.56–0.62 | 0.23–0.29 | 0.53–0.68 | 0.23–0.29 | 0.50–1.50 |
| ⅜ (0.375) | 16 | 1.25–1.31 | 0.56–0.62 | 0.23–0.29 | 0.59–0.68 | 0.23–0.29 | 0.75–2.00 |
Materials for Wing Screws
| Wing Screw Type | Primary Material | Shank Treatment | Alternative Materials |
|---|---|---|---|
| Type A | Carbon steel | Shank portion case hardened | Corrosion resistant steel, brass |
| Type B | Carbon steel | Standard | Corrosion resistant steel, brass |
| Type C, Style 1 | Die cast zinc alloy only | N/A (one-piece) | None |
| Type C, Style 2 | Zinc alloy wings + carbon steel shank | Standard | Shank in stainless or brass |
| Type D | Carbon steel | Standard | Corrosion resistant steel, brass |
Critical note for Type A wing screws: The case-hardened shank is a distinguishing feature. This means Type A wing screws have a harder, more wear-resistant thread than other types—making them superior for applications with frequent insertion and removal.
Thumb Screws: The Flat-Head Alternative
A thumb screw has a flattened head (rather than wings) designed for manual turning without a driver or wrench. Thumb screws are classified by type based on design characteristics.
Type A Thumb Screws — With Shoulder
Forged one-piece screws with a shoulder under the head. Available in Regular and Heavy series.
The shoulder provides a precise bearing surface and controlled clamping depth—critical for jig and fixture applications where the screw must locate a workpiece accurately.
Type A Thumb Screw — Regular Series
| Nominal Size | TPI | A (Head Width) | B (Head Height) | C (Head Thick.) | E (Shoulder Dia.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|
| #6 (0.138) | 32 | 0.29–0.31 | 0.31–0.33 | 0.04–0.05 | 0.23–0.25 | 0.25–0.75 |
| #8 (0.164) | 32 | 0.34–0.36 | 0.36–0.38 | 0.05–0.06 | 0.29–0.31 | 0.38–0.75 |
| #10 (0.190) | 24, 32 | 0.40–0.42 | 0.46–0.48 | 0.05–0.06 | 0.32–0.35 | 0.38–1.00 |
| #12 (0.216) | 24 | 0.46–0.48 | 0.52–0.54 | 0.05–0.06 | 0.38–0.40 | 0.38–1.00 |
| ¼ (0.250) | 20 | 0.52–0.55 | 0.61–0.64 | 0.05–0.07 | 0.44–0.47 | 0.50–1.50 |
| 5⁄16 (0.3125) | 18 | 0.67–0.70 | 0.75–0.78 | 0.07–0.09 | 0.56–0.59 | 0.50–1.50 |
| ⅜ (0.375) | 16 | 0.80–0.83 | 0.92–0.95 | 0.09–0.11 | 0.71–0.76 | 0.75–2.00 |
Type A Thumb Screw — Heavy Series
| Nominal Size | TPI | A (Head Width) | B (Head Height) | C (Head Thick.) | C′ (Head Thick.) | E (Shoulder Dia.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|---|
| #10 (0.190) | 24 | 0.83–0.89 | 0.72–0.84 | 0.16–0.18 | 0.08–0.10 | 0.31–0.33 | 0.50–2.00 |
| ¼ (0.250) | 20 | 0.99–1.05 | 0.81–0.94 | 0.22–0.24 | 0.08–0.10 | 0.38–0.40 | 0.50–3.00 |
| 5⁄16 (0.3125) | 18 | 1.15–1.21 | 0.88–1.00 | 0.25–0.27 | 0.09–0.11 | 0.44–0.46 | 0.50–4.00 |
| ⅜ (0.375) | 16 | 1.34–1.41 | 1.03–1.16 | 0.28–0.30 | 0.09–0.11 | 0.53–0.55 | 0.50–4.00 |
| 7⁄16 (0.4375) | 14 | 1.53–1.59 | 1.09–1.22 | 0.34–0.36 | 0.11–0.13 | 0.69–0.71 | 1.00–2.50 |
| ½ (0.500) | 13 | 1.72–1.81 | 1.16–1.28 | 0.38–0.40 | 0.12–0.14 | 0.81–0.83 | 1.00–3.00 |
Type B Thumb Screws — Without Shoulder
Forged one-piece screws without a shoulder. Available in Regular and Heavy series.
Without the shoulder, Type B thumb screws rely entirely on thread engagement for positioning. They're simpler, less expensive, and better suited for applications where precise axial location isn't critical.
Type B Thumb Screw — Regular Series
| Nominal Size | TPI | A (Head Width) | B (Head Height) | C (Head Thick.) | C′ (Head Thick.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|
| #6 (0.138) | 32 | 0.43–0.45 | 0.26–0.28 | 0.06–0.08 | 0.02–0.03 | 0.25–1.00 |
| #8 (0.164) | 32 | 0.49–0.51 | 0.30–0.32 | 0.07–0.09 | 0.02–0.04 | 0.38–1.00 |
| #10 (0.190) | 24, 32 | 0.54–0.58 | 0.36–0.39 | 0.08–0.10 | 0.03–0.05 | 0.38–2.00 |
| #12 (0.216) | 24 | 0.67–0.71 | 0.43–0.45 | 0.09–0.11 | 0.03–0.05 | 0.38–2.00 |
| ¼ (0.250) | 20 | 0.80–0.83 | 0.48–0.52 | 0.14–0.16 | 0.03–0.06 | 0.50–2.50 |
| 5⁄16 (0.3125) | 18 | 0.91–0.96 | 0.60–0.64 | 0.14–0.17 | 0.06–0.09 | 0.50–3.00 |
| ⅜ (0.375) | 16 | 1.03–1.09 | 0.67–0.71 | 0.18–0.22 | 0.08–0.11 | 0.75–3.00 |
| 7⁄16 (0.4375) | 14 | 1.35–1.40 | 0.91–0.96 | 0.24–0.27 | 0.11–0.14 | 1.00–4.00 |
| ½ (0.500) | 13 | 1.46–1.54 | 1.03–1.09 | 0.29–0.33 | 0.11–0.15 | 1.00–4.00 |
Type B Thumb Screw — Heavy Series
| Nominal Size | TPI | A (Head Width) | B (Head Height) | C (Head Thick.) | C′ (Head Thick.) | L (Screw Lengths) |
|---|---|---|---|---|---|---|
| #10 (0.190) | 24 | 0.83–0.89 | 0.66–0.78 | 0.16–0.18 | 0.06–0.08 | 0.50–2.00 |
| ¼ (0.250) | 20 | 0.99–1.05 | 0.72–0.81 | 0.22–0.24 | 0.09–0.11 | 0.50–3.00 |
| 5⁄16 (0.3125) | 18 | 1.15–1.21 | 0.78–0.88 | 0.25–0.27 | 0.09–0.11 | 0.50–4.00 |
| ⅜ (0.375) | 16 | 1.34–1.41 | 0.84–0.94 | 0.28–0.30 | 0.12–0.14 | 0.50–4.00 |
| 7⁄16 (0.4375) | 14 | 1.53–1.59 | 0.91–1.00 | 0.34–0.36 | 0.12–0.14 | 1.00–3.00 |
| ½ (0.500) | 13 | 1.72–1.81 | 0.97–1.09 | 0.38–0.40 | 0.16–0.18 | 1.00–3.00 |
Material for All Thumb Screws
All types of thumb screws are normally made from good commercial quality carbon steel with a maximum ultimate tensile strength of 48,000 psi. When specified, carbon steel thumb screws can be case hardened. They are also available in corrosion resistant steel, brass, and other materials by agreement between manufacturer and user.
Default finish is plain (unplated or uncoated) unless otherwise specified.
How to Specify Wing Screws and Thumb Screws
Specification Sequence
Nominal Size → Threads Per Inch → Length → Type → Style and/or Series → Point (if not plain) → Material → Finish
Correct Specification Examples
10–32 × 1¼, Thumb Screw, Type A, Regular, Steel, Zinc Plated0.375–16 × 2.00, Wing Screw, Type B, Style 2, Steel, Cadmium Plated0.250–20 × 1.50, Wing Screw, Type C, Style 2, Zinc Alloy Wings, Steel Shank, Brass Plated
Lengths of Wing and Thumb Screws
How Length Is Measured
The length of a wing or thumb screw is measured parallel to the axis of the screw, from the intersection of the head or shoulder with the shank to the extreme point of the screw.
Standard Length Increments
For sizes #4 through ¼ inch:
- Nominal lengths 0.25" to 0.75" → 0.12-inch increments (e.g., 0.25, 0.37, 0.50, 0.62, 0.75)
- Nominal lengths 0.75" to 1.50" → 0.25-inch increments (e.g., 0.75, 1.00, 1.25, 1.50)
- Nominal lengths 1.50" to 3.00" → 0.50-inch increments (e.g., 1.50, 2.00, 2.50, 3.00)
For sizes 5⁄16 through ½ inch:
- Nominal lengths 0.50" to 1.50" → 0.25-inch increments
- Nominal lengths 1.50" to 3.00" → 0.50-inch increments
- Nominal lengths 3.00" to 4.00" → 1.00-inch increments (e.g., 3.00, 4.00)
Threads for Wing Screws and Thumb Screws
All types of wing screws and thumb screws use threads conforming to ANSI Standard Unified Thread, Class 2A.
Key Thread Rules
- Additive finish: Class 2A maximum diameters apply to the unplated screw or the screw before plating. The basic diameters (Class 2A max diameters plus the allowance) apply to the screw after plating.
- Thread completeness: All types should have complete (full form) threads extending as close to the head or shoulder as practicable.
Points for Wing and Thumb Screws
Standard Point
Wing and thumb screws are normally supplied with plain points (sheared ends).
Alternate Points Available
When specified, wing and thumb screws can be obtained with five alternate point styles per ANSI B18.17-1968 (R1983):
| Point Type | Description | Best Application |
|---|---|---|
| Plain | Sheared end (default) | General purpose |
| Cup | Concave end with sharp edge | Set screw applications, gripping soft materials |
| Cone | Pointed conical end | Self-centering in countersunk holes |
| Flat | Machined flat end | Clamping against finished surfaces |
| Dog | Cylindrical pilot extending from end | Locating in drilled holes, anti-rotation |
| Oval | Rounded hemispherical end | Clamping without surface damage |
Alternate Point Dimensions
| Nominal Size | O: Cup & Flat Point Dia. | P: Dog Point Dia. | P: Dog Point Length | R: Oval Point Radius |
|---|---|---|---|---|
| #4 (0.112) | 0.051–0.061 | 0.070–0.075 | 0.051–0.061 | 0.084–0.099 |
| #6 (0.138) | 0.064–0.074 | 0.087–0.092 | 0.065–0.075 | 0.109–0.140 |
| #8 (0.164) | 0.076–0.087 | 0.103–0.109 | 0.075–0.085 | 0.125–0.156 |
| #10 (0.190) | 0.088–0.102 | 0.120–0.127 | 0.085–0.095 | 0.141–0.172 |
| #12 (0.216) | 0.101–0.115 | 0.137–0.144 | 0.105–0.115 | 0.156–0.188 |
| ¼ (0.250) | 0.118–0.132 | 0.149–0.156 | 0.120–0.130 | 0.188–0.219 |
| 5⁄16 (0.3125) | 0.156–0.172 | 0.195–0.203 | 0.151–0.161 | 0.234–0.256 |
| ⅜ (0.375) | 0.194–0.212 | 0.241–0.250 | 0.183–0.193 | 0.281–0.312 |
| 7⁄16 (0.4375) | 0.232–0.252 | 0.287–0.297 | 0.214–0.224 | 0.328–0.359 |
| ½ (0.500) | 0.270–0.291 | 0.334–0.344 | 0.245–0.255 | 0.375–0.406 |
| ⅝ (0.625) | 0.347–0.371 | 0.456–0.469 | 0.305–0.321 | 0.469–0.500 |
Important: The external point angles apply to the portions below the thread root diameter. The angle within the thread profile may vary due to manufacturing processes. Dog point eccentricity must not exceed 3% of basic screw diameter or 0.005 inches, whichever is smaller.
. The "Full Specification" Rule
No fastener purchase order at Graystone leaves without a complete specification string. "Wing nuts, quarter-inch" is now a rejected purchase request. The minimum is:
¼–20 Type A Wing Nut, Regular Series, Carbon Steel, Zinc Plated
. The Application Classification System
the practitioner created a three-tier system for every wing nut application in the plant:
| Tier | Criteria | Acceptable Wing Nut Types |
|---|---|---|
| Tier 1 — Critical | Vibration present, corrosive environment, or safety-related guard | Type A or Type B only, stainless or brass |
| Tier 2 — Standard | Moderate use, indoor, non-safety application | Type A, B, or C |
| Tier 3 — Light Duty | Static, infrequent removal, non-critical | Any type including D |
. The Incoming Inspection Protocol
Every fastener shipment now gets a spot check against the purchase specification. the practitioner's team verifies type (solid vs. stamped), material (magnetic test for steel vs. stainless), and wing dimensions (caliper check against the ANSI tables).
. The Bin Labeling System
Every wing nut bin in the maintenance crib now shows the full ANSI designation, not just the thread size. A typical label reads:
¼-20 TYPE A WING NUT
REGULAR SERIES | CARBON STEEL | ZINC PLATED
TIER 1 APPROVED — CHEMICAL LINE USEQuick-Reference Decision Matrix
Use this when you're standing in front of a parts bin trying to make a fast, correct decision:
"Do I need tool-free removal?"
- Yes → Wing nut, wing screw, or thumb screw
- No → Use a standard hex nut with wrench
"Do I need to retain the fastener on the bolt/stud?"
- Yes → Wing nut (stays on the bolt) or thumb screw
- No → Wing screw (self-contained)
"Will the joint experience vibration?"
- Yes → Type A or Type B only
- No → Any type
"Is corrosion a concern?"
- Yes → Specify stainless steel or brass (avoid Type C zinc alloy)
- No → Carbon steel with appropriate plating
"Do operators wear heavy gloves?"
- Yes → Type B Style 2 (high wings) for maximum grip
- No → Any style
"Is this a high-volume consumer product?"
- Yes → Type C (die cast) for dimensional consistency and cost
- No → Type A or B for durability
"Is budget the primary constraint?"
- Yes → Type D (stamped) for non-critical, static applications
- No → Type A for best all-around performance
Engineering takeaway
the practitioner's story isn't unusual. Across manufacturing plants, maintenance shops, and design offices worldwide, wing nuts, wing screws, and thumb screws are treated as commodity items—ordered by thread size alone, pulled from mixed bins, and installed without a second thought about type, style, series, or material.
Until something fails.
The engineering behind these "simple" fasteners spans four manufacturing methods, multiple wing styles, three weight series, five point options, four material families, and dimensional tables covering dozens of sizes. ANSI B18.17-1968 (R1983) exists for a reason: because the wrong wing nut in the wrong application creates consequences that far exceed its cost.
The lesson is universal: Specification precision prevents failure. Whether you're designing a new machine, maintaining an existing line, or purchasing fasteners for a shop, the investment of specifying wing nuts, wing screws, and thumb screws correctly—by type, style, series, material, and finish—pays for itself the first time you avoid a shutdown, a warranty claim, or a safety incident.
Your Next Step
Pull up your last three purchase orders for wing nuts, wing screws, or thumb screws. Check them against the specification format in this guide:
Nominal Size → TPI → Type → Style/Series → Material → Finish
If any of those fields are missing, you have a specification gap that could produce the same failure the practitioner experienced at Graystone.
Close that gap today. Your production line will thank you.
All specifications referenced from ANSI B18.17-1968 (R1983). Standard dimensional data in inches. For metric conversions, multiply inch values by 25.4. Verify current standard revisions with your national standards body before use in critical applications.