steve/inch-lock-washer

Inch lock washers, ASME B18.21.1: regular split (helical spring) and external tooth, #2 to 1/2.

v1.0.0 Latest STEVE MIT 0

Open in STEVE

Isometric

Parameters

Preset18 sizes

Screw size9 options

Style

splittooth

split: regular helical spring lock washer; tooth: external tooth lock washer.

Material2 options

Defaults built

part.py 35 lines · Python · STEVE runtime · checked

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"""Inch lock washers, ASME B18.21.1: regular helical spring lock washers (split) and external tooth lock washers.

Envelope models for assemblies: the flat blank, an annulus from the minimum inside diameter to the maximum outside

diameter, as thick as the section (split: the minimum mean section thickness; tooth: the maximum thickness), lying on

the XY plane, centred on the origin. The split washer's helical split and the tooth washer's twisted teeth are not

dimensioned by the standard's tables and are not modelled. The model is in millimetres (1 in = 25.4 mm).

"""

from steve import Model

size = "#10" # Nominal size (screw)

style = "split" # Washer style

material = "steel" # Material

# Inches. ASME B18.21.1-2009 (R2016) Table 1, regular helical spring lock washers: (d min, dc max, h min)

SPLIT = {"#2": (0.088, 0.172, 0.020), "#4": (0.114, 0.209, 0.025), "#6": (0.141, 0.250, 0.031),

"#8": (0.167, 0.293, 0.040), "#10": (0.193, 0.334, 0.047), "1/4": (0.252, 0.487, 0.062),

"5/16": (0.314, 0.583, 0.078), "3/8": (0.377, 0.680, 0.094), "1/2": (0.502, 0.869, 0.125)}

# Inches. ASME B18.21.1 external tooth lock washers: (d min, dc max, t max); #2 from the 1999 edition.

TOOTH = {"#2": (0.086, 0.189, 0.013), "#4": (0.115, 0.260, 0.018), "#6": (0.141, 0.320, 0.022),

"#8": (0.168, 0.381, 0.023), "#10": (0.195, 0.410, 0.024), "1/4": (0.256, 0.510, 0.028),

"5/16": (0.320, 0.610, 0.034), "3/8": (0.384, 0.694, 0.040), "1/2": (0.513, 0.900, 0.045)}

MATERIALS = {"steel": ("steel-generic", "#8d9096"), "stainless-18-8": ("stainless-304", "#c9ccd0")}

INCH = 25.4

d, D, t = (v * INCH for v in {"split": SPLIT, "tooth": TOOTH}[style][size])

material_id, colour = MATERIALS[material]

model = Model()

with model.sketch("washer_sketch", on="XY", name="Washer") as sk:

sk.circle("outside", (0, 0), D / 2)

sk.circle("inside", (0, 0), d / 2)

model.extrude("washer", "washer_sketch", distance=t, name="Washer")

model.material(material_id, color=colour)

result = model.result()

"""Inch lock washers, ASME B18.21.1: regular helical spring lock washers (split) and external tooth lock washers.

Envelope models for assemblies: the flat blank, an annulus from the minimum inside diameter to the maximum outside
diameter, as thick as the section (split: the minimum mean section thickness; tooth: the maximum thickness), lying on
the XY plane, centred on the origin. The split washer's helical split and the tooth washer's twisted teeth are not
dimensioned by the standard's tables and are not modelled. The model is in millimetres (1 in = 25.4 mm).
"""
from steve import Model

size = "#10"  # Nominal size (screw)
style = "split"  # Washer style
material = "steel"  # Material

# Inches. ASME B18.21.1-2009 (R2016) Table 1, regular helical spring lock washers: (d min, dc max, h min)
SPLIT = {"#2": (0.088, 0.172, 0.020), "#4": (0.114, 0.209, 0.025), "#6": (0.141, 0.250, 0.031),
         "#8": (0.167, 0.293, 0.040), "#10": (0.193, 0.334, 0.047), "1/4": (0.252, 0.487, 0.062),
         "5/16": (0.314, 0.583, 0.078), "3/8": (0.377, 0.680, 0.094), "1/2": (0.502, 0.869, 0.125)}
# Inches. ASME B18.21.1 external tooth lock washers: (d min, dc max, t max); #2 from the 1999 edition.
TOOTH = {"#2": (0.086, 0.189, 0.013), "#4": (0.115, 0.260, 0.018), "#6": (0.141, 0.320, 0.022),
         "#8": (0.168, 0.381, 0.023), "#10": (0.195, 0.410, 0.024), "1/4": (0.256, 0.510, 0.028),
         "5/16": (0.320, 0.610, 0.034), "3/8": (0.384, 0.694, 0.040), "1/2": (0.513, 0.900, 0.045)}
MATERIALS = {"steel": ("steel-generic", "#8d9096"), "stainless-18-8": ("stainless-304", "#c9ccd0")}
INCH = 25.4

d, D, t = (v * INCH for v in {"split": SPLIT, "tooth": TOOTH}[style][size])
material_id, colour = MATERIALS[material]

model = Model()
with model.sketch("washer_sketch", on="XY", name="Washer") as sk:
    sk.circle("outside", (0, 0), D / 2)
    sk.circle("inside", (0, 0), d / 2)
model.extrude("washer", "washer_sketch", distance=t, name="Washer")
model.material(material_id, color=colour)
result = model.result()

pypart.toml 157 lines · TOML

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name = "steve/inch-lock-washer"

version = "1.0.0"

runtime = "steve"

license = "MIT"

summary = "Inch lock washers, ASME B18.21.1: regular split (helical spring) and external tooth, #2 to 1/2."

description = """Lock washers for inch screws #2 to 1/2 (ASME B18.21.1): regular helical spring lock washers (split) \

and external tooth lock washers. Envelope geometry for assemblies: the flat blank from the minimum inside diameter to \

the maximum outside diameter at the section's thickness; the split and the twisted teeth are not modelled.

It lies on the XY plane, centred on the origin (the model is in millimetres). Dimensions: see the README."""

tags = ["fastener", "washer", "lock-washer", "split-lock-washer", "tooth-lock-washer", "asme-b18-21-1", "inch"]

[parameters.size]

type = "choice"

default = "#10"

choices = ["#2", "#4", "#6", "#8", "#10", "1/4", "5/16", "3/8", "1/2"]

label = "Screw size"

[parameters.style]

type = "choice"

default = "split"

choices = ["split", "tooth"]

label = "Style"

description = "split: regular helical spring lock washer; tooth: external tooth lock washer."

[parameters.material]

type = "choice"

default = "steel"

choices = ["steel", "stainless-18-8"]

label = "Material"

[[presets]]

id = "split-no2"

title = "#2 split lock washer"

params = { size = "#2", style = "split" }

aliases = ["#2 split lock washer", "#2-56 split lock washer", "ASME B18.21.1 #2 split lock washer", "#2 helical spring lock washer", "#2 regular lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "split-no4"

title = "#4 split lock washer"

params = { size = "#4", style = "split" }

aliases = ["#4 split lock washer", "#4-40 split lock washer", "ASME B18.21.1 #4 split lock washer", "#4 helical spring lock washer", "#4 regular lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "split-no6"

title = "#6 split lock washer"

params = { size = "#6", style = "split" }

aliases = ["#6 split lock washer", "#6-32 split lock washer", "ASME B18.21.1 #6 split lock washer", "#6 helical spring lock washer", "#6 regular lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "split-no8"

title = "#8 split lock washer"

params = { size = "#8", style = "split" }

aliases = ["#8 split lock washer", "#8-32 split lock washer", "ASME B18.21.1 #8 split lock washer", "#8 helical spring lock washer", "#8 regular lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "split-no10"

title = "#10 split lock washer"

params = { size = "#10", style = "split" }

aliases = ["#10 split lock washer", "#10-24 split lock washer", "ASME B18.21.1 #10 split lock washer", "#10 helical spring lock washer", "#10 regular lock washer", "#10-32 split lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "split-1-4"

title = "1/4 split lock washer"

params = { size = "1/4", style = "split" }

aliases = ["1/4 split lock washer", "1/4-20 split lock washer", "ASME B18.21.1 1/4 split lock washer", "1/4 helical spring lock washer", "1/4 regular lock washer", "1/4-28 split lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "split-5-16"

title = "5/16 split lock washer"

params = { size = "5/16", style = "split" }

aliases = ["5/16 split lock washer", "5/16-18 split lock washer", "ASME B18.21.1 5/16 split lock washer", "5/16 helical spring lock washer", "5/16 regular lock washer", "5/16-24 split lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "split-3-8"

title = "3/8 split lock washer"

params = { size = "3/8", style = "split" }

aliases = ["3/8 split lock washer", "3/8-16 split lock washer", "ASME B18.21.1 3/8 split lock washer", "3/8 helical spring lock washer", "3/8 regular lock washer", "3/8-24 split lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "split-1-2"

title = "1/2 split lock washer"

params = { size = "1/2", style = "split" }

aliases = ["1/2 split lock washer", "1/2-13 split lock washer", "ASME B18.21.1 1/2 split lock washer", "1/2 helical spring lock washer", "1/2 regular lock washer", "1/2-20 split lock washer"]

standard = "ASME B18.21.1"

[[presets]]

id = "tooth-no2"

title = "#2 external tooth lock washer"

params = { size = "#2", style = "tooth" }

aliases = ["#2 external tooth lock washer", "#2-56 external tooth lock washer", "ASME B18.21.1 #2 external tooth lock washer", "#2 star washer", "#2 external star lock washer"]

100

standard = "ASME B18.21.1"

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[[presets]]

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id = "tooth-no4"

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title = "#4 external tooth lock washer"

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params = { size = "#4", style = "tooth" }

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aliases = ["#4 external tooth lock washer", "#4-40 external tooth lock washer", "ASME B18.21.1 #4 external tooth lock washer", "#4 star washer", "#4 external star lock washer"]

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standard = "ASME B18.21.1"

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[[presets]]

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id = "tooth-no6"

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title = "#6 external tooth lock washer"

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params = { size = "#6", style = "tooth" }

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aliases = ["#6 external tooth lock washer", "#6-32 external tooth lock washer", "ASME B18.21.1 #6 external tooth lock washer", "#6 star washer", "#6 external star lock washer"]

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standard = "ASME B18.21.1"

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[[presets]]

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id = "tooth-no8"

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title = "#8 external tooth lock washer"

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params = { size = "#8", style = "tooth" }

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aliases = ["#8 external tooth lock washer", "#8-32 external tooth lock washer", "ASME B18.21.1 #8 external tooth lock washer", "#8 star washer", "#8 external star lock washer"]

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standard = "ASME B18.21.1"

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[[presets]]

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id = "tooth-no10"

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title = "#10 external tooth lock washer"

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params = { size = "#10", style = "tooth" }

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aliases = ["#10 external tooth lock washer", "#10-24 external tooth lock washer", "ASME B18.21.1 #10 external tooth lock washer", "#10 star washer", "#10 external star lock washer", "#10-32 external tooth lock washer"]

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standard = "ASME B18.21.1"

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[[presets]]

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id = "tooth-1-4"

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title = "1/4 external tooth lock washer"

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params = { size = "1/4", style = "tooth" }

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aliases = ["1/4 external tooth lock washer", "1/4-20 external tooth lock washer", "ASME B18.21.1 1/4 external tooth lock washer", "1/4 star washer", "1/4 external star lock washer", "1/4-28 external tooth lock washer"]

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standard = "ASME B18.21.1"

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[[presets]]

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id = "tooth-5-16"

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title = "5/16 external tooth lock washer"

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params = { size = "5/16", style = "tooth" }

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aliases = ["5/16 external tooth lock washer", "5/16-18 external tooth lock washer", "ASME B18.21.1 5/16 external tooth lock washer", "5/16 star washer", "5/16 external star lock washer", "5/16-24 external tooth lock washer"]

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standard = "ASME B18.21.1"

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[[presets]]

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id = "tooth-3-8"

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title = "3/8 external tooth lock washer"

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params = { size = "3/8", style = "tooth" }

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aliases = ["3/8 external tooth lock washer", "3/8-16 external tooth lock washer", "ASME B18.21.1 3/8 external tooth lock washer", "3/8 star washer", "3/8 external star lock washer", "3/8-24 external tooth lock washer"]

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standard = "ASME B18.21.1"

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[[presets]]

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id = "tooth-1-2"

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title = "1/2 external tooth lock washer"

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params = { size = "1/2", style = "tooth" }

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aliases = ["1/2 external tooth lock washer", "1/2-13 external tooth lock washer", "ASME B18.21.1 1/2 external tooth lock washer", "1/2 star washer", "1/2 external star lock washer", "1/2-20 external tooth lock washer"]

156

standard = "ASME B18.21.1"

157

name = "steve/inch-lock-washer"
version = "1.0.0"
runtime = "steve"
license = "MIT"
summary = "Inch lock washers, ASME B18.21.1: regular split (helical spring) and external tooth, #2 to 1/2."
description = """Lock washers for inch screws #2 to 1/2 (ASME B18.21.1): regular helical spring lock washers (split) \
and external tooth lock washers. Envelope geometry for assemblies: the flat blank from the minimum inside diameter to \
the maximum outside diameter at the section's thickness; the split and the twisted teeth are not modelled.

It lies on the XY plane, centred on the origin (the model is in millimetres). Dimensions: see the README."""
tags = ["fastener", "washer", "lock-washer", "split-lock-washer", "tooth-lock-washer", "asme-b18-21-1", "inch"]

[parameters.size]
type = "choice"
default = "#10"
choices = ["#2", "#4", "#6", "#8", "#10", "1/4", "5/16", "3/8", "1/2"]
label = "Screw size"

[parameters.style]
type = "choice"
default = "split"
choices = ["split", "tooth"]
label = "Style"
description = "split: regular helical spring lock washer; tooth: external tooth lock washer."

[parameters.material]
type = "choice"
default = "steel"
choices = ["steel", "stainless-18-8"]
label = "Material"

[[presets]]
id = "split-no2"
title = "#2 split lock washer"
params = { size = "#2", style = "split" }
aliases = ["#2 split lock washer", "#2-56 split lock washer", "ASME B18.21.1 #2 split lock washer", "#2 helical spring lock washer", "#2 regular lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "split-no4"
title = "#4 split lock washer"
params = { size = "#4", style = "split" }
aliases = ["#4 split lock washer", "#4-40 split lock washer", "ASME B18.21.1 #4 split lock washer", "#4 helical spring lock washer", "#4 regular lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "split-no6"
title = "#6 split lock washer"
params = { size = "#6", style = "split" }
aliases = ["#6 split lock washer", "#6-32 split lock washer", "ASME B18.21.1 #6 split lock washer", "#6 helical spring lock washer", "#6 regular lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "split-no8"
title = "#8 split lock washer"
params = { size = "#8", style = "split" }
aliases = ["#8 split lock washer", "#8-32 split lock washer", "ASME B18.21.1 #8 split lock washer", "#8 helical spring lock washer", "#8 regular lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "split-no10"
title = "#10 split lock washer"
params = { size = "#10", style = "split" }
aliases = ["#10 split lock washer", "#10-24 split lock washer", "ASME B18.21.1 #10 split lock washer", "#10 helical spring lock washer", "#10 regular lock washer", "#10-32 split lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "split-1-4"
title = "1/4 split lock washer"
params = { size = "1/4", style = "split" }
aliases = ["1/4 split lock washer", "1/4-20 split lock washer", "ASME B18.21.1 1/4 split lock washer", "1/4 helical spring lock washer", "1/4 regular lock washer", "1/4-28 split lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "split-5-16"
title = "5/16 split lock washer"
params = { size = "5/16", style = "split" }
aliases = ["5/16 split lock washer", "5/16-18 split lock washer", "ASME B18.21.1 5/16 split lock washer", "5/16 helical spring lock washer", "5/16 regular lock washer", "5/16-24 split lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "split-3-8"
title = "3/8 split lock washer"
params = { size = "3/8", style = "split" }
aliases = ["3/8 split lock washer", "3/8-16 split lock washer", "ASME B18.21.1 3/8 split lock washer", "3/8 helical spring lock washer", "3/8 regular lock washer", "3/8-24 split lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "split-1-2"
title = "1/2 split lock washer"
params = { size = "1/2", style = "split" }
aliases = ["1/2 split lock washer", "1/2-13 split lock washer", "ASME B18.21.1 1/2 split lock washer", "1/2 helical spring lock washer", "1/2 regular lock washer", "1/2-20 split lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-no2"
title = "#2 external tooth lock washer"
params = { size = "#2", style = "tooth" }
aliases = ["#2 external tooth lock washer", "#2-56 external tooth lock washer", "ASME B18.21.1 #2 external tooth lock washer", "#2 star washer", "#2 external star lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-no4"
title = "#4 external tooth lock washer"
params = { size = "#4", style = "tooth" }
aliases = ["#4 external tooth lock washer", "#4-40 external tooth lock washer", "ASME B18.21.1 #4 external tooth lock washer", "#4 star washer", "#4 external star lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-no6"
title = "#6 external tooth lock washer"
params = { size = "#6", style = "tooth" }
aliases = ["#6 external tooth lock washer", "#6-32 external tooth lock washer", "ASME B18.21.1 #6 external tooth lock washer", "#6 star washer", "#6 external star lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-no8"
title = "#8 external tooth lock washer"
params = { size = "#8", style = "tooth" }
aliases = ["#8 external tooth lock washer", "#8-32 external tooth lock washer", "ASME B18.21.1 #8 external tooth lock washer", "#8 star washer", "#8 external star lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-no10"
title = "#10 external tooth lock washer"
params = { size = "#10", style = "tooth" }
aliases = ["#10 external tooth lock washer", "#10-24 external tooth lock washer", "ASME B18.21.1 #10 external tooth lock washer", "#10 star washer", "#10 external star lock washer", "#10-32 external tooth lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-1-4"
title = "1/4 external tooth lock washer"
params = { size = "1/4", style = "tooth" }
aliases = ["1/4 external tooth lock washer", "1/4-20 external tooth lock washer", "ASME B18.21.1 1/4 external tooth lock washer", "1/4 star washer", "1/4 external star lock washer", "1/4-28 external tooth lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-5-16"
title = "5/16 external tooth lock washer"
params = { size = "5/16", style = "tooth" }
aliases = ["5/16 external tooth lock washer", "5/16-18 external tooth lock washer", "ASME B18.21.1 5/16 external tooth lock washer", "5/16 star washer", "5/16 external star lock washer", "5/16-24 external tooth lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-3-8"
title = "3/8 external tooth lock washer"
params = { size = "3/8", style = "tooth" }
aliases = ["3/8 external tooth lock washer", "3/8-16 external tooth lock washer", "ASME B18.21.1 3/8 external tooth lock washer", "3/8 star washer", "3/8 external star lock washer", "3/8-24 external tooth lock washer"]
standard = "ASME B18.21.1"

[[presets]]
id = "tooth-1-2"
title = "1/2 external tooth lock washer"
params = { size = "1/2", style = "tooth" }
aliases = ["1/2 external tooth lock washer", "1/2-13 external tooth lock washer", "ASME B18.21.1 1/2 external tooth lock washer", "1/2 star washer", "1/2 external star lock washer", "1/2-20 external tooth lock washer"]
standard = "ASME B18.21.1"

README.md 48 lines · Markdown

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Inch lock washers (ASME B18.21.1)

Regular helical spring lock washers (split) and external tooth lock washers for inch screws #2 to 1/2. Presets cover the catalogue's inch split and external-tooth lock washers.

Geometry

Envelope for assemblies: the flat blank, an annulus from the minimum inside diameter d to the maximum outside diameter dc, as thick as the section (split: h, the minimum mean section thickness; tooth: t max), lying on the XY plane, centred on the origin. The tables do not dimension the split washer's helix or gap, nor the tooth washer's teeth (count, shape, twist), so neither is modelled. The model is in millimetres (1 in = 25.4 mm).

Parameters

Parameter	Meaning
`size`	Screw size, #2 to 1/2
`style`	`split` (regular helical spring lock washer) or `tooth` (external tooth lock washer)
`material`	`steel` or `stainless-18-8` (304)

Sources

ASME B18.21.1-2009 (R2016), Washers: Helical Spring-Lock, Tooth Lock, and Plain Washers (Inch Series), Table 1 "Regular Helical Spring-Lock Washers" (reproduction consulted: https://www.globalfastener.com/standards/detail_22194.html) and the External Tooth-Lock Washers table (https://www.globalfastener.com/standards/detail_22201.html; it starts at #3).
#2 external tooth: ASME B18.21.1-1999 as reproduced by Aspen Fasteners, "External Tooth Lock Washers ASME B18.21.1-1999", p. 2 (https://www.aspenfasteners.com/content/pdf/external_tooth_lockwasher_specification.pdf), whose values for #3 to 1/2 are the same as the 2009 table's.

Inches:

Size	Split d min	Split dc max	Split h min	Tooth d min	Tooth dc max	Tooth t max
#2	.088	.172	.020	.086	.189	.013
#4	.114	.209	.025	.115	.260	.018
#6	.141	.250	.031	.141	.320	.022
#8	.167	.293	.040	.168	.381	.023
#10	.193	.334	.047	.195	.410	.024
1/4	.252	.487	.062	.256	.510	.028
5/16	.314	.583	.078	.320	.610	.034
3/8	.377	.680	.094	.384	.694	.040
1/2	.502	.869	.125	.513	.900	.045

Not covered: #0 (in neither table).

Preset list: sizes of the step.parts catalogue (MIT), see library/NOTICE.md.

# Inch lock washers (ASME B18.21.1)

Regular helical spring lock washers (split) and external tooth lock washers for inch screws #2 to 1/2. Presets

cover the catalogue's inch split and external-tooth lock washers.

## Geometry

Envelope for assemblies: the flat blank, an annulus from the minimum inside diameter **d** to the maximum outside

diameter **dc**, as thick as the section (split: **h**, the minimum mean section thickness; tooth: **t** max), lying on

the XY plane, centred on the origin. The tables do not dimension the split washer's helix or gap, nor the tooth

washer's teeth (count, shape, twist), so neither is modelled. The model is in millimetres (1 in = 25.4 mm).

## Parameters

| Parameter | Meaning |

|---|---|

| `size` | Screw size, #2 to 1/2 |

| `style` | `split` (regular helical spring lock washer) or `tooth` (external tooth lock washer) |

| `material` | `steel` or `stainless-18-8` (304) |

## Sources

- ASME B18.21.1-2009 (R2016), *Washers: Helical Spring-Lock, Tooth Lock, and Plain Washers (Inch Series)*,

**Table 1** "Regular Helical Spring-Lock Washers" (reproduction consulted:

https://www.globalfastener.com/standards/detail_22194.html) and the **External Tooth-Lock Washers** table

(https://www.globalfastener.com/standards/detail_22201.html; it starts at #3).

- #2 external tooth: ASME B18.21.1-1999 as reproduced by Aspen Fasteners, "External Tooth Lock Washers ASME

B18.21.1-1999", p. 2 (https://www.aspenfasteners.com/content/pdf/external_tooth_lockwasher_specification.pdf),

whose values for #3 to 1/2 are the same as the 2009 table's.

Inches:

|---|---|---|---|---|---|---|

| #2 | .088 | .172 | .020 | .086 | .189 | .013 |

| #4 | .114 | .209 | .025 | .115 | .260 | .018 |

| #6 | .141 | .250 | .031 | .141 | .320 | .022 |

| #8 | .167 | .293 | .040 | .168 | .381 | .023 |

| #10 | .193 | .334 | .047 | .195 | .410 | .024 |

| 1/4 | .252 | .487 | .062 | .256 | .510 | .028 |

| 5/16 | .314 | .583 | .078 | .320 | .610 | .034 |

| 3/8 | .377 | .680 | .094 | .384 | .694 | .040 |

| 1/2 | .502 | .869 | .125 | .513 | .900 | .045 |

Not covered: #0 (in neither table).

Preset list: sizes of the step.parts catalogue (MIT), see `library/NOTICE.md`.

# Inch lock washers (ASME B18.21.1)

Regular helical spring lock washers (split) and external tooth lock washers for inch screws #2 to 1/2. Presets
cover the catalogue's inch split and external-tooth lock washers.

## Geometry

Envelope for assemblies: the flat blank, an annulus from the minimum inside diameter **d** to the maximum outside
diameter **dc**, as thick as the section (split: **h**, the minimum mean section thickness; tooth: **t** max), lying on
the XY plane, centred on the origin. The tables do not dimension the split washer's helix or gap, nor the tooth
washer's teeth (count, shape, twist), so neither is modelled. The model is in millimetres (1 in = 25.4 mm).

## Parameters

| Parameter | Meaning |
|---|---|
| `size` | Screw size, #2 to 1/2 |
| `style` | `split` (regular helical spring lock washer) or `tooth` (external tooth lock washer) |
| `material` | `steel` or `stainless-18-8` (304) |

## Sources

- ASME B18.21.1-2009 (R2016), *Washers: Helical Spring-Lock, Tooth Lock, and Plain Washers (Inch Series)*,
  **Table 1** "Regular Helical Spring-Lock Washers" (reproduction consulted:
  https://www.globalfastener.com/standards/detail_22194.html) and the **External Tooth-Lock Washers** table
  (https://www.globalfastener.com/standards/detail_22201.html; it starts at #3).
- #2 external tooth: ASME B18.21.1-1999 as reproduced by Aspen Fasteners, "External Tooth Lock Washers ASME
  B18.21.1-1999", p. 2 (https://www.aspenfasteners.com/content/pdf/external_tooth_lockwasher_specification.pdf),
  whose values for #3 to 1/2 are the same as the 2009 table's.

Inches:

| Size | Split d min | Split dc max | Split h min | Tooth d min | Tooth dc max | Tooth t max |
|---|---|---|---|---|---|---|
| #2 | .088 | .172 | .020 | .086 | .189 | .013 |
| #4 | .114 | .209 | .025 | .115 | .260 | .018 |
| #6 | .141 | .250 | .031 | .141 | .320 | .022 |
| #8 | .167 | .293 | .040 | .168 | .381 | .023 |
| #10 | .193 | .334 | .047 | .195 | .410 | .024 |
| 1/4 | .252 | .487 | .062 | .256 | .510 | .028 |
| 5/16 | .314 | .583 | .078 | .320 | .610 | .034 |
| 3/8 | .377 | .680 | .094 | .384 | .694 | .040 |
| 1/2 | .502 | .869 | .125 | .513 | .900 | .045 |

Not covered: #0 (in neither table).

Preset list: sizes of the step.parts catalogue (MIT), see `library/NOTICE.md`.

Use this part

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Open it in STEVE The STEVE runtime runs in STEVE: open the part there, or download the code and bundle.

Get the code

curl -o part.py "https://pythonparts.org/p/steve/inch-lock-washer/v/1.0.0/raw/part.py"

Raw files, bundle and API

part.py
pypart.toml
README.md
bundle.tar.gzthe package, as published

curl "https://pythonparts.org/api/v1/parts/steve/inch-lock-washer/1.0.0"

The version's JSON (parameters, presets, files); add /build?name=value for a build at other values.

About this part

steve58 parts

Profile

Steel (generic)Carbon & alloy steels · Custom finish · 7.9 g/cm³

Mass: 0.36 g

At the parameters shown in the viewer.

License: MIT

Permissive: use, change and sell it; keep the copyright notice.

Runtime: STEVE
Built with: CadQuery 2.9.0.dev0
Published: Nov 1, 2026
Downloads: 0
Builds: 0
Stars: 0
Bundle: 410e6a65fc1b…

#fastener #washer #lock-washer #split-lock-washer #tooth-lock-washer #asme-b18-21-1 #inch

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Lock washers for inch screws #2 to 1/2 (ASME B18.21.1): regular helical spring lock washers (split) and external tooth lock washers. Envelope geometry for assemblies: the flat blank from the minimum inside diameter to the maximum outside diameter at the section's thickness; the split and the twisted teeth are not modelled. It lies on the XY plane, centred on the origin (the model is in millimetres). Dimensions: see the README.

Inch lock washers (ASME B18.21.1)

Regular helical spring lock washers (split) and external tooth lock washers for inch screws #2 to 1/2. Presets cover the catalogue's inch split and external-tooth lock washers.

Geometry

Parameters

Parameter	Meaning
`size`	Screw size, #2 to 1/2
`style`	`split` (regular helical spring lock washer) or `tooth` (external tooth lock washer)
`material`	`steel` or `stainless-18-8` (304)

Sources

ASME B18.21.1-2009 (R2016), Washers: Helical Spring-Lock, Tooth Lock, and Plain Washers (Inch Series), Table 1 "Regular Helical Spring-Lock Washers" (reproduction consulted: https://www.globalfastener.com/standards/detail_22194.html) and the External Tooth-Lock Washers table (https://www.globalfastener.com/standards/detail_22201.html; it starts at #3).
#2 external tooth: ASME B18.21.1-1999 as reproduced by Aspen Fasteners, "External Tooth Lock Washers ASME B18.21.1-1999", p. 2 (https://www.aspenfasteners.com/content/pdf/external_tooth_lockwasher_specification.pdf), whose values for #3 to 1/2 are the same as the 2009 table's.

Inches:

Size	Split d min	Split dc max	Split h min	Tooth d min	Tooth dc max	Tooth t max
#2	.088	.172	.020	.086	.189	.013
#4	.114	.209	.025	.115	.260	.018
#6	.141	.250	.031	.141	.320	.022
#8	.167	.293	.040	.168	.381	.023
#10	.193	.334	.047	.195	.410	.024
1/4	.252	.487	.062	.256	.510	.028
5/16	.314	.583	.078	.320	.610	.034
3/8	.377	.680	.094	.384	.694	.040
1/2	.502	.869	.125	.513	.900	.045

Not covered: #0 (in neither table).

Preset list: sizes of the step.parts catalogue (MIT), see library/NOTICE.md.

1.0.0 Latest Nov 1, 2026 · 1 day ago

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Inch lock washers (ASME B18.21.1)

Geometry

Parameters

Sources

Inch lock washers (ASME B18.21.1)

Geometry

Parameters

Sources

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