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3 files changed, +80 −19 1.1.0: Looks like a bearing: rings and rolling elements. detail = simple keeps one solid ring.

Requirements

at each version’s default parameters

4 changes 4 added

19638148tolerance_class addedNote: ISO 492 normal tolerance class
29309899width added? 0/−0.120
42771306bore added? 0/−0.010 (SD) (ACS)
64593396outside_diameter added⌀47 0/−0.011 (SD) (ACS)

1.1.0 has 2 broken requirements.

part.py +53 −11

@@ -1,18 +1,60 @@

"""Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm: envelope for assemblies, one solid with the boundary dimensions bore d, outside

diameter D and width B. Rolling elements, cage and the gaps between the rings are not modelled. Axis along Z, centred on the origin."""

"""Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm. Bore d, outside diameter D, width B, chamfer r and the raceway diameters Fw (inner) and Ew (outer) are sourced and make the fit. detail = "full": a plain inner ring, an outer ring with a rib at each end, and the rollers between them, whose diameter follows from (Ew - Fw) / 2. Rib height, roller length and roller count are proportions for looks, not for design, and never change the fit dimensions; the cage is not drawn. detail = "simple": one solid ring. Axis along Z, centred on the origin."""

import math

from steve import Model

designation = "NU208" # Bearing number

designation = "NU204" # Bearing number

detail = "full" # full: rings and rolling elements; simple: one solid

# number: (d, D, B). NTN Ball and Roller Bearings CAT. No. 2203-3/E (2024), pp. B-71 to B-72 (PDF pages 147 and 148), boundary dimensions.

BEARINGS = {"NU204": (20, 47, 14), "NU205": (25, 52, 15), "NU206": (30, 62, 16), "NU207": (35, 72, 17), "NU208": (40, 80, 18), "NU209": (45, 85, 19), "NU210": (50, 90, 20), "NU304": (20, 52, 15), "NU305": (25, 62, 17), "NU306": (30, 72, 19), "NU307": (35, 80, 21), "NU308": (40, 90, 23), "NU309": (45, 100, 25), "NU310": (50, 110, 27)}

# number: (d, D, B, r, Fw, Ew). NTN Ball and Roller Bearings CAT. No. 2203-3/E (2024), pp. B-71 to B-72 (PDF pages 147-148), https://www.ntnglobal.com/en/products/catalog/pdf/2203E.pdf

BEARINGS = {"NU204": (20, 47, 14, 1, 26.5, 41.5), "NU205": (25, 52, 15, 1, 31.5, 46.5), "NU206": (30, 62, 16, 1, 37.5, 55.5), "NU207": (35, 72, 17, 1.1, 44, 64), "NU208": (40, 80, 18, 1.1, 49.5, 71.5), "NU209": (45, 85, 19, 1.1, 54.5, 76.5), "NU210": (50, 90, 20, 1.1, 59.5, 81.5), "NU304": (20, 52, 15, 1.1, 27.5, 45.5), "NU305": (25, 62, 17, 1.1, 34, 54), "NU306": (30, 72, 19, 1.1, 40.5, 62.5), "NU307": (35, 80, 21, 1.5, 46.2, 70.2), "NU308": (40, 90, 23, 1.5, 52, 80), "NU309": (45, 100, 25, 1.5, 58.5, 88.5), "NU310": (50, 110, 27, 2, 65, 97)}

d, D, width = BEARINGS[designation]

# Requirements: ISO 492 normal tolerance class, deviations in mm (upper deviation 0), by size range (over, up to and including). NTN CAT. No. 2203-3/E, Table 6.4,

# pp. A-58 to A-59, https://www.ntnglobal.com/en/products/catalog/pdf/2203E.pdf (checked 2026-11-03).

BORE_DEVIATION = ((2.5, "-0.008"), (10, "-0.008"), (18, "-0.008"), (30, "-0.010"), (50, "-0.012"), (80, "-0.015"))

OD_DEVIATION = ((6, "-0.008"), (18, "-0.008"), (30, "-0.009"), (50, "-0.011"), (80, "-0.013"), (120, "-0.015"))

WIDTH_DEVIATION = ((2.5, "-0.040"), (10, "-0.120"), (18, "-0.120"), (30, "-0.120"), (50, "-0.120"), (80, "-0.150"))

def lower_deviation(rows, size):

return next(value for upto, value in rows if size <= upto)

d, D, W, r, Fw, Ew = BEARINGS[designation]

model = Model()

with model.sketch("rings", on="XY", name="Rings") as sk:

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

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

model.extrude("body", "rings", distance=width, both=True, name="Bearing")

model.material("steel-generic", color="#b9bdc2")

if detail == "simple":

outline = [(d / 2 + r, -W / 2), (D / 2 - r, -W / 2), (D / 2, -W / 2 + r), (D / 2, W / 2 - r), (D / 2 - r, W / 2), (d / 2 + r, W / 2),

(d / 2, W / 2 - r), (d / 2, -W / 2 + r)]

with model.sketch("section", on="XZ", name="Section") as sk:

sk.polyline("ring", outline, closed=True)

model.revolve("inner", "section", axis="Z", name="Bearing")

bore_face, od_face, low_face, high_face = "inner.side(ring.side6)", "inner.side(ring.side2)", "inner.side(ring.side0)", "inner.side(ring.side4)"

else:

roller = (Ew - Fw) / 2

pitch_r = (Ew + Fw) / 4

rib_width = 0.14 * W

rib_r = Ew / 2 - 0.3 * roller

roller_length = W - 2 * rib_width - 0.1 * W

clear = 0.01 * roller

inner = [(d / 2 + r, -W / 2), (Fw / 2 - r / 2, -W / 2), (Fw / 2, -W / 2 + r / 2), (Fw / 2, W / 2 - r / 2), (Fw / 2 - r / 2, W / 2), (d / 2 + r, W / 2), (d / 2, W / 2 - r), (d / 2, -W / 2 + r)]

outer = [(rib_r, -W / 2), (D / 2 - r, -W / 2), (D / 2, -W / 2 + r), (D / 2, W / 2 - r), (D / 2 - r, W / 2), (rib_r, W / 2), (rib_r, W / 2 - rib_width), (Ew / 2, W / 2 - rib_width), (Ew / 2, -W / 2 + rib_width), (rib_r, -W / 2 + rib_width)]

with model.sketch("inner_section", on="XZ", name="Inner ring section") as sk:

sk.polyline("inner_ring", inner, closed=True)

model.revolve("inner", "inner_section", axis="Z", op="new", body="inner_body", name="Inner ring")

with model.sketch("outer_section", on="XZ", name="Outer ring section") as sk:

sk.polyline("outer_ring", outer, closed=True)

model.revolve("outer", "outer_section", axis="Z", op="new", body="outer_body", name="Outer ring")

with model.sketch("roller_section", on="XZ", name="Roller section") as sk:

sk.polyline("roller_half", [(pitch_r, -roller_length / 2), (pitch_r + roller / 2 - clear, -roller_length / 2), (pitch_r + roller / 2 - clear, roller_length / 2), (pitch_r, roller_length / 2)], closed=True)

model.revolve("roller", "roller_section", axis=((pitch_r, 0, 0), (0, 0, 1)), op="new", body="roller_body", name="Roller")

rollers = max(6, int(2 * math.pi * pitch_r / (1.25 * roller)))

model.circular_pattern("rollers", axis="Z", count=rollers, bodies=["roller_body"], name="Rollers")

bore_face, od_face, low_face, high_face = "inner.side(inner_ring.side7)", "outer.side(outer_ring.side2)", "inner.side(inner_ring.side0)", "inner.side(inner_ring.side5)"

model.material("steel-generic")

model.appearance(color="#b9bdc2")

model.standard("ISO")

model.size("bore", bore_face, tol=("0", lower_deviation(BORE_DEVIATION, d)), modifiers=["SD", "ACS"])

model.size("outside_diameter", od_face, tol=("0", lower_deviation(OD_DEVIATION, D)), modifiers=["SD", "ACS"])

model.size("width", [low_face, high_face], tol=("0", lower_deviation(WIDTH_DEVIATION, d)))

model.note("tolerance_class", "ISO 492 normal tolerance class")

result = model.result()

--- 1.0.0/part.py
+++ 1.1.0/part.py
@@ -1,17 +1,59 @@
-"""Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm: envelope for assemblies, one solid with the boundary dimensions bore d, outside
-diameter D and width B. Rolling elements, cage and the gaps between the rings are not modelled. Axis along Z, centred on the origin."""
+"""Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm. Bore d, outside diameter D, width B, chamfer r and the raceway diameters Fw (inner) and Ew (outer) are sourced and make the fit. detail = "full": a plain inner ring, an outer ring with a rib at each end, and the rollers between them, whose diameter follows from (Ew - Fw) / 2. Rib height, roller length and roller count are proportions for looks, not for design, and never change the fit dimensions; the cage is not drawn. detail = "simple": one solid ring. Axis along Z, centred on the origin."""
+import math
+
 from steve import Model
 
-designation = "NU208"  # Bearing number
+designation = "NU204"  # Bearing number
+detail = "full"  # full: rings and rolling elements; simple: one solid
 
-# number: (d, D, B). NTN Ball and Roller Bearings CAT. No. 2203-3/E (2024), pp. B-71 to B-72 (PDF pages 147 and 148), boundary dimensions.
-BEARINGS = {"NU204": (20, 47, 14), "NU205": (25, 52, 15), "NU206": (30, 62, 16), "NU207": (35, 72, 17), "NU208": (40, 80, 18), "NU209": (45, 85, 19), "NU210": (50, 90, 20), "NU304": (20, 52, 15), "NU305": (25, 62, 17), "NU306": (30, 72, 19), "NU307": (35, 80, 21), "NU308": (40, 90, 23), "NU309": (45, 100, 25), "NU310": (50, 110, 27)}
+# number: (d, D, B, r, Fw, Ew). NTN Ball and Roller Bearings CAT. No. 2203-3/E (2024), pp. B-71 to B-72 (PDF pages 147-148), https://www.ntnglobal.com/en/products/catalog/pdf/2203E.pdf
+BEARINGS = {"NU204": (20, 47, 14, 1, 26.5, 41.5), "NU205": (25, 52, 15, 1, 31.5, 46.5), "NU206": (30, 62, 16, 1, 37.5, 55.5), "NU207": (35, 72, 17, 1.1, 44, 64), "NU208": (40, 80, 18, 1.1, 49.5, 71.5), "NU209": (45, 85, 19, 1.1, 54.5, 76.5), "NU210": (50, 90, 20, 1.1, 59.5, 81.5), "NU304": (20, 52, 15, 1.1, 27.5, 45.5), "NU305": (25, 62, 17, 1.1, 34, 54), "NU306": (30, 72, 19, 1.1, 40.5, 62.5), "NU307": (35, 80, 21, 1.5, 46.2, 70.2), "NU308": (40, 90, 23, 1.5, 52, 80), "NU309": (45, 100, 25, 1.5, 58.5, 88.5), "NU310": (50, 110, 27, 2, 65, 97)}
 
-d, D, width = BEARINGS[designation]
+# Requirements: ISO 492 normal tolerance class, deviations in mm (upper deviation 0), by size range (over, up to and including). NTN CAT. No. 2203-3/E, Table 6.4,
+# pp. A-58 to A-59, https://www.ntnglobal.com/en/products/catalog/pdf/2203E.pdf (checked 2026-11-03).
+BORE_DEVIATION = ((2.5, "-0.008"), (10, "-0.008"), (18, "-0.008"), (30, "-0.010"), (50, "-0.012"), (80, "-0.015"))
+OD_DEVIATION = ((6, "-0.008"), (18, "-0.008"), (30, "-0.009"), (50, "-0.011"), (80, "-0.013"), (120, "-0.015"))
+WIDTH_DEVIATION = ((2.5, "-0.040"), (10, "-0.120"), (18, "-0.120"), (30, "-0.120"), (50, "-0.120"), (80, "-0.150"))
+
+
+def lower_deviation(rows, size):
+    return next(value for upto, value in rows if size <= upto)
+
+d, D, W, r, Fw, Ew = BEARINGS[designation]
 model = Model()
-with model.sketch("rings", on="XY", name="Rings") as sk:
-    sk.circle("outer", (0, 0), D / 2)
-    sk.circle("bore", (0, 0), d / 2)
-model.extrude("body", "rings", distance=width, both=True, name="Bearing")
-model.material("steel-generic", color="#b9bdc2")
+if detail == "simple":
+    outline = [(d / 2 + r, -W / 2), (D / 2 - r, -W / 2), (D / 2, -W / 2 + r), (D / 2, W / 2 - r), (D / 2 - r, W / 2), (d / 2 + r, W / 2),
+               (d / 2, W / 2 - r), (d / 2, -W / 2 + r)]
+    with model.sketch("section", on="XZ", name="Section") as sk:
+        sk.polyline("ring", outline, closed=True)
+    model.revolve("inner", "section", axis="Z", name="Bearing")
+    bore_face, od_face, low_face, high_face = "inner.side(ring.side6)", "inner.side(ring.side2)", "inner.side(ring.side0)", "inner.side(ring.side4)"
+else:
+    roller = (Ew - Fw) / 2
+    pitch_r = (Ew + Fw) / 4
+    rib_width = 0.14 * W
+    rib_r = Ew / 2 - 0.3 * roller
+    roller_length = W - 2 * rib_width - 0.1 * W
+    clear = 0.01 * roller
+    inner = [(d / 2 + r, -W / 2), (Fw / 2 - r / 2, -W / 2), (Fw / 2, -W / 2 + r / 2), (Fw / 2, W / 2 - r / 2), (Fw / 2 - r / 2, W / 2), (d / 2 + r, W / 2), (d / 2, W / 2 - r), (d / 2, -W / 2 + r)]
+    outer = [(rib_r, -W / 2), (D / 2 - r, -W / 2), (D / 2, -W / 2 + r), (D / 2, W / 2 - r), (D / 2 - r, W / 2), (rib_r, W / 2), (rib_r, W / 2 - rib_width), (Ew / 2, W / 2 - rib_width), (Ew / 2, -W / 2 + rib_width), (rib_r, -W / 2 + rib_width)]
+    with model.sketch("inner_section", on="XZ", name="Inner ring section") as sk:
+        sk.polyline("inner_ring", inner, closed=True)
+    model.revolve("inner", "inner_section", axis="Z", op="new", body="inner_body", name="Inner ring")
+    with model.sketch("outer_section", on="XZ", name="Outer ring section") as sk:
+        sk.polyline("outer_ring", outer, closed=True)
+    model.revolve("outer", "outer_section", axis="Z", op="new", body="outer_body", name="Outer ring")
+    with model.sketch("roller_section", on="XZ", name="Roller section") as sk:
+        sk.polyline("roller_half", [(pitch_r, -roller_length / 2), (pitch_r + roller / 2 - clear, -roller_length / 2), (pitch_r + roller / 2 - clear, roller_length / 2), (pitch_r, roller_length / 2)], closed=True)
+    model.revolve("roller", "roller_section", axis=((pitch_r, 0, 0), (0, 0, 1)), op="new", body="roller_body", name="Roller")
+    rollers = max(6, int(2 * math.pi * pitch_r / (1.25 * roller)))
+    model.circular_pattern("rollers", axis="Z", count=rollers, bodies=["roller_body"], name="Rollers")
+    bore_face, od_face, low_face, high_face = "inner.side(inner_ring.side7)", "outer.side(outer_ring.side2)", "inner.side(inner_ring.side0)", "inner.side(inner_ring.side5)"
+model.material("steel-generic")
+model.appearance(color="#b9bdc2")
+model.standard("ISO")
+model.size("bore", bore_face, tol=("0", lower_deviation(BORE_DEVIATION, d)), modifiers=["SD", "ACS"])
+model.size("outside_diameter", od_face, tol=("0", lower_deviation(OD_DEVIATION, D)), modifiers=["SD", "ACS"])
+model.size("width", [low_face, high_face], tol=("0", lower_deviation(WIDTH_DEVIATION, d)))
+model.note("tolerance_class", "ISO 492 normal tolerance class")
 result = model.result()

pypart.toml +19 −5

@@ -1,17 +1,24 @@

name = "steve/cylindrical-roller-bearing"

version = "1.0.0"

version = "1.1.0"

runtime = "steve"

license = "MIT"

summary = "Cylindrical roller bearing, NU2 and NU3 series, bore 10 to 50 mm, as a boundary-dimension envelope."

description = """Cylindrical roller bearing (NU2 and NU3 series) as an envelope for assemblies: one solid with the boundary dimensions. Rolling elements, cage and \

the gaps between the rings are not modelled. Axis along Z, centred on the origin. Dimensions from a maker's public catalogue (see the README); not affiliated with any maker."""

summary = "Cylindrical roller bearing, NU2 and NU3 series, bore 10 to 50 mm,."

description = """Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm. Bore d, outside diameter D, width B, chamfer r and the raceway diameters Fw (inner) and Ew (outer) are sourced and make the fit. detail = \"full\": a plain inner ring, an outer ring with a rib at each end, and the rollers between them, whose diameter follows from (Ew - Fw) / 2. Rib height, roller length and roller count are proportions for looks, not for design, and never change the fit dimensions; the cage is not drawn. detail = \"simple\": one solid ring. Axis along Z, centred on the origin. Dimensions from a maker's public catalogue (see the README); not affiliated with any maker."""

tags = ["bearing", "roller-bearing", "cylindrical-roller", "iso-15", "metric"]

changes = "Looks like a bearing: rings and rolling elements. detail = simple keeps one solid ring."

[parameters.designation]

type = "choice"

default = "NU208"

default = "NU204"

choices = ["NU204", "NU205", "NU206", "NU207", "NU208", "NU209", "NU210", "NU304", "NU305", "NU306", "NU307", "NU308", "NU309", "NU310"]

label = "Bearing number"

[parameters.detail]

type = "choice"

default = "full"

choices = ["full", "simple"]

label = "Detail"

description = "full: rings and rolling elements. simple: one solid ring with the same boundary dimensions, for big assemblies."

[[presets]]

id = "NU204"

@@ -111,3 +118,10 @@

111

118

aliases = ["NU310 bearing", "cylindrical roller bearing NU310", "50x110x27 roller-bearing"]

112

119

standard = "ISO 15"

113

120

121

[[presets]]

122

id = "NU204-simple"

123

title = "NU204, simple (one solid)"

124

params = { designation = "NU204", detail = "simple" }

125

aliases = ["NU204 simple"]

126

standard = "ISO 15"

127

--- 1.0.0/pypart.toml
+++ 1.1.0/pypart.toml
@@ -1,17 +1,24 @@
 name = "steve/cylindrical-roller-bearing"
-version = "1.0.0"
+version = "1.1.0"
 runtime = "steve"
 license = "MIT"
-summary = "Cylindrical roller bearing, NU2 and NU3 series, bore 10 to 50 mm, as a boundary-dimension envelope."
-description = """Cylindrical roller bearing (NU2 and NU3 series) as an envelope for assemblies: one solid with the boundary dimensions. Rolling elements, cage and \
-the gaps between the rings are not modelled. Axis along Z, centred on the origin. Dimensions from a maker's public catalogue (see the README); not affiliated with any maker."""
+summary = "Cylindrical roller bearing, NU2 and NU3 series, bore 10 to 50 mm,."
+description = """Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm. Bore d, outside diameter D, width B, chamfer r and the raceway diameters Fw (inner) and Ew (outer) are sourced and make the fit. detail = \"full\": a plain inner ring, an outer ring with a rib at each end, and the rollers between them, whose diameter follows from (Ew - Fw) / 2. Rib height, roller length and roller count are proportions for looks, not for design, and never change the fit dimensions; the cage is not drawn. detail = \"simple\": one solid ring. Axis along Z, centred on the origin. Dimensions from a maker's public catalogue (see the README); not affiliated with any maker."""
 tags = ["bearing", "roller-bearing", "cylindrical-roller", "iso-15", "metric"]
+changes = "Looks like a bearing: rings and rolling elements. detail = simple keeps one solid ring."
 
 [parameters.designation]
 type = "choice"
-default = "NU208"
+default = "NU204"
 choices = ["NU204", "NU205", "NU206", "NU207", "NU208", "NU209", "NU210", "NU304", "NU305", "NU306", "NU307", "NU308", "NU309", "NU310"]
 label = "Bearing number"
+
+[parameters.detail]
+type = "choice"
+default = "full"
+choices = ["full", "simple"]
+label = "Detail"
+description = "full: rings and rolling elements. simple: one solid ring with the same boundary dimensions, for big assemblies."
 
 [[presets]]
 id = "NU204"
@@ -110,3 +117,10 @@
 params = { designation = "NU310" }
 aliases = ["NU310 bearing", "cylindrical roller bearing NU310", "50x110x27 roller-bearing"]
 standard = "ISO 15"
+
+[[presets]]
+id = "NU204-simple"
+title = "NU204, simple (one solid)"
+params = { designation = "NU204", detail = "simple" }
+aliases = ["NU204 simple"]
+standard = "ISO 15"

README.md +8 −3

@@ -1,7 +1,10 @@

# Cylindrical roller bearing

Nu2 and nu3 series, bore 10 to 50 mm, as an envelope for assemblies: one solid with the boundary dimensions. Axis along Z,

centred on the origin. Rolling elements, cage and the gaps between the rings aren't modelled.

## Geometry

Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm. Bore d, outside diameter D, width B, chamfer r and the raceway diameters Fw (inner) and Ew (outer) are sourced and make the fit. detail = "full": a plain inner ring, an outer ring with a rib at each end, and the rollers between them, whose diameter follows from (Ew - Fw) / 2. Rib height, roller length and roller count are proportions for looks, not for design, and never change the fit dimensions; the cage is not drawn. detail = "simple": one solid ring. Axis along Z, centred on the origin.

**For the fit:** the sourced dimensions below. **For looks only, not for design:** every other proportion named above.

## Source

@@ -24,5 +27,7 @@

| NU309 | 45 | 100 | 25 |

| NU310 | 50 | 110 | 27 |

No tolerance class is stated here yet. Maker names identify the source; this part isn't made by or affiliated with any maker.

Maker names identify the source; this part isn't made by or affiliated with any maker.

Raceway diameters Fw and Ew and chamfers r are in `part.py` (`BEARINGS`), from the same tables; the ISO 492 normal class is from Table 6.4, pp. A-58 to A-59.

--- 1.0.0/README.md
+++ 1.1.0/README.md
@@ -1,7 +1,10 @@
 # Cylindrical roller bearing
 
-Nu2 and nu3 series, bore 10 to 50 mm, as an envelope for assemblies: one solid with the boundary dimensions. Axis along Z,
-centred on the origin. Rolling elements, cage and the gaps between the rings aren't modelled.
+## Geometry
+
+Cylindrical roller bearing, NU2 and NU3 series, bore up to 50 mm. Bore d, outside diameter D, width B, chamfer r and the raceway diameters Fw (inner) and Ew (outer) are sourced and make the fit. detail = "full": a plain inner ring, an outer ring with a rib at each end, and the rollers between them, whose diameter follows from (Ew - Fw) / 2. Rib height, roller length and roller count are proportions for looks, not for design, and never change the fit dimensions; the cage is not drawn. detail = "simple": one solid ring. Axis along Z, centred on the origin.
+
+**For the fit:** the sourced dimensions below. **For looks only, not for design:** every other proportion named above.
 
 ## Source
 
@@ -24,4 +27,6 @@
 | NU309 | 45 | 100 | 25 |
 | NU310 | 50 | 110 | 27 |
 
-No tolerance class is stated here yet. Maker names identify the source; this part isn't made by or affiliated with any maker.
+Maker names identify the source; this part isn't made by or affiliated with any maker.
+
+Raceway diameters Fw and Ew and chamfers r are in `part.py` (`BEARINGS`), from the same tables; the ISO 492 normal class is from Table 6.4, pp. A-58 to A-59.