@fluidcad/gears

Gear features, parts and assemblies for FluidCAD, built on the custom-features SDK (fluidcad/sdk).

npx fluidcad install @fluidcad/gears

import { gear, gearTeeth, internalGear, rack } from '@fluidcad/gears';

feature	id	what it makes
`gear`	`gear`	a spur, helical or herringbone gear with hub and bore options
`gearTeeth`	`gear-teeth`	involute teeth cut into an existing shaft or bore
`internalGear`	`internal-gear`	a ring gear, checked against its mate for interference
`rack`	`rack`	a straight or helical rack

Layout

The package keeps what it shares in three folders. fluidcad pack ships them and nothing else.

fluidcad.json   the package block (@fluidcad/gears)
features/       the gear features, their icons/ and option pictures (img/)
  lib/            plain ES modules the features import
    bspline.js      B-spline interpolation and adaptive fitting with measured deviation
    gear-math.js    gear geometry and standards (ISO 21771, ISO 53, ISO 54, KHK, AGMA)
    profile.js      exact 2D tooth profiles (involute, generated trochoid root, rack)
    tooth.js        the tooth values the dialogs share, and face sorting
    occ-gear.js     OpenCascade construction: toothed bodies, hub, bore, chamfers
    placement.js    the frame a feature stands on: face, edge, connector or plane
parts/          example gears, each on an `axis` connector
  mechanisms/     bases, a parametric spur gear, the reducer's shaft, the planet and carrier
assemblies/     gear mechanisms: mates plus gear / rack-and-pinion relations

These stay in the workspace and never ship: main.assembly.js (a scratch model), init.js, tests/ (vitest unit tests for features/lib), tools/ (scripts that draw the icons) and the npm files.

Geometry

Tooth flanks are B-rep curves fitted to the exact equations: the involute, the root trochoid generated by the basic rack's tip round, and so on. The fits are non-rational B-splines in OpenCascade's convention (unique knots plus multiplicities) and each one reports the deviation it reached from the exact curve (default tolerance 1e-5 mm). Lines and circles stay analytic.

Assemblies

Each mechanism is one flat assembly(): it inserts the parts, grounds one, puts every gear on a revolute mate (a rack on a slider) and couples the mates with relation() in the same body — no relation inside a sub-assembly. Every part starts where it meshes, so the file's poses set the mesh phase. Drive any joint from the Joints panel and the rest follow.

file	parts	relations	ratio
`gear-pair.assembly.js`	base, 18-tooth pinion, 30-tooth wheel (m 2)	gear 18/30, reversed	1.667 : 1
`reducer.assembly.js`	base, 14-tooth input, 42/14 intermediate shaft, 42-tooth output (m 2)	two gear 14/42, reversed	9 : 1, same sense
`internal-pair.assembly.js`	base, 60-tooth ring, 24-tooth pinion (m 2)	gear 24/60, same sense	2.5 : 1
`planetary.assembly.js`	60-tooth ring (grounded), carrier, 18-tooth sun, three 21-tooth planets (m 1.5)	ring–planet 60/21 ×3 reversed, carrier–sun 1 + 60/18	sun : carrier 4.333 : 1
`rack-drive.assembly.js`	base, 20-tooth helical pinion (mn 2, 20°), helical rack	rack-and-pinion 2π r ≈ 133.73 mm/turn, reversed	133.73 mm per turn

In the planetary set the carrier and the sun turn on the ring's axis and the planets on the carrier's pins. Each ring–planet mesh is written in the carrier's frame (planet = −60/21 × carrier), and the sun–planet mesh comes out as the carrier–sun relation sun = (1 + 60/18) × carrier, so the sun's joint reads its absolute angle (see the file's comments for the derivation). Every relation is held exactly, so the train can be dragged from the sun, the carrier or any planet.

Development

npm install
npm test            # unit tests
npm run typecheck   # checkJs over the workspace
npx fluidcad pack   # → fluidcad-gears-<version>.fluidpkg

To release, raise the version with npx fluidcad version patch|minor|major, pack, then npx fluidcad publish.

Parameter	Control	Default	Label
face	Pick a cylinder face	picked	Cylinder
type	Cards with imagesSpurHelicalHerringbone	Spur	Type
fitBy	Buttons: Tooth count, Module	Tooth count	Fit by
teeth	Whole number, stepper, 4 to 1000Shown when fitBy is teeth	20	Teeth
sizeBy	Select: Module, Diametral pitch, Circular pitchShown when fitBy is module	Module	Size by
module	Select: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1, +43Shown when fitBy is module and sizeBy is module	2	Module
diametralPitch	Select: 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, +19Shown when fitBy is module and sizeBy is dp	12	Diametral pitch
circularPitch	Length, at least 0.03Shown when fitBy is module and sizeBy is cp	6.283185307179586 mm	Circular pitch
customModule	Length, at least 0.01Shown when fitBy is module and module is custom and sizeBy is module	2 mm	Module (custom)
customPitch	Number, at least 0.1Shown when fitBy is module and sizeBy is dp and diametralPitch is custom	12 1/in	Pitch (custom)
helixAngle	Angle, 0 to 45Shown when type is helical or herringbone	20°	Helix angle
hand	Buttons: Right, LeftShown when type is helical or herringbone	Right	Hand
gap	Length, at least 0Shown when type is herringbone	0 mm	Centre gap
extent	Buttons: Whole face, Stretch	Whole face	Length
width	Length, at least 0.01Shown when extent is stretch	10 mm	Face width
offset	Length, at least 0Shown when extent is stretch	0 mm	Offset
from	Buttons: Start, EndShown when extent is stretch	Start	From
rack	Grid with imagesISO 53 AISO 53 BISO 53 CISO 53 DAGMA 20° full depthAGMA 25° full depthAGMA 14.5° full depthAGMA 20° stub+1	ISO 53 A	Basic rack
pressureAngle	Angle, 10 to 35Shown when rack is custom	20°	Pressure angle
addendum	Number, 0.3 to 2Shown when rack is custom	1 × m	Addendum
dedendum	Number, 0.5 to 2.5Shown when rack is custom	1.25 × m	Dedendum
rootRadius	Number, 0 to 0.6Shown when rack is custom	0.38 × m	Root radius
profileShift	Number, -1 to 1.5	0	Profile shift x
clearance	Select: None (nominal teeth), Fine — 0.025 × m per gear, 3D print — 0.1 mm per gear, Custom	None (nominal teeth)	Backlash
allowance	Length, at least 0Shown when clearance is custom	0.05 mm	Thinning
tip	Cards with imagesSharpRoundChamfer	Sharp	Tip corners
tipSize	Length, at least 0Shown when tip is round or chamfer	0.2 mm	Tip break
phase	Angle	0°	Rotation

Parameter	Control	Default	Label
at	Pick a face, edge, connector or point, optional	picked	At
type	Cards with imagesSpurHelicalHerringbone	Spur	Type
teeth	Whole number, stepper, 4 to 1000	24	Teeth
width	Length, at least 0.01	10 mm	Face width
sizeBy	Select: Module, Diametral pitch, Circular pitch	Module	Size by
module	Select: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1, +43Shown when sizeBy is module	2	Module
diametralPitch	Select: 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, +19Shown when sizeBy is dp	12	Diametral pitch
circularPitch	Length, at least 0.03Shown when sizeBy is cp	6.283185307179586 mm	Circular pitch
customModule	Length, at least 0.01Shown when module is custom and sizeBy is module	2 mm	Module (custom)
customPitch	Number, at least 0.1Shown when sizeBy is dp and diametralPitch is custom	12 1/in	Pitch (custom)
helixAngle	Angle, 0 to 45Shown when type is helical or herringbone	20°	Helix angle
hand	Buttons: Right, LeftShown when type is helical or herringbone	Right	Hand
gap	Length, at least 0Shown when type is herringbone	0 mm	Centre gap
bore	Grid with imagesNoneRoundKeywayD flatDouble DHex	None	Bore
boreDiameter	Length, at least 0.1Shown when bore is round, keyway, dflat, doubleD or hex	8 mm	Bore diameter
keyStandard	Buttons: DIN 6885, ANSI B17.1, CustomShown when bore is keyway	DIN 6885	Keyway
keyWidth	Length, at least 0.1Shown when bore is keyway and keyStandard is custom	3 mm	Key width
keyDepth	Length, at least 0.05Shown when bore is keyway and keyStandard is custom	1.4 mm	Depth in hub
flat	Length, at least 0Shown when bore is dflat or doubleD	3.5 mm	Axis to flat
hubSide	Cards with imagesNoneFrontBackBoth	None	Hub
hubDiameter	Length, at least 0.1Shown when hubSide is front, back or both	20 mm	Hub diameter
hubLength	Length, at least 0.01Shown when hubSide is front, back or both	8 mm	Hub length
recessSide	Select: None, Front, Back, Both	None	Web recess
recessDepth	Length, at least 0.01Shown when recessSide is front, back or both	2 mm	Recess depth
recessInner	Length, at least 0Shown when recessSide is front, back or both	0 mm	Inner Ø
recessOuter	Length, at least 0Shown when recessSide is front, back or both	0 mm	Outer Ø
chamfer	Length, at least 0	0 mm	Tip edge chamfer
rack	Grid with imagesISO 53 AISO 53 BISO 53 CISO 53 DAGMA 20° full depthAGMA 25° full depthAGMA 14.5° full depthAGMA 20° stub+1	ISO 53 A	Basic rack
pressureAngle	Angle, 10 to 35Shown when rack is custom	20°	Pressure angle
addendum	Number, 0.3 to 2Shown when rack is custom	1 × m	Addendum
dedendum	Number, 0.5 to 2.5Shown when rack is custom	1.25 × m	Dedendum
rootRadius	Number, 0 to 0.6Shown when rack is custom	0.38 × m	Root radius
profileShift	Number, -1 to 1.5	0	Profile shift x
clearance	Select: None (nominal teeth), Fine — 0.025 × m per gear, 3D print — 0.1 mm per gear, Custom	None (nominal teeth)	Backlash
allowance	Length, at least 0Shown when clearance is custom	0.05 mm	Thinning
tip	Cards with imagesSharpRoundChamfer	Sharp	Tip corners
tipSize	Length, at least 0Shown when tip is round or chamfer	0.2 mm	Tip break
offset	Length	0 mm	Axial offset
phase	Angle	0°	Rotation
flip	Toggle	off	Flip direction

Parameter	Control	Default	Label
at	Pick a face, edge, connector or point, optional	picked	At
type	Cards with imagesSpurHelicalHerringbone	Spur	Type
teeth	Whole number, stepper, 8 to 1000	60	Teeth
width	Length, at least 0.01	10 mm	Face width
sizeBy	Select: Module, Diametral pitch, Circular pitch	Module	Size by
module	Select: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1, +43Shown when sizeBy is module	2	Module
diametralPitch	Select: 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, +19Shown when sizeBy is dp	12	Diametral pitch
circularPitch	Length, at least 0.03Shown when sizeBy is cp	6.283185307179586 mm	Circular pitch
customModule	Length, at least 0.01Shown when module is custom and sizeBy is module	2 mm	Module (custom)
customPitch	Number, at least 0.1Shown when sizeBy is dp and diametralPitch is custom	12 1/in	Pitch (custom)
helixAngle	Angle, 0 to 45Shown when type is helical or herringbone	20°	Helix angle
hand	Buttons: Right, LeftShown when type is helical or herringbone	Right	Hand
gap	Length, at least 0Shown when type is herringbone	0 mm	Centre gap
rimBy	Buttons: Thickness, Outer diameter	Thickness	Rim
rimThickness	Length, at least 0.01Shown when rimBy is thickness	5 mm	Rim thickness
outerDiameter	Length, at least 0.1Shown when rimBy is diameter	140 mm	Outer diameter
checkMate	Toggle	off	Check the pinion
mateTeeth	Whole number, stepper, 4 to 1000Shown when checkMate is true	20	Pinion teeth
mateShift	Number, -1 to 1.5Shown when checkMate is true	0	Pinion shift x
rack	Grid with imagesISO 53 AISO 53 BISO 53 CISO 53 DAGMA 20° full depthAGMA 25° full depthAGMA 14.5° full depthAGMA 20° stub+1	ISO 53 A	Basic rack
pressureAngle	Angle, 10 to 35Shown when rack is custom	20°	Pressure angle
addendum	Number, 0.3 to 2Shown when rack is custom	1 × m	Addendum
dedendum	Number, 0.5 to 2.5Shown when rack is custom	1.25 × m	Dedendum
rootRadius	Number, 0 to 0.6Shown when rack is custom	0.38 × m	Root radius
profileShift	Number, -1 to 1.5	0	Profile shift x
clearance	Select: None (nominal teeth), Fine — 0.025 × m per gear, 3D print — 0.1 mm per gear, Custom	None (nominal teeth)	Backlash
allowance	Length, at least 0Shown when clearance is custom	0.05 mm	Thinning
offset	Length	0 mm	Axial offset
phase	Angle	0°	Rotation
flip	Toggle	off	Flip direction

Parameter	Control	Default	Label
at	Pick a face, edge, connector or point, optional	picked	At
along	Pick a line edge, optional	picked	Along
type	Cards with imagesStraightHelical	Straight	Type
helixAngle	Angle, 0 to 45Shown when type is helical	20°	Helix angle
hand	Buttons: Right, LeftShown when type is helical	Right	Hand
sizeBy	Select: Module, Diametral pitch, Circular pitch	Module	Size by
module	Select: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1, +43Shown when sizeBy is module	2	Module
diametralPitch	Select: 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, +19Shown when sizeBy is dp	12	Diametral pitch
circularPitch	Length, at least 0.03Shown when sizeBy is cp	6.283185307179586 mm	Circular pitch
customModule	Length, at least 0.01Shown when module is custom and sizeBy is module	2 mm	Module (custom)
customPitch	Number, at least 0.1Shown when sizeBy is dp and diametralPitch is custom	12 1/in	Pitch (custom)
lengthBy	Buttons: Tooth count, Length	Tooth count	Length by
teeth	Whole number, stepper, 1 to 5000Shown when lengthBy is teeth	20	Teeth
length	Length, at least 0.01Shown when lengthBy is length	100 mm	Length
width	Length, at least 0.01	10 mm	Face width
ends	Buttons: Full tooth, Half tooth, Flat	Full tooth	Ends
endLength	Length, at least 0.01Shown when ends is flat	5 mm	Land length
heightBy	Buttons: Total, To the pitch line	Total	Height
height	Length, at least 0.01Shown when heightBy is total	20 mm	Total height
pitchHeight	Length, at least 0.01Shown when heightBy is pitch	15 mm	Pitch line height
rack	Grid with imagesISO 53 AISO 53 BISO 53 CISO 53 DAGMA 20° full depthAGMA 25° full depthAGMA 14.5° full depthAGMA 20° stub+1	ISO 53 A	Basic rack
pressureAngle	Angle, 10 to 35Shown when rack is custom	20°	Pressure angle
addendum	Number, 0.3 to 2Shown when rack is custom	1 × m	Addendum
dedendum	Number, 0.5 to 2.5Shown when rack is custom	1.25 × m	Dedendum
rootRadius	Number, 0 to 0.6Shown when rack is custom	0.38 × m	Root radius
clearance	Select: None (nominal teeth), Fine — 0.025 × m per gear, 3D print — 0.1 mm per gear, Custom	None (nominal teeth)	Backlash
allowance	Length, at least 0Shown when clearance is custom	0.05 mm	Thinning
tip	Cards with imagesSharpRound	Sharp	Tip corners
tipSize	Length, at least 0Shown when tip is round	0.2 mm	Tip radius
direction	Buttons: Face's X, Face's Y	Face's X	Direction
shift	Length	0 mm	Tooth shift
offset	Length	0 mm	Offset
flip	Toggle	off	Flip direction

@fluidcad/gears

@fluidcad/gears

Layout

Geometry

Assemblies

Development

Gear teeth gear-teeth

Gear gear

Internal gear internal-gear

Rack rack