Spur gear geometry
Key data includes module or diametral pitch, tooth count, pressure angle, profile shift, face width and the bore or shaft details. The mating gear and operating centre distance are important when the pair is already defined.
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Cut or ground tooth forms
The manufacturing route depends on accuracy, material condition, surface finish and duty. Spur gears can be cut for many precision applications or finished by grinding where the design requires tighter tooth control.
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The whole component matters
Hub geometry, bores, keyways, splines, bearing journals and shaft features can affect the datum strategy and inspection plan. A complete drawing is therefore more useful than isolated tooth data.
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What to send
Provide the drawing or model, quantities, material, heat treatment, gear quality, tolerances and inspection requirements. Where the design is new, include the mating gear or ratio and centre-distance information.
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Need help with a specific gear?
Send Ondrives the drawing, model or available gear data. For new designs, include the operating duty and mating-component information so the manufacturing route can be reviewed in context.
Spur gear geometry in context
A spur gear has teeth parallel to the axis, but its working geometry still depends on the full mesh: tooth size, pressure angle, tooth count, profile shift, centre distance and backlash are interconnected.
Pitch and outside diameters
Pitch diameter is the theoretical rolling diameter used for ratio and centre-distance calculations. Outside diameter is over the tooth tips and must not be substituted for pitch diameter when identifying an unknown gear.
Undercut and profile shift
Low tooth counts can create undercut with a standard generating tool. Profile shift/addendum modification can be used to influence tooth thickness, centre distance and undercut, but the mating gear and working pressure angle must be considered together.
Backlash and duty
Required backlash depends on accuracy, temperature, lubrication, mounting and application. Zero nominal backlash is not automatically appropriate for a running gear mesh.
Use GearCALC to explore basic geometry and tooth-profile effects, then confirm the final design, material, heat treatment and quality requirement against the application and drawing.