Can a gear be made without a bore?

Q: Can a gear be made without a bore?

Gear without a bore: define the later interface firstYes. A gear blank can be made without a finished bore when its tooth form, hub and locating datum are defined first. The later bore, keyway or spline must be related to that datum so machining and inspection preserve runout and face location. PairGears treats the shaft interface as a controlled design input, not an afterthought.Keep the locating datum and later shaft interface in the same drawing plan.What to define before releasePut the functional interfaces on the drawing: identify the finished or future bore diameter and tolerance, the hub length, the locating face, the keyway or spline standard, and the clocking requirement if tooth position matters. Also state whether the bore is to be machined before or after heat treatment, because that decision affects distortion risk and the inspection route.A boreless part is not automatically a finished mounting solution. A later operation still needs enough stock, safe wall thickness, accessible tooling and a datum scheme that links the bore to the tooth form. The PairGears gear-design guide similarly treats geometry and manufacturing route as connected decisions.Tooth machining and the later bore operation need compatible reference surfaces.A staged route helps keep blank, tooth and bore operations traceable.Example and decision checkFor a blank that will later receive a 35 mm bore and keyway, identify which face establishes axial position and whether the keyway must be clocked to a tooth, a tooth space or an arbitrary angle. The inspection plan can then check bore size, face runout, radial runout and the agreed tooth-to-keyway relationship before assembly.Related questionsHow do I verify gear concentricity and runout?What drawing or sample information helps define a custom gear?

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Accepted Answer

Gear without a bore: define the later interface first

Yes. A gear blank can be made without a finished bore when its tooth form, hub and locating datum are defined first. The later bore, keyway or spline must be related to that datum so machining and inspection preserve runout and face location. PairGears treats the shaft interface as a controlled design input, not an afterthought.

Gear blank mounted during a machining operation — Keep the locating datum and later shaft interface in the same drawing plan.

What to define before release

Put the functional interfaces on the drawing: identify the finished or future bore diameter and tolerance, the hub length, the locating face, the keyway or spline standard, and the clocking requirement if tooth position matters. Also state whether the bore is to be machined before or after heat treatment, because that decision affects distortion risk and the inspection route.

A boreless part is not automatically a finished mounting solution. A later operation still needs enough stock, safe wall thickness, accessible tooling and a datum scheme that links the bore to the tooth form. The PairGears gear-design guide similarly treats geometry and manufacturing route as connected decisions.

Large ring gear being machined on a gear grinding machine — Tooth machining and the later bore operation need compatible reference surfaces.

CNC production line used for precision component machining — A staged route helps keep blank, tooth and bore operations traceable.

Example and decision check

For a blank that will later receive a 35 mm bore and keyway, identify which face establishes axial position and whether the keyway must be clocked to a tooth, a tooth space or an arbitrary angle. The inspection plan can then check bore size, face runout, radial runout and the agreed tooth-to-keyway relationship before assembly.

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Can a gear be made without a bore?

Gear without a bore: define the later interface first

What to define before release

Example and decision check

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