Spline Gages

Wherever a splined shaft transmits torque or locates a mating part, Go/No-Go inspection is mandatory — and WESTport designs, manufactures, laps, and certifies spline gages for every major profile in-house. We build to both actual and effective tolerance requirements, for internal and external splines, across involute, straight-sided, helical, angular, parallel, and serration forms. Every gage is finished by hand and certified in our ISO/IEC 17025 accredited laboratory with NIST-traceable documentation.

The WESTport spline gage line

Spline gaging comes down to three questions: internal or external, pass/fail or variable data, and which profile. This collection covers all three.

• Involute Spline Plug Gage — Go/No-Go Set. Checks internal splined bores for composite error, tooth form, pitch, and effective/actual size. The Go member verifies full-form (effective) fit; the No-Go checks individual space width.
• Straight-Sided & Serration Spline Plug Gage. Go/No-Go plug gaging for straight-sided and serration internal forms where involute profiles don't apply.
• Helical Spline Plug Gage. Internal gaging for helical splines, built to your helix angle and hand.
• Involute Spline Ring Gage — Go/No-Go. Inspects external splined shafts for full-form composite error and functional diameter. Compatible with taper master plug gages for setup.
• Variable (Indicating) Spline Gage Set. Combines a Go plug or ring with a measuring insert and setting master to read actual space width or tooth thickness — variable data, not just pass/fail, with SPC output available.
• Taper Master Plug Gage. The setting master used to zero and verify ring and indicating gages, ensuring your whole spline gaging system traces to a common standard.

What spline gages inspect

• Composite (effective) error
• Tooth form & profile
• Index / pitch
• Space width
• Tooth thickness
• Functional diameter
• Actual size
• Internal & external splines

Plug vs. ring vs. indicating

Which gage you need depends on whether you're inspecting an internal bore or external shaft, and whether you need variable measurement data.

Actual vs. effective tolerance

Splines are toleranced two ways, and good inspection checks both. Effective size is what the mating part actually feels — the composite result of profile, index, and lead deviations combined; a full-form Go gage verifies it. Actual size is the real space width or tooth thickness at a single point, checked by a No-Go member or read directly on an indicating gage. WESTport gages are designed to both, so a part that assembles correctly (effective) and stays within individual-feature limits (actual) is confirmed in one workflow.

Standards we manufacture to

We design and build to all major US and international spline standards. Specify the standard on your request for quote, or send a drawing for a custom form.

Industries served

Why WESTport

• Every profile, in-house. Involute, straight-sided, helical, angular, parallel, and serration — designed, ground, and hand-lapped under one roof.
• Actual and effective tolerance. Gages built to verify both how the spline assembles and how each feature measures.
• Variable data when you need it. Indicating sets read actual space width and tooth thickness with SPC output for statistical process control.
• ISO/IEC 17025 accredited, NIST-traceable. Certified in our environmentally controlled laboratory; recertification and setup masters available.