Western Machine Works


Motor Armature New Shaft Manufacture


Western Machine Works reverse engineered and manufactured a new shaft for a motor armature. The old shaft was severely damaged and repairing it was not a viable option. Western Machine Works’ engineering group took on the challenge of generating the manufacturing drawings and verifying all critical fits. The armature bore was precision machined to 100% concentricity and the new shaft was installed with the required interference fit. 


  • Part: 3000 HP Motor Armature


  • Existing shaft was damaged beyond repair.
  • No detailed manufacturing drawings exist.

Engineered Solutions:

  • Dimensionally inspect existing shaft to generate manufacturing drawings.
  • Work with the customer to correctly dimension all critical fits.
  • Cut off the existing shaft on both sides of the armature.
  • Set up armature in VBM to bore out the remaining shaft.
  • Machine armature bore to 100% concentricity.
  • Manufacture new shaft out of 4140 alloy steel.
  • Freeze new shaft in liquid nitrogen and install to the armature with interference fit.
  • Set up armature and shaft in the lathe, and machine slip rings to 100% concentricity.
  • Balance to ISO G1.0 specification.
  • QC to inspect and approve prior to shipping.


With precision machining and reverse engineering, the new shaft fit in the armature perfectly.

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