A Broken Shaft Still Holds Its Spec
When a drive shaft, spindle or axle shears, it feels like a disaster — but a shaft is a rotational part defined by a row of diameters along its length, and almost all of that survives the break. Bearing journals, the keyway, threaded ends, shoulders and shaft length are all still measurable. We reconstruct the few millimetres lost at the fracture from the mating parts.
The part that demands precision isn't the round body — it's the keyway (or spline) and the bearing fits. Get those right and the new shaft drops into your existing hub, bearings and key as if it were the original.
What We Measure on a Shaft
| Feature | How & why it matters |
|---|---|
| Bearing journals | Micrometer + correct fit class (e.g. k5/m6) so bearings seat right |
| Keyway width & depth | To standard (DIN 6885 / ISO 773) and to the key/hub it drives |
| Threaded ends | Thread gauge — pitch, diameter, class for retaining nuts |
| Shoulders & steps | Axial positions that locate bearings and spacers |
| Overall length & centres | Total length; centre holes for grinding between centres |
| Spline (if any) | Count, module/DP, fit — measured like a gear |
Why the Mating Hub Is Your Best Friend
If you can send the hub, gear or pulley the shaft drives — even just photos and the bore size — it pins down the keyway and the shaft diameter independently of the worn shaft. The key itself is a standard size that confirms the keyway. Between the broken shaft and the mating parts, there's rarely any genuine ambiguity. We reconstruct, then confirm every critical fit with you before cutting.
We've done exactly this on a snapped coupling — see the real case: reverse engineering a broken drive shaft. The full method is on our reverse engineering page, and threaded ends are covered in identifying an unknown thread.
Send both halves of the shaft and the hub if you can. Mail the broken shaft (both pieces) plus the mating component; we machine and grind a new one to standard fits. No drawing? Start with no-CAD ordering or our CNC turning service.
Frequently Asked Questions
Yes. Even snapped in two, a shaft carries its journals, keyway, threads, shoulders and length. We measure the surviving sections, cross-check with the mating hub and bearings, and machine a new one. No drawing required.
Keyways follow standards tied to shaft diameter (DIN 6885 / ISO 773 or imperial). We measure the worn keyway, confirm against the standard and the key/hub, and cut it to a precise fit.
Yes. We identify the bearing, apply the standard shaft fit class (e.g. k5/m6) and grind the journal to size so it seats like the original.
Commonly 1045/4140 steel (hardened and ground at journals), 304/316 stainless, and 4340 for high load. We match or upgrade the original and can induction-harden keyway and bearing areas.
Quote a Shaft
Send the broken shaft (both halves) + the hub it drives. Engineers reply within 24 hours.
No drawing needed · Files kept confidential