Reverse Engineering a Door Handle Gear
A discontinued internal gear component was scanned, modelled, and reproduced to restore a failed door mechanism — avoiding full assembly replacement at significant cost.
Overview
When the Part No Longer Exists
A customer brought in a failed internal door mechanism with a cracked gear that was no longer available from the manufacturer as an individual component. The only option offered by the supplier was full door assembly replacement at significant cost.
A single small gear was responsible for the entire failure. Replacing the assembly would have meant discarding components that were otherwise in perfect working order.
The Challenge
Accuracy Without a Reference File
The gear was small, worn, and showed signs of fatigue cracking that had distorted its original geometry in places. No drawings or digital files existed for the component. The replacement needed to match the original dimensions and tooth profile precisely enough to mesh correctly with the surrounding mechanism.
Standard measurement tools alone were insufficient to capture the gear geometry accurately. Any dimensional error in the tooth profile would result in a part that either would not fit or would fail prematurely under normal use.
The Process
Scan, Model, and Reproduce
The gear was scanned to capture its geometry despite the wear and cracking present on the original. The scan data was used to reconstruct a clean CAD model with corrected geometry, removing artefacts introduced by wear while preserving the original design intent.
The reproduced part was printed in an engineering-grade material selected for appropriate hardness and wear resistance for the application. Dimensions were verified against the original before the part was released.
Outcome
The reproduced gear fit directly into the existing mechanism and restored full operation of the door. The customer avoided replacing the entire assembly and received the replacement part within two days of bringing the original in. The cost saving compared to full assembly replacement was substantial.
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Work in Progress & Finished Outputs
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