Chapter 7 of 13

Sanding and Polishing Gear Axles

A noticeable reduction in gear noise from polishing the gear axles against the bushings. Skip for bearings; mandatory for any bushing build.

5 min

Step 1
Overview
Polishing the gear axles where they ride in the bushings reduces friction and noticeably drops the noise of the finished gearbox. Skip this step entirely if the build is running bearings on those axles — there is no axle/bushing contact to polish.
Step 2
Supplies
- 120 grit sandpaper
- Rotary tool
- Polishing compound
- Clean paper towel or cloth
Step 3
Procedure
1. Clamp the gear into the rotary tool with the axle exposed and centered.
2. With the tool running at its lowest speed, lightly press the 120 grit paper against the upper axle just enough to leave a uniform scuff. This is a finishing pass, not a re-machining pass — a few seconds is enough.
3. Apply a small amount of polishing compound to the cloth and press it against the spinning axle. Continue at the lowest speed until the axle takes a mirror finish.
4. Wipe completely clean with a fresh cloth before installing. Any abrasive grit left on the axle ends up in the bushing.
Reference video: https://youtube.com/shorts/5ZvDFILD58Q

Repeat for every gear axle that rides in a bushing — typically the bevel, spur, and sector lower axles.

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