Rolex Microstella Tool: Balance Wheel Adjustment Guide

Jocke - Bad Santa's highly requested post from 2013 provides an in-depth, visual guide to the Rolex Microstella tool, essential for precise balance wheel adjustments. This detailed explanation, complete with historical context and practical application, demystifies a critical aspect of Rolex's COSC-certified accuracy, making complex watchmaking accessible to enthusiasts.

The Rolex Microstella Tool

The Microstella is Rolex system to adjust the balance wheel to make sure the watch

keep the COSC standard. To do that there is a special tool to adjust the screws with.

The old tool looks like this and it's oil filled to be a little more exact and stable.

At the backside there is graduation which means 1 second per day for the low type of head nut and 2 seconds for the high type of head nut for each line.

A closer look to the tool.

Here we have a balance wheel with the Microstella screws.

Here is how it works.

A few pics of the tool in action.

The instuctions from Rolex.

And some pics of the new/current Microstella tool.

Photo credit for the new Microstella tool: Tony Axelzon

So lets put up a watch at the timing machine. Not good -17 seconds a day.

So I pull off the bracelet.

With the Ref 2100 tool.

Take place in the case opener.

Off we go.

Let the fun begin

This is a little tricky.

22 minutes later we are close. A little low amplitude so maybe a service will made it perfect in the future.