Accurate instruments often contain specialized components that are essential to their functionality, but failing to replace them is almost impossible. [Andre] There was a problem with an optical comparator, a device commonly used in machine shops to help test the endurance of a finished part. It does this by projecting an magnified image of an object on a glass screen with angles showing the angles and distances.
In the old comparator [Andre] Bought on eBay, the glass markings faded in such a way that the device was almost unused. So he contacted [James] In Clough42, who was able to create a near-perfect replacement screen using a laser cutter, as shown in the embedded video below.
The first step was to copy the screen symbols to a CAD program. [James] Fusion 360 explains the process, demonstrating how you can create almost all different scales almost automatically through proper use of constraints, variables, and patterns. He then transfers the drawing to Lightburn, which drives the laser cutter and engraves the marks on a glass sheet covered with Sermark, a marking solution that turns deep black when heated by the laser.
After etching, the final step was to apply frosting to the glass so that it turned into a projection screen. Although there are several ways to achieve this, [James] Went for a simple spray-based method that gave surprisingly good results. It has done a few experiments to find the best combination of sharpness and durability, as well as engraving marks on the back of the glass and applying frosting to it.
[James]Its project shows that even fine instruments can be repaired with custom glass components, if you have the right tools. A similar technique can be used to create custom scales for analog meters or even older radio dials. If you are not familiar with laser cutters, check out our tests with an Ortur model Thanks for the tip, [poiuyt]!