When you need to replace a watch crystal, sometimes you will have to order a generic watch crystal or a crystal blank that comes in one of several standard sizes but might not be the exact size for your watch case.
If this is the situation that you find yourself in and you realize that you’ll have to cut down the crystal quite a bit to ensure a perfect fit for your watch case you can do so with the help of a crystal grinder. Learn how to use a crystal grinder to cut your crystals to the right size and shape with this guide.
The first thing you need to do is determine how much you need to change the crystal, particularly noting which sides you need to trim and by how much. Once you have that figured out, put on your safety glasses to protect your eyes while grinding.
Start your crystal grinder and lubricate the wheel. Then, holding the crystal firmly in one hand, press the edge that needs to be changed lightly against the rotating wheel. Be sure to hold it at a ninety degree angle to the grinder to ensure an even change to the crystal edge.
DO NOT hold the crystal steady in one place. You can wear down the grinder and potentially damage the crystal with debris from previous grindings if you don’t move the crystal slightly across the surface of the grinder as you work.
Remove the crystal from the grinder and check the progress you have made.
Once you have a feel for how quickly the grinder trims the crystal, you can increase the pressure against the grinder to achieve a more drastic cut. Before continuing to shape the crystal, be sure to re-lubricate it to protect it. By keeping both the crystal and the grinder lubricated throughout the trimming process you protect the crystal from chipping or breaking while you trim it.
Check your progress frequently. Once you are satisfied with the size and shape of the crystal, you can clean up any rough edges by very lightly pressing the crystal against the grinder at a slight angle.
Finally, you should buff and polish the crystal to remove any scratches that may have occurred while trimming before setting it in your watch case. Learn How to Polish and Buff Away Scratches from a Watch Crystal here, or to learn more about placing watch crystals, you can check out our Learning Center today.