Cutting Circles in Stained Glass

Have you ever seen in the movies a cat burglar cut a circle in the window and pull it out with a suction cup? Us glass artists know that it’s impossible. But how do you go about doing it?

I use the Glastar Strip/Circle Cutter but there are many out there that are just as good. The circle cutter setup may be different but the cutting technique is the same.

1. Make sure your piece of glass is at least 1 inch larger than the circle you need.
2. Place circle cutter in center of piece of glass.
3. Do a test run around the circle to make sure you are comfortable pressing down all the way around the circle but do not press down on the cutter. Also make sure the cutter stays on the glass.
4. Press down on the circle cutter and score the glass in circle making sure to have the start and stop points of your score line match up. (Don’t let the center point of the circle cutter move)
5. Break your score line all the way around the circle by using the Morton M80, Morton Safety Break, or flip your glass over with score side down on short pile carpet or rubber pad and press on score line to run the break all the way around.
6. Make 4 relief cuts from your broken score line of the circle to the edge of the glass.
7. Break relief cuts and circle should come out in one piece.

Circles from 4” to 20” will typically break out clean with this technique. Smaller circles than this will usually have flares that will need to be ground. Larger circles are just harder to handle by yourself.