Cutting circles
Posted: Mon Oct 28, 2013 11:43 am
Cutting circles works fine for me, but I wondered about removing the waste surrounding the circle and how best to do it without the glass breaking including the circle.
There are different approaches to this, and many of them work fine. After running the entire circle, after you score it (I use my thumb up to 6mm thick and a special tapping tool I make for any thicker glass. I have described how to make this dozens of times in this BB), My approach is to make 3 scores perpendicular to the circle's edge. There is a big trick. I always begin the score well away from the circle's edge and score to the edge of the glass. Then I use running pliers to break the scores out. The break starts with the running pliers and will always end at the circle (after it is completely run). With thinner glasses, you can get the exterior to open enough to lose the circle with some outward pressure, after the first score has been run.
For glasses 6mm or thicker, there is a nifty trick. After I have run the score all around, it is not always through top to bottom. The solution to finish the break is to use a propane torch over the run. I keep the torch moving slowly and go around the circle at least 2 times. You will hear some snap crackle and pop as the glass finishes the break to the opposite surface. I do this on the bottom side after it has been run. When you do this right, the edge is square with no flare.