Many of the glass parts fabricated by an auto glass shop include radius corners. Experienced glass cutters can create their own radiuses through geometric procedures. However, there are radius templates available for purchase, which makes this job a lot easier.
To make your own radius corners you will need a tape measure, compass and marker. Measure in from the two edges the amount of the radius. For example, if you want a 2-inch radius corner, measure in two inches from the horizontal edge and make a mark then measure in two inches from the vertical edge and make a mark. The two marks should cross.
Place the point of the compass on the crossed mark and create a curve from the horizontal edge to the vertical edge. This creates a 2-inch radius.
Do the same procedure for any radius desired.
Once the radius corner pattern markings are drawn on the glass, the next step is to score and break the glass. This is where the rubber meets the road, so to speak. If the corners are mis-scored or broken with too much pressure, the entire part can be lost to a runner stretching into the main part. There are two ways to score and break the glass; the straight and grind or the curved and break.
The straight and grind is the safest method when starting out cutting. It is simply scoring the radius at its highest point and then grinding and rounding off the remaining edges.
The curved and break method is scoring the radius directly on the curved pattern markings and then using a drop-jaw pliers to gently break the score. I usually started on the score that leaves the glass edge and break it to the height of the radius. Just gently squeeze the handles and don’t bend the glass down. This will cause pressure at the edge points and cause an unwanted fracture.
I also scored and broke one side before I scored and broke the other. I feel that the solid underside gives me better control. Once both sides are scored and broke, I then pull the scrap outward to stretch the lamination and cut it with my tape measure cutter. Do not bend down on the scrap piece or the edges can chip the main part and cause a fracture.
The part is now at the size and shape needed to install but the part is not finished yet. Next week we will talk about the finishing edges.