Cutting Laminated Glass
Last week we talked about the equipment necessary to successfully fabricate glass parts, the proper handling of the glass to the cutting table, the different thicknesses of glass and where they may be used. This week we want to address the actual preparation of the glass and use of the equipment in set up.
Once you have the glass positioned on the cutting table and the pattern placed beneath it, the next step is to prepare the glass for the score and break. Line up the glass so the bug etched in the glass will be visible on the finished part. If this is a leftover piece of glass or if the monogram will be cut off, partially or completely, by the fabrication, the cutter must re-etch or emblazon on the glass the labeling required by FMVSS 205/ANSI Z26.1. This must include the DOT# and the AS grading of the glass cut. The only exception is if it will not be used in a vehicle for the roadway.
Next, line up the straight edge to the pattern and clamp it to the glass on the table. Don’t forget to allow for the thickness of the glass cutter at the wheel. The body of the cutter can change the actual size by as much as 1/8 of an inch on each side, which can make a significant difference in the installation of the part.
Now apply a coating of lightweight oil to the surface to be scored. I use an old peanut can with a sponge cut to fit the base. Then I soak the sponge three-in-one oil or leftover motor oil. I store my cutters and I have a cotton dauber resting in the can. When I am ready to apply oil to the score line, I use the dauber to apply a coat of oil directly over the score line. Then I grab a soaking glass cutter and make my score. The oil “cools” the score and lubricates the wheel of the cutter to make a smooth and accurate score.
Make your first score and then break that score immediately. The longer you wait between the score and the break the more possibly of the break running away from the score. The reason for the score is to control the break. The score creates a fissure in the glass surface and controls the direction and travel of the break.
The score is very important to the success of the cut. If you score too lightly, the break has no guidance and if you score too “hot,” you can cause the glass to break erratically. With a perfect score you can hear the score and feel the drag of the tool, but it does not result in the flaking of the glass surface.
The proper way to score glass takes practice and a steady hand. It is always better to move your body than to move your hands. If you stand still and move your hands you are likely to have an uneven score line. It will be light on the ends and “hot” in the middle. Once the score is commenced, do not stop and do not score over another score. Know what is around you before beginning the score and move items that will hinder movement.
Use the straight edge as the guide and run the cutter along the edge of the straight edge. Once you start the score, lean back or step back to keep the score smooth and with even pressure applied to the cutter. Do not stop and start.
Repeat the above procedures for all scores on the same side of the glass. Then turn the glass over and carefully line up the straight edge on the opposite side using the score and break from the other side for alignment. Make sure the opposite score is directly above the opposite cut.
Next week we will discuss the different methods of breaking the score and separating the lamination.