The cutter is not a knife! It is designed to create a single, consistent score line. It is not a device to force itself through glass or dig into the glass. When you are working with art glass at an entry level, being able to work the cutter with a more gentle hand than usual is more useful than having a cutter that “cuts better.”
Before attempting a score cut on a project piece, set up your scrap glass and work table to cut glass. Wear safety goggles and cut-resistant gloves. Remove all old glass chips from the surface and set your glass down on a mat. Be sure your glass sheet is very clean. Dust, oils or marker residue can affect the score. Watch for the score line to disappear if you are pushing the score too hard. The best score cut creates an even and crisp line. A bad score cut often is noisy or sounds like it is scraping or cracking through the surface.
You can get a sense of the proper hand pressure by cutting several straight lines on scrap glass with different amounts of hand pressure. Cut one line at a higher pressure than you think you may need. Then, cut another line with a lighter pressure. Under the light, the cut at a lower pressure is more even than the cut at the higher pressure, as shown below. The line at a higher pressure is much more crushed and has a “dusty” appearance.
Once you have made a good score cut on glass, move the score cut over to the running pliers and apply a steady pressure on the glass to break off the score line. If the glass breaks away from the glass cut score line, first examine the score. Was the glass cutter broken away from the line? Was the glass cutter slowing down during the cut? Was there an increase in pressure when the glass cutter was getting close to the end of the sheet? Many of the problems with glass cutting occur at the score line, only become obvious after the glass piece is snapped off. This is why it is a good practice to experiment with scrap glass before attempting to score a project.
Start with straight glass cuts. It is easier to control your scoring hand when you cut a straight line. A gentle glass curve can be worked with, and a glass curve is a bit later. A glass cut can begin and continue without stopping from one glass cut sheet edge to the other. If your score cut hand is shivering, shorten your straight glass cuts and score smaller glass pieces. If the glass cutter jumps, first check if the glass surface has been cleaned and the glass cutter is being held at a constant angle. The goal at this point is to make a straight score cut that looks good!
As you improve, your score cut lines start to appear similar in each test glass cut. You will notice the scoring sound becoming more consistent and the glass snapping off more consistently from the score line, and your edges will need less dressing prior to the polishing operation. Make some notes in a small notebook about the changes that you make to the hand pressure, speed of the cut, glass piece, or glass surface. This is an important early stage in learning the skills of making glass art.