A glass cutter does not cut glass. It scores it. You draw a hardened wheel across the surface to open a tiny fracture, then you break the glass along that fracture with a second tool. Once that clicks, the whole job gets easier, because you stop pressing hard and start paying attention to the line.
Karina from Delphi Glass walks through the basics here: the cutters, the grips, and the two kinds of pliers that turn a score into a clean edge. Everything below is a beginner setup for stained glass, mosaics or fusing.
The three tools you actually need
A cutter, a pair of running pliers, and a pair of breaker-grozer pliers. That is the whole kit. The cutter makes the score. Running pliers apply even pressure on both sides of the score so it opens along its whole length. Breaker-grozer pliers grab strips too narrow for running pliers, and the curved jaw crumbles rough spots back toward the line.
Which cutter should you buy?
There is no correct answer, and anyone who tells you otherwise is selling something. A pistol-grip cutter sits in your fist and lets you push from the shoulder, which is kind to arthritic hands and to anyone cutting for an hour. A pencil-style cutter goes between your fingers like a pen and gives you finer control on tight curves. Custom-grip and Thomas-grip cutters split the difference with a saddle that rests in the web of your thumb.
Try one. Practice on scrap. Comfort beats brand every time.
Oil-filled or dry?
Many pencil cutters have a reservoir you fill through a knob on the back end. Add a few drops, not a full tank, or the oil runs straight through and makes a mess. You do not need oil on every score. It is worth keeping in the workshop anyway so you can lubricate the wheel now and then, and always before the cutter goes away for a while.
What a good score looks like
Run the wheel from one edge of the glass to the other in a single pass. Do not go back over it. You should hear a soft scratchy creak the whole way across. Then look at the line: a good score is faint, like a hair laid on the surface. If it looks like you trailed salt across the glass, you pressed too hard, and that score will fight you when you try to break it.
Three ways to break a score
On transparent or lightly textured glass, flip the sheet score-side down on a breaking mat and press gently from the back. Gentle curves pop apart on their own.
For anything with at least half an inch of glass on both sides of the line, use running pliers. Set them on the glass, tighten the screw until it touches, then back it off a quarter turn. That sets them to your glass thickness.
When the strip is narrower than that, running pliers cannot get purchase and you switch to breaker-grozer pliers.
Safety
Glasses on before the first score, every time. Cutting glass throws shards and slivers you will not see. Sweep the bench with a brush between pieces and tip the sweepings into a bin rather than brushing them onto the floor.
