Glass Running Pliers vs Nipping Tools: Which Do You Need?
What happens between the score and the break
A glass cutter scores the surface and does not cut through. Bullseye Glass’s cutting guide describes the cutter’s wheel creating a shallow fissure that the glass then breaks along. The tool you choose for the next step depends on where that fissure runs and how much glass lies on each side of it.
Running pliers apply even pressure along a score to extend the break. Breaking and grozing pliers take hold of an edge and snap or chip off material. Nippers and nibblers remove small pieces. Deglazing is a separate job, taking out existing glass and its seal, and has nothing to do with a fresh score. Mixing these up wastes glass or leaves a ragged edge.
Running pliers: pressure along a score
Running pliers have a curved jaw that helps you control a long or difficult break. Delphi’s instructions say to line the score up with the indicator line on the upper jaw, place the pliers a quarter to a half inch over the glass edge, and clamp down gently. The break then runs along the score.
They suit a score that runs from one edge to the other. They suit stretches where both sides are wide enough for the jaws to grip and where the break would otherwise run unevenly under hand pressure.
Their limits come from the geometry. The jaw needs glass on both sides of the score to hold, so a narrow strip, a score that does not reach an edge, or a deep curve is outside what they do well. Check the maker’s stated glass thickness range before relying on a pair for thick architectural lites, and do not assume a pair sold for art glass handles thick plate.
Breaking and grozing pliers
Breaking pliers have flat jaws and a wide grip. They hold the edge of a scored piece so you can snap the break by hand, which is useful for short scores. Grozing pliers have serrated jaws and nibble away small bites from an edge to shape or smooth it.
The Delphi cutting guide lists breaker/grozer pliers and running pliers as separate hand tools with different jobs. Use breaking pliers when you can grip enough glass to control the snap, and use grozing pliers to remove slivers rather than to make a primary break.
Keep your hands out of the path of the break and keep pieces from falling. A running pair that is working correctly breaks the glass along the score, so what falls away is a clean offcut, not a shower of chips.
Nipping tools: small bites and awkward shapes
Glass nippers, chippers and nibblers take small bites out of an edge. Suppliers such as CR Laurence group chippers and nibblers together in their glass-cutting listings. They are the tool when the leftover strip is too narrow for pliers, or when you need to bring an edge to a line, notch a corner or ease a curve.
They remove material from the edge and do not extend a break. Using them as a primary breaker produces uneven edges and chips. They also create small fragments, so eye protection is mandatory. The Delphi guide lists safety glasses with its hand-tool setup.
Check the jaw width and the stated glass thickness for any nipper you buy. A jaw built for thin material will not bite through thicker plate without chipping.
Where deglazing tools fit
Deglazing means removing glass that is already installed, along with the sealant, tape or gasket holding it. The tools are for cutting through the bond and lifting out stops or beads, not for shaping new glass.
In practice you choose them by the sealing system on the opening: butyl or foam tape, wet sealant or a roll-in gasket. Each releases differently. Look for the tool maker’s description of the sealant types the tool is designed for.
Treat deglazing as a separate purchase from your cutting set. Having running pliers and nippers on the truck does not equip you to take out old glass without damaging the frame.
Choosing for the work in front of you
- Long straight score edge to edge on flat glass: running pliers.
- Short score or a piece you can grip: breaking pliers.
- Narrow strip, notch or curve: nippers or grozers after scoring.
- Edge clean-up: grozing pliers or an abrasive method.
- Removing existing glass: deglazing tools for the sealant system on the opening.
None of these cut tempered glass, which cannot be cut after tempering. Laminated glass needs scoring on both faces and cutting through the interlayer, so check the glass maker’s instructions.
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Get Glass Breaking And Grozing PliersRelated guides
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- Setting Block Sizing and Glass Thickness Measurement Guide
FAQ
Do I need both running pliers and nippers?
If you cut and break flat glass regularly, they do different jobs. Running pliers extend a break along a score. Nippers remove small pieces from an edge, such as narrow strips or notches that the pliers cannot grip.
How do I use running pliers correctly?
Following Delphi’s instructions, line the score up with the indicator line on the upper jaw, set the jaws a quarter to a half inch over the edge, and clamp gently. Make one score at a time and break it before scoring again.
Are deglazing tools the same as nipping tools?
No. Deglazing tools remove installed glass and its sealant, and nipping tools remove small bits of edge from new glass. Choose deglazing tools by the sealing system on the opening.