How to Cut Gauge Sight Glass

Don’t Glass It Over

How to Cut Gauge Sight Glass

When you think about it, gauge glass is your window into a boiler’s inner workings, giving you the ability to keep it operating properly, safely, and efficiently. Every piece is custom-cut for the boiler in which it’s installed, and there are several ways to do it. While the process of cutting gauge glass has gotten safer and more precise over the years, it’s always focused around the simple process of scoring. 

You Know the Score

Rather than applying a saw to the glass, which just creates a lot of broken glass, scoring involves scratching a fine, consistent, circular groove all the way around the outside of the glass with a fine, hard cutting tip. Once that groove is deep enough, lateral pressure is applied to the glass. Since glass has a strong, orderly, crystalline lattice structure, it will invariably break at its weakest point, which will be the score you’ve just created. When scored properly, the glass will snap off with a clean, smooth edge, requiring perhaps only a little bit of polishing before installation.

The Chain, Gang

One of the old, trusted, but somewhat complex and cumbersome ways to score glass involves the use of a glass cutterchain. This hand tool looks like a large pair of pliers with a small chain attached to the top. To use a cutterchain, the sight glass piece is held in place in its jaws, the measurement mark is lined up with the fine-edge cutting wheel inside, then the chain is wrapped around the glass and locked into place. As the glass is rotated, the cutterchain’s handles are squeezed slowly and steadily together to press the glass tighter and tighter against the cutting wheel. Enough turns, and noila, a nice, even groove around the glass. The glass cutterchain is not without its hazards, though. Squeezing the chain too tightly will shatter the glass, while holding it too loosely will result in a groove that’s too shallow, and won’t give you a clean break.

Just A Pinch

The newest method for cutting sight glass still follows the same method of scoring the glass, but it uses a smaller, simpler handheld sight glass cutter that resembles a staple remover. It only has two moving parts, it’s much lighter and more portable than a glass cutterchain, and it’s easy to operate. Simply line up the cutting tip with the measurement mark on the glass, pinch the tool’s jaws together, and hold them as you rotate the glass. With slow, steady pressure, you’ll have a perfect groove in no time.

Making the Cut

When cutting sight glass, there are a few important things to remember. Safety glasses are absolutely crucial, because the last thing you want is a fine sliver of glass flying into your eye. It’s also extremely important to measure your glass accurately, and make sure the cutting bit or wheel lines up exactly with the mark you’ve carefully measured. Glass can’t be stretched, obviously, and trying to re-cut it with very small margins can often end in glasstastrophe.

If you need a sight glass cut, sight glass parts, or any sight glass work done, the skilled experts at WARE are standing by to help. We also offer maintenance, repair, and service on every part of your boiler. Contact us and let us know how we can help. 

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WARE is a commercial & industrial boiler rental and service company that specializes in sales, service, valve repair, rentals, parts, turn key and boiler training.