How to cut Flat Glass



 


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With a little practice, most handymen can cut flat glass.
This page is devoted to the standard single-strength, double-strength, and 1/4" plate glass and mirrors usually found in the home. Some other types of glass may require professional facilities and abilities.



 

ALWAYS wear adequate Gloves AND
Safety Eye-wear when cutting glass.

It is easiest to cut or "score" glass when it is super clean.
The thicker the glass is, the more important clean becomes.

Glass seems to be more forgiving when it is warm, than when it is cold. If you are cutting a tapered piece, start your cut on the wide end, and run the cutter off the narrow end.

There are two general types of cutters:
(1) - Is a metal casting with a single cutting wheel, various notches to nibble glass, and a ball on the handle to crack glass. I consider this ball a joke.
(2) - Has a wooden handle and a turret with multiple cutters, and no joke.
The numbered turret is rotated when a cutter becomes dull.
I prefer those made in USA, Germany, or Sweden.

The little wheel on the glass cutter presses against the glass so hard that it forces tiny chips of glass out of its path. That weakens the glass at the cut line. Thinner panes are much easier to cut, because the depth of the cut is a larger percentage of the glass thickness.

The wheel must revolve in order to cut. You need all the friction you can get. If there is any dirt, moisture, or oily film on the glass, the wheel will slide instead of revolving. Then the ripping/tearing sound will stop and there will be a smoother feeling to the cutter.

Even if you correct the condition, there is a good chance that the glass will not break along your intended line from he point where the wheel quit cutting. Then the glass may be ruined, and  you must start over.

Be sure to measure and mark correctly the first time; if your cut is slightly oversize, it will be nearly impossible to remove 1/8" or 1/4" without the use of a special grinder. Removing 1 inch is not too difficult, but removing 1 foot is MUCH easier. Consider the width of the cutter wheel and frame in your measurement. If you are cutting a rectangular piece, a Fence and Square will be useful.

This is not a Baseball Game; ONE strike, and you're out !



 

Practice on single-strength sacrificial glass
before attempting the real thing.
Remember to make the cut in one continuous motion,
or you may have lost the game already.
 

(1) - Cutters are cheap - use a new one.

(2) - Wash and completely dry  the glass.

(3) - Work on a clean flat surface.

(4) - Fasten your work Securely

(5) - Mark the glass and
use a secure straight edge as a cutter guide.

Double-check the dimension;
you only get one chance to do this right.

(6) - Tilt the cutter slightly toward you and pull the wheel firmly across the glass in one continuous motion.

(7) - Then crack the glass by "bending" the cut open in one of two ways:

(a) - With the CUT DOWN:
Elevate the two edges that are parallel with the cut
and apply an even downward  pressure directly above the cut line.

(b) - With the CUT UP:
Place a round dowel or broomstick directly under the cut and put an even pressure on both edges of the glass that are parallel with the cut.
 

 
You can smooth the edges somewhat with emery cloth,
but it takes a lot of effort.
 

Remember to:
!! BE SAFE !!

! Scrub the glass
! Use a new cutter
! Cut in one motion
! Fasten your work securely
! Mark it right the first time
! Work on a clean flat surface
! Exert an even pressure to crack the glass
 
 
 

When you think you're getting pretty good at this, try cutting some freehand gentle "S" Curves. Hold the cut between your two gloved hands and "bend" the cut open. If the curved piece is tapered, bend it from the wider end. When you get good at this, try making a Glass Picture Frame; a square piece of glass with a square or oval cutout.

Hint: Drill holes at inside corners. Then connect the dots with the glass cutter and cut diaganally from opposite corners. Working from the center out, drill additional holes and remove small pieces of glass as you go. A "putty pond" around the hole-to-be with 1/8" of coolant will aid your cause.

If you need a special curve, make a hardboard template. Sand the working edge very smooth. You may find the template easier to use if the cutter rides against an inside edge rather than an outside edge; so your template may resemble an oval picture frame rather than an egg. Secure everything.

Metal extrusions are available to make anything from a storm window to a fish aquarium or display case. Glass can be stained or etched. A glass cutter has the ability to make something out of nothing, or to make nothing out of something;
it all depends on you. Practice !