Chipping Glass while Sawing

Frequently there are chips on the bottom surface or breakouts at the end of cuts while sawing glass. There are several methods to reduce these effects.

Saw blade depth

The blade on an adjustable depth overhead saw should be set to just below the saw table depth. This reduces the break outs on the bottom surface. It helps to make the angle at which the saw blade meets the glass more acute, helping to reduce the chipping of the surface.

Of course, on an adjustable overhead saw blade could be set to just mark the surface to reduce chipping on the top. Then the table drawn back to adjust the blade to the full cutting depth. However, that is a lot of adjustment to reduce minor chipping that will be remedied in further cold work or fire polishing.

For saws that do not have adjustable depth, bottom surface chipping can be reduced by placing sacrificial glass below the main piece. This raises the main glass and creates a more acute angle between the glass and the blade, also reducing chipping on the upper surface.

Ends of Cuts

Break outs often occur at the ends of the cuts. Placement of a sacrificial piece of glass vertically at the exit of the cut helps to give a clean cut at the end. This will apply whether using a fixed or adjustable saw blade.

Of course, the two can be combined:

Stencils vs. Saw

Saw

Frequently when people want to make a complicated shape they resort to a saw to create the shape.  This is used in both stained glass and fused glass work.  Although it may be necessary in stained glass applications, it is not as necessary in fusing.

One of a variety of saws

Stencils

There is an alternative to an expensive saw – stencils and frits.  You can make a stencil from stiff card. Place the stencil in the appropriate place. Then sift powder or sprinkle frit over the stencil.  Lift carefully and the shape is there ready for fusing.

Example of sifting powder over a complicated stencil

To get the depth of colour obtained from sheet glass, you need to apply the powder or frit to at least 2mm or 0.079". This also means that you need to go to a contour or full fuse with the powder or frit on the top surface.  You can, of course, later cap and fire again.

Example of the cutting of a stencil

More guidance on stencils is available here.

Revised 5.1.25