The document provides guidelines for cutting and drilling tempered glass: - Holes must have a minimum diameter of the glass thickness and be positioned with at least 2x glass thickness from edges and between holes. Corner holes require 4x to 6x glass thickness from edges/corners. - The glass width must be at least 8x the thickness to be tempered. Rectangular cuts cannot exceed 1/3 the glass length/width and require 0.5x rounding from edges. - Hole and cut dimensions and positions depend on glass thickness, size, shape and number of holes to minimize breakage when tempered. Proper rounding and edge work is required before tempering.

1. Pre-Processing required for
Tempered Glass
Glass School By
Ahmed Bahaa El Din

2. Cutting and Drilling
• All notches and holes must be made and finished with the proper
edge work before tempering.
• In general, the limitations on hole positions relative to the edges of
the glass, the corners of the glass
• and to each other depends on:
– nominal glass thickness (d)
– Dimensions of the glass
– Hole diameter (D)
– Shape of the glass
– Number of holes

3. Minimum Glass Width
• Minimum width (W) of the glass with round holes is 8 × glass
thickness (d).
W ≥ 8 × d
w

4. Diameter of the Holes
• The minimum diameter of the hole (Dmin) is not recommended to be
less than the nominal thickness (d) of the glass.
• The maximum diameter (Dmax) should not be more than a third of
the narrowest point of the glass.
Dmin ≥ d Dmax ≤ 1/3 × Wmin
w
Dmax Dmin

5. Position of the Holes
• The distance (a) from the edge of the hole to the edge of the glass
should be not less than 2 × glass
• thickness (d).
• The distance (b) between the edges of two holes should be not less
than 2 × glass thickness (d).
a ≥ 2 × d
b ≥ 2 × d
a
b

6. Holes in Corners
• When having a corner, 90° or more with the rounding, the distance
(a) from the datum point of the corner to the edge of the hole must
be at least 4 × glass thickness (d).
• The distance (c) from the edge of the corner to the edge of the hole
should not be less than 6 × glass thickness (d).
a ≥ 4 × d
c ≥ 6 × d
a
c

7. • If the hole is placed in a corner nearer the glass edge than
recommended, the risk of glass breakage increases substantially.
• The risk can be minimized by making a cut in a narrower supporting
belt of the corner. See picture below.

8. Rectangular Holes & Rounding
• The maximum size (X × Y) of the rectangular cutting depends on the
dimensions of the glass.
• Cutting’s length (X) should not be more than third of the glass length
(L) and cutting’s width (Y) should not be more than third of the glass
width (W).
X ≤ 1/3 × L
Y ≤ 1/3 × W
ax
b
Y
w
L
r

9. • The distance (a) from the edge of the glass to the edge of the cutting
should be at least half of the cuttings length (X).
• The distance (b) from the edge of the glass to the edge of the cutting
should be at least half of the cuttings width (Y).
a ≥ ½ × X
b ≥ ½ ×Y
• Edges and notches of the cuttings must be rounded.
• The rounding radius (r) should not be less than the glass thickness
(d).
r ≥ d

10. The End