Hole Drilling
Viracon offers holes drilling capabilities starting at 1/4 inch. Our Z. Bavelloini vertical two-sided hole drilling equipment offers precision accuracy.

Maximum Number of Holes:
• The maximum number of holes allowed in any lite of glass is ten (10.)

Guideline for Holes Dimension:

Minimum Size: Circular holes must have a diameter at least 1/16" greater than the thickness of the glass, with 1/4" (6mm) being the smallest hole allowed.
Maximum Size: The maximum size of a hole can not be more than 1/3 the narrowest dimension of the glass.

For holes that have a straight edge, or are non-circular, fillets are required in the corners. A fillet is a rounded corner from which the straight edge emerges. The radius of the fillet must be equal to or greater than the thickness of the glass, but not less than 1/2".
Inches Millimeters
Glass
Thickness		 Minimum
Diameter		 Glass
Thickness		 Minimum
Diameter
1/8 3/16 3 5
5/32 7/32 4 6
3/16 1/4 5 6
1/4 5/16 6 8
5/16 3/8 8 10
3/8 7/16 10 11
1/2 9/16 12 14
5/8 11/16 16 17
3/4 13/16 19 21
Guideline for Minimum Glass Width with Holes:

The minimum width of glass containing holes that can be satisfactorily tempered is eight (8) times the thickness of the glass. All other requirements of hole location, spacing of holes, and dimensions of holes must also be met.
Inches Millimeters
Glass
Thickness		 Minimum
Width		 Glass
Thickness		 Minimum
Width
1/8 1 3 25
5/32 1-1/4 4 32
3/16 1-1/2 5 38
1/4 2 6 51
5/16 2-1/2 8 64
3/8 3 10 76
1/2 4 12 102
5/8 5 16 127
3/4 6 19 152
Guidelines for Hole Spacing:

The distance from any edge of glass to the nearest point on the rim of the hole (x) must be at least 1.5 times the thickness of the glass for glass that is 1/2" (12mm) or less in thickness.

The distance must be at least two (2) times the thickness of the glass, when glass is over 1/2" (12mm) in thickness. The rules are the same for distances between holes.
Inches Millimeters
Glass
Thickness		 X = Min.
(1/2"glass
or less)		 Glass
Thickness		 X = Min.
(1/2"glass
or less)
1/8 3/16 3 5
5/32 15/64 4 6
3/16 9/32 5 7
1/4 3/8 6 9
5/16 15/32 8 12
3/8 9/16 10 14
1/2 3/4 12 19
5/8 1-1/4 16 32
3/4 1-1/2 19 38
Guideline for Holes Placement Near the Glass Corners:

Holes near corners must be located so that the nearest edge of the hole is at least 6.5 times the thickness of the glass from the tip of the corner when the corner is 90° or more.
Inches Millimeters
Glass
Thickness		 X = Min. Glass
Thickness		 Minimum
Diameter
1/8 13/16 3 21
5/32 1-1/64 4 26
3/16 1-7/32 5 31
1/4 1-5/8 6 41
5/16 2-1/32 8 52
3/8 2-7/16 10 62
1/2 3-1/4 12 82
5/8 4-1/16 16 103
3/4 4-7/8 19 124