It is important always to keep the drill bit and glass wet, otherwise the glass gets too hot and will break. There are a variety of things you can do to achieve this.
- Drill under water in a container
- Drill in a ring of clay, plasticine, etc., holding water. To do this, you need to make a ring about 50mm / two inches in diameter and press it around the drill site. Fill the ring with water and a little diamond coolant. This will cool the drill site and glass. Diamond coolant is not necessary, but extends the life of the bits.
- Use a recirculating water pump such as those made for indoor water features. Direct the small flow of water to the drilling site and catch the water in the bucket in which the pump is submerged.
- Use a glass drill with hollow core bits and an internal water feed. This is the most expensive but it is the best equipment with which to drill large holes.
Keeping things wet
Using a drill press
Drilling with a Flushing Head
Drilling holes with copper tube and grit
Drilling glass without a drill press
Drilling speeds for diamond bits in glass