Drilling glass or tile is terrifying for beginners because the material is brittle. One mistake, and you crack the entire bathroom wall. The secret lies in choosing the right bit.
1. Spear Point Bits: The DIY Choice
Look Like: A small spear or arrow head made of Tungsten Carbide.
Best For: Small holes (3mm to 10mm) in glass, mirrors, and soft ceramic tile.
Pros: Very cheap and easy to start (they don't walk).
Cons: They drill slowly and wear out quickly on hard porcelain.
2. Diamond Core Bits: The Pro Choice
Look Like: A hollow tube with a rim coated in diamond grit.
Best For: Hard Porcelain, Granite, Marble, and large holes (12mm+).
Why Pros Use Them: Instead of chipping the material, diamonds grind it away. This creates a much cleaner hole with almost zero risk of cracking, even on the hardest Grade 5 Porcelain.
The Golden Rule: Keep It Wet
You cannot drill glass dry. Friction raises the temperature, and thermal shock causes the crack.
Cooling Methods:
- Spray Bottle: Have a helper spray water continuously at the tip.
- Putty Dam: Build a small ring of plumbers putty around the hole and fill it with water.
- Dipping: Dip the bit in water every 5 seconds.
Warning: Porcelain Hardness (PEI Rating)
Modern floor tiles (Porcelain) are harder than steel. Do not attempt to use a standard masonry bit or even a cheap spear point bit on PEI 4/5 Porcelain. You must use a Diamond Core bit, or you will burn the bit and potentially crack the tile from heat stress.
