Drilling glass
Drilling glass isn’t difficult; it just takes patience, a steady hand and – most crucially – water. Why? Because the water acts as a coolant and prevents the glass from over-heating and cracking. There’s basically two types of kit you can drill glass with safely – one is the pillar, bench or pedestal drilling machine which will look something like the one pictured here, but fitted with a special chuck that allows a flow of water to run through the tube of the diamond drill attached to it. If you’re a bit confused (like I was) with the terminology - ‘diamond drill’ is what I would call the ‘drill bit’, it’s not the whole machine. The other method of drilling glass is to use a flexible drive unit like the one below. Theoretically, you can use hand held drills for drilling glass, but in practice it’s quite tricky, as they’re a bit difficult to control.
The diamond drills for drilling glass are hollow steel tubes coated at the end and around the top edge with a diamond surface. You can buy three different types of diamond coating, ranging from single layer (cheaper and not so durable) to impregnated (longer lasting but more expensive). The diamond drills come in sizes from 2-100mm – the bigger the drill the slower the recommended rpm.
And now I’ll tell you about my flexible drive unit. It’s just like a dentist’s drill – so if you know any dentist who’s upgrading, offer to take it off their hands! This is a simple motor unit with a flexible drive and handpiece that holds the diamond sintered burrs for drilling glass. Originally mine had a foot pedal to adjust the speed, but I upgraded this to a simple dial that I can easily set to hold a particular speed consistently. This equipment is more normally used for engraving on glass, but it is very good if you’re drilling small holes in your art glass to make stained glass wall hangings. Again, water is the key to success. With this set up you have to manually add water – there’s no automatic feed. Ideally you would put your piece of glass in a 
flat container on top of newspaper covered with a bit of water. The main advantage of flexible drive units is cost – this one was about £100 ($200) – far less than the outlay for the pillar machine set up. It also gives you the option of engraving your stained glass panels should you wish to. What you can’t do is drill big holes – as you can see from this photo with a one pence piece, the diamond burrs are only very little!
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