Frightened of Drilling Glass?

Learn How to Drill Glass Safely Without Breakage

So where to start? First of all, think about your drilling glass project. If you want to make big holes or lots of holes – eg for a mirror or a fusing project – then you need access to a drill press as they are quicker and the drill bits come in various sizes. If you already have a glass grinder and want to set it up for drilling glass, then you can simply buy an extra drill bit for it and get going for a few bucks. If you’re interested in having more options – drawing on glass for example – and want smaller holes for hanging your art work invisibly, then a flexible rotary shaft tool is for you.

How to Drill Glass with a Drill Press

Chances are you probably won’t have the space, money or need to buy one of these, so your best bet is to hire one for an hour or so from your glaziers or from your local stained glass studios. If you can afford one, you can buy a table top drill press for a reasonable price. These drills are only for drilling holes in glass, so are great if you have loads of fused panels you want to hang, or if you want to drill lots of different sized circles out of a piece of glass for a fused project, but you won’t be able to do any engraving with them.

The most crucial thing to remember when learning about drilling glass safely and without breakage is that you need water. It acts as a coolant and prevents the glass from over-heating and cracking.

The pillar drilling glass machine 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 drill bit attached to it. The diameters of the bits range from ¼” (6.5mm) to 1” (25.5mm).

Before turning the drill on put on an apron and safety goggles. Pull down the drill bit and position your glass in the correct place for the hole. Pillar drills are connected to the mains water supply, and this has to be turned on first, at a steady, gentle flow. Hold your glass firmly with your left hand, turn the drill on and slowly introduce the drill bit down to your glass by turning the handle wheel towards you with your right hand. It’s not wood, so don’t press hard – rather let the diamond coating do the work and gradually introduce a bit of pressure. It’s a good idea to take a bit of scrap glass to get the feel of it first. When you feel the drill bit is nearly through, ease off the pressure so that you don’t chip the glass on the underside. Turn off the drill and the water.

Drilling Glass with a Flexible Rotary Shaft Tool

This is just a fancy name for a drill that is very similar your dentist’s drill, with a moveable ‘arm’ and a handpiece that holds the diamond drill bit. These drills are the most multi-purpose of the drills available as it doubles up as a glass engraving tool. On mine the speed is adjustable with a foot pedal, which allows you to do a range of different creative things with it. They’re small, inexpensive and excellent for drilling smaller holes in glass – great if you want to hang your glass work up invisibly with thin wire or fishing wire, or bolt a small shape of glass on to a base glass. These drills are also great for engraving pictures or text on to the surface of the glass – one idea is to use it for copying your children’s drawings or your favourite poem on to your glass work.  One of my students once engraved a fish with all the scales, which was then fire-polished in a kiln. It looked amazing.

The most reasonably priced drill like this that I’ve found in the US is the Rotary Tool Set from Delphi Stained Glass. It’s been rated 4 out of 5 stars by reviewers, who say it’s a “good quality tool” and “great value”. The only thing it seemed to fall down on according to users was that the instructions were a bit minimal and that you had to buy the bits separately for glass. The same thing happened to me, but I’m a fan of decent drill bits – the cheap ones go blunt too quickly and end up being a false economy. This packet of six diamond drill bits from Delphi are rated quite highly in the reviews, but if you really want the best, you need the impregnated diamond coated bits which cost more. I get mine from a specialist drill supplier and they last for ages.
 
Again, water is the key to safety and success, and with a flexible rotary drive unit you have to manually add water as there’s no automatic feed. This is great because it means that it can be used anywhere with ease and doesn’t need any complicated plumbing.

Firstly, you need an apron and goggles. For both drilling holes in glass and using it as a glass engraving tool, it’s best to put the glass in a shallow container – I use a plastic photographic tray – with a bit of newspaper at the bottom to stop you drilling a hole in the container. Cover the glass and paper with about ¼” (6.5mm) water. If you can’t find a tray big enough, simply dab water on with your left hand throughout the drilling/engraving process so that it doesn’t get hot and break.

Turn the drill on. The fastest speed is best for drilling holes. Holding the handpiece like a pen, introduce the drill bit to the glass slowly, from the side to start with to make a small dip to prevent slipping and scratching. Once the hole is started hold the drill bit vertically and let the diamond burr eat into the glass with a little bit of pressure. Gently move up and down, so that water can get into the hole. Don’t push hard or you’ll break the glass - let the diamonds do the work. When nearly through to the other side reduce the pressure even more so that you don’t chip around the hole. 

Use your Glass Grinder for Drilling Holes in Glass

So what about drilling glass with a glass grinder? This is the cheapest but least flexible solution as you can only drill holes the size of the drill bit you buy – either 1/8”, ¼” or 3/8” – and there’s obviously no option for engraving any pictures on to your glass. Mine works well, it’s an Inland glass grinder, and they make the diamond drilling bits necessary for drilling holes. You’ll have to buy an adapter too, but that’s a good idea as it can remain on top of the existing grinding drum on your grinder, making it ready and easy to use for any of their different drilling bits. Delphi Glass sell both these products – all you need to do is screw the Inland Bit Adapter on top of your grinding drum, and then screw the diamond drilling bit into that.

So how does it work? Wear goggles to protect your eyes. The water this time is provided via a wet sponge that you keep under the glass. Introduce your glass slowly over the top of the drill bit at an angle to start with, and then slowly straighten it up so that it’s flat on top of the drill bit. Don’t press too hard otherwise the glass will break – the diamond will do the work. Just before the drill bit comes through the top of the glass, reduce the pressure a bit so that it doesn’t chip the glass. Here’s a video from Inland that goes through the process for you:

So that’s it, simple! Hopefully you’ll have a really good idea now about drilling glass, and the equipment that you need to do it. Don’t forget, before you buy anything, think about not only what you need it for now, but also what creative possibilities you might need it for in the future. Do you simply want to drill holes, or do you want the option of engraving your glass art with your unique designs?

Tech Talk - Drilling Glass

You can buy diamond drill bits with three different types of diamond coating, ranging from single layer (cheaper and not so durable) to impregnated (longer lasting but more expensive). The diamond drill bits come in sizes from 1/16”- 2” (3-50mm) – the bigger the bit the slower the recommended rpm. To give you a rough guide; drill bits up to ½” (13mm) can be used at speeds from 3500-4000rpm, for ½”-1” (13-25mm) bits go at 2000rpm, slow down to 1000rpm for drill bits between 1”-2” (25-50mm)

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