Tell me how to cut and drill glass.

I’m thinking about building a terrarium/fishtank (bottom 6 inches with water, orchids up above). I’d like to cut a hole in the glass in the back to string the electrical cords through. I’ve never cut glass before- how do I do it?


Very, Very carefully. It can be difficult, and the bit is usually pretty expensive. What you need is a diamond-tipped carbide drill bit, or anything specifically made for glass. I’ve had success using the teal colored Dremel grinding wheels, but it was very tedious and slow going. I recommend you ask at your local pet store about getting a tank drilled–people do it all the time for large and saltwater tanks. The cost shouldn’t be any more than the cost of a carbide drill bit. If the pet store doesn’t know where, call up a glass shop that does custom work–most window replacement places do. The cost to have it done should be minimal.

If you do decide to do it yourself, PLEASE follow at LEAST the basic safety tips–

WEAR GLASSES! (and heavy gloves)
Drill slowly–if the glass heats up, it will crack, especially if water hits it when its wet.
Do a little at a time, and clear the glass dust (sand) out frequently with a tiny brush or piece of paper–your breath may actually contain enough moisture to crack the class when hot.

I really recommend having a professional do it.
Unless, of course, you’re really making a bong, in which case, be very careful.

I think it also helps if you clamp the workpiece with thick cloth or some such, to dampen any vibrations.

Does the glass have to be tempered first?

I’d just take it to a glass shop.

A few years ago, I made shelves for a display case from scrap glass.

Cutting glass results in near-microscopic shards on the surrounding floor.

So wear good shoes, and vacuum after each session.

After cutting, edges should be sanded smooth. If you don’t have time to sand a piece immediately, tape thick newspaper over all sharp edges. Which brings up a good point.

Cut glass is **sharp**. I'm sure you figured on that. But, cutting a pane of glass can result in edges that are literraly sharper than razor blades. As a gadget lover, a project lover, and a total klutz, I'v cut myself many, many times over the years. Exacto knives, liineolum knives, whitling knives, Swiss army knives, computer housings-none of these were as easy to cut myself on.
This leads me to ask- Why drill a hole in the back? Why  not use a standard aquarium top? Or, if you want to do it all from scratch, why not use a wire mesh top?   Glass is dangerous and not easy to work with. The display case shelves are glass. But for the cabinet doors, I used window insulation kits.

Get yourself one very small drill bit.

Put gaffa tape on the area to be drilled, make it several layers.

Put the last layer folded back so that there is a large part of it with the sticky side up.

The sticky layer of tape will trap most of the glass shards.

The other tape provides a guide to stop the drill bit skidding across the surface of the glass.

Once you have drilled a pilot hole, make it large enough to take a rotary file.

Make sure you wear sealed eyewear, dust mask and if you can get one, one of those plastic suits you see forensic scenes of crime operatives wearing, and make sure you throw it out after use.

I have read that car customizers have drilled holes in tempered auto glass by taping a steel washer where they want the hole to be, then using a sandblaster to erode a hole through the glass (the washer acts as a mask).

Of course, one has to have a sandblaster in order to try this.

The other question was how to cut glass, which I believe that no-one has responded to. Easiest is to have the store you buy the glass from cut it to size.

Failing that, you buy a glass cutter, which is a thingie shaped like a toothbrush handle with a tiny sharp-edged hardened steel wheel set into the end. You lay your glass on a towel, then, using a straightedge for guidance, run the steel wheel along your cut line. Press fairly hard; the idea is to scribe a line into the glass with the little wheel.

Then you slide a dowel under the sheet of glass right under your scribe line, and tap the glass sheet with your hand; it should snap off right along the scribe line. Try it on scrap glass first; it takes a little practice.

You can also buy “glass-cutter’s pliers” which have little ridges on the jaws (two ridges on one jaw and a single ridge on the other). You align the single ridge with the scribe line and gently squeeze the pliers closed. The pliers try to “bend” the glass along the scribe line and of course the glass snaps off neatly. (Ahem)

From my limited experience, 1) it’s important to press down quite hard while scribing the glass, and 2) the pliers are better for small pieces, the dowel method for large.

If you go the diamond bit/grinding bit route, use wintergreen oil to lubricate/cool the bit, and use a relatively slow speed. And don’t press too hard or be in too much of a hurry, it’s self-defeating.

And don’t forget the sealed eyewear and dust mask that casdave mentioned. I don’t use the disposable suit, I just wash my stuff all by itself. Sorta like whatever clothes I’m wearing when we do fiberglass insulation.

Oops, minor point of technique I forgot. The single ridge on the pliers goes on the side of the glass opposite the scribed line.

You can read about drilling holes in glass here:

What I’ve been told is get a special drill bit made for drilling glass.
Lay your piece of glass on a horizontal surface.
Build a circular dam using glaziers putty around the spot you want a hole.
put a piece of tape over the target to keep the bit from wandering.
pour some lubricant, to keep the glass from heating up too much, into the dam. I’ve heard kerosine for this but that seems hokey to me, I’d use a very light oil, like thread-cutting oil.
Drill very slowly, without using very much pressure.
I’ve also heard about putting a piece of scrap glass under the piece of glass to be drilled.

Crap! if you hit ENTER by mistake it defaults to SUBMIT REPLY.
I was almost done anyway.

I was just going to post this site which shows you what to look for when you go for a glass drilling bit:
At least that’s what the bits I’ve seen look like, there may be other kinds as well.

FTR, I’ve done stained glass both professionally and as a hobby, but I’ve never had occasion to drill holes in glass, so what I related above is strictly hear-say and should be taken as such…

I used to make lamps out of the big glass wine jugs (bottles) and I would make a hole on the side, near the bottom, witha grindstone, very slowly and patiently. If you do go to fast you get a big crack but otherwise it works.

Well now that you mention it…

Nope, really for an aquarium. I was going to try and go the cheap way which was to tank a standard 30 to 50 gal. long fish tank and turn it on its side so that it is tall. Then glue a plate of glass over the bottom of the opening so there can be 6 inches of water. I was going to cut the hole in the now upper part for a light bulb and/or other electrical cables (filter).

I think I’ll follow most people’s advice and just pay someone else to make this thing for me…Probably cheaper that way anyhow…

Thanks, y’all just saved me some nasty cuts. I am a mega-klutz.


      • Two Points:
  • Aquariums must be made of tempered glass, else over time they become brittle and shatter. All aquariums made of glass are made of tempered glass.
  • You can’t use a (cheap) carbide drill bit in tempered glass: you have to use an all-diamond bit, and cool it with water or cutting fluid, or else it heats up fast and the diamonds all get knocked off pretty darn quick. This is possible with an inexpensive diamond bit in a Dremel tool, but it ain’t the best way of doing it.

Caution you CANNOT drill a hole in Tempered glass unless you are a professional even then it’s not recomended. All holes should be drilled before the glass is tempered. You should drill holes as Bumbazine describes you can use water as a cooling agent instad of oil. When cutting glass as Rocketeer describes use lite oil as a cooling agent. Just dip a small brush in mineral spirits and swipe alone your stright edge before scoreing.

I am glad you will take it to a pro the cost will be cheaper than a drill bit. And you will be happier with the results. I have been a glazer for over 7 years and this takes a little practice to do well.

Good luck with your orchids.