# How to Drill your glass



## Pumilo (Sep 4, 2010)

OK guys, I am a Glazier by trade for the last 20 years and I've drilled more than a few holes. I am going to show you how to drill glass professionally, with a drill press. Then I will follow up with how most of us are going to have to drill, with just a hand held drill.

Here you can see that I have put a piece of scrap, backing wood on the drill press table. I have set the glass on top. It is already marked with an x where I am going to drill. I have put another piece of wood on top of the glass and LIGHTLY clamped the whole assembly together. You can also see the suction cup ring I am using to hold in a cooling lubricant. In the next picture you can see that you can also make a cooling lubricant retaining ring with ordinary modelers clay or even plumbers putty. Mine is modeling clay. It is of the utmost importance to use yellow! Unless you're out of yellow. Red might work.


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## klik339 (May 17, 2010)

Pumilo said:


> It is of the utmost importance to use yellow! Unless you're out of yellow. Red might work.


drats all i have is the beige plumbers putty lol


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## Pumilo (Sep 4, 2010)

Now we need to use a cooling lubricant or we will ruin our diamond drill bit with only one hole and we might even crack the glass. I am using a cooling lubricant specially formulated for drilling glass. It comes by the gallon and you mix it something like 20 to one with water so I have like 40 lifetimes worth! LOL! Another great cooling lubricant is ordinary Antifreeze from your car. You can also use water but your bit will not last nearly as long. You can see from the rust I have been using this 5/8 diamond drill for years!
You don't need to much, maybe 1/8 to 1/4 inch deep.

By the way, you can get diamond drill bits nice and cheap all over eBay! I am very partial towards the hole saw style.


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## Pumilo (Sep 4, 2010)

klik339 said:


> drats all i have is the beige plumbers putty lol


Go ahead! Try the beige! You never know!


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## Pumilo (Sep 4, 2010)

One of the tricks to getting a good hole is keeping the speed of your drill LOW. So I have set my drill press to its slowest setting. On my press that is 540 RPMs. Another trick is to keep your bit and your glass cool. We use the coolant for that. We will also go slowly.

You do NOT want to put much pressure on the glass, i.e. don't force the bit. Let it go in slowly with a minimum of pressure. Generally, you want to use just enough pressure to get a good grinding sound. Too much pressure cracks the glass and can also ruin the bit.

To keep things cool, I like to drill for about 5 seconds then back off for 3 to 5 seconds. When you back off, don't pull the bit all the way out of the coolant, leave the bit just submerged to help cool it off.

Here you can see the bit just entered the solution and is touching the glass. YOUR drill should be running before you touch the glass. You might notice the absence of ripples showing that mine is not. Thats because I am drilling at 2 in the morning and for some reason, my wife and my son, Frogboy, didn't want to come take pictures for me. So I'm holding the handle of the drill press down with my right hand and shooting photo's with my left! Forgive me if its blurry!


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## Pumilo (Sep 4, 2010)

For the best, cleanest hole, you want to drill about 2/3 of the way through. This was easy for me using the depth stop. Then you flip your glass over, line up the bit to the hole and LIGHTLY clamp it down. Then you reset your ring with more coolant, and finish the hole. Don't worry, I know that is not always possible when drilling a tank instead of flat glass. We will go into that, also.

Here is a shot of the hole about 2/3 drilled through. Then I flipped it and finished it using my lovely yellow clay. As you are about to break through to the other side, you should be very careful about using very little pressure.


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## Pumilo (Sep 4, 2010)

Here is a picture of the finished hole. It would be a little cleaner if you are not using a bit that's about 10 years old!

Use your preferred method of cleanup to get the lubricant and glass dust off. Personally, I use a dish soap and a bristle brush. That's right, I said soap! Follow it up with a really good warm water rinse. Finally, I wipe it down twice with rubbing alcohol. 

_(Whispered) Did he really say soap? I think he did! He said soap!_

Back in the day, I constructed 40 Vivs from flat glass using soap on every one. Followed up with rubbing alcohol and never had a problem, from tincs to pumilio's to Thumbs.


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## Pumilo (Sep 4, 2010)

OK, now lets talk about drilling without a drill press. I did this one JUST for you! This is the first and only hole I have ever drilled without a drill press. I was successful my first time and YOU CAN BE TOO!! It's not that hard!

First of all, you can't skip the rest of the post and just jump to here figuring that you don't have a drill press. You need to read the first part to get the good stuff about cooling and all that.

Here we are going Native! No suction ring, no drill press, no clamps, no flipping the glass. Just a man, a drill, and his Play-Dough! Ok, modelers clay, Play-Dough just sounded funny 

Using a backing board is still a good idea, although I have done it here simply supported on two 2x4's, as if it were a tank that you can't really use a backer board on. 

Make your clay ring and put in your coolant of choice.


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## Pumilo (Sep 4, 2010)

I recommend using a battery powered drill as the run at a slower speed. What's important when going freehand is to angle the drill at first to start a groove in the glass. As the groove gets deeper, you will *gradually* move the drill into an upright position. This is done while the drill is running.

When drilling freehand, you do not want to drill for 5 seconds and lift for 3 to 5 seconds. Instead, just quit pushing for a couple of seconds while drill is still running and touching the glass. This will cool the bit and glass sufficiently.


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## Pumilo (Sep 4, 2010)

Ooops! no pics!


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## Pumilo (Sep 4, 2010)

As you drill, slowly putting your drill into the upright position, you will notice that the groove you have started helps to hold the bit exactly where you want it. If you try to just drill straight in without angling it, the bit will try to walk all over the glass.

Here you can see we are finally into the upright position, (or close to it).

In pic 2 you see we have drilled through to the other side! Successful the first time I ever tried it!


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## Pumilo (Sep 4, 2010)

Now when you drill through glass without flipping the work, it is pretty common to get some chipping. It's no big deal. Works just fine! Here are some blown up shots showing the kind of chipping you might expect. Remember, this is a 5/8 inch hole blown up. These are TINY chips!

Plus, the chips would probably be smaller if my bits weren't 10 years old!

Don't forget your cleanup!


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## Pumilo (Sep 4, 2010)

I recently saw a thread where someone asked about drilling into a tank with frogs in it. 
I do NOT recommend this!! However, if you must try it, duct tape a rag under the spot you are drilling. Tape all around it to catch any glass bits. Use water instead of cooling lubricant and just figure on ruining a bit. 
Ever see an old war movie where they have tape criss-crossed all over the windows? This is to keep broken glass more or less in place when the bombs drop. So criss-cross the top of your tank with masking tape JUST IN CASE! I cannot stress this enough, people, *Don't bomb your frogs!!* If that glass breaks, you have enough to worry about without your froggys jumping all over the place!

One last thing, I keep seing "Pumilo-Junior Member". It feels kind of nice to be called "junior"!

(Big Booming Voice)
*This has been a public service announcement from...Pumilo! Tune in next time for... "How to Cut Glass-So Simple an 11 year old can do it!"*

_Yes! I know Pumilo is misspelled! I misspelled it 8 years ago on eBay!! Now it's just an inside joke...Duhh!_


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## fleshfrombone (Jun 15, 2008)

Cool thread man, thanks. I'll have to give this a try sometime.


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## Jason (Oct 14, 2004)

If you can't figure it out by the above posts here is a video. 

http://www.dendroboard.com/forum/parts-construction/44979-how-drill-glass-diy.html]How to Drill Glass DIY


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## OH23 (Sep 19, 2008)

Great thread,
thanks for sharing.
Looking forward to the "how to cut glass" thread.


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## BlueRidge (Jun 12, 2010)

Glass-holes.com has a great video as well and they sell the bits. I used their kit to drill a hole in a reef tank and was sooooo scared I was going to mess it up but it turned out easier than I thought. AND, they send you free candy with every order 

Drilling GH


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## snmreptiles (Feb 26, 2004)

One thing I have found that helps with the glass chipping is to put tape on the backside of the hole before drilling...

DOUG, had no idea this was you until I got the phone call from Ric tonight...I was at work until a few minutes ago. I will give you a call on my way home tomorrow!

Mike
www.snmreptiles.com


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## tachikoma (Apr 16, 2009)

Pumilo said:


> One of the tricks to getting a good hole is keeping the speed of your drill LOW.


I am in no way trying to say you are wrong or that I do not have faith in your professional opinion, rather since you are a professional I am seeking your opinion on this matter. On my rigid diamond drill bit 5/8" the directions said to make sure to keep the speed high. I have done both methods and do not notice a difference, I am curious if maybe this was written on the back just because it's a smaller diameter bit?


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## gjr210 (Sep 21, 2010)

All I do is put the garden hose so the water runs where Im drilling and go at a moderate speed. It has worked every time with minimal to no chipping. I think the main thing is to take your time and not rush it or else your bound for disaster.


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## Jason (Oct 14, 2004)

tachikoma said:


> I am in no way trying to say you are wrong or that I do not have faith in your professional opinion, rather since you are a professional I am seeking your opinion on this matter. On my rigid diamond drill bit 5/8" the directions said to make sure to keep the speed high. I have done both methods and do not notice a difference, I am curious if maybe this was written on the back just because it's a smaller diameter bit?


I keep the speed fairly high and have never had any problems. Check out the video in my signature to see it in action. I think the key to drilling is the amount of pressure you put on the drill. Keep it fast, but very little pressure. The weight of the drill is almost enough to give you what you need.


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## Pumilo (Sep 4, 2010)

I am going to agree that going easy on the pressure is the most important thing. The instructions that came with my bits almost 10 years ago said to use a slow speed. I know that there are different kinds of diamond bits. Cheaper ones have the diamond bits glued to them. The more expensive ones are actually imbedded into the metal. Perhaps it depends on the manufacturer and how their bit is made? I would go with what speed your bit says to use. All I can say for sure is that mine are almost 10 years old and I am just now considering replacement.
Doug


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## Rusty_Shackleford (Sep 2, 2010)

Many many huge thanks to Doug for this thread. I just drilled my first tank today using this method and it turned out great!!! I pretty much did everything according to this thread with two exceptions. 1. I don't have a drill press so I had to go hand held. I used a slow to medium speed. I had to prop up the tank outside and taped the garden hose to the back of the tank and ran a steady stream of water across the bit and hole to cool it. 2. I used a longer piece of tubing than Doug did as I'm planning on adding a ball valve. I figured if it was too long I could always trim the tubing, but you can't ever make the tubing longer once it's installed. 
Thanks again Doug!!!!


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## AlexD (Sep 19, 2007)

As my late grandfather always told me when building things, "you can cut it shorter, but you can't cut it longer".


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## J Teezy (Jan 25, 2012)

i've drilled several holes with a handheld battery drill. Here are some of my tips as well

I set my drill on low speed and a low torque (usually around 4 just in cast the bit snags it won't try to power through the snag. I feel if this happens at the breaking through part the drill trying to power through the snag could cause the glass to crack).

When i drill a hole, lets say a 5/8" for a mist nozzle, i take a wood shim and drill an 11/16" hole in it as a guide hole, this way i don't have to start the bit at an angle. starting a bit at an angle you may get some walking of the bit if you're not fimilair with drilling glass. the guide hole allows me to start straight up and down on the glass (glass-holes.com also sells a guide but i feel its way overpriced and making my own is very easy and pretty much free).

for cooling i use the garden hose method as well. Just keep a steady stream of water flowing over the bit and hole and the bit stays cool the whole time.

While drilling i usually just drill for a good while at the start to get it started. Once get a good start i use a plunge method every so often just to get some water in the cut and flush the glass dust out. So what i do is lift the drill up just enough to get it off the glass then back down till i hear the glass grinding again.

Another trick i use is what i call a "wobble". When you are freehand drilling its not always easy to keep the bit perfectly parallel to the glass to get even grinding all around, so i since i'm left handed i kind of swirl the drill ever so slightly in a counter clockwise motion to get uniform grinding all around (may not make since to you in words but hopefully it does). I picked this method up from a guy down the street from me who does a lot of tank drilling for members in our local reef club. he actually did my bulkhead hole in my 29 gallon tank since he had the bit and saved me from having to buy one just for one hole.

Now when i'm close to breaking through the other side i lower the speed of my drill even more by just barely pullign on the trigger. In my opinion the faster you're bit is running when breaking through the more chance of cracking glass. This is just my opinion on this matter (i've never cracked any glass i've drilled). Also usually when breaking through when using a handheld drill you'll break through in just a certain area due to not holding the drill perfectly perpendicular. Once i notice i've partially broke through i stop drilling to assess the glass to see exactly where i broke through so i know how to tilt the drill in order to finish the hole out.

Biggest tip i can give is slow and steady wins the race. Glass drilling is not a fast process. You are not "drilling" or cutting the glass you are grinding it away. So common sense tells you the slower the grind the smoother it will be.

the first time is always nerve racking but once you do it once you'll see its not that hard


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## ndame88 (Sep 24, 2010)

What is the recommended minimum distance to drill from the edge?

Thanks


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## Pumilo (Sep 4, 2010)

ndame88 said:


> What is the recommended minimum distance to drill from the edge?
> 
> Thanks


1/2" from edge of glass to the edge of your hole if you are careful. 1" is safer.


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## samsffr (May 10, 2011)

Another great bit of info. So helpful for us diy folks!
Thanks again Doug.


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## diggenem (Sep 2, 2011)

I've drilled quite a few tanks, but I enjoyed reading thru this thread, great post Doug!

Sent from my Galaxy Nexus using Tapatalk 2


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## radiata (Jul 24, 2010)

I've been drilling holes in glass without using any circular diamond coated hole bits. I've been using a Roto-Zip tool with a "tile bit". I haven't seen any demos of this method on YouTube. I've done three holes in three 15G tanks for bulkhead and a few holes in a marine reef "sump" (to kill off the sump effect) with no problems. And, I'll be drilling bulkhead holes in a 29G and a 55G real soon now...


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## rahunt2 (Jan 4, 2009)

A friend and I bought a bit and practiced some drilling with the battery powered hand drill. It is nice to know that the slight chipping is not because we were doing anything wrong, just a consequence of the technique.


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## cbridgeman (Sep 30, 2013)

I just finished drilling a 2" hole in my lid for a vent. I followed the drill press instructions and the hole came out perfectly. I took my time, and ended up taking 40 minutes on 1/4" glass. Thanks so much for posting this!


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## Ray (May 12, 2009)

As a ceramic engineer with lots of years of glass experience, I can tell you some simple keys to successful drilling of glass:


First and foremost - drill under water! Not only does it cool the process, but the water actually chemically interacts with the glass to relieve stress imbalances caused by the breaking of the silica bonds.
Use a diamond bit. Carbide is an OK second choice, but only if diamond is unavailable.
If possible, especially if using a "cup" saw to make a large hole, drill from both sides of the glass, meeting in the middle, so you don't get "break out chips" on the exit side of a single-side-drilled hole.
Let the bit do the work - don't press hard
Take it slow!


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## Pumilo (Sep 4, 2010)

I love this tip that Zonz540 has given us! This would be so slick for drilling an already planted vivarium. http://www.dendroboard.com/forum/parts-construction/191609-drilling-glass-no-mess.html#post2025449 
It uses hot glue instead of putty, for a dam. I love the extra step he presents. A film canister is hot glued to the bottom of the hole. The film canister catches the glass disc, all the glass bits, and the cutting fluid. It keeps 100% of the mess OUT OF YOUR VIVARIUM!


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## Mike1239 (May 15, 2012)

A tip for drilling with a handheld is getting a piece of wood with hole that glass hole saw snuggly fits into to minimize the bit from skipping around.


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## EricT (Nov 10, 2007)

sorry for digging up an old thread... but I've got a question and I've searched and can't seem to find the answer(Although I am positive i've seen it before and I just can't find it again , and my tiny brain does not retain information as it once did) 

I ordered my bits , I have my bulkhead... but the bits arent marked and the package is just a plastic bag because.. well ... cheap ... Anyhow ... Should I use the bit that the bulkhead fits inside of? or should I use the bit that matches the diameter of the bulkhead? 

To clarify.. If I matched the gasket to the bit for reference... Should the gasket fit the outside of the drill bit snugly or should the gasket hole be the same size as the hole on the bit?

Hope this makes sense


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## Blueper (Feb 27, 2016)

If the gasket is tight on the bit, chances are the bulkhead won't fit through the hole.
If it's snug and you try to force the bulkhead through, you will likely crack the glass. 
The bit that matches the diameter of the bulkhead should work. As long as that includes the extreme outside of the threads.


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## EricT (Nov 10, 2007)

Thanks for the response... I appreciate it .. 

I actually decided to just drill an extra piece I had around to see what would work .. and in the process found that the answer was in all the videos I watched already .. As soon as I traced the inside of the gasket on to the glass I felt real dumb for coming on here and posting about it , and even more so for searching for the answer for about 45 minutes when I coulda been drilling! =) 

Thanks everyone.. sorry for making this pop up in all of your notifications... you're all saints!


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## nyskiffie (Mar 6, 2016)

For those without a drill press, this type of thing is a great cheap alternative!

http://ecx.images-amazon.com/images/I/41FFVQ2P9wL.jpg

I'm still having a bit of trouble with my practice pieces but I think I was just being impatient, and not lifting/stopping drilling to let the bit and glass cool. Both times I've tried, about 3/4 of the way through the glass the cut got MUCH MUCH harder, and nearly stopped. I (stupidly) just figured I would press harder... that was not the solution. 

Hopefully my next ones go better.


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## Alter Ego Trip (Oct 23, 2011)

Bumping a semi old thread for a question. 

Is there any reason you can't drill from the inside of the tank? I'm drilling the bottom of an Exo x large and would feel better resting the bottom of the tank on a sheet of MDF. I think there would be less chance of cracking the bottom if fully supported as opposed to flipping upside down and drilling the outside. 

Thoughts?


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## Judy S (Aug 29, 2010)

you better check that the bottom is regular glass before you get too far along in your plans....


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## easttex (Oct 29, 2012)

Tempered glass *should* have some type of logo or other marking etched on to it to show that it's tempered. If it does not and you aren't sure, please call the manufacturer to verify. 

Remember: Tempered glass doesn't break; it explodes!! So make doubly certain your glass is not tempered, or else!

Sent from my SAMSUNG-SM-G900A using Tapatalk


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## Alter Ego Trip (Oct 23, 2011)

Judy S said:


> you better check that the bottom is regular glass before you get too far along in your plans....





easttex said:


> Tempered glass *should* have some type of logo or other marking etched on to it to show that it's tempered. If it does not and you aren't sure, please call the manufacturer to verify.
> 
> Remember: Tempered glass doesn't break; it explodes!! So make doubly certain your glass is not tempered, or else!
> 
> Sent from my SAMSUNG-SM-G900A using Tapatalk


Exo's don't use tempered glass. It's fine. Just always wondered even if drilling the back panel why people don't drill from the inside? This would allow you to completely support the back/bottom of the tank and decrease chance of breakage.


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## davecalk (Dec 17, 2008)

*Sorry, guys work in progress.*
I've been writing an article documenting the process of understanding and manipulating glass.

I'm getting close to being done. I wrote it in MS Word hoping I could format it for readability, and then copy and paste it easily, and it would retain the formatting. I did it in the past when I wrote the article about Building and Using a CO2 Generator. But when I paste it, the formatting doesn't transfer Is there a tutorial around that documents the process with the newer forum formatting ??? I think I used Unicode but its been years so I'm having to refigure things out.

I don't want to completely reformat the thing after I paste it in. It is an arduous process.

This is what is in the works.

*THE ZEN ART OF MANIPULATING GLASS*​
Through knowledge, understanding, and practice you can become "enlightened" on how to use and manipulate glass.


*THIS ARTICLE WILL BE BROKEN DOWN INTO THREE SECTIONS*

UNDERSTANDING THE PROPERTIES OF GLASS
LEARNIG HOW TO CUT GLASS
LEARNING HOW TO DRILL GLASS


*UNDERSTANDING THE PROPERTIES OF GLASS*​
*THE STUCTURE OF GLASS AND WHY IT IS BRITTLE*
This is an important question for us to understand as we are working with glass.

Glass is an amorphous structure. That means that its internal molecular structure is not ordered, having no regular arrangement within its molecules. This is one aspect of which makes glass brittle.
The atomic bonds within glass are actually very strong and rigid. These bonds give glass its strength, but it is this rigidity contributes to its brittleness.
Glass does not contain planes of atoms or have any kind of crystalline structure within its molecular organization. Metal’s molecular structure allows it to bend before breaking, but glass, has no way for its atoms to slip past each other, so it fractures when exposed to certain kinds of stress, pressure or shock.*







*
*Lots more to come...

DUCT TAPE APPLICATION DRILLING:*
This last year I figured out an even easier way to help me drill glass using duct tape which helps prevent the back side of the glass from being blown out. I also found that duct tape can also me to consistently drill holes within ⅜ of an inch of the edge of the glass without the glass breaking.

*WHAT CAUSES GLASS SHATTER, BREAK, OR BLOWOUT ??? *
The amorphous structure of glass makes it brittle. The actual bonds of the atoms within glass are very strong, rigid, and reinforced by the poorly ordered placement of molecules. Because glass doesn’t contain planes of atoms that can slip past each other, there is no way to relieve certain kinds of stress without breaking. Any kind of microscopic crack, scratch or impurity in the glass becomes the weak point and when glass is under certain kinds of physical or thermal stress, its structure can rupture.​
Tempered glass is created by, thermally or chemically changing the internal / external tension within the glass which gives it is great strength. It can withstand tremendous repeated impacts. But if you scratch tempered glass or attempt to drill it, explode into thousands of tiny pieces.Glass is a beautiful complex and delicate material.

There are two main ways that causes glass to fracture or blow out.

One is thermal shock. When used properly, the diamond drill bit should NEVER be HOT. The drill bit should never be more than warm, to the touch. If a bit becomes hot, it is an indication of inadequate lubrication, too fast a drill speed or too much pressure being applied to the glass. But if any one of these three are missing, heat buildup occurs.

This leads to the second cause of glass fracture / blow out comes from pressure and physical shock. As glass is removed the strength of the remaining glass at the rear surface becomes almost minimal. I use duct tape and finger pressure help support the surface allowing the bit to grind out the last bits of glass with little fracturing.

While temperature and bit pressure are the main causes of drilling failures, they are not the only factors.

Glass thickness, distance from the edge, drill speed, drill pressure, consistency of one's drilling angle, the size of the glass, the size of the bit, the age of the bit, the amount and temperature of the water, and properly clearing the slurry, all of these are factors in drilling glass properly.

People do worry and think that drilling glass is a mysterious art which is difficult to master. It is not. Drilling glass and cutting glass are pretty easy skills to master because glass is very forgiving. A person can make a lot of mistakes and still drill and make a usable hole.


*PPE - PERSONAL PROTECTION EQUIPMENT*
Drilling glass can be hazardous to your health. To protect yourself when drilling glass.

*N95 Mask: Glass dust is very hazardous to your lungs if inhaled. 
A**lways* use a high quality dust mask. The fineness of the glass dust that drilling can produces can cause serious health issues. At a minimum always use an N95 mask. A year after COVID19, N95 masks are finally available again in hardware stores and big box stores like Home Depot.
Drilling a hole horizontally can produce glass dust. Drilling horizontally with a water dam doesn't produce as much dust.
*Safety glasses: *Glass can fracture. Protect your eyes.
*Gloves: *A thick pair of gloves is helpful if you have a break. On the hand that I am attempting to feel when the bit breaks through, I don't wear a glove.
*DRILLING TECHNIQUES SPEED, PRESSURE, LUBRICATION*
There are three primary drilling techniques that need to be mastered as we learn to drill glass. Drill Speed, Drill Pressure and Lubrication all work together to allow the bit to properly function without overheating and destroying either the glass and the bit. A faster drill speed or increased pressure may slightly reduce the cutting time, but they will also significantly increase the friction between two very hard substances, glass and diamonds. The heat if it is not dissipated will drastically reduce the life span of the bit and will greatly increasing the chance of damaging the glass from heat fractures, cracking and blowouts.

*1. DRILL SPEED FOR BIT SIZE*​​

​Material Bit Size -->​​1/8"
to 1/2"​5/8"
to 1"​​1-1/8"
to 1-1/2"​​1-3/4"
to 2"​​2-1/4"
to 2-1/2"​​2-3/4"
to 3"​Glass, Ceramic & China​​800​500​​375​​250​​200​​160​
​​*2. DRILLING PRESSURE*​When using diamond drills, it is very important to only use light pressure on the drill letting the bit "cut at its own speed". Increasing drill bit pressure will not noticeably speed up the cutting, but it will increase the friction considerably which quickly causes things to overheat. This heat not only burns up bits, but also overheats the glass causing micro fractures, glass breakage and back side blowouts.​​*Hammer Drills*​NEVER EVER use Impact type "hammer drills" to drill glass. The impact increases pressure on the brittle glass which increases micro fractures, cracks, glass breakage and blowouts. When hammer drills are used to drill other materials the hammering can cause the diamond bit's tip to mushroom or split.​​When drilling holes through fragile materials such as glass, it is extremely important to "lighten up" considerably on the pressure when the drill bit is near the back of the material. Backing the glass with duct tape and supporting it with your fingers greatly reduces chipping, fracturing and blowout on the back of the glass as the bit emerges from the back surface.​​*3. * *LUBRICATION*​The purpose of lubricants such as water or coolant lubrication (such as Shaving Cream or Shaving Gels) is to provide both lubrication to reduce friction and to increase thermal transfer away from the glass and bit.​​Water lubrication is critical because it aids in heat transfer away from the brittle glass and bit, reducing heat build-up in the materials. This prolonging drill bit life and it helps avoid micro fractures, stress fractures, cracked and broken.​​*Create a Plumbers Putty or Medaling Clay Dam*​The easiest and least messy lubrication technique is to build a "dam" around the drill hole using a small amount of plumber's putty or modeling clay rolled into a snake and wrapped around the hole.​​Others use a hose or plastic milk jug filled with water with a small dribble hole near the bottom to flush away heat and debris from around the drill site providing a continuous stream of water and lubrication as you drill. But both of these methods are much messier, and both methods use a lot more water than does a plumber's putty dam.​
* RATING DIFFERENT LUBRICATION METHODS*


 Drill Bit
Lubrication Method
Squirt Bottle
Hose
Clay Dam
Under Water
Squirt Bottle w/pumping action
Clay Dam w/pumping action
Under Water w/pumping action
Water FeedRating
(1 poor - 10 good)
2
3
4
4
6
10
10
10​



*LUBERICATION AND BIT LIFE*
Lubrication has a significant affect upon drill bit life. While minimal lubrication will keep the bit from burning up, but good lubrication techniques will extend bit life by a factor of 5 or even 10.Using a good water lubrication method can double or triple drill bit life. For example: On standard 1/8" glass, an electroplated diamond bit may last for 200 to 300 holes, or more, depending upon the specific glass and specific drilling techniques used. Drilling in 1/4" glass, being twice as thick, will normally produce only half as many holes over a drill bit's life, if the glass hardness and drilling techniques are the same.

*DRILLING USING WATER TO LUBRICATE AND COOL:*
This is most people's normal way to drill glass. When drilling a hole on a horizontal piece of glass I first layout and mark to location of the hole on the inside of the tank with a sharpie.


*Horizontally Drilled Holes
PEPARING THE GLASS FOR DRILLING*
The duct tape method allows you to support the glass better which helps to prevent the back side from being blown out giving you a much a cleaner, stronger more unified hole.

Start by installing two strips of duct tape, on the inside of the tank, which highlights the location of the hole.

Surround the hole location with plumber's putty creatIng a dam and then fill the well with water. The water keeps the bit cool and glass dust from being produced and becoming airborne. If a hole is drilled too near or through the tank's Plastic Rim, plumber's putty may not allow you to get a good seal as the water slurry tends to leak out all over while the hole is being drilled.


*DRILLING HOLES IN GLASS*
When drilling a hole, either vertically or horizontally, most aspects of the drilling techniques and process are the same. There are three phases to drilling a hole, starting the hole, angering out the center, and exiting or finishing the hole. Starting the hole and finishing the hole are the trickiest parts of drilling glass. When drilling, your diamond drill bit should NEVER be HOT. The drill bit should actually never be more than warm to the touch. If a bit becomes hot, it is an indication of inadequate lubrication, too fast a drill speed or too much pressure being applied. If a drill bit develops yellow, brown, blue or black 'burn marks' around the tip, it is an indication of extreme heat and that the drill speed being used is too fast, the amount of pressure on the drill is too great, or the amount of water lubrication is completely inadequate. Any of these problems will cause premature bit failure and can lead to broken or blown out glass.


*PHASE 1. STARTING THE DRILL*
Starting a hole is tricky. I use a cordless drill when drilling glass. It takes two hands to keep the bit from trying to walk across the glass which causes scratches and scarring. To start the drill, angle the bit like this to start the cut as you carefully lower the bit into the glass.​





​Once you have a starting groove in the glass that is tracking, begin to slowly straighten the angle of the bit allowing the bit to start cutting a circle shape groove in the surface of the glass. Once the bit has started cutting a complete circle shape and is easily tracking in the groove, switch over to one hand drilling.​
*PHASE 2. THE CENTER PHASE OF DRILLING *
AT THIS POINT NEVER PUSH THE DRILL WITH ANY PRESSURE INTO THE GLASS. Let the drill bit slowly chew its way through the glass at its own pace.​​Your other hand will now reach inside the tank and will cover the duct taped drill area.​With this hand you are doing several things.​​1. With your fingers you are feeling when and where the bit begins to penetrate the glass.​​2. Your fingers along with the double layer of duct tape are going to be supporting the glass as the surrounding glass gets thinner and thinner. thus preventing major blowout. In the past we've tried to put wood, foam or glass pressed against the glass to prevent blowout. Duct tape is much easier and quicker and is almost as effective. With duct tape you don't have to clamp the support deep in the tank for your bulkhead.​
*DRILLING MOTION*
*CIRCULAR BIT MOVEMENT WITH ANGLE OSCILLATION*​Many folks say never tilt the bit and only to drill straight and perpendicular to the glass. This is true in the final phase of drilling when you are exiting the glass. But I have found that there are many advantages to oscillating / rotating the angle of the bit during the middle phase of drilling. This motion is circular and angular where you change the cutting angle a little bit so it is not perpendicular to the glass.​​The motions does several things.​​It widens the Kurf of the cut, which is the area of glass that is actually being removed. This spreads and releases some of the pressure being placed upon the glass helping to prevent glass the from cracking. This is especially important when drilling close to the glass' edge.​​This movement also narrows the width of the slug a small fraction allowing the slug to pull free from the bit and remain stuck to the duct tape. If the slug does remain in the bit, the narrowing of the slug makes it easier to remove from the center of the bit. Before doing this, I sometimes had to break the glass slug in order to get it out of the bit.​​Continue the bit oscillation until you are about ¾ of the way through the glass. Then begin reducing the angle until you are just shy of being perpendicular.​​*PUMPING THE BIT / OSCILLATING THE BIT'S DEPTH*​As you drill, lightly move the bit in and out of the hole, raising it up and down a fraction of an inch as you drill (every 30 seconds or so) which helps clears glass particles from the hole and from the bit, reducing friction and freeing the bit to cut more efficiently. This pumps water into the drill hole fully lubricating the very tip of the bit. The in and out motion allows the bit to be cooled. This "pumping" technique is especially helpful when drilling larger tanks with thick walls.​​​​*Remember that heat is the enemy of both the glass and the bit.*​​​
*PHASE 3. THE FINAL PENETRATION PHASE OF DRILLING*
Finishing a hole can be tricky as well. When you begin to feel the bit begin to penetrate through the glass, stop all oscillation and return the bit's angle to a completely perpendicular angle. Hold the entire weight of the drill and carefully drill until you can feel all areas of the bit under the duct tape. Then remove the bit.










*Vertically Drilled Tank.*
I have found that drilling a tank vertically, at times, has many advantages. You can drill holes in existing tanks, even tanks that have frogs in them safely and efficiently. You also can can easily drill holes around the top rim of the tank.

I'll describe the technique that I have developed.

To drill vertical holes I have found that Shaving Gel works extremely well.










*Duct Tape Application and Procedures:*
The process works with only one layer of duct tape, but I have found that two layers gives me some added benefits. With only one layer I have had the drill cut through the tape allowing the water drain out of the well of water into tank before the hole was finished being drilled out. With two layers of tape I haven't had the water does drain out while I was drilling a hole. The duct tape also does prevent my finger from being exposed to the diamond bit as it cuts through the glass. With one layer I have had the bit to a diamond drill bit bump my skin several times, but it has never broken my skin. With two layers the bit has never come in contact with my skin.

This post will show how to install and use duct tape to help you drill better, smoother holes. It will also show how to drill a tank that is upright. I have used this method many times to safely drill and modify finished tanks, even tanks that have frogs in them. (Without needing to remove the frogs.)

*Advantages of being able to drill in and around a tank's rim:*
I have used this technique to invisibly install and hide many things behind the tank's Top Rim. In my latest tank I installed an LED light along the front of the tank hidden behind the rim (with a gap for ventilation; I ran fan wiring inside of the tank, from the rear; and installed the Mist King tubing inside of the tank from the rear around tot the front. Everything was installed with the with the tank being visually clean and clear both inside and outside of the tank because all of the wiring and tubing was hidden inside the tank running behind the aquarium's top plastic rim band. Inside and out it looks great. I have photos of the entire build, it just takes tons of time to document the build well. Thats for a build journal. This is to document how to drill glass in a different way.

*Duct Tape To Use:*
I use a cheap duct tape. The more expensive stuff, like gorilla tape, tends to grip the surface much tighter / harder. Cheaper duct tape makes removal easier and with less potential for glass cracking when your hole is nearer the edge of the glass.


*DUCT TAPE: THE LAYOUT AND THE PROCESS*
Install two layers of duct tape on the inside of the tank centered on the hole location.

*DUST CATCHING V:*
Install a V shaped trough below the drilling point using either duct tape or paper.

In this photo you can see a hole drilled through the rim of the tank to allow the plug for interior light at the front of the tank to be routed and plugged in out of the tank.

*COATING THE AREA WITH SHAVING GELL:*









*COATING THE BIT WITH SHAVING GELL:*











Often remove the bit and feel its temperature with your fingers. This is to make sure that the bit is not getting too hot. If you can't hold the bit in your fingers it is too hot. You need to stop, remove and check the bit often, adding more gel to the bit as the glass dust removes it.
​On the inside of the tank, under the duct tape, your fingers should be able to feel when the hole has been completely drilled through. A light, delicate touch should insure no blowout.
​











The glass has completely cut through and you can see the slug is still attached to the duct tape in the hole.











*Dust Cleanup:*
Gather and carefully wad all of the dust into the tape or paper. Sometimes I will create a 6 or 9 inch paper V to make the dust collection / removal easier.

*Duct Tape Removal:*
When removing the duct tape from the inside of the tank, it does have to be removed slowly and carefully so you don't crack the glass as you remove the tape.












This photo shows the tape has been removed and plug still stuck to the tape. You know you have done a great job where there are few sharp or jagged edges.











*Final Results.*
Installing duct tape on the inside of the tank, while supporting the glass while that is being drilling will give you a far superior, smooth hole on the inside of your tank than one can get used to getting with most other methods.

This technique also helps to prevent glass cracking when you are drilling near the edge of the glass. I routinely drill holes within ¼ of an inch from the edge of the glass without cracking the glass.

I have several times used this method to drill tanks that were fully set up and had frogs in the tank. No dust or gel ever got in the tank. The frogs just hid from the noise of the drill and were right back out after I completed. the pipe install.



As you can see from the next photo, you can easily drill through the plastic rim of the tank along with the glass.

My thumb is holding the Mist King tubing line which runs inside the rim of the tank and is hidden from sight both inside and out. The other small hole to the right was going to be for the internal fan, but I ended up deciding to run the line out the same hole that the mist tubing runs. I filled the hole with black pond foam and using grocery bags to formed and molded the foam to make it look like a rock.

The bottom hole is for the fogger. I have fog coming into the tank on both side. The PVC fittings inside the tank are covered with foam rock and disappear. You can't see where the fog is coming in.











For this tank I used this drilling method to drill these holes while the tank was sitting upright, due to changes I decided to make after building several portions of the tank and I didn't want to lay the tank down.









I initially installed the fog plumbing run on the inside of the tank but chose to move it to the outside of the tank because I could not make round pipe look natural. You can see the glass cut hole to the right of the union that I was abandoning. I changing it and running it along the back which allowed the tank to look completely natural inside.

The cord is for a light that I ran inside the tank hidden by the rim runs to an LED light at the from lip which is hidden behind the front rim. In front of the light is a vent. The heat predicted by the light is vented out while it creates a convection for the tank to help keep the front of the glass clear. I have not found that the light adds a heat load to the tank. Temps remain good.

I could only add 10 photos to the post so I couldn't add a shot of the completed tank from the front.

The Black PVC was white but I stained it black.

Not meaning to change or hijack the thread with this info, but this was all about drilling glass in a different way and the reasons why.

Hope this helps folks.
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## Kmc (Jul 26, 2019)

*Hmmm.*

Mustering the upper lip to drill my exo terras, one used one new. (Mint 4 Mints haha)

Being able to do this would be a dream maker.


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## Chris S (Apr 12, 2016)

Great guide Dave, thanks for keeping it updated.


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## jgragg (Nov 23, 2009)

LOVE IT! Thanks a ton, man, I learned a ton. Sweet!


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## Jennifer (Dec 1, 2008)

Very thorough and helpful, thank you for the tips!!


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