I am gonna b drilling a 75 gallon next week. I need advice on the best way to do it. I have a bit that I got from brs and I did a practice run on a 2.5 gallon tank and it kept cracking the glass, I hope it is just because the glass was too thin. Any pointers would help I don't want to ruin the 75. Thanks. Paul
Advice on drilling a tank
- Thread starter lilman024
- Start date
AmherstReef
New member
I drilled a 40 breeder for my new sump, used the same BRS bit and had non problems.
Go slow . Let the drill bit do the work . Put very little pressure on the drill , lots of water
Go slow . Let the drill bit do the work . Put very little pressure on the drill , lots of water
PufferNut
New member
I used plumbers putty to build a dam around the drill site and hold water. Had someone help by running a trickle of water into the puddle to keep it fresh so speak. Let gravity do the work, no pressing on it. I went slower than I needed to from what i read.. took me 30min per hole.
mr.maroonsalty
New member
I cut a square hole in a piece of wood just big enough for the round peg to fit in, lay it out and start the cut with water of course. Use something to build a dam: plumbers putty is probably best, but because I'm in the middle of a build and have plenty of silicon on hand I use a big bead of that when I drilled. Reset the hole saw and cut nice and evenly stopping once in awhile to see if you are cutting parallel through or need to straighten out, also to see how close to the end because then is when you need to take it extra light on the preasure to avoid big flaking. Heat is the enemy, so go slow and steady with plenty of water. Also, I believe 2 1/2" from the edge of the cut to the edge of the glass is minimum; further is better. You might want to stop and get some 1/4" practice glass to work things out before the real run.
ReeferSteve78
New member
A 2.5 gallon tank will crack easily since its a small and thin glass tank. I drilled a lot if tanks and you just need to keep it wet and go slow when drilling. Don't push on it let the drill do it job and it will cut right threw
gmneil
New member
i have drilled over 40 tanks. only cracked 1 while drilling, that was a 10g (thin glass) and doing a inch and a half hole. my advice is
get a piece of ply wood drill thru that with the drill bit. this will act as a guide for the bit. secure the wood to the tank where you want the hole. duct tape works well for this. this way you wont have any issues while starting the hole.
put some tape over where the hole will be inside of the tank. also put a towel in the tank so if the glass puck drops it dosent hit any glass. the towel will also catch any water that falls thru the hole
i use a spray bottle spraying the bit often . the water should turn white from all of the ground glass i use the color as a indicator of when to spray.
use just the weight of the drill. drill at a speed you feel comfortable with. the end is the tricky part you want to keep it as smooth a flow as possible to help avoid chiping.
with all the above tips i havent had any issues.
get a piece of ply wood drill thru that with the drill bit. this will act as a guide for the bit. secure the wood to the tank where you want the hole. duct tape works well for this. this way you wont have any issues while starting the hole.
put some tape over where the hole will be inside of the tank. also put a towel in the tank so if the glass puck drops it dosent hit any glass. the towel will also catch any water that falls thru the hole
i use a spray bottle spraying the bit often . the water should turn white from all of the ground glass i use the color as a indicator of when to spray.
use just the weight of the drill. drill at a speed you feel comfortable with. the end is the tricky part you want to keep it as smooth a flow as possible to help avoid chiping.
with all the above tips i havent had any issues.
I've drilled about 15 tanks or so, from 5g up to 75g. The smaller tanks are MUCH harder. If you can drill a 10g, you can drill a larger tank.
Go slow, let the drills weight do the work. Speed doesn't really matter all that much if you can keep the drill/bit from wobbling and don't have much down force. Cordless drills tend to wobble a bit more, but that's all I've ever used. I usually start pretty slow and speed up as I go.
Drill the tank from the correct way, which means you shouldn't always start on the outside of the tank. When drilling a tank, when the drill bit goes through the last little piece of glass, it will chip a bit. If this chip is big, the gasket won't seal well. This matters more with smaller gaskets/bulkheads, but is applicable to them all. Start drilling the hole from whichever side the gasket will be on. If you are drilling from the inside of the tank out, there's no need for a water damn, just fill the tank with 1/2" of water. Or, set the tank on it's side and fill it up until the water runs over the 3/8" plastic edge.
Build a guide to start the hole perfectly. With a guide, the bit won't "walk" and you will have a perfect hole in the glass where you start drilling. I take a 6"x6" piece of 3/4" plywood and cut a "V" shape into one end. Clamp or tape (electrical tape doesn't leave adhesive behind) this down to the tank. Press the bit against the V when drilling (at least until you get the hole started).
Go slow, let the drills weight do the work. Speed doesn't really matter all that much if you can keep the drill/bit from wobbling and don't have much down force. Cordless drills tend to wobble a bit more, but that's all I've ever used. I usually start pretty slow and speed up as I go.
Drill the tank from the correct way, which means you shouldn't always start on the outside of the tank. When drilling a tank, when the drill bit goes through the last little piece of glass, it will chip a bit. If this chip is big, the gasket won't seal well. This matters more with smaller gaskets/bulkheads, but is applicable to them all. Start drilling the hole from whichever side the gasket will be on. If you are drilling from the inside of the tank out, there's no need for a water damn, just fill the tank with 1/2" of water. Or, set the tank on it's side and fill it up until the water runs over the 3/8" plastic edge.
Build a guide to start the hole perfectly. With a guide, the bit won't "walk" and you will have a perfect hole in the glass where you start drilling. I take a 6"x6" piece of 3/4" plywood and cut a "V" shape into one end. Clamp or tape (electrical tape doesn't leave adhesive behind) this down to the tank. Press the bit against the V when drilling (at least until you get the hole started).
lcs
It's Spring!!!!!!!
This all came at a great time for me. I've had my 125 ready (I think!) to be drilled for about two weeks now, I'm just afraid to pull the trigger. 
No matter how many videos I watch, it's nice to hear from as many people has possible who have done it so thank you for sharing your experiences.
This is what I did. There is no way I'm going to try this free hand :uhoh2: and I'm too cheap to buy a guide. When I cut the plywood the bit caught a couple of times; I'm hoping this was because of the diamond against the wood and not something that will happen with the glass?
No matter how many videos I watch, it's nice to hear from as many people has possible who have done it so thank you for sharing your experiences.
captain7359
Active member
Just relax a little before you start....
Duct tape the back of the hole to prevent big chips from blowing out and support it with either a spreader style bar clamp if you're drilling from the outside, or support from the outside. I use a small drill press mounted on suction cups for a constant speed and even drilling. Build a plumbers putty dam and use a constant supply of soapy water or a running hose to keep the pool clean. I flush the pool out when it gets too murky from the glass. Go slow like everyone said and use a template if you don't have a drill press.
Duct tape the back of the hole to prevent big chips from blowing out and support it with either a spreader style bar clamp if you're drilling from the outside, or support from the outside. I use a small drill press mounted on suction cups for a constant speed and even drilling. Build a plumbers putty dam and use a constant supply of soapy water or a running hose to keep the pool clean. I flush the pool out when it gets too murky from the glass. Go slow like everyone said and use a template if you don't have a drill press.
