Step-by-Step: Drilling Holes in Your Glass Tank for Bulkheads
- Thread starter JustOneMoreTank
- Start date
Some tips I thought I would share after drilling lots of small holes in my 75g (8mm holes drilling slots for an external overflow).
- Using a drill press is easiest, but if this does not work, I recommend using a cordless drill. I haven't found a corded drill which offers good enough speed control.
- Do not drill at fast speeds, use slow. I used 600 rpm on the drill press and use a cheap cordless drill (6.8V) that does not go very fast either. Using a corded drill was hard to control the speed and went WAY too fast and did not produce a good smooth cut.
- My technique:
1. The best way to start a hole without any slippage is to make a guide for the hole. I use a small piece of acrylic with a hole drilled the same size as the drill bit. I recommend not using the same bit as you may wear-out some of the diamond dust from the bits. Use this guide to drill your hole by either clamping it in place, or if you can not clamp it, you can put a small amount of plumbers putty to form a thin sheet on the acrylic to keep it in place on the glass. You only need to use the guide for a little bit until you have cut away enough for the bit to fit in without sliding around.
2. I tried dozens of methods trying to eliminate any glass knicks and shards from happening while the bits goes through the back side. Using duct tape on the back side works alright, but you will still get some knicks and shards. The best way to eliminate this is to start drilling one side as described above in #1. Once you have gone a little bit, remvoe the guide and do the same process on the back side of the glass. Make sure to line the guide up so it lines up with the front side where you started to drill and do the same process. Drill at least 1/16" deep on the back so that there will be no shards or pieces that break away once you finish the hole. I have found that I did not need a water dam by keeping the drill bit wet with a spray bottle every 5-10 seconds (drill for 5-10 seconds, stop drilling to spray off bit, then drill another 5-10 seconds). 1/16" shouldn't take too long to drill.
3. After drilling the back I recommend putting a piece of duct tape to keep the piece of glass from falling. More importantly, I found that occasionally the drill bit would get loose in my cheap cordless drill. If the bit is loose, you dont want it coming out and falling through the hole.
4. After drilling the back, finish with the front. Initially, I used water dams to hold a lot of water but I found that I did not need a lot of water to keep it cool. This added a lot of time and was a mess to do (especially with the 70+ holes I drilled). I found all I needed to do was keep a small puddle of water where I was drilling the hole. Monitor the bit while you are cutting by feeling the bit and the glass to make sure they are not hot. If they are noticeably hot, you need more water or maybe you should just use a water dam (my holes were much smaller than what others may be).
Hopefully these tips will help out.
Bob
- Using a drill press is easiest, but if this does not work, I recommend using a cordless drill. I haven't found a corded drill which offers good enough speed control.
- Do not drill at fast speeds, use slow. I used 600 rpm on the drill press and use a cheap cordless drill (6.8V) that does not go very fast either. Using a corded drill was hard to control the speed and went WAY too fast and did not produce a good smooth cut.
- My technique:
1. The best way to start a hole without any slippage is to make a guide for the hole. I use a small piece of acrylic with a hole drilled the same size as the drill bit. I recommend not using the same bit as you may wear-out some of the diamond dust from the bits. Use this guide to drill your hole by either clamping it in place, or if you can not clamp it, you can put a small amount of plumbers putty to form a thin sheet on the acrylic to keep it in place on the glass. You only need to use the guide for a little bit until you have cut away enough for the bit to fit in without sliding around.
2. I tried dozens of methods trying to eliminate any glass knicks and shards from happening while the bits goes through the back side. Using duct tape on the back side works alright, but you will still get some knicks and shards. The best way to eliminate this is to start drilling one side as described above in #1. Once you have gone a little bit, remvoe the guide and do the same process on the back side of the glass. Make sure to line the guide up so it lines up with the front side where you started to drill and do the same process. Drill at least 1/16" deep on the back so that there will be no shards or pieces that break away once you finish the hole. I have found that I did not need a water dam by keeping the drill bit wet with a spray bottle every 5-10 seconds (drill for 5-10 seconds, stop drilling to spray off bit, then drill another 5-10 seconds). 1/16" shouldn't take too long to drill.
3. After drilling the back I recommend putting a piece of duct tape to keep the piece of glass from falling. More importantly, I found that occasionally the drill bit would get loose in my cheap cordless drill. If the bit is loose, you dont want it coming out and falling through the hole.
4. After drilling the back, finish with the front. Initially, I used water dams to hold a lot of water but I found that I did not need a lot of water to keep it cool. This added a lot of time and was a mess to do (especially with the 70+ holes I drilled). I found all I needed to do was keep a small puddle of water where I was drilling the hole. Monitor the bit while you are cutting by feeling the bit and the glass to make sure they are not hot. If they are noticeably hot, you need more water or maybe you should just use a water dam (my holes were much smaller than what others may be).
Hopefully these tips will help out.
Bob
Barto
Alleged Lounge Moron
Thanks for the tips, I'm going to test my drilling technique on some small tanks this afternoon. I want to do a cascade/steped setup, connecting a few 20's and 15's with a single pump. I'm having a springtime outbreak of aggression among some of my cichlids. I think this will work.
Did you use the same process for making the slots? Any issues with structural integrity with the tank?
The process of setting up the new tank is taking me a while as I have had very little free time the last few months to work on it. I should have the tank finished by the end of the week and ready to do a leak test/structural integrity test.
Bob
The process of setting up the new tank is taking me a while as I have had very little free time the last few months to work on it. I should have the tank finished by the end of the week and ready to do a leak test/structural integrity test.
Bob
I made my slots using a dremel and two bits: a ball-tip and a tapered one. After drawing out the shape of the slots I traced them by hand with the ball-tip to make a shallow groove along the perimeter of each slot. At that point I used one of the bits to make a small hole through the other side, then used the tapered bit like a file in and out to spread the hole up the groove until each slot was cut. About ten hours of Dremel time!
It works, but you can tell they're done by hand.
If I could go back in time I might see if I could get some tiny 1/4" hole saws to cut out the top and bottom of each slot, then use the dremel to make the sides.
The tank has been full for about four months now and I have no structural issues yet. There are at least a couple external overflows out there that have failed--I tried to find all the threads I could about the failures to try and mitigate that in my tank. The failures I found all were done on the rear pane and IIRC all were done by cutting one large slot and not small ones. I believe there was one failure involving square corners! If anyone knows of any other failures, let me know.
With those in mind, here's what I did with my 75g: 25 slots, each planned to be 1/4" x 3/4" with 1/4" between (the glass is 5/16"). Ultimately they ended up being a little bigger, maybe 5/16" wide just due to my inexperience. The slots are on the side pane and end about 1/4" below the top of the tank. I used 1/4" glass for the overflow box and have two standpipes inside.
Everything ever built is a compromise, and this is a good example: 25 1/4" slots isn't very much flow, but I did not want to cut all these holes in the longer span of the rear pane. The flow is enough for my FOWLR system, though.
Dan
It works, but you can tell they're done by hand.
If I could go back in time I might see if I could get some tiny 1/4" hole saws to cut out the top and bottom of each slot, then use the dremel to make the sides.
The tank has been full for about four months now and I have no structural issues yet. There are at least a couple external overflows out there that have failed--I tried to find all the threads I could about the failures to try and mitigate that in my tank. The failures I found all were done on the rear pane and IIRC all were done by cutting one large slot and not small ones. I believe there was one failure involving square corners! If anyone knows of any other failures, let me know.
With those in mind, here's what I did with my 75g: 25 slots, each planned to be 1/4" x 3/4" with 1/4" between (the glass is 5/16"). Ultimately they ended up being a little bigger, maybe 5/16" wide just due to my inexperience. The slots are on the side pane and end about 1/4" below the top of the tank. I used 1/4" glass for the overflow box and have two standpipes inside.
Everything ever built is a compromise, and this is a good example: 25 1/4" slots isn't very much flow, but I did not want to cut all these holes in the longer span of the rear pane. The flow is enough for my FOWLR system, though.
Dan
You've got me a bit worried now regarding my slots. I drilled 20 slots 8mm wide (.314") by 3/4" or 1" tall on the back panel with 3/4" space between each slot. Also, I did not drill any slots in the center and left about 10" of sloid glass so that the center brace would not be useless. All of the holes I drilled have their top about 1"-1.5" from the top of the glass - pretty much at the bottom of the frame of the tank.
I'm hoping that I will not have issues since I have the glass intact by the center brace and I have a bit of spacing between the slots. Any thoughts on this as far as good idea/bad idea? Do you have any links or anything to those who did have tank failure from drilling the slots? Do you know if it failed right away or if it held water for a while and then failed?
Sorry for all the questions, I'm a little paranoid about setting up the tank in my office now.
Bob
I'm hoping that I will not have issues since I have the glass intact by the center brace and I have a bit of spacing between the slots. Any thoughts on this as far as good idea/bad idea? Do you have any links or anything to those who did have tank failure from drilling the slots? Do you know if it failed right away or if it held water for a while and then failed?
Sorry for all the questions, I'm a little paranoid about setting up the tank in my office now.
Bob
Willy315
New member
I drilled 3 holes in my 75. After I got done I figured one way to keep the glass from "splintering",would be to clamp a piece of glass on the back side of the hole you are drilling to keep the bit from "busting" through... Just a thought....also i rounded all the edges of all 3 holes with sandpaper, made for a very nicely finished hole with no sharp edges.
Bob,
Not all tanks that have been cut for slots in the back have failed. Yours are widely spaced and you seem to have put quite a bit of attention into mitigating these risks. IIRC I haven't read of anyone cutting individual slots in the rear of a tank, all the failures were one wide slot.
Level the stand in the garage or in the basement (near a floor drain!) and test fill it for a couple weeks. I don't have any links handy, but the failures I mentioned were posted within another thread (I think one of the very first threads on the topic).
I clamp glass behind when I drill for bulkheads and it works great (didn't really need it with my slots).
Dan
Not all tanks that have been cut for slots in the back have failed. Yours are widely spaced and you seem to have put quite a bit of attention into mitigating these risks. IIRC I haven't read of anyone cutting individual slots in the rear of a tank, all the failures were one wide slot.
Level the stand in the garage or in the basement (near a floor drain!) and test fill it for a couple weeks. I don't have any links handy, but the failures I mentioned were posted within another thread (I think one of the very first threads on the topic).
I clamp glass behind when I drill for bulkheads and it works great (didn't really need it with my slots).
Dan
This guy didn't drill it for a bulkhead but dremmelled holes in the side of his tank for and external box... lots of pics and he describes how it was done... should be able to be done for a bulkhead too... I'm certain there is a thread somewhere here on doing it for bulkheads-- this thread should cover the basics of dremeling a tank-- just trace out the bulkhead and I would drill holes on your traced line and then connect the dots.
here is the thread...
http://reefcentral.com/forums/showthread.php?s=&threadid=534878
yes they sell diamond edge dremel bits.. look at HD, Lowes, Menards, Ace, Sears, etc...
http://www.mytoolstore.com/dremel/dmdbits.html
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