Glass drilling (again)

[coralnerd]

I'm thinking about building a sump for my 4 ft glass aquarium. The plan is use it for a freshwater setup for now, with scope to add a skimmer and convert to marine in the future. My problem is finding a way to shift the water from the tank to the sump. I have more or less decided that a wier or standpipe in the corner with drilled hole at the bottom with a fitted PVC bulkhead is the way to go. I prefer the aesthetics and simplicty of this setup compared to an overflow box setup.

I rang around most of the local glass workers, and almost all of them refused to drill an aquarium, because they're afraid of cracking it. So I'm starting to lean towards doing it myself. Can anyone give me some advice? I read another old thread on this forum that discussed this issue, but there wasn't much detail. I gather that it's not too hard as long as your glass isn't tempered. The question is, how can you tell if it is tempered or not?

[vidiots]

I did this same thing last weekend, only I wanted to drill a side overflow into my sump tank for automatic water changes. I too could not find a glass place willing to drill a glass aquarium even though I called many of them. The best they would tell me is that they would drill the glass if I could seperate it from the tank. If you've tried this you found as I did, it's asking the impossible.

I went to home depot and bought the largest glass bit they had which was (1/2") and bought a cheap 10gal tank to try it on. I did some searching on the internet for how to drill glass and found a number of links, which I'll add to the end of this.

Anyway I managed to drill the 10gal tank no problem, however, with the hole only being 1/2" in diameter I figured I'd need at least 6 to 8 of them to get an outgoing flow rate that exceeded the incomming flow rate. I abandoned this idea figuring it would be a chore to get a water tight seal on that many holes.

I found a cheap 40mm diamond coated glass drill bit on ebay, seller was lautszyan0@netvigator.com from Hong Kong. I bought some bulkheads from Big Al's online that would fit in a 1.5" hole (close to 40mm).

I have a small cheap benchtop drill press in my garage. I mounted in on the edge of my workbench with the table over hanging. I clamped some scrap wood to the bench to support the tank, and mounted the tank on it's side with the drill press table inside the tank. I also attached a small piece of wood to the metal drill press table to protect the table and the glass that would be in contact with it.

After marking my holes with magic marker I used my daughter's play dough to form a bowl around where I was drilling to fill with water. I set the drill press to the slowest speed (500rpm).

For the drilling, it is a little different than drilling through wood. You dont drive the drill bit through the glass, you allow it to just come into contact and rub it's way though very slowly. It took me about 30 mins to grind my way though 1/8" glass and about 45 mins to grind my way through 1/4" glass.

The sites I found strongly recommend that you drill part way through on one side then flip the glass over and finish from the other side. I did not do this because the top of my drill press would not fit inside the tank. As a result when the bit came out the other side on the 40mm holes, it was not a nice clean sharp edge, but instead had some tiny minor chips around the inside corner of the hole. Not a big problem since the bulkheads I bought have a large rubber gasket that completly covers all the chips, however, I'd imagine that if the bulk heads ever experience a good strike from something that is where a crack will form.

The best tips I can give you are, start cheap, that way if you screw up your not out much, and wear hearing protection. Some of the squeeks that were produced while drilling would resonate in the tank and get loud enough to get your ears ringing. At no time durring drilling should the drill bit get hot to the touch.

As promised here are some of the links I found:

http://www.drillglass.com/drillingglass.html

http://www.uhh.hawaii.edu/~pacrc/bigisaquapg/Drilling.htm
http://www.wetdryfilter.com/drilling_holes.htm

[coralnerd]

Thanks a lot. That's a big help. Especially the playdough idea to keep the area wet. I'd already been shopping around on ebay for drill bits, and now I'm thinking that this the best way to go.

I would have to use a hand held drill, since I'm talking about a 4' tank, and its too big to get under a drill press from any angle. It probably would be possible to go halfway then turn the tank over, but I'd be worried that the bit would not line up exactly with the groove I'd already made on the other side. I have visions of the bit catching on the glass when it breaks through and sending enourmous cracks across the base of my tank. Should I be worried, or is it really as easy as it looks in the pictures I've seen on the web?

[tank90]

Hey Vidiots.... Great Post

[vidiots]

I would strongly recommend the drill press if you have access to one, it gives you much better control while drilling and allows you to stop and restart with everything staying in position. The only draw back is you loose the sense of feel for the amount of force you are appling, so you have to be very careful.

I just had a thought on how you could drill the bottom with a drill press. You would mount the drill press so that the top is overhanging a work bench edge and turn both the base and the table around backwards out of the way so that they are not under the drill bit. I suggest clamping or bolting the drill press in place. Then mount the tank upside down under the drill bit. I would recommend that you support the area under the glass you are drilling with a block of wood. I suppose this would also work with a hand drill.

The only limitation with using a drill press would be how far in from any edge of the tank you can drill. You'd be limited to a maximum of the distance between the drill bit and the center support column of the drill press. I don't think this would be an issue though, because I can't think of a reason anyone would want to drill the center of the glass on any aquarium side.

[vidiots]

Oh, one more thing I found. The small glass drill bits look like a rod with a flat metal spade shaped tip. The larger glass drill bits look more like a hole saw with like diamond sand paper around the edge instead of teeth.

I also saw references somewhere to using a piece of pipe as the drill bit and using and abrasive material between the pipe and the glass. I didn't really look into this much, but it is probably much cheaper than buying a glass bit. I bought the bit, to keep things simple for my level of inexperience.

[Native American]

If you drill the side of a tank, chances are it is not tempered glass, and therefore can be drilled.

Larger tanks usually have a tempered glass bottom. Any holes desired must be drilled before the tempering process. In my younger days I tried to drill tempered plate to achieve a small hole using the same type of spade style bit. The result I got was an instant explosion of glass shards from end to end with total destruction of the plate. There were no salvageable pieces left.

In short, before you drill the bottom of your tank, contact the people who made your tank and find out if the bottom is tempered glass plate. Some makers are now using tempered plate for the backs of their tanks, as well.

Here is a link to a pic of what happens when one tries to drill or re-shape glass plate after the tempering process:

Tempered Glass Fragmentation (http://fins.actwin.com/killietalk/month.200509/jpg00000.jpg)

v/r, N-A

[vidiots]

Oops, I forgot to mention that I verified the glass in the tank I drilled was not tempered before I even tried.

Here is an article I found about tempered glass:

http://www.thekrib.com/TankHardware/glass.html#6

[coralnerd]

After reading that article posted by vidiots, I suspect that the bottom pane of my tank isn't tempered, as it is quite thick (about 7 or 8 mm), and feels like it has some give in it when I tap on it. Ie. it vibrates and seems to flex slightly in response to pressure.

I doubt that I'll be able to find out from the manufacturer, because I have no idea who the manufacturer is. I've had the tank for over ten years. I'll try calling the shop I bought it from (if they still exist) and ask them if they can help me.

[coralnerd]

Before I can get this hole drilled, the question I need to sort out is what size bulkhead fitting I should use.

The only ones I can find that are available through Asutralian suppliers are a 25 mm or a 40 mm fitting. I'm planning to use a 2500 lph powerhead to pump the water from the sump back into the tank. It will be lifting the water about 1.2 m (4' for the americans), which according to the manufacturer will produce about 2000 lph at the outlet. Does a 25mm (1") bulkhead fitting sound big enough to accomodate that kind of flow rate? Or should I play it safe and go for the slightly more expensive 40mm fitting (which will require a larger and more expensive drill bit for the hole)

[Native American]

Tempered glass also flexes and vibrates. A better way to tell is to get a pair of small polarized sheets and put them on either side of the glass with an illumination source opposite the side you're viewing from. Don't orient the polarized sheets to get a completely darkened viewing. The lines of compression and tension in tempered plate will almost always show up like the lines on a topographical map.

It's pretty neat. BTW, el cheapo 10-gal tanks from Wal-Mart now use tempered plate for the tank bottoms (judging by the stickers affixed to them that say "do not drill").

Drilling into glass plate without knowing if it is tempered or not is a bit of a gamble.

v/r, N-A

[coralnerd]

I'm about 95% certain that the bottom plate isn't tempered. Through a series of phone calls that got confused and uncertain responses, I managed to track down the manufacturer of the tank. They told me that the bottom pane is not tempered, and that they regularly drill holes in their tanks before they are sold. They also told me that drilling the tank will void the warranty. . . .

I've ordered both a 25 mm (42 mm hole) and a 40mm (60 mm hole) bulkhead, and 45mm and 65 mm diamond coated glass drill bits, so we'll see how things pan out. I'll post some pictures of the process and the result (positive or otherwise) when I have it done.

[Native American]

Grind away!

v/r, N-A

[vidiots]

I took a number of pics when I was drilling mine, just haven't gotten around to getting them off the camera and onto the internet yet. Hopefully I will soon. I'd like to see pics of your process and results, incase I ever have to do it again.

Also as for bulk head size, my 180gal tank came predrilled with dual overflows and return lines in the bottom. The two drain pipes are 1" and the and the return lines are 0.75" both pipe outside diameters. The pipes have much thinner walls than standard household PVC pipes and I don't know the inside diameters. The barbed hose connectors under the tank are 1.25" inside diameter hose for drain and 0.75" inside diameter for the pump return hoses.

I know that ideally you needs your drain to be larger than your fill, and also that you generally get more flow through a pipe with a pump on the end than you do just using gravity to supply the water. Also if you double the diameter you multiply the area by a factor of 4. So two pipes under an equal amount of pressure a pipe with twice the diameter can handle 4x the flow.

I'm guessing that twice the pressure would equal twice the flow.

You can't use the rated max flow rate of the pump to figure this out, because the actual flow rate will drop signifigantly with vertical height.

[coralnerd]

Success!

I managed to drill the tank without any problems. I ended up putting the hole in the back pane, a couple of inches from the bottom, and used a bulkhead with a 90 deg elbow fitting on it. I installed a weir across the corner of the tank using a piece of 4mm glass cut to size. The whole thing works beautifully, except that when the pump is running the sound of the water flowing is way louder than I anticipated. Its like having a river running through my living room. I've been fiddling around with putting different materials behind the weir to dampen the sound of the water spilling over it. Haven't had much success yet. If I ever do it agan I think I'll drill the hole near the top of the tank, close to water level, so that the water doesn't have so far to spill before it goes out through the bulkhead.

Anyway I'll post some photos of the drilling process soon.

[bpimm]

Success!

I managed to drill the tank without any problems. I ended up putting the hole in the back pane, a couple of inches from the bottom, and used a bulkhead with a 90 deg elbow fitting on it. I installed a weir across the corner of the tank using a piece of 4mm glass cut to size. The whole thing works beautifully, except that when the pump is running the sound of the water flowing is way louder than I anticipated. Its like having a river running through my living room. I've been fiddling around with putting different materials behind the weir to dampen the sound of the water spilling over it. Haven't had much success yet. If I ever do it agan I think I'll drill the hole near the top of the tank, close to water level, so that the water doesn't have so far to spill before it goes out through the bulkhead.

Anyway I'll post some photos of the drilling process soon.


If your bulkhead fitting has a threaded interior put a 90 degree fitting inside and a standpipe to set the water level.

Brian

[coralnerd]

Step one was to support the tank on a sheet of chipboard. The black plastic frame on the tank is hanging over the edge to eliminate the small gap that it would have caused.

http://i38.photobucket.com/albums/e126/coralnerd/glass-drill4.jpg

Since I was using a hand drill, it was necessary to make a guide for the holesaw bit, to stop it from skidding all over the glass. I just used a cheap sheet of masonite, and made a hole in it the same size as the bit. This fit into the corner of the tank. I imagine that ply or something would work better, but the masonite was good enough.

http://i38.photobucket.com/albums/e126/coralnerd/glass-drill3.jpg

I wet the surface and the bit thoroughly, and used the guide just long enough to make a groove in the glass. After that I moved the guide out of the way.

http://i38.photobucket.com/albums/e126/coralnerd/glass-drill2.jpg

With the guide out of the way, I built a wall of play-dough around the hole, and filled it with water.

http://i38.photobucket.com/albums/e126/coralnerd/glass-drill5.jpg

The hand drill was fine, but I had to very careful to keep it straight, and maintain just enough pressure to keep the bit in the groove. I let the drill's weight push it down, and kept the revs at about 100-200 rpm.

http://i38.photobucket.com/albums/e126/coralnerd/glass-drill1.jpg

http://i38.photobucket.com/albums/e126/coralnerd/glass-drill7.jpg

http://i38.photobucket.com/albums/e126/coralnerd/glass-drill6.jpg