Glass drilling (again)

[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]

Photos

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]

Photos

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.

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.

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.

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

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.