Tempered Glass or Not?

malicemethods

New member
I want to drill a hole into the top right back panel of my tank but I dont know if the back panel is tempered or not. The dimensions 24" wide x 20" high x 12" deep = roughly 25 gallons. The tank was a hand me down from my sister probably about 6-8 years old. I can see a sticker that says "built by H.A..." But i cant see past the "A". Is there any way to tell if the front and back panels are tempered? I want to avoid using a U tube, and use a bulkhead fitting with an attachment.
 

malicemethods

New member
Im also new to posting threads. How do you know if someone replied to your thread? is there any ways of seeing only the threads that I posted? thanks
 

Siberia

Premium Member
Usually, the bottom pane is the only one that is tempered, especially on large tanks. You would have to check with the manufacturer of the tank to confirm it, but I really doubt it. One way to "test" is to use polarized sun glasses and look sideways at the glass. If you don't see dark streeks/spots, it is safe to assume it is not tempered.

HTH

As for replies, you can see it right here since you are ready my response. ;)
 

hllywd

Premier World Traveler
Two polarized camera filters or polarized sunglasses can even work. Take the tank out in the sun and hold 1 filter on each side of the glass you want to test, rotate them until most of the light is blocked by the filters. It works good to use the sky as a background when you do this because it is uniform and bright. Move the filters across the glass simultaneously looking for light and dark areas or a pattern in the glass. The light and dark areas indicate the glass is tempered if there are none then it's most likely not tempered. You can try this on the side windows of your car first so you know what to look for, they are tempered.

Tim
 

coralnut99

New member
I would feel really confident that the back isn't tempered. You should put as much concern into where you drill. Keep the hole at a distance from any edge that's at least equal to it's diameter. In a 25, you're looking at relatively thin glass, take extra care to support whatever hangs from that hole, so no stress is put on it.
 

malicemethods

New member
<a href=showthread.php?s=&postid=10443722#post10443722 target=_blank>Originally posted</a> by coralnut99
I would feel really confident that the back isn't tempered. You should put as much concern into where you drill. Keep the hole at a distance from any edge that's at least equal to it's diameter. In a 25, you're looking at relatively thin glass, take extra care to support whatever hangs from that hole, so no stress is put on it.

coralnut, what is a good e/d "edge distance ratio" if I want to drill a 1/3/4" hole on the top left back panel? e = distance from center of hole to closest edge. d = diameter of hole. I heard ~1.5-2 is a good ratio to keep the strength of the material?
 
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coralnut99

New member
The outside edge of your hole should be 2 inches from any edge. The minimum I've seen recommended is 1 3/4 in your case. I would go with 2 simply because of the thinner glass. Not to beat a dead horse, but please give extra care to the weight you put on the bulkhead, whatever hangs from the back of that hole needs to be supported to bring it horizontal to the hole itself. A leaking bulkhead would be the least of your worries, if the tank were to crack running from the edge of the hole the nearest edge of the glass pane. In most cases the crack will run to a corner. Yes, I've been there.
 

malicemethods

New member
thanks, what is the best way to support a pipe to make sure it is horizontal to the tank when running vertically? ( the best way to minimize the moment force at the hole and to increase the load where its safe?)
 

coralnut99

New member
Generally when drilling thicker glass this isn't an issue, since the shear weight of a run of PVC is unlikely to cause enough stress to cause a crack to run from the hole to an edge. Also, there no set way to support what comes out the back of the tank, each settup will be different and unique. Just keep inmind that you're just trying to "suspend" the pipe, and see what makes the most sense for your case.
 

mmm55645

New member
will any brand of glass drilling drill bit work for drilling holes in glass? I saw some at Lowes, hitachi I think whose point looked like spears, and I saw different ones at Harborfrieght.com.

Does it make any difference what brand or design you buy? The ones at Lowes were more expensive, but I don't know if that is because the bits are higher quality or not. I'd hate to try and save a few bucks on a bit that will not work right and cost much more money in the long run.
 

coralnut99

New member
Steer clear of the "spear pointed" bits in the box stores. They work better in ceramics. Stick with diamond bits as hllywd suggested. Harborfreight sells them in the catalog too. It sounds like you'd better practice on a scrap piece before attempting the tank.
 

supereri

Premium Member
You're only going to get a few uses out of the Harborfreight ones, but it should be enough to do several holes. Keep it cool, use enough water.
 

hllywd

Premier World Traveler
I've cut about 20 holes and have another to do toninght with the saw I posted above. It is showing some wear but still worked pretty good the last time I used it... I'd say very good for 7 bucks...
Tim:cool:
 

coralnut99

New member
<a href=showthread.php?s=&postid=10452281#post10452281 target=_blank>Originally posted</a> by hllywd
I've cut about 20 holes and have another to do toninght with the saw I posted above. It is showing some wear but still worked pretty good the last time I used it... I'd say very good for 7 bucks...
Tim:cool:

I agree. These hole saws should be fine for this particular project, and at minimal investment.
 

malicemethods

New member
I emailed perfect and called AGA and asked both manuf about the same exact dimension tank that I have. 24" x 12" x 20" = 25 gallon and both manuf said none of the panels are tempered. I however DO NOT know if my tank was manufactured by these companies. I only have a sticker that reads "built by H.A." But from the replied on this thread and from both companies inputs I think I am pretty safe to drill on the back. I will try the polarized sunglass method to be 100%

Now its time to make the stand, hood, refugium, and pipe that sucker. this my first time doing all of this. should be fun!

Im gonna get the LFS to help me out a lot. I will probably ask a lot of question on this forum so please help me out!

thanks for all the help.
 
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