what size hole?

[steve slack]

hey guys

im looking at setting up a central filter system and am wanting to use 20mm tnak fittings.i was wondering what size hole to get drilled?

cheers

[chimera]

about 28mm. 20mm fitting is inside diameter of ball valve, so then you have thread width of both sides plus a bit of room for some silicon measure the width of the ball valve first then add another 5mm

[Feelers]

Chim - I'm about to get my tank drilled (I know finally!) , but cant use the search thing. I want to go with 32mm plumbing(is this what you use) I think?

So what size drill hole for that?

Also am I best to have 2 corner overflows or one corner, or on in the middle?

And how can I tell if the glass is tempered, and how much should I worry about where I drill the holes.

Sorry for the torrent of questions? Its all a bit scary.

Ohhh- anyone have the drill bit for this that I could borrow?

[chimera]

Chim - I'm about to get my tank drilled (I know finally!) , but cant use the search thing. I want to go with 32mm plumbing(is this what you use) I think?

So what size drill hole for that?

Can't remember for the 32mm ball valve. Although according to my post in July '04 here I used 35mm holes for 25mm ball valves and that had a good 3-4mm each side to spare from memory. So, to be on the safe side I'd add another 8mm to the ball valve size to cover thread width and some room to add silicon.

Also am I best to have 2 corner overflows or one corner, or on in the middle?

Typically one overflow will be enough, positoning more for aesthetics. Two overflows for redundancy or massively high flow (greater flow, greater the water level)

And how can I tell if the glass is tempered, and how much should I worry about where I drill the holes.

Not sure about tempered (and as it sounds like you already know it can't be drilled) Make sure holes are drilled too close together or too close to edges. Closest mine are is the overflow hole at about 50mm (edge of hole to edge of glass)

Sorry for the torrent of questions? Its all a bit scary.

Try having two holes drilled when you have a full tank!

Ohhh- anyone have the drill bit for this that I could borrow?

Nope, I paid a dude to do mine, as above, its all a bit scary :lol:

[alanmin4304]

As you are probably aware you cannot drill or cut tempered glass. You can tell tempered glass by looking at it through your highly up market polaroid sunglasses. If you rotate the glasses you will see the difference.

[Alan]

It's very easy to tell tempered glass.

If you try cutting or drilling it, you end up with app. 5mm. roughly square pieces.

If you have a look on the glass there is normally a little brand stating the fact.

Also if you look carefully, you can see two little dimples where it was held,

the edges alo wont be as sharp as a normal, cut piece of glass.

Alan 104

[suphew]

Chim - I'm about to get my tank drilled (I know finally!) , but cant use the search thing. I want to go with 32mm plumbing(is this what you use) I think?

So what size drill hole for that?

I used 32mm pressure plumbing (nb: 32mm non-pressure plumbing is a different size so make sure you know what you are using) I had 40mm holes drilled and they were just a bit too small, fixed with a dremal, so if I was you would go 42-45mm, it doesn't matter that much cause as Chim says the silicon will fill any small gaps.