Hey all

Following on from my doggie threads, I'm having to fit a cat flap (escape route!) from my kitchen into a utility room. The door is basically one complete double glazed unit.
I'm not bothered about breaking the pressure inside the double glazing, however I'd obviously prefer not to have the glass crack on me!

My current idea is to put 1 or 2 layers of masking tape around the section I intend to cut out, use a glass/tile drill bit and very slowly and carefully drill a couple of holes and then use a glass cutter for the rest of the way...

Sounds like fun! Anyone done anything like this before and have any heplful hints!? :help:

Cheers

wouldnt even contemplate it.your gonna have to drill & cut twice through the double galzing.
is it upvc?
u could remove the glass & replace with a upvc panel from a door shop which would be easier to cut etc.

Originally posted by willman
wouldnt even contemplate it.your gonna have to drill & cut twice through the double galzing.
is it upvc?
u could remove the glass & replace with a upvc panel from a door shop which would be easier to cut etc.

Yeah, I thought I could approach this from both sides and drill/cut one at a time. The frame is metal so it's not really easy to just change the panel.
My other option would be to just replace the door with a 15 glass panel wooden one and remove one of the lower glass panels!

Well Briano,
I have drilled through ceramic tiles by this method on loads of occasions to mount things in bathrooms and toilets etc..

I would do an experiment on a spare piece of glass first.

My instinct says that if you get the feed or speed wrong the glass is just going to shatter. Or if you leave any sharp bits in the glass door, then the pane will crack the first time the door is slammed, and the crack will get bigger and bigger over time until it falls out. Just like a crack in a car windscreen develops.

My advice would be to replace it with a wooden door. Or a panelled door like you suggested before.

Yeah, that seems sound advice! I am doubtful myself if this is actually going to work but I'll give it a go over the weekend and we'll see what happens! :o

(Expect a wanted post next week for an internal door lol :thumbsup: )

I think you might have troubled drilling tempered glass too.

Originally posted by Phanerothyme
I think you might have troubled drilling tempered glass too.

Nah, I'll just start the hole off with a hammer and nail and drill from there.. :heyhey:

(Good point actually, hadn't thought of that! :rolleyes: )

Just make sure you turn the drill off hammer mode...

Originally posted by TimmyR
Just make sure you turn the drill off hammer mode...

:hihi: :clap: :hihi:

you need a diamond tip bit for your drill

internal doors r £15 @ focus.

Originally posted by willman
internal doors r £15 @ focus.

With glass panels!? :o

Originally posted by willman
internal doors r £15 @ focus.

They're also crap :)

Try the reject door warehouse at attercliffe if you want them on the cheap.

As already mentioned if it's tempered then you can't drill it anyway.

It is impossible to cut a hole in a double glazed unit without splitting the two panes first.You then have to cut a hole in them both,which would be almost impossible without the propper equipment,also when you join the panes together again you will get "misting"when the weather changes..Also any glass in a door must be safety glass ie.Toughened or laminated..Toughened cannot be drilled or cut without it exploding into thousands of bits ..laminate will only be able to be cut by an expert glass cutter..Believe me you would be better off getting a new dg unit made ..prob cost about 30 to 40 quid .Its not worth the hassle trying to do it yourself ...By the way Im in the trade and know what im talking about .Best of luck:thumbsup:
By the way if you do attempt it yoursef:loopy: inform the accident and emergency first just to make sure they have plenty of your type of blood in stock:hihi:
Lets know how you go on..:thumbsup:

I used to work in a glass factory, cutting the stuff .

To cut a hole in a sheet of glass, asuming is 4/6mm float and not toughend or laminate, you have to start with your glass on the bench before it is made into a sealed unit.

There is a cutting tool that works like a compass which you set to the size you need and make your outer circle. You then take a normal glass cutter and inside this cicle you score loads of lines in a criss-cross pattern until the trianglular gaps that form between these lines are quite small.

Then you have to turn the glass over carefully and using a very small pointed hammer start tapping gentley in the centre of your hole, knocking a piece out at a time until all of the waste glass is out.

Finaly you have to mark the second piece of glass in exactly the same place and repeat this process so that when you seal the unit up the hole are in line.

One of these panes (and they were a pain) would take me a hour or so if not longer and that was in a factory set up to cut glass. Doing it in your kitchen dosent bare thinking about. And like Burnttoast said , get ready for the inevitable trip to A&E.

ttfn

Those double glazed panels are 'filled' with a vacuum, so when you pierce it, it'll sound like a gun going off, plus the shock to the glass of suddenly no longer being under stress will probably shatter it into a million pieces.

Lets see then - A&E checklist....
Shock
Heart attack
Facial abrasions
Foreign body removal from eyes
......
I wouldn't bother if I were you :thumbsup:

Originally posted by Strix
Those double glazed panels are 'filled' with a vacuum, so when you pierce it, it'll sound like a gun going off, plus the shock to the glass of suddenly no longer being under stress will probably shatter it into a million pieces.


Most double glazed units are filled with nowt!

Salesmen tell you they are filled with a vacume but its phooey.

If the air between the pains was removed the atmospheric presure would bust them.

Also depending on how they are sealed filling them with air under pressure is almost impossible too.

Most of them only contain the air that was trapped in them the day they were sealed up.

Having said all that, this is based on my limited knowledge, as I only worked for the glass company for a year before I went back to my old job. Things might have changed since then as that was over ten years ago.

Thanks for all your advice on this, much appreciated :thumbsup: - I don't think there is anything you forumers don't know!

I have been in touch with A&E and informed them they can step down the alert level back to green. I'll be replacing the door rather than causing a fallout!

Cheers all :clap:

Originally posted by hj dary
Most double glazed units are filled with nowt!

Salesmen tell you they are filled with a vacume but its phooey.

If the air between the pains was removed the atmospheric presure would bust them.

Also depending on how they are sealed filling them with air under pressure is almost impossible too.

Most of them only contain the air that was trapped in them the day they were sealed up.

Having said all that, this is based on my limited knowledge, as I only worked for the glass company for a year before I went back to my old job. Things might have changed since then as that was over ten years ago.
You've never wondered why large panes such as patio doors appear concave? Or why they sound like a gun being fired when they are pierced? :confused:

Double glazing units don't have a vacuum inside them - they'd implode. Generally they have a negative pressure compared to the atmosphere but that's usually by mistake. The units tend to be sealed when they are horizontal and the top pane sags so if it's sealed like that then you'll get an inbuilt negative pressure. There are ways round it e.g. sealing most of it then standing it up and letting the pressure equalise.

If they only have air in them, why don't they all mist up in cold weather?

if the units 'toughened', then its obviously gonna shatter
whether ya drill or cut it.

truth be known, there aint no vaccum whatsoever, thats just bull, as dj or burntoast said earlier.

you could get a unit made up specifically (not toughened of course) already with the hole in ready!...

alls ya need to do is draw a template, cut it out of cardboard, drop it by a glass factory, and pay as a casual customer, and bobs ya uncle basically, (i'm in the game also, cutting glass 'to be toughened',

if ya need any more info, feel free to pm me (could get it ya done no probs) :thumbsup: :)

Originally posted by Strix
If they only have air in them, why don't they all mist up in cold weather?

They may have something else, other than air.

Nitrogen is commonly used to fill sealed optical units to prevent misting.

Most evacuated spaces tend to be cylindrical or spherical to cope with the external pressure. An evacuated double glazing unit would be a serious liability, as the panes would be under extreme stress all the time.

There is very little energy to be saved by using evacuated units, not enough IMO, to make the technical challenge worthwhile.

Ah, now I could believe the 'nitrogen' theory :)

Originally posted by Strix
If they only have air in them, why don't they all mist up in cold weather?

They have a dessicant inside them

Originally posted by Strix
If they only have air in them, why don't they all mist up in cold weather?

The reason why they dont mist up is the spacer bar round the edge of the unit is filled with silicone beads which keeps the air dry.
Also units now can be filled with argon gas .This gives a better "U"value to comply with document "L"regulations on low emition ..could go on but dont want to bore the t*ts off you.
Hope this clears a few thing up..........:thumbsup:

People are actually working on a type of vacuum double glazing also known as evacuated windows but it's very expensive to fix the pressure problem.

Not really 'silicone' though. Desiccants are like 'silica gel'.

Here is one known as XL8 (http://www.thermosealgroup.com/pages/DOUBLEGLAZE/dessicant/xl8.htm)

Originally posted by burnttoast
The reason why they dont mist up is the spacer bar round the edge of the unit is filled with silicone beads which keeps the air dry.
Also units now can be filled with argon gas .This gives a better "U"value to comply with document "L"regulations on low emition ..could go on but dont want to bore the t*ts off you.
Hope this clears a few thing up..........:thumbsup:
Ah, I've heard of the argon ones before, and discovered the silica beads by googling after reading this thread :thumbsup: