Cutting Glass with a Diamond Disc?

[Stevekane]

Hello everyone, I have a pair of Glass Mullions (Bullseyes) they are used but I dont think they are of any great age, and the present size is 8 x 12ins. I would like to reduce the height of both by trimming off about an inch top and bottom. I have cut old glass many years ago but they were always bits of plain glass that I could cut another if it didnt go well, with these I will have just the one shot and whilst I dont have to cut near the mullioned bit I suspect the glass wouldnt be as uniform as flat glass. So Ive invested in a cheap chinese diamond glass cutting disc that fits an angle grinder. Ive looked online for info on cutting window glass with one but all I can find is people cutting bottles,,,and they seem to cut well enough,,anyone got any thoughts ( or experience?)
BTW it will be 2 or 3 weeks before the disc arrives and I will of course post an update,
Steve.

 

[Lorenzl]

I have drilled glass - use water to keep the glass cool and wear a mask. The water should reduce the dust but better to be safe.

The disc will cut wider than you expect and I would think it will be hard to hold to a line. Make some sort of a guide?

 

[Tris]

Never used a cutting disc, always used a well oiled cutter and cleaned the glass really well beforehand, soapy water, dry off then wipe over with meths to be sure. Be interested to hear how the disc does.

 

[flying haggis]

Would a wet tile cutter work I wonder? Easy to use as the glass is resting on a flat surface.

 

[Stevekane]

Many thanks to you both, yes will def use water,,and my glass cutting teqnique is to make sure the glass is warm and really polish the cut line,,works most of the time, but the disc will indeed be an interesting project,,

 

[Stevekane]

Would a wet tile cutter work I wonder? Easy to use as the glass is resting on a flat surface.

Ah yes, I had one that one of the kids borrowed and then dumped!! Dont ask,,I keep my eyes open for one as I had planned on using it to touch up TCT saw blades and your right Im sure it would work for glass,,but I sadly dont yet have one and the glass cutting 1mm thin disc was less than £3 inc postage,,,looking at people cutting bottles on the Tube they attack them in a very gung ho fashion with several people just using segmented diamond masonary discs,,,and get a reasonable cut,,
Steve.

 

[Ollie78]

Just get a good oil filled glass cutter.
Clean the glass completely, then clean it again. Cut it in one shot with a positive motion.
This is your best shot at cutting it.

Ollie

 

[baldkev]

Hi steve,
GOGGLES!
beyond that, how much needs to come off? I remember years ago watching a hotrod program where they cut down a toughened windscreen with a sandblaster, with a steel plate shaped to the new size, covering the windscreen from damage ( acting as a template )
It took a while i think

I did glazing at one point for an emergency glazing company and we had a sander bolted to the bench which was used to zip over the edges at 45° so sanding works in its not much to remove.

I havent used a glass disc

Edit: i just googled glass mullions, if they are just sheet glass, a traditional glass cutter would be fine

 

[Stevekane]

I suspect Olli is right in that if I were a regular glass cutter it would probably work just fine, but Im not and my last go at cutting glass would have been 10 yrs or more ago, and I suspect glass cutting is 90% technique and confidence,,,I also recall many years ago getting a glazier to cut some used glass for me and he was wary of it being old and he said, fractured where it wouldn't break on the cut line, but I think it went okay. Watching people cutting bottles its seems a reasonably gentle process of grinding the glass away and my plan is to use my cordless angle grinder with a flow of water and to score through a strip of masking tape taking several passes to complete the cut.
I have to remove about 1inch x 8inch from both top and bottom of two mullions, so 4x 8ins cuts, and I will def wear goggles and I have some heavy leather gloves.
My other thought was to pop into a glaziers and ask them to cut it but I had some fairly recent experience of trying to buy a similar small piece of glass for a stable door, it seems like the glass business has gone all Corgi/Gas Safe and I was questaioned about its placement and told that it had to be toughned glass, was going to take two weeks to get and would cost £30, I suspect I would get the same response now,,,
Steve.

 

[Sheptonphil]

other thought was to pop into a glaziers and ask them to cut it

that’s the way to go.

I cut glass for many years using the same hand held diamond cutter, still have it, as it has my ‘edge’ on it so anyone else using it who didn’t hold to my angle, wouldnt score the same.

Using a diamond or wheel cutter dip it in white spirit before the cut, lubricates it perfectly. Draw one firm line towards you against a thin (4-5mm) straight edge. Never go back over the scribe. If you want to see where the snap will be, lightly tap the underside of score with back edge of cutter along the scribe. It will pop off no prob.

Any glazing company will do the job in ten minutes, one score, one snap.

cutting really old glass is often dodgy, it does get more brittle and doesn’t always snap to the score. Glass is still truly a state between solid and liquid at room temp.

 

[Stevekane]

Indeed Phil, that would have been my tack, but as I said, glaziers have got very funny in recent years about supplying glass and want to know where its being used, i had one refuse to supply a small piece for a stable door and then had to lie to another telling them it was in a fixed fanlight high up and inaccessible before I could get it, this way I spend £3 buying a supposedly specialist disc and maybe learn something along the way! Its going to be up to 3 weeks before the disc arrives and I will of course let you all know how it goes,,
Steve.

 

[Phill05]

I have a Dremel that takes small 40 mm diamond disks and they cut glass well, and I have the cone diamond shape to take the sharp edge off, yes you do need water to keep the fine dust down and cool.

 

[Phil Pascoe]

I've done courses in both slumped and stained glass in the past and not once did I ever see or hear recommended a diamond cutter - all the tutors and experienced people used tungsten wheeled ones.

 

[Stevekane]

Yes, what the experts do is great if your an expert,,which Im def not!, as I said Ive got one shot at this and perhaps wrongly it looks to me like the disc might offer me the best chance of cutting it myself,,a good quality glass cutter in the right hands would probably work just fine,,but there probably not my hands!
The Dremel, I never thought about it and I have one, use it for amongst other things grinding down the dogs nails,, very effective it is too, Ive got some cheap diamond Burrs but my case of discs and sanding drums is a Lidl set, was your glass cutting disc a special purchase?
Steve.

 

[Phill05]

Not a special set just the same from Lidl in my case I wanted a cloverleaf shape in green glass I printed the shape out in film stuck it to the glass and held it under a running tap while I cut it, I also cut a green glass ball into two pieces for eyes for an owl at the same time.

 

[okeydokey]

Do as sheptonphil suggests your local glazing/glass suppliers will cut it either by hand or a diamond tipped saw

 

[Phill05]

Do as sheptonphil suggests your local glazing/glass suppliers will cut it either by hand or a diamond tipped saw

Where is getting the experience and the fun in that.

 

[okeydokey]

The fun is knowing that they will be cut to size, and you won't have to try and buy one to match the remaining if you broke one of them (maybe thats fun as well)
The experience is cutting 1 and it broke and then cutting the 2nd and it broke, the leaning point is to leave it alone until you practiced a little more on plain glass