cutting circles out of glass - tips ?
 

Hi All

Fresh from my success with the big (to me!) stained glass window ...
- the new project requires me to cut a hole out of a piece of 'art'
glass.

The hole needs to be circular - and in the region of 1" to 2.5"
diameter...

I have the Morton hole-cutter attachment - and have become reasonably
good at cutting circular pieces of glass with it - but in this case i
want to end up with the 'negative' of this .

I can make the circular score - no problem. It's geting the piece of
scrap glass out of the middle of the hole without losing/cracking the
main piece that's causing me problems.

Anybody prepared to share their special tips, please ?
(And, no, I don't expect it to be as easy as in the movies! g)

Thanks in advance
Adrian
Suffolk UK

Your safest bet is to core drill the hole. Do not try to scratch it.

Randy Hansen
SC Glass Tech.
Scam Diego, Comi-fornia

i did this. i took a 3" hole out of the interior of a 16" disk.

draw out the interior hole with a sharpie. use a minibit on your grinder to
drill a sequence of holes around the perimeter of this line, and a few on
the interior of the circle in a small area. score around the perimeter. make
lots of scores between the perimeter holes and the interior holes, and
across the diameters in a lot of places. CAREFULLY break out the small areas
between the interior holes with grozers. work on grozing out the rest of the
interior pieces. use the large grinder head to smooth out the perimeter.

if you do it wrong, you just start over.

ps: i heard of someone just scoring the interior cut, and then just punching
out the hole with a fist.

"Adrian Brentnall" wrote in message
...
Hi All

Fresh from my success with the big (to me!) stained glass window ...
- the new project requires me to cut a hole out of a piece of 'art'
glass.

The hole needs to be circular - and in the region of 1" to 2.5"
diameter...

I have the Morton hole-cutter attachment - and have become reasonably
good at cutting circular pieces of glass with it - but in this case i
want to end up with the 'negative' of this .

I can make the circular score - no problem. It's geting the piece of
scrap glass out of the middle of the hole without losing/cracking the
main piece that's causing me problems.

Anybody prepared to share their special tips, please ?
(And, no, I don't expect it to be as easy as in the movies! g)

Thanks in advance
Adrian
Suffolk UK

even after repeated attempts and should you be successful, the doughnut
(hole) will always be at risk for cracking.
Add heat from a soldering iron and for sure a recipe for a crack.

Watch how they "cut a hole" on TV or the movies ....they usually show a
sliding door, and we all know that is safety glass, cannot cut a hole in it.

\if they could tap on the inside (other side) of the glass why would they
have to cut a hole to gain entry......

MUST BE TRUE MARTHA, I saw it on TV!!!!!!!!!!!

BUT, I too have succumbed to the hole cutting in glass fro an "unusual"
effect.....

h



--

In the words of the IMMORTAL USED CAR DEALER:
THERE IS AN ASS FOR EVERY SEAT!

Although it's easier to just drill the hole out, you can cut a circle
out from inside a piece of glass. Here's a method I use as a demo in
my Cutting Clinics. It's very effective at demonstrating "impossible"
cuts.

1. Score the circle you want. Unless you're EXTREMELY good cutting
by hand, I'd suggest using a circle cutter.

2. Turn the glass over, lay it flat on your table, and tap the
circular score until it has cracked completely along the score.

3. Turn the glass back to the original side and score an "X" and a
"+" to divide the circle into 8 pie-shaped pieces. (BE CAREFUL to NOT
run the score past the original score for the circle. Stop those
scores about 1/8" short of the circle score.

4. Turn the glass over, again lay it flat on the table, and tap those
scores until they have all completely cracked.

5. Stand the glass up vertical and tap the center where the scores
intersect. The pie-shaped pieces will fall out leaving a hole in the
glass.

You can also use this same method to cut out extremely complex shapes
other than circles.

"Adrian Brentnall" wrote in message
...
Hi All

Fresh from my success with the big (to me!) stained glass window ...
- the new project requires me to cut a hole out of a piece of 'art'
glass.

The hole needs to be circular - and in the region of 1" to 2.5"
diameter...

I have the Morton hole-cutter attachment - and have become reasonably
good at cutting circular pieces of glass with it - but in this case i
want to end up with the 'negative' of this .

I can make the circular score - no problem. It's geting the piece of
scrap glass out of the middle of the hole without losing/cracking the
main piece that's causing me problems.

Anybody prepared to share their special tips, please ?
(And, no, I don't expect it to be as easy as in the movies! g)

Thanks in advance
Adrian
Suffolk UK

As I tell my beginner students.... all those cat burglar movies where the
guy scores a circle and suction cups it cleanly out are BS.... you need to
be on the inside of the window to tap it!

--
JK Sinrod
Sinrod Stained Glass Studios
www.sinrodstudios.com
Coney Island Memories
www.sinrodstudios.com/coneymemories

Hi Randy


Your safest bet is to core drill the hole. Do not try to scratch it.

Thanks for the advice.....
.....unfortunately I don't have a core drill. I'm going to need to be
able to do this to produce a range of specific sizes - might involve
quite a few core drills.

Time is the one commodity that I have plenty of - I'll just have to
try the other techniques that people have suggested - but thanks for
the suggestion anyway....

Regards
Adrian
Suffolk UK

HI Howard

even after repeated attempts and should you be successful, the doughnut
(hole) will always be at risk for cracking.
Add heat from a soldering iron and for sure a recipe for a crack.

Yes - I suppose that's where the core drill solution wins - in that
there's no extra stresses induced in the glass.

Thanks
Adrian
Suffolk UK

Hi Charles
Thanks for the comments

i did this. i took a 3" hole out of the interior of a 16" disk.

Same principle, I'm looking at 1" holes from a 3" x 2" rectangle


draw out the interior hole with a sharpie

= glass cutter ?

use a minibit on your grinder to
drill a sequence of holes around the perimeter of this line, and a few on
the interior of the circle in a small area. score around the perimeter. make
lots of scores between the perimeter holes and the interior holes, and
across the diameters in a lot of places. CAREFULLY break out the small areas
between the interior holes with grozers. work on grozing out the rest of the
interior pieces. use the large grinder head to smooth out the perimeter.

Sounds like a plan.
The problem I was getting was that the circular score was OK, then I
made scores across the circle like spokes of a wheel - and they ran OK
- but they wouldn't break out because they had 'nowhere to go'.

I guess that the ground out holes help with that....


if you do it wrong, you just start over.

I've had plenty of practice at that step ! g


ps: i heard of someone just scoring the interior cut, and then just punching
out the hole with a fist.

Sounds like a recipe for a trip to the Emergency ward!
Don't think I'll try that g

Many thanks
Adrian
Suffolk UK

Hi Dennis
Thanks for the detailed reply.

Although it's easier to just drill the hole out, you can cut a circle
out from inside a piece of glass. Here's a method I use as a demo in
my Cutting Clinics. It's very effective at demonstrating "impossible"
cuts.

1. Score the circle you want. Unless you're EXTREMELY good cutting
by hand, I'd suggest using a circle cutter.

yes - was going to use a circle cutter anyway...


2. Turn the glass over, lay it flat on your table, and tap the
circular score until it has cracked completely along the score.

I've been running the crack by tapping with the 'blunt end' of the
glasscutter - your way sounds more controllable - I'll try it.


3. Turn the glass back to the original side and score an "X" and a
"+" to divide the circle into 8 pie-shaped pieces. (BE CAREFUL to NOT
run the score past the original score for the circle. Stop those
scores about 1/8" short of the circle score.

Tried this with 4 sectors - but not been able to get 'the first piece'
to come out - I'm sure that, once one piece is out then the rest will
follow without too much drama


4. Turn the glass over, again lay it flat on the table, and tap those
scores until they have all completely cracked.

5. Stand the glass up vertical and tap the center where the scores
intersect. The pie-shaped pieces will fall out leaving a hole in the
glass.

Presumably to the accompanyment of a drum-roll g - certainly sounds
like Magic! - I'll gve it a try.


You can also use this same method to cut out extremely complex shapes
other than circles.

I think I'll stick to circles for the time being - but what kind of
shapes were you thinking of ...?

Many thanks
Adrian
Suffolk UK