granite slab edge chipping

[Anthony Tribby]

Hello again,

I've tried several methods and so far not gotten satisfactory results
from any.

I'm working with my 3cm scraps of granite still. I'm trying to find
the best way to take a piece that already has a straight-cut edge and
chip off just enough to give a nice, natural looking edge instead.
I've tried a cheap "masons chisel" from HD which works ok on the very
softest granites but not at all on the black. I was thinking a more
high end "mason chipper" might be the way to go but wanted some
confirmation before dropping $100 or so on one.

Also I found a reference online to a patent for a device called a
"granite and marble nipping tool" that was like a pair of adjustable
cutters specifically designed for this purpose, and also for a
studded drill bit also designed for edge chipping, but no evidence
either product was actually marketed. Anyone ever seen such a thing?

Thanks again

-Tony

[blb]

Post by Anthony Tribby
I'm trying to find
the best way to take a piece that already has a straight-cut edge and
chip off just enough to give a nice, natural looking edge

What you want is a pitching chisel with a flat surface face. The
trick is to place the flat faced surface of the chisel tight against
the edge and whack it with a very high velocity. This shears the
stone off at exactly the edge of the chisel. You also would place
slab stone just over the edge of the table so the table prevents the
stone from moving anywhere except where you hit it. You also use
gloves so you only bruise your left hand when you miss the chisel.
This can be an extreme sport. It will shorten the life span of your
left thumb!

Some people consider pitching a fine art and love to use the
technique to get as far into a sculpting project as possible before
getting out the other tools.

Bill B

[Musgrove, Richard (PIRSA - SARDI)]

=20
Hi All,=20
Its great to see Emily's wonderful work used to illustrate an article in
one of science's more interesting magazines - have a look at the June
2nd edition of New Scientist - Archangel 2 makes quite an impact on pg
54! Interesting/disturbing comment by Emily on our possible future, and
the relative durability of chalcedony and marble. Let us hope such work
is a continued source of wonder/pleasure, not our memorial.

Cheers,

Richard =20


-----Original Message-----
From: blb [mailto:blb-***@public.gmane.org]=20
Sent: Sunday, 10 June 2007 3:16 PM
To: stone-***@public.gmane.org
Subject: [stone] Re: granite slab edge chipping

Post by Anthony Tribby
I'm trying to find
the best way to take a piece that already has a straight-cut edge and=20
chip off just enough to give a nice, natural looking edge

What you want is a pitching chisel with a flat surface face. The trick
is to place the flat faced surface of the chisel tight against the edge
and whack it with a very high velocity. This shears the stone off at
exactly the edge of the chisel. You also would place slab stone just
over the edge of the table so the table prevents the stone from moving
anywhere except where you hit it. You also use gloves so you only bruise
your left hand when you miss the chisel. =20
This can be an extreme sport. It will shorten the life span of your left
thumb!

Some people consider pitching a fine art and love to use the technique
to get as far into a sculpting project as possible before getting out
the other tools.

Bill B




=20
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[blb]

Richard,

Haven't seen the magazine you mentioned, but her work is really nice.
I had to look her up on the web. Here's the link to her work I found
if anyone else wants to look:

http://www.emilyyoung.com/index.html


Bill

[edie heller]

hi bill - thanks for the reference to emily young - her work is
absolutely FABULOUS , imho ... edie

Post by blb
Richard,
Haven't seen the magazine you mentioned, but her work is really nice.
I had to look her up on the web. Here's the link to her work I found
http://www.emilyyoung.com/index.html
Bill

[George Graham]

Anthony Tribby wrote:

I'm trying to find
the best way to take a piece that already has a straight-cut edge and
chip off just enough to give a nice, natural looking edge

Anthony,
Pitching a 2 or 3 cm thick stone is one of the most difficult things to do
by hand. I'd rather pitch 8" granite all day long.
The problems are,
1 you have no idea how strong , or fragile the stone is . It will often
break apart in the middle because of preexisting flaws and fractures.
2. You have to hit it hard, very hard!
3.Most countertop and tile stone would be rejected by monument and building
stone people because of flaws and unreliable grain. Diamond saws have made
it possible to manufacture beautiful and exotic stone that will not stand up
to traditional stone cutting methods.

The only reliable way I know of to split countertop granite and tile is to
score the stone on both sides and then try to snap it as you would glass.
Use a very thin diamond blade and cut a 1\16 to 1\8", then put the line on
the edge of board and give a sharp push down.
Otherwise spend a lot of money on hydraulic splitters and nippers.

Pitching stone looks so simple, and it is when you watch the right tools
being used by an expert. But its really like a great golf swing. It takes a
lot of practice.
Best of luck ,
George Graham

_________________________________________________________________
Don’t miss your chance to WIN $10,000 and other great prizes from Microsoft
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[Oscar Bearinger]

Your "live" experience with stone work is always so appreciated, George,
thanks !!

Just picked up a few gorgeous countertop offcuts myself, to use for bases,
and I guess I'll be trying glass-cutting granite ! Why do I think it might
just break a little tougher than glass :o) ?!

Thanks again, George (and many others on the stonelist too!)

Oscar

----- Original Message -----
From: George Graham <georgergraham-***@public.gmane.org>
Subject: [stone] Re: granite slab edge chipping
.
Pitching stone looks so simple, and it is when you watch the right tools
being used by an expert. But its really like a great golf swing. It takes a
lot of practice.

[Bill Ostrie]

My experience pitching the edges of 3/4" granite slab to make bases
echoes George's analysis: I got some nice rough edges that I liked,
and I also broke some pieces in the middle by striking them near the
edge.

Bill Ostrie

Post by George Graham
1 you have no idea how strong , or fragile the stone is . It will often
break apart in the middle because of preexisting flaws and fractures.
2. You have to hit it hard, very hard!
3.Most countertop and tile stone would be rejected by monument and building
stone people because of flaws and unreliable grain. Diamond saws have made
it possible to manufacture beautiful and exotic stone that will not stand up
to traditional stone cutting methods.
Best of luck ,
George Graham

[Don Dougan]

Hi Tony,

I'd agree with what Bill and George said about pitching thin slabs being
tricky —
when it works it is great looking, but I have reduced many slabs
absolutely
to gravel in the attempt to acheive a pitched edge where I wanted it.

On average I figure three slabs will become gravel in order to end-up
with
one slab looking the way I want it after pitching. I have tried the
method
George describes to creat a broken edge so as to mimic a pitched edge
by cutting a shallow kerf on the back side and then breaking it like
glass.
This works fairly well for more-or-less straight lines, but often the
whole
point of wanting a pitched edge is to achieve an irregular outline rather

than a straight one. Using a small diamond wheel in a die-grinder allows
you to make an irregular-shaped kerf, but snapping the waste off the edge
becomes problematic.

I will mention that a good alternative is to use a pair of nippers like a
mosaic
artist would use — working to the desired shape with many small easily-
controlled nips. The bench-mounted cutting nippers made for mosaic
shop are too expensive to make it practical for the limited amount of use
I'd put
to them, but I do use a small-size pair of ceramic-tile nippers to shape
slabs
up to about three-quarters-of-an-inch in limestone and soft marble, but I
never
tried granite over about three-eighths-of-an-inch thick. The biggest
problem
with the small nippers is getting the jaws to open wide-enough
(three-quarter
-inch is maximum jaw-opening on my small pair), and then having the
length-
of-handle for required leverage for the thicker slabs.
For what it is worth I have considered buying a big pair of blacksmith's
nippers with 24-inch long handles next time I come across a pair in a
flea
market or junk shop — just haven't come across any in the last couple
years
since I started using the small nippers for 'pitching.'

Good pitching to you,
Don

www.dondougan.com

[blb]

Post by Don Dougan
I have reduced many slabs
absolutely
to gravel in the attempt to acheive a pitched edge where I wanted it.
Pitching a 2 or 3 cm thick stone is one of the most difficult
things to do
by hand.

You know this only encourages a stone worker! I mean, think of the
irony. You hammer on rocks all day and something is hard to do!

Anyway, I gave all my granite slab scraps away and kept the marble
and limestone ones. In the northwest I can get all the granite I
want. So, I can't go out to the yard and try pitching granite slab
edges again. But if you really want a rough edge on a granite slab
then here are two possible ways not mentioned:

1. Flaming using an acetylene torch. But this is tricky because the
corner of the edge will go first. It should work though, even if it
leaves a rounded edge. Use a lot of flowing water to prevent the heat
from traveling away from the edge.

2. Clamping the slab between two hardwood boards up to the edge to be
removed to immobilize the slab and to dampen the vibration from
traveling across the slab. Possibly making saw cut notches every
little way so that you are pitching off little tabs.

Sorry to beat a dead horse!

Bill B

[David Modine]

Post by Anthony Tribby
I was thinking a more
high end "mason chipper" might be the way to go but wanted some
confirmation before dropping $100 or so on one.

I think this is exactly the tool you should get. Assuming you are
referring to a Trow & Holden tool, I would specifically recommend the
one with a 3/4" stock & a 1 1/4" blade. Use in conjunction with about a
2 to 2 1/2 pound striking hammer. I really like T&H's striking hammers,
with the quite skinny wood handles. The skinny wood handle really makes
a difference in my opinion. Something about the vibration transfered to
the chisel as I recall. I was taught this pitching advice by the very
knowledgeable & giving Constantine Seferlis when I first began cutting
stone.

Another key to success, again IMO, is a solid stable benchtop on which
to chisel. A big thick slab of stone, preferably 3 to 4" thick, atop a
stout table, makes an ideal chiseling table. I prefer to not have the
this stone overhanging the edge, that causes under-breakage for me.
For 3 cm material I like to go about 3/8" into the stone. The first
chisel bite is about 1/4" in, with the chipper held pretty much
perpendicular to the stone. This should give a straight break top to
bottom. Then move in the last 1/8", and hold the chisel about 15 degrees
off perpendicular.
With a few hundred (or thousand) lineal feet done successfully, you will
almost be able to do it with your eyes closed.
Until then, expect to ruin quite a good percentage of your edges getting
to know the stone & technique.

David Modine