I need to cut a couple of pieces of slate off a bigger slab, which
is about 6mm (1/4") thick. I’d like them to be rectangular, about
35mm x 30mm; two adjacent sides straight, the other two adjacent
sides roughly broken to look like a natural flake. Thickness can be
thinner than 6mm, that’s just what I have to start with.
Without lapidary equipment, what can I use?
I have the usual assortment of jewelers’ saws, diamond saw blades,
and household wood and hack saws.
Is scoring and breaking an option?
For the “flaked and broken” part, what is the best way to do this
without leaving tools marks?
I cut slate with my jewelers saw frame mounted with a saw blade that
is round and coated with diamond, Rio Grande has them. It’s slow
but works and be sure to wear a dust mask.
I have cut 1/4" thick and up to 1" thick slate slabs with a
Craftsman circular saw using a carbide blade. Cut slowly and it’s a
piece of (dusty) cake. Wear a mask.
For the natural broken edge, try a few sample cuts, but my guess
would be that if you made a thin score cut on the backside and then
broke it through, you’d get the edge that you want. Or else you
could use a chisel or some other type of blade or flint and flake
the edges by hand after you have cut the shapes, similar to the way
you would knap an arrowhead to shape.
When natural slate is used for roofing, it is trimmed to size by
hand using a rectangular section steel ‘iron’ mounted firmly to
support the slate and cutting it with a heavy knife in a hacking
motion. - Kind of like a large pair of scissors in action. This
produces the kind of edge I imagine you are lookin for as the rough
edge. Maybe you could do something similar using a steel edge (maybe
an anvil) and an axe.
Maybe you could do something similar using a steel edge (maybe an
anvil) and an axe.
Please do not try to approximate a tile and shingle cutter with an
anvil and an ax! This would be very dangerous, and will not produce
an even cut - it will fracture the slate, and possibly injure you! A
slate tile cutter not only has an anvil and a drop shear, but it
also has a built in clamp: when you use one to cut slate it first
clamps down completely (top and bottom faces) on one edge of the
slate, leaving the other side unsupported. The drop “blade” comes
straight down so that the shearing action is applied over the entire
tile at one moment. Anything less than this total control will not
work, and is very dangerous.
A slate tile cutter not only has an anvil and a drop shear, but it
also has a built in clamp: when you use one to cut slate it first
clamps down completely (top and bottom faces) on one edge of the
slate, leaving the other side unsupported. The drop "blade" comes
straight down so that the shearing action is applied over the
entire tile at one moment. Anything less than this total control
will not work, and is very dangerous.
I take your point Jim but assume you have no long contact with the
roofing business. Back in the 60’s and 70’s when I was more involved
in the practical aspects of the building trade and most British
houses had slate roofs, this was the way all slates were cut on site
and most of the thinner slates in the Welsh slate quarries.
The one thing I could see as giving a problem in using an axe is
that the cutting edge is curved whereas a slate knife (ax) had a
straight edge. As the anvil and knife were two separate parts, there
was, of course, some skill involved in striking so that the heel of
the knife struck the slate first and slid cleanly along the edge of
the ‘iron’ and new slates cut much easier than old ones. Things have
changed nowadays and Health and Safety have become more important
than doing the job - so much so that many jobs have now become
uneconomic. I remember working on a church roof which had to be
re-slated and many new slates cut and fitted. It was all done using
ladders only - no scaffolding and the slates were cut on the roof
with an ‘iron’ fitted into a piece of railway sleeper and a hand
‘knife’. Can you imagine doing this using a modern machine and having
to climb up and down the long ladders for each cut slate and again to
trim them to exact size!!!
Anyway, ignore the ramblings of this old fool and don’t do anything
which might be unsafe…