I have some large (5′ X 7′ X 2′ thick) granite slabs lying around my property that I would like to split into fenceposts. I’ve split smaller boulders with chisels, and I’ve cut stones with feathers and wedges, but I haven’t tried to split really big slabs. The grain is running parallel to the ground, which adds to the difficulty.
What I want to do is split the the stone along the grain into slabs 6-8″ thick. Then I can bore holes to “rip” the posts using feathers and wedges. From previous experience, I know that this stone (S. New England) splits pretty well, but has a tendency to crack perpendicular to the grain if you get too aggressive with it.
I believe the official old-time approach would be to have two guys using a slab splitter (the hammer, not the hydraulic splitter for counter tops) and sledge, but not sure how that would work with this grain orientation (and I don’t have a slab splitter anyway). My thought was to trace all the way around, then bore a couple of holes along the trace and use feathers/wedges to split it.
Anyone out there with experience doing this?
Pete
Replies
Have you thought of rigging a cable cutter. I don't know what the stone industry calls it, but it's basically a bandsaw with a wire rope for a blade. The cutting is done by sand, and you drip water on the wire rope to cool it and to make the sand stick to it.
It's called a wiresaw. Invented in 1854 by Italian stone cutters. You can get them computer controlled nowadays.
The wire is two strands of steel twisted around one another. The twist reverses direction every 10 feet. A hard mineral, like silicon carbide, is used as the abrasive. Water carries the abrasive, removes the swarf, and keeps everything cool.
I think finding one will be difficult. They are not common.
For the splitting job it might be wise to hire it out to a stone mason.
pete.. i'd probably stick to the feathers and wedges... i'd just use a lot of 'em.. and modify my technique based on results... especially once you find the grain
you could try a score with a diamond blade in your grinder also
Mike Smith Rhode Island : Design / Build / Repair / Restore
> you could try a score with a diamond blade in your grinder also
Now that's a good idea! I think you'd still want to hit it with a tracer to get the crack started, but whacking the tracer into a score line might save a lot of time.
Pete
tracer.. is that like a wide mason's chisel ?... we used to use them for scoring brick ?Mike Smith Rhode Island : Design / Build / Repair / Restore
Where in CT?
I've got carbide tipped tracer chisels, and I might have a slab splitter out in the shed. You've got to flip them pieces up so that you can strike along with the grain, and let gravity help you. Also, there's a certain finesse about picking the right grain line.
Comes with practice.
I use 3/8" feather and wedges, you can get bigger ones at UBS in Niantic CT.
Rod