Splitting Rock

Egon · May 23, 2005

Perhaps look at the rock to see if it is layered and would have natural fracture planes. Then try and split along one of those planes.

From the picture I'm guessing there are planes running at a downward angle. It you are lucky it may be slate which slits easily with a hammer and rock chizel.

You could also build a big hot fire that will produce many coals on top of it. Heat it well and then douse it with cold water.

Egon /forums/images/graemlins/grin.gif

JimMorrissey · May 23, 2005

Thanks everybody....This is a topic I've never had to deal with in the past. My last two home sites (subdivided) were built on quarry grade gravel hill. The engineer who designed the septic system said "you are lucky you're not Monkton, because the town would take the land if they knew what was under here". Now I'm dealing with clay and rocks....what a difference /forums/images/graemlins/tongue.gif It's OK though, I'm getting some serious seat time and learning a lot about building a real road. My gravel roads were so stable, I just had to scrape off a bit of topsoil and throw down some sure-pak.

crashz · May 23, 2005

I'd rent a air compressor and jack hammer (80 lb hammer) and break it up in less than an hour.

SteveBenson · May 23, 2005

Do you have to use water with these air powered rock drills to keep the dust down?

If I remember correctly weren't the first air powered drills that were developed for tunneling referred to as "widow makers" because they would fill the opereators lungs up with silica and caused severe lung damage in a matter of weeks.

AndyR · May 24, 2005

You don't need to buy the biggest set of feathers & wedges to split a rock. Depending on how it is made up, you can get anywhere from 4" to 2' or more on a split using the smaller devices. A picture and/or description of the type of rock you have locally would help. What you are trying to do is create a fault line across the rock face. Pay particular attention to any existing cracks or veins as they often will tell you the direction of the grain of the rock (direction in which it will split most easily). I am working with granite up here - but it is not always smooth going. Some types of stone have a much "rounder" feel and may have occlusions of various minerals which makes them into non-compliant /forums/images/graemlins/crazy.gifpains in the you-know-what. Sometimes you have to use an abrasive or diamond saw and grinders to work off troublesome areas on those - so I try to avoid them. Some rocks (not around here) are just too soft to split and you have to resort to other methods.

As you drive the series of feathes and wedges in (go along and hit each one at a time) you will feel and hear everything tighten up and sometimes they "sing" just before the break - as in so tight that they chime when you hit them. Everything goes dull when the tension is off though you usually know when the fracture starts. Be prepared to rescue a few of your sets if the fracture line does not follow them - it happens. You can usualy just knock the wedges side to side a little bit and loosen them up but soemtimes have to drill a relief hole nearby.

Someone mentioned dust and silicosis. Serious stuff. If you are working in any kind of operation where the dust is doing anything more then mounding around your drill bit you should wear a good mask. Same rules apply as with motorcycle helmets - what's your life worth? Forget the paper masks - get a good strap on repirator mask with dual filters and prefilters (around $30-50) and change the prefilters frequently.

jhb · May 24, 2005

Hmm, brings up an intersting question for me. What is the best way to drill a hole in rock for the feather and wedges?

I have heard two trains of thought, hammer drill, or diamond encrusted core bits with a no-hammer drill. What is better?

If hammer drill, what kind of bit should one use for rock, a normal HD quality masonry bit?

Also, I have a mounded rock I need to shave down a few inches to place a terrace over. I was going to get a 10" gas saw with a diamond blade and just cut ruts and pop them out. NE1 have an opinion on that (gee, should start another thread, sorry)

Jagmandave · May 24, 2005

If it's just sandstone, you can rent an electric jackhammer, they actually work pretty well. They weigh about 80lbs and run on 120V. I used one to bust up a 20' X20' concrete patio, the concrete was over 30 years old and hard as can be, but it broke it all up in about 5 hours, cost less than $100. Rented it from Home Depot.

jhb · May 24, 2005

No, its granite or whatever we grow here in New England. It is sediment rock, that is, it is layered.

Egon · May 24, 2005

If it's layered it's not granite. You may find it easier to split as it possible could be slate or a form of metamorphised slate which will be harder.

Egon /forums/images/graemlins/grin.gif

Gunnahafta · May 24, 2005

Funny you should bring this up. I am just going through the learning curve on doing this very thing these past couple of weeks. I would like to make some stone steps and have access to some granite from an old quarry on a friend's property. Here's what I've done.

I first went and checked out the price of buying the steps at a nearby stone company--big bucks. So I decided to see if I could split the granite myself figuring that whatever toys (excuse me, I mean tools) I needed would be paid for by the money I saved not buying the stone.... Anyway, attached is the setup I put together.

Basically, it's a high-torque, 12V cordless drill; a 1/2-inch diamond core bit with a water swivel adapter (to supply the water to the bit) [www.ukam.com]; a hand-pump sprayer [Home Depot]; and 20 or so feathers and wedges [www.trowandholden.com]. I have no access to electricity way back in the woods, thus all the portables... People scoffed at the idea of drilling holes in granite with a cordless drill, but....

to be continued....