Granite Splitting (New Hampshire)

[DaveNH]

(Saga of granite splitting continues)

I'm from New Hampshire, the granite state. I'm trying to rid the yard of some of the larger boulders so grass mowing will be easier, look nicer, etc. I have a small tractor and skidded "the little ones" away to the side of my field. I'm starting to split the larger ones, down in size so that my tractor can pull them. So far I haven't figured out the knack of getting nice square straight pieces. I'm drilling with a rotary hammer, 3/4" bit about 6-7 inches deep. I'm using 3/4" feather and wedges (about 6" long). My problem is that once the boulder starts to split, it always curves off at about a 45 degree angle from the bottom of the feather and wedges. Yes, the objective is met, the stones are smaller but I'd like to know what I'm doing wrong? (if anything, maybe it's just these New Hampshire rocks) I've seen pictures of rocks split right down the middle. I'd at least like get a few good square pieces for steps in front of my sheds.

ANY HELP WOULD BE GREATLY APPRECIATED.
Dave

 

[Egon]

How thick are the pieces you are trying to split off?
Egon

 

[gator]

Dave,
I've never done it but saw on T.V. after they drill the holes, they use a chisel and "fracture" or weaken it from one side, over the holes, to the other side to end up with a straight break.

 

[DaveNH]

Bigger than this one. (4X4X3 triangle shaped)
This was the largest that my tractor could pull.
These rocks are very heavy, being from Nova Scotia, I think you'll know what I mean when I say heavy! The ones I'm tackling now are about 5+ feet.

 

[Joe_W]

After you chisel the line across the rock, tap all the wedges in until they are tight, then hit them one at a time across the rock, then go back and hit each one again, repeating that until the crack opens up.
Good Luck,
Joe W.

 

[Egon]

Dave:
Yea, I got a few little ones like that and then some a little bigger. Drug a bunch in to make a fence at the entrance to a field so jacklighters can't drive in. Lots of slate too. What I find hard to pull are the round ones as I have trouble keeping the chain on them. It can also get interesting if your going down a 20% grade with one.
Back to the splitting. What I was trying to ask is how thick a piece do you try to split off? There is an old house site at our place that has granite foundation blocks that are approximately 18 inches thick and up to 3 feet long. One can still see the 3/8 in. by about 3in. deep holes spaced at 5 in. where they broke the rock.
Egon

 

[AndyR]

Have you tried rotating your plane of cut to match that 45 degree angle? It may be that you are not following the grain (you can read some rocks, other are a mystery). Show us some pictures.

 

[DaveNH]

Gator and Joe
I now recall seeing a "This old house" where Steve helps split some stone steps.
I recall them scoring the line! I also remember that
Steve was about to stick his fingers in somewhere
where they shouldn't have gone!/w3tcompact/icons/shocked.gif /w3tcompact/icons/shocked.gif
A granite kiss!

Egon,
That's the look I'm looking for! There are plenty of cut
rocks here in NH just as you described. We have
old "pounds" in just about every town and they show
the cut marks as well. Old retaining walls around
cemetaries, etc. How'd they do it??????
If you look at the rock in the picture, I'm trying to half
something like that. That puts them about a ton and a
half and the BX can skid that amount of weight. I go slow.

Andy

These rocks are so weathered I can't tell where the
grain is.

Have you heard the joke about a fellow from down south comes up to New England and asks an old farmer about all the rocks. The fellow asks where all these rocks came from? The farmer answers "A glaicier brought them down from Canada." The fellow ask again, "Well, what happen to the glaicier?"
Farmer says "it went back to Canada for more rocks!" /w3tcompact/icons/smile.gif

I'll try again tomorrow.

Should have bought one of those 50 dollar digital camera with my Bush Tax refund. I'll have to take regular pictures and get them developed and put on a CD.

Thanks for your help![image]/w3tcompact/icons/grin.gif[/image]

 

[Egon]

Dave:
I also saw the rock splitting on This old house. Perhaps you will have to almost circle the stone with holes to get a good break. From the looks of the foundation rocks it would seem they have been broken from larger flater pieces. Just guessin as my rock splitting knowledge is zero. I have split some of the slate for a campsite down at the lake but that do not qualify as rock splitting.
Keep trying and when it happens let me know.
Egon

 

[Egon]

Dave:
From what I can remember granite does not have any defined fracture planes. If this helps any.

Egon