Use a jackhammer to dig postholes in rock?

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Lucky_P
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Use a jackhammer to dig postholes in rock?

Postby Lucky_P » Sun Mar 12, 2017 2:50 pm

Trying to put up a short run of HT fence - only about 1000ft... but at one end of the run, there's a shelf of sandstone bedrock about a foot down... doesn't matter which way I move it, it's not gonna be any better anywhere in that vicinity.
Been out there for a couple of hours today beating away at it with a breaking bar... without much progress.

I know this question's been posted before... but I'm just looking for more input...
Anybody ever rented a gas or electric jackhammer at a local equipment rental place and had any success busting a posthole through that kind of rock? I only need the ONE hole...
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Re: Use a jackhammer to dig postholes in rock?

Postby talltimber » Sun Mar 12, 2017 3:03 pm

Hammer drill? How big does the hole to be?
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Re: Use a jackhammer to dig postholes in rock?

Postby callmefence » Sun Mar 12, 2017 3:12 pm

Just one hole a 60 pound electric hammer will work fine. A bunch of holes rent a compressor and pneumatic hammer. Or rock augur.

With a jackhammer. Work from the outside diameter of the hole towards the center. Don't create a hole with sloped sides and pointed in the center.
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Re: Use a jackhammer to dig postholes in rock?

Postby Lucky_P » Sun Mar 12, 2017 7:50 pm

Thanks, y'all. Keep 'em coming

Hole needs to accomodate something like a 5-6" locust post. Would like to get it down at least 2.5 ft, if I can.
Busted up all the loose, cracked layers of sandstone, then hit a solid piece that I managed to crack a little with the breaking bar, but can't get any farther with it.
Guess I'll check around for a rental hammer.
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Re: Use a jackhammer to dig postholes in rock?

Postby Ky hills » Sun Mar 12, 2017 9:24 pm

I can sympathize, we have a lot of limestone rock. In some places we have to use ready mix concrete, and around the house/yard and barn lots have had to rent a gasoline engine jackhammer, because the electric ones weren't powerful enough.
When we remodeling the house, we had to get a jackhammer on a backhoe to go through the rock enough to get the waterline down low as it needed to be.
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Re: Use a jackhammer to dig postholes in rock?

Postby hillbilly beef man » Wed Mar 15, 2017 8:30 am

Pile up rocks and wrap the stack with a couple rounds of woven wire to make a corner post. It might be easier.
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Re: Use a jackhammer to dig postholes in rock?

Postby dun » Wed Mar 15, 2017 9:55 am

We're on glade rock so a post more then 3-4 inches in the ground is impossible in some places. What I did was took a 5/8 hammer drill and drilled down a foot in several sposts close to where the post was needed. Drove rebar into the holes and left it 6 inches above the ground. I then built a concrete form around them and the post a foot square and poured ready mix in. We have some of those that have been in for 15 years or more. I did that with both T-posts and 4 inch pipe.
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Re: Use a jackhammer to dig postholes in rock?

Postby midTN_Brangusman » Wed Mar 15, 2017 1:38 pm

If using a jackhammer, just make sure you wear hearing protection. I know it probably goes without saying but I guess im a special case. It gave me a concussion believe it or not, not sure if it was the vibration or sound. First day just got head aches, second day I was in the er and didn't know what year it was.
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Re: Use a jackhammer to dig postholes in rock?

Postby Dave » Thu Mar 16, 2017 12:24 pm

Lots of fence in eastern Washington and Oregon built on solid basalt. The corners and often the low spots they build frame a 4 by 4 frame 5 feet tall and stack it full of rock. There are ones on my wife's parents ranch that are built out of big channel iron welded up. You can stretch wire all you want against one of those.
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Re: Use a jackhammer to dig postholes in rock?

Postby callmefence » Sun Mar 19, 2017 3:22 pm

midTN_Brangusman wrote:If using a jackhammer, just make sure you wear hearing protection. I know it probably goes without saying but I guess im a special case. It gave me a concussion believe it or not, not sure if it was the vibration or sound. First day just got head aches, second day I was in the er and didn't know what year it was.


Good advice. I've never worn hearing protection until the last few years. I pay for it daily. My most commonly used word is huh?
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Re: Use a jackhammer to dig postholes in rock?

Postby midTN_Brangusman » Mon Mar 20, 2017 4:49 pm

callmefence wrote:
midTN_Brangusman wrote:If using a jackhammer, just make sure you wear hearing protection. I know it probably goes without saying but I guess im a special case. It gave me a concussion believe it or not, not sure if it was the vibration or sound. First day just got head aches, second day I was in the er and didn't know what year it was.


Good advice. I've never worn hearing protection until the last few years. I pay for it daily. My most commonly used word is huh?



Huh? :lol:

Same here fence!
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Re: Use a jackhammer to dig postholes in rock?

Postby bird dog » Mon Mar 20, 2017 9:25 pm

I did some kinda like Dun. I could dig a hole but only about 8". Hammer drilled some some holes, Drove in rebar, welded the rebar to a 3" pipe. Filled the shallow hole with very wet sakrete. High strength grout works even better.
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Re: Use a jackhammer to dig postholes in rock?

Postby Lucky_P » Wed Mar 22, 2017 6:34 am

Between a rock/concrete hammer-drill borrowed from the shop at work and continued pounding with the breaking bar, I got the hole deepened to about 18-20 inches. Gonna set a 2 ft section of 6" steel pipe in the hole, concrete around it and slide a 'big' 5" post into the sleeve once the concrete has set up. Hopefully, that'll do the job; It's HT fencing, but not gonna be cranked up to high tension.
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