I need some ideas.

[pitt_md]

I am trying to put in a new fence and I run into bed rock about two feet down. Normally I have been able to take a 25 lb. iron bar and beat my way through it. I have spent several hours chipping away at it and there seems to be no end to it. I have tried to move the hole all around the area to find a way through with no luck. Do any of you know if there is some kind of hydraulic jack hammer or something that I could use to get through this stuff?
This is a corner post and I do not believe that two feet deep even set in concret will hold up.

Thanks for any ideas.

 

[MikeInEburg]

If I were in your shoes, I'd probably rent an electric jackhammer and generator. Or clear off a 2'X2' area of the rock and use a hammerdrill - set some pins into the rock to enhance adhesion, and use concrete.
Mike

 

[pat32rf]

You might just have to resort to the old "angle post from the top of the corner post to the bottom of the next one". We often do this with wooden (cedar) corner posts when we have wet soil.....If you are using steel pipe posts then you can do the same, just weld the whole assembly up as a unit..
At least if you are down to bedrock the frost won't heave it.

 

[texasjohn]

There are electric drills that have a "hammer" feature. This means that while the drill rotates it also hammers up and down at a high frequency. You use a concrete/rock drill with a special tip that is hardened to stand the impacts. You can purchase rather long bits... a foot or more. I assume you could get electricity to the site... or have an electric generator....

You are willing to do some work... so, I'd drill several holes, maybe .5 inch diameter, close together... hopefully, you can drill them straight... this would give you several holes into the rock in close proximity. Use your bar to enlarge the area you have drilled sufficient to take the post.

I'd recommend a pipe as the corner post... strong and smaller hole needed than with an 8 inch wood post... and concrete it in... if you can get about 1 foot into the rock, the concrete should hold that post forever.

I'd purchase the drill and bit(s) ... even the generator if you have to... you have hit one difficult hole... likely there will be others.... purchase of these items now likely would be about the same cost as renting a air driven jack hammer... and you have the equipment for future projects and problems.

If you have a Harbor Freight Tools nearby, try there, they have the stuff I mentioned. If not... a box store such as Home Depot, Lowes, etc.

 

[AchingBack]

I once saw a stretch of fence set on rocky ground. The posts were set in 55gal. drums filled with rock. Concrete would be heavier though.

 

[JoeinTX]

This is what the professional fencers use:

Air Compressor Rental, Compressor Rental | United Rentals


You should be able to rent one from any major rental lot but I don't know what they charge since I've never used one myself.

 

[donawilcox]

There are several options. Home Depot rental has several of them.

first is an electric jack hammer. They should care a Hilti 905. or at least that is the older number. it ways 25 lbs. They also rent a Hilti TE 76 hammer drill/chipper. They also have a core bit for that and should have a
3"-4" cores. The only issue is they are only about 4" deep an then you have to clear it out. Just make sure to get the chisels along with the core bit if you go this way.



Then there are diamond core rigs. I have heard of these mounted to bumpers. They are designed to be mounted to a concrete slab where you are drilling. Some use water but also can get dry ones.

Another option as one said id the rock is sold you could anchor to it. Hilti makes a two part epoxy. it is strong stuff. This epoxy is actually stronger if say you epoxied a piece of rebar in a concrete vs putting the rebar in when wet. The RE500 can even be used under water. Great stuff. on this route if you go metal post you could epoxy in some 1/2 rebar and weld to them or set some all thread and put a plate down. if going wood you could set a piece of larger rebar in the rock and then drill a hole in the post and slide it over it.

some home depots have hilti reps in them that can help you with this. I use to be one about 4 years ago but they are only in a limited number. There are also hilti centers. in major cities.


Now that I have given you the options my recomendation would be the large hammer drill/chipper and a core bit and chisels.

Later

 

[pitt_md]

Just an update of how I chose to go about getting these posts into the rock.

I bought this electric jackhammer and it went through layer after layer or dense rock like it was peanut brittle. The price of renting a gas powered unit was 150/day. This one cost me $175. It weighs in at about 50 lbs and can be beast to handle but it does what it says it will.

 

[teg]

Where did you end up buying it from?

 

[Captinjack]

Boy what model is this and where can you get one? I have a need myself, but even Harbour Freight costs over $400.