What to dig post holes with in rock?

[Gomer pyle]

I have a JD5090E tractor. I'm trying to find the right attachment to dig my post holes. I hand dig most of mine but I'm unable to get some down due to solid rock, TN blue limestone. I know it's probably better to get a rock drill and jack hammer but, due to a back injury, I can't run the jack hammer due to vibrations. Looking at different things online, the Belltec TM-48 looks like it would possibly be the best option but it is out of my price range. How well do the hydraulic skid steer mount augers do? My tractor's flow is around 17gpm, which would pair best to my machine? I would like to get something to dig all my holes from now on.

 

[2manyrocks]

One of my friends in middle TN rented a rock drill which I believe was track driven. Nothing else would bore through the layer of limestone on his farm.

 

[gsganzer]

I have a JD5090E tractor. I'm trying to find the right attachment to dig my post holes. I hand dig most of mine but I'm unable to get some down due to solid rock, TN blue limestone. I know it's probably better to get a rock drill and jack hammer but, due to a back injury, I can't run the jack hammer due to vibrations. Looking at different things online, the Belltec TM-48 looks like it would possibly be the best option but it is out of my price range. How well do the hydraulic skid steer mount augers do? My tractor's flow is around 17gpm, which would pair best to my machine? I would like to get something to dig all my holes from now on.

SDS-Max drill might get you there. The thing with the rock soil, you don't need to dig near as deep to secure a cemented post.

On my clay soil, I sink a post at least 3 feet deep in a 9" cemented hole. If I hit limestone, I'll SDS-Max a smaller diameter hole to 2', set the poll in cement and call it good.

 

[Hay Dude]

I use an iron post spade.

 

[RjCorazza]

I have a Land Pride ssqa auger that would work with that hydraulic flow available. Rock bits are available, but I suspect they are not cheap.
The down pressure makes a big difference in rocky soil (not talking solid rock layer) with a regular auger.

 

[M59]

What size and shape ( dia or x by y dimension) posts are you trying to plant and how deep do you go before you hit the TN blue stone?

Rock augers are available and work very well in the softer stone or ground littered with hard stone. I prefer running the hydraulic driven auger off the SSQA and using the 3rd function because I can back the auger out of a jam.
Pic of rock auger with carbide points and hard facing along flight edges.
Pic of Mcmillen X1475 that I run on the M59. Loads of down pressure ( close to 5,000 Lbs) when front wheels off ground.

 

[Gomer pyle]

One of my friends in middle TN rented a rock drill which I believe was track driven. Nothing else would bore through the layer of limestone on his farm.

That doesn't really work for me because I need to do a few here and there. But yes, that is the best option to get the job done

 

[Gomer pyle]

I use an iron post spade.

I'm not sure what that is

 

[Gomer pyle]

What size and shape ( dia or x by y dimension) posts are you trying to plant and how deep do you go before you hit the TN blue stone?

Rock augers are available and work very well in the softer stone or ground littered with hard stone. I prefer running the hydrualic driven auger of the SSQA and using the 3rd function because I can back the auger out of a jam.
Pic of rock auger with carbide points and hard facing along flight edges.
Pic of Mcmillen X1475 that I run on the M59. Loads of down pressure ( close to 5,000 Lbs) when front wheels off ground.

8-9" posts. Some of mine start rock on top of the ground, some are a foot down before it starts.
I have rented skid steer augers when I have a few to do and like it. All the ones I've rented have dirt augers. I just want to make sure that one will do the job before I invest that much money

 

[bcp]

Several years ago I watched a school construction. They poured concrete steps. Some time later handrail posts were installed by core-drilling about 2.5-3. inch holes, with a large hand-held drill, maybe air powered. Then the post was "glued" into the hole, with a smooth gray substance, maybe epoxy.

Maybe you could do something similar using T-posts.

Bruce

 

[bdhsfz6]

I don't bother trying to dig holes in solid rock to hold a post. I use these square post anchors and fasten them to the rock ledge with four masonry bolts. 10 minutes with a cordless drill & masonry bit and their as solid as the rock their bolted to. Take advantage of the rock rather than fight it.

They can get pricey if you need a lot of them, so I make my own by welding a piece of square stock to a 6" x 6" x 1/4" plate.

Most times, they outlast the fence post. I have some that have been in the ground for 20 years.

 

[Gomer pyle]

I don't bother trying to dig holes in solid rock to hold a post. I use these square post anchors and fasten them to the rock ledge with four masonry bolts. 10 minutes with a cordless drill & masonry bit and their as solid as the rock their bolted to. Take advantage of the rock rather than fight it.

View attachment 2097000
They can get pricey if you need a lot of them, so I make my own by welding a piece of square stock to a 6" x 6" x 1/4" plate.

Most times, they outlast the fence post. I have some that have been in the ground for 20 years.

Makes since. Do you use these for corner or gate post also?

 

[bdhsfz6]

Makes since. Do you use these for corner or gate post also?

I have one corner post where I had to use a larger 12' x 12" plate with 6 bolts. It's held well for several years now but I don't over tension the wire.

Not sure how it would work with a heavy gate though.

 

[Hay Dude]

I'm not sure what that is

 

[M59]

8-9" posts. Some of mine start rock on top of the ground, some are a foot down before it starts.
I have rented skid steer augers when I have a few to do and like it. All the ones I've rented have dirt augers. I just want to make sure that one will do the job before I invest that much money

Looks like you have several options for posts. The bolting to exposed rock is an option but limestone is relatively soft stone so side loading such as a gate may cause anchor failure but use in a straight fence line would work well. Have you considered smaller diameter posts such as iron "T" posts or 2" fencing posts so your holes are smaller and require less effort. Boring a 4" dia hole would be much less work than a 12" dia hole using a rock auger.
An electric rotary drill and 2" dia carbide tipped bit would bore holes in limestone really quickly ( expect less than a minute per 12" deep hole ) but may not be feasible given your indicated your back injury.

Would contracting the job to someone with proper tools be considered?

 

[BlueKnife]

8-9" posts. Some of mine start rock on top of the ground, some are a foot down before it starts.
I have rented skid steer augers when I have a few to do and like it. All the ones I've rented have dirt augers. I just want to make sure that one will do the job before I invest that much money

A standard dirt auger will not go anywhere in the conditions you describe. I've not used a rock auger on mine yet, but I'll probably end up with one eventually. I'll be curious to hear how it works for you if you get one.

 

[BlueKnife]

I don't bother trying to dig holes in solid rock to hold a post. I use these square post anchors and fasten them to the rock ledge with four masonry bolts. 10 minutes with a cordless drill & masonry bit and their as solid as the rock their bolted to. Take advantage of the rock rather than fight it.

View attachment 2097000
They can get pricey if you need a lot of them, so I make my own by welding a piece of square stock to a 6" x 6" x 1/4" plate.

Most times, they outlast the fence post. I have some that have been in the ground for 20 years.

How are you attaching the post to that base?

 

[MAX-24-Dean]

I use the method that @M59 stated above, I've gotten to the point where I can't work with the vibration of my SDS- Max rotary hammer for very long due to physical pain in my wrist. So I changed to a core drill with no hammer action. It works fine, just takes a little longer. Hole diameter is drilled so the T-post is tight going in.

I knock off the wings on the T-posts, add cementall to the hole then install the T-posts.
Some of the T-posts have been in the rock for 14 years using this method and still doing there job.

 

[BlueKnife]

I use the method that @M59 stated above, I've gotten to the point where I can't work with the vibration of my SDS- Max rotary hammer for very long due to physical pain in my wrist. So I changed to a core drill with no hammer action. It works fine, just takes a little longer. Hole diameter is drilled so the T-post is tight going in.

I knock off the wings on the T-posts, add cementall to the hole then install the T-posts.
Some of the T-posts have been in the rock for 14 years using this method and still doing there job.

How do you get the "core" out of the hole? If it's solid rock, it would still be attached at it's base.

 

[MAX-24-Dean]

Run a bit down the pilot hole.

Then vacuum out the leftovers.