Drilling t_post holes in rock?

[texasjohn]

The idea of drilling successively larger holes until proper diameter is reached and T-post can drop or be pounded into the hole had occured to me... clearly a good idea since it has been tried and recommended.

depth only needs to be enough to keep post from falling over when wind/rain strress is put on it... I'm thinking 4-5 inches of rock hole.. am sure experience would teach me best..

The idea of putting a tip on the posts is good... there used to be something called "rock point posts" that came with a point on them. They were shaped like a Y and I have several left over from the existing fences of 50+ years ago. The metal is still good.... but there are places where the rock points don't do the trick.... thus the reason for this thread.

Anybody know of another location to get the 1.5 inch masonry drill other than the one that I linked to in the first post? I can get some long but smaller masonry bits at Harbor Freight so I know my source for the bits to use to drill the starter holes.

 

[texasjohn]

The idea of drilling successively larger holes until proper diameter is reached and T-post can drop or be pounded into the hole had occured to me... clearly a good idea since it has been tried and recommended.

depth only needs to be enough to keep post from falling over when wind/rain strress is put on it... I'm thinking 4-5 inches of rock hole.. am sure experience would teach me best..

The idea of putting a tip on the posts is good... there used to be something called "rock point posts" that came with a point on them. They were shaped like a Y and I have several left over from the existing fences of 50+ years ago. The metal is still good.... but there are places where the rock points don't do the trick.... thus the reason for this thread.

Anybody know of another location to get the 1.5 inch masonry drill other than the one that I linked to in the first post? I can get some long but smaller masonry bits at Harbor Freight so I know my source for the bits to use to drill the starter holes.

 

[Birdhunter1]

You might try instead to find a core bit instead of a solid drill bit. You'll have to take teh core out in pieces but drills are usally rated for a larger core bit than their solid drill capacity. Plus with a core bit you don't have to drill in a successional course of smaller holes to larger holes.

 

[Birdhunter1]

You might try instead to find a core bit instead of a solid drill bit. You'll have to take teh core out in pieces but drills are usally rated for a larger core bit than their solid drill capacity. Plus with a core bit you don't have to drill in a successional course of smaller holes to larger holes.

 

[texasjohn]

Interesting idea, Birdhunter1. Knowing nothing about core bits, I hunted on the net and found this site which shows numerous bits.

However, I couldn't quite figure out the total costs and components involved... seems like one needs to get the bit ($104), then an adapter for a hammer drill ($18.26), then possibly an attachment that lets one dribble water into the hole while drilling...

this sounds like an idea worth persuing, but I don't think I've quite got all the pieces understood.... or where to acquire them...

I looked at Harbor Freight and they have this set with 6 pieces. for $70.

Was this what you had in mind?

How would one use this... my current ignorance says that you insert an adapter into the hammer drill, screw a bit into that adapter, then pour some water in the ground where a t-post hole is needed and start drilling. I assume that it will be difficult to hold by hand since the rock it is working on will be uneven and of differential hardness, at least until the hole is well started. Then, pick up the bit every half inch or so and remove the rock/dirt material that has accumulated inside the bit... and/or blow it out of the hole with an air gun. How much of this seems right? Anybody used the core bit approach??

 

[texasjohn]

Interesting idea, Birdhunter1. Knowing nothing about core bits, I hunted on the net and found this site which shows numerous bits.

However, I couldn't quite figure out the total costs and components involved... seems like one needs to get the bit ($104), then an adapter for a hammer drill ($18.26), then possibly an attachment that lets one dribble water into the hole while drilling...

this sounds like an idea worth persuing, but I don't think I've quite got all the pieces understood.... or where to acquire them...

I looked at Harbor Freight and they have this set with 6 pieces. for $70.

Was this what you had in mind?

How would one use this... my current ignorance says that you insert an adapter into the hammer drill, screw a bit into that adapter, then pour some water in the ground where a t-post hole is needed and start drilling. I assume that it will be difficult to hold by hand since the rock it is working on will be uneven and of differential hardness, at least until the hole is well started. Then, pick up the bit every half inch or so and remove the rock/dirt material that has accumulated inside the bit... and/or blow it out of the hole with an air gun. How much of this seems right? Anybody used the core bit approach??

 

[3RRL]

We used core bits like that in machining large clearance holes in thick steel plates. They were called Routa-Broach. But as I understand it, those core bits are primarily for through-hole drilling....such as through a marble plate stock. They leave a round remnant inside the drill that you take out once you drill through. I don't know how the "core" would come out of a solid pice of rock if you went 5" deep and not through it completely. I guess you could take a hammer or something and bust it off and then pick it out??

 

[3RRL]

We used core bits like that in machining large clearance holes in thick steel plates. They were called Routa-Broach. But as I understand it, those core bits are primarily for through-hole drilling....such as through a marble plate stock. They leave a round remnant inside the drill that you take out once you drill through. I don't know how the "core" would come out of a solid pice of rock if you went 5" deep and not through it completely. I guess you could take a hammer or something and bust it off and then pick it out??

 

[Birdhunter1]

Correct, if the core bit passes completely through then you simply remove teh core out of your bit and go on with whatever work you were doing. I used a 2" bit not long ago to run a 1 1/2" sch 40 pvc pipe through my 1" think foundation wall. The core bit woudl only bore in about 4" at most, when I felt the bit bottom out I'd grad my concrete chisel and small sledge and whack it a few times then pull it out in pieces with a pair of pliers. Alot of times if you are able to turn the bit just slightly inside that hole it will break the core off and leave it inside teh bit and then it just comes right out no problem.

I've never used water on them before but I could see why that might be needed when using a hammer drill at a much higher speed than a rotary hammer. Another idea would be to rent a rotary hammer and the core bit you need, I think last time I rented one it was like $30 for a half day or something like that.

 

[Birdhunter1]

Correct, if the core bit passes completely through then you simply remove teh core out of your bit and go on with whatever work you were doing. I used a 2" bit not long ago to run a 1 1/2" sch 40 pvc pipe through my 1" think foundation wall. The core bit woudl only bore in about 4" at most, when I felt the bit bottom out I'd grad my concrete chisel and small sledge and whack it a few times then pull it out in pieces with a pair of pliers. Alot of times if you are able to turn the bit just slightly inside that hole it will break the core off and leave it inside teh bit and then it just comes right out no problem.

I've never used water on them before but I could see why that might be needed when using a hammer drill at a much higher speed than a rotary hammer. Another idea would be to rent a rotary hammer and the core bit you need, I think last time I rented one it was like $30 for a half day or something like that.