Drilling t_post holes in rock?

texasjohn · Jun 2, 2006

Many places I can use my FEL to mash t-posts in. When an occasional rock is hit, I put a meta lpipe sheath over the post to be driven (keeps it from bending too much) and drop the FEL on it a few times to see if the impulse will pound the t-post in. 50% of the time this works sufficiently well.

There are a few places where continuous limestone rock, somewhat brittle, certainly drillable is within 2 inches of the surface. 15 feet on either side can be fine and can drive a t-post OK there. So, occasionally I need to insert a t-post (without spade) into a hole drilled in rock. This hole doesn't need to be much more than a few inches deep.

I need to drill at most 20 of these holes for all the fence I am doing. It is a 4 smooth wire, 2 strands are permanent electric fence for cattle.

I have a generator, 3/4 horse power hammer drill and have very successfully used it to drill holes in rock and concrete. I also have an air compressor to blow out the holes while being drilled to prevent drill from getting stuck. However, I have never used a masonry bit of 1.5 inches diameter.

I found such a big masonry bit here .

I'm wondering how effective an 18 inch long 1.5 inch diameter carbide tipped masonry bit would be for the purpose. I'm willing to take a little time to do the drilling since I have so few holes to do.

I know that there are jack hammers and other more expensive tools that drill rock... but am looking for a satisfactory solution without spending a fortune on specialty tools for a few holes...

Experienced rock drilling comments invited!

texasjohn · Jun 2, 2006

Many places I can use my FEL to mash t-posts in. When an occasional rock is hit, I put a meta lpipe sheath over the post to be driven (keeps it from bending too much) and drop the FEL on it a few times to see if the impulse will pound the t-post in. 50% of the time this works sufficiently well.

There are a few places where continuous limestone rock, somewhat brittle, certainly drillable is within 2 inches of the surface. 15 feet on either side can be fine and can drive a t-post OK there. So, occasionally I need to insert a t-post (without spade) into a hole drilled in rock. This hole doesn't need to be much more than a few inches deep.

I need to drill at most 20 of these holes for all the fence I am doing. It is a 4 smooth wire, 2 strands are permanent electric fence for cattle.

I have a generator, 3/4 horse power hammer drill and have very successfully used it to drill holes in rock and concrete. I also have an air compressor to blow out the holes while being drilled to prevent drill from getting stuck. However, I have never used a masonry bit of 1.5 inches diameter.

I found such a big masonry bit here .

I'm wondering how effective an 18 inch long 1.5 inch diameter carbide tipped masonry bit would be for the purpose. I'm willing to take a little time to do the drilling since I have so few holes to do.

I know that there are jack hammers and other more expensive tools that drill rock... but am looking for a satisfactory solution without spending a fortune on specialty tools for a few holes...

Experienced rock drilling comments invited!

CurlyDave · Jun 3, 2006

When I had to drill as few 1" holes in concrete with an under powered rotary hammer (only rated for 3/4" in concrete) I started by drilling a 3/4" hole to the correct depth, then switching bits to the 1" and drilling the full diameter.

This worked quite well, and didn't seem to over load the drill.

Usually rotary hammers are rated for a hole size. If yours is rated for 1 1/2" it should work. If it isn't, try drilling a 1" hole first & then the 1-1/2 one.

CurlyDave · Jun 3, 2006

When I had to drill as few 1" holes in concrete with an under powered rotary hammer (only rated for 3/4" in concrete) I started by drilling a 3/4" hole to the correct depth, then switching bits to the 1" and drilling the full diameter.

This worked quite well, and didn't seem to over load the drill.

Usually rotary hammers are rated for a hole size. If yours is rated for 1 1/2" it should work. If it isn't, try drilling a 1" hole first & then the 1-1/2 one.

JoeinTX · Jun 3, 2006

Whew.....drilling holes for t-posts in June, huh?

Rough work and I've done it myself. From all that I've done, a 3/4 hp rig sounds awfully small for this. Yeah, you may be able to do it, but those 20 holes at a satisfactory depth (atleast 20") will take a long time to do. I never paid too much attention to the air-hammers I've rented, but they were heavy outfits needed to drill a decent hole in an hour or two's time.

JoeinTX · Jun 3, 2006

Whew.....drilling holes for t-posts in June, huh?

Rough work and I've done it myself. From all that I've done, a 3/4 hp rig sounds awfully small for this. Yeah, you may be able to do it, but those 20 holes at a satisfactory depth (atleast 20") will take a long time to do. I never paid too much attention to the air-hammers I've rented, but they were heavy outfits needed to drill a decent hole in an hour or two's time.

Egon · Jun 3, 2006

Currly Dave's advice seems real good. /forums/images/graemlins/grin.gif

Surely can't hurt to try it!

Egon

Egon · Jun 3, 2006

Currly Dave's advice seems real good. /forums/images/graemlins/grin.gif

Surely can't hurt to try it!

Egon

WhyNot · Jun 3, 2006

I don't know much about drilling rock since all we have up here is clay but I was thinking maype you could take a torch and put a tip on the end of those post and pound them in with the sleeve and loader or sledge. My thinking is that the point may be enough to shatter the limestone. good luck /forums/images/graemlins/smile.gif

WhyNot · Jun 3, 2006

I don't know much about drilling rock since all we have up here is clay but I was thinking maype you could take a torch and put a tip on the end of those post and pound them in with the sleeve and loader or sledge. My thinking is that the point may be enough to shatter the limestone. good luck /forums/images/graemlins/smile.gif