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#1
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how to drill post holes in solid rock
I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in
solid rock for steel T-posts for a fence and I haven't decided how to go about it. What type of bit/drill combination would be most cost effective? Electric drill (size?) with core bit? Pneumatic drill with impact bit? Other combo? The location is far from power so the job would require a portable generator or a compressor if a pneumatic drill was used. I have a 2hp 20 gallon compressor - would be sufficient to run a pneumatic drill to drill the 1 1/2" holes? |
#2
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how to drill post holes in solid rock
klim wrote:
I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in solid rock for steel T-posts for a fence and I haven't decided how to go about it. What type of bit/drill combination would be most cost effective? Electric drill (size?) with core bit? Pneumatic drill with impact bit? Other combo? The location is far from power so the job would require a portable generator or a compressor if a pneumatic drill was used. I have a 2hp 20 gallon compressor - would be sufficient to run a pneumatic drill to drill the 1 1/2" holes? Call in the pros with the commercial equipment. It will be a lot cheaper in the long run. -- Joseph E. Meehan 26 + 6 = 1 It's Irish Math |
#3
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how to drill post holes in solid rock
"klim" wrote in message ... I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in solid rock for steel T-posts for a fence and I haven't decided how to go about it. I haven't any idea, but know enough to ask if it is granite or shale. |
#4
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how to drill post holes in solid rock
"klim" wrote in message ... I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in solid rock for steel T-posts for a fence and I haven't decided how to go about it. What type of bit/drill combination would be most cost effective? Electric drill (size?) with core bit? Pneumatic drill with impact bit? Other combo? The location is far from power so the job would require a portable generator or a compressor if a pneumatic drill was used. I have a 2hp 20 gallon compressor - would be sufficient to run a pneumatic drill to drill the 1 1/2" holes? Rent a core drill? As suggested, it MIGHT be cheaper to have someone do it. It WOULD be a whole lot easier. You might be opening a bag of snakes. Steve |
#5
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how to drill post holes in solid rock
Way back when some friends and I generated a bid for 8' cyclone in
extremely rocky soil. A California company came in 40% lower than any other local outfits. We went out to laugh thinking they would not be prepared for local soil conditions. They had a heavy steel dome, inserted approximately 1/4 stick of dynamite. When the charge went off, the lid was upside down next to the hole ready for the next load and the hole was clean to the bottom waiting for the post and concrete. Don't ever assume the low bidder is nuts. These guys went all over the world setting fence. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing. . . . DanG "klim" wrote in message ... I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in solid rock for steel T-posts for a fence and I haven't decided how to go about it. What type of bit/drill combination would be most cost effective? Electric drill (size?) with core bit? Pneumatic drill with impact bit? Other combo? The location is far from power so the job would require a portable generator or a compressor if a pneumatic drill was used. I have a 2hp 20 gallon compressor - would be sufficient to run a pneumatic drill to drill the 1 1/2" holes? |
#6
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how to drill post holes in solid rock
Rent an 90 cfm air compressor and a drifter drill. Most equipmet rental
companies rent these items. Get a drill bit to fit the drifter that is equal in diameter as the maximum size as your post. Then drill by going down about 6 inches and lifting the drill to within 1" of the top of the hole. continue this until you reach the plan depth of your hole. Once at the bottom flip the lever of the air drill to blow out the hole. There are usually three positions for the operating lever on the drifter drill. There is one that shuts it off. One that drills the hole and one that blows air to the bottom of the hole to clean out the cuttings. It is important that when you rent the drill, you show rent two drill bits. One is to be used to drill and the other is to be used in case you lock up the first drill bit. If the first bit gets locked in the hole, then simply use the second bit to drill beside the other bit to relieve the pressure and remove the bit. Wear heavy duty clothing and steel toe shoes when working. Safety glasses are best due to the fact that the high pressure air will blow cuttings into your face. Make a plywood template that you can secure to the ground with your foot or other item to hold the bit in place on unlevel ground. Becareful not to let the plywood spin and cause injury. Spend some time and plan a safe work experience. Expect the work to be very energy consuming. Watch for hand injury due to the vibration of the drill. Good luck. "klim" wrote in message ... I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in solid rock for steel T-posts for a fence and I haven't decided how to go about it. What type of bit/drill combination would be most cost effective? Electric drill (size?) with core bit? Pneumatic drill with impact bit? Other combo? The location is far from power so the job would require a portable generator or a compressor if a pneumatic drill was used. I have a 2hp 20 gallon compressor - would be sufficient to run a pneumatic drill to drill the 1 1/2" holes? |
#7
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how to drill post holes in solid rock
"klim" wrote in message ... I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in solid rock for steel T-posts for a fence and I haven't decided how to go about it. What type of bit/drill combination would be most cost effective? Electric drill (size?) with core bit? Pneumatic drill with impact bit? Other combo? The location is far from power so the job would require a portable generator or a compressor if a pneumatic drill was used. I have a 2hp 20 gallon compressor - would be sufficient to run a pneumatic drill to drill the 1 1/2" holes? You do not mention the type of rock. That makes a big difference. Electric, Hilti or Bosh your going to need the biggest badest one they have. You will probably wear it out when your done. Pneumatic, You could let it run for a week, and probably burn it out and still not have enough air for a pneumatic hammer. I used to work on a line truck digging holes and setting poles. There was a air compressor on board and a 90 lb pneumatic hammer. Set the truck rpms to 1800, then engage the air pump by the PTO. Wait a few minutes and go to work. Took 20-30 minutes to drill a 2 inch hole in granite 2 feet deep. I do not think that the 6 inch holes are deep enough for a regular fence post. More like a foot or more will be needed. Have fun your in for some long hours. |
#8
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how to drill post holes in solid rock
On Sun, 7 Mar 2004 17:39:57 -0700, "SQLit"
wrote: [snipped] I do not think that the 6 inch holes are deep enough for a regular fence post. More like a foot or more will be needed. Have fun your in for some long hours. Thanks for the experienced replies. It is granite rock here in the CO foothills and steep. Pneumatic sounds like the way to go to drill holes. But it does sound as arduous as I feared especially considering I'd need about 300' of hose to reach some of the places. But, I'm also considering an alternative plan and I'd appreciate any comments on it. A buck fence made out of 2" used well pipe. I can weld the A-frames in my shop, haul them up the mountain and weld the rails in place with my 110v wire feed welder and a portable generator. Materials would cost more than a T-post and smooth wire fence, but this might be easier to build in the long run. Any thoughts? |
#9
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how to drill post holes in solid rock
I had to drill a large number of 1-1/4" holes 15 inches deep in granite
to place a dock two years ago. The local Makita rep offered me the loan of a Makita HR3851 rotary hammer and with it I was able to drill them quite easily. Your compressor isn't big enough to run a pneumatic drill of any size but would be useful to clean out the holes. The bit doesn't lift granite dust well from deep holes. I fashioned a 1/4" diameter copper tube that would reach to the bottom of the hole and attached it to an air chuck. Every couple of inches I'd pull the bit back, insert the tube and clear the hole. (Eye protection and a dust mask were needed.) Not a bad job. No more than 10 to 15 minutes per hole, including beer breaks. RB klim wrote: I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in solid rock for steel T-posts for a fence and I haven't decided how to go about it. What type of bit/drill combination would be most cost effective? Electric drill (size?) with core bit? Pneumatic drill with impact bit? Other combo? The location is far from power so the job would require a portable generator or a compressor if a pneumatic drill was used. I have a 2hp 20 gallon compressor - would be sufficient to run a pneumatic drill to drill the 1 1/2" holes? |
#10
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how to drill post holes in solid rock
On Sun, 07 Mar 2004 18:39:01 GMT, "Joseph Meehan"
wrote: klim wrote: I need to drill many (50 to 100) 1 1/2" diameter holes 6" deep in solid rock for steel T-posts for a fence and I haven't decided how to go about it. What type of bit/drill combination would be most cost effective? Electric drill (size?) with core bit? Pneumatic drill with impact bit? Other combo? The location is far from power so the job would require a portable generator or a compressor if a pneumatic drill was used. I have a 2hp 20 gallon compressor - would be sufficient to run a pneumatic drill to drill the 1 1/2" holes? Call in the pros with the commercial equipment. It will be a lot cheaper in the long run. Don't be such a weenie. That is not what alt.home repair is all about. Pj |
#11
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how to drill post holes in solid rock
On Mon, 08 Mar 2004 02:19:09 GMT, klim wrote:
On Sun, 7 Mar 2004 17:39:57 -0700, "SQLit" wrote: [snipped] I do not think that the 6 inch holes are deep enough for a regular fence post. More like a foot or more will be needed. Have fun your in for some long hours. Thanks for the experienced replies. It is granite rock here in the CO foothills and steep. Pneumatic sounds like the way to go to drill holes. But it does sound as arduous as I feared especially considering I'd need about 300' of hose to reach some of the places. But, I'm also considering an alternative plan and I'd appreciate any comments on it. A buck fence made out of 2" used well pipe. I can weld the A-frames in my shop, haul them up the mountain and weld the rails in place with my 110v wire feed welder and a portable generator. Materials would cost more than a T-post and smooth wire fence, but this might be easier to build in the long run. Any thoughts? My advice is to put on your design cap and spend some time coming up with a design that would let you use the environment to your advantage. If you have granite on the surface and welded well pipe as a frame, then not much drilling is necessary. 4 to 8 inch deep holes with concrete in granite would hold anything but elephants. It would look good too. And you could do that with a chisel bar. PJ |
#12
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how to drill post holes in solid rock
On Mon, 08 Mar 2004 08:50:29 -0600, PJx wrote:
My advice is to put on your design cap and spend some time coming up with a design that would let you use the environment to your advantage. If you have granite on the surface and welded well pipe as a frame, then not much drilling is necessary. 4 to 8 inch deep holes with concrete in granite would hold anything but elephants. It would look good too. And you could do that with a chisel bar. PJ Yeah. I like the hand tool idea. I'm a blacksmith so I can make whatever chisels I need. I could go vertical posts (pipe) where there's enough depth to stabilize in concrete and use an occasional A-frame over the solid rock areas. Weld a top rail across the entire length and stretch 3 or 4 wires below. Getting a better feeling for this project. Thanks for your input. |
#13
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how to drill post holes in solid rock
On Sun, 07 Mar 2004 22:21:36 -0500, RB wrote:
I had to drill a large number of 1-1/4" holes 15 inches deep in granite to place a dock two years ago. The local Makita rep offered me the loan of a Makita HR3851 rotary hammer and with it I was able to drill them quite easily. snipped Thanks, RB. That might be a good way to go. I used a rotary hammer a few years ago to pin some footings to bedrock and it worked pretty well. One question maybe you can answer. I come across the terms SDS, and SDS-MAX in researching rotary hammers - what do they mean? And when a hammer is described as being 1" or 1 1/2", what exactly do those specs refer to? |
#14
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how to drill post holes in solid rock
SDS, SDS-MAX and SDS-Plus refer to the Spline Drill mounting of the bit.
SDS-Max is trademarked by Bosch. I don't know who owns the trademark SDS and SDS-Plus but I suspect it is also Bosch. A couple of spline configurations are shown in the link below. http://www.coastaltool.com/cgi-bin/S...f+107885941 9 The numeric descriptions, 1", 1-1/2" 2", etc. indictae the maximum diameter bit for that tool. RB klim wrote: On Sun, 07 Mar 2004 22:21:36 -0500, RB wrote: I had to drill a large number of 1-1/4" holes 15 inches deep in granite to place a dock two years ago. The local Makita rep offered me the loan of a Makita HR3851 rotary hammer and with it I was able to drill them quite easily. snipped Thanks, RB. That might be a good way to go. I used a rotary hammer a few years ago to pin some footings to bedrock and it worked pretty well. One question maybe you can answer. I come across the terms SDS, and SDS-MAX in researching rotary hammers - what do they mean? And when a hammer is described as being 1" or 1 1/2", what exactly do those specs refer to? |
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