Drilling holes in rocks - Help

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Bentworker
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Re: Drilling holes in rocks - Help

Post by Bentworker » Tue Jan 21, 2020 6:52 pm

The drills that everyone has suggested so far are nice, but that Hilti is a little small - at only SDS plus.

1) Get something that uses SDS MAX bits.
2) Get someone younger and dumber to hold onto it.

Honestly rocks are pretty safe to drill, there is no rebar hidden inside to snag on. Larger drills are amazing, but are also capable of wrapping you up if you are not prepared.
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Russ Hanscom
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Re: Drilling holes in rocks - Help

Post by Russ Hanscom » Tue Jan 21, 2020 6:55 pm

100 ft of extension cord is acceptable if you use #12 wire - cords rated for 20 amps.

John Hasler
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Re: Drilling holes in rocks - Help

Post by John Hasler » Tue Jan 21, 2020 7:01 pm

I've got a 100' 12 gauge extension cord that works fine. 3 volt drop at 10 amps. You may have branch circuits that long.

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warmstrong1955
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Re: Drilling holes in rocks - Help

Post by warmstrong1955 » Tue Jan 21, 2020 7:07 pm

Battery powered work well, but I haven't seen any with the blow energy of the corded models.
That just means they drill slower.
Something like this: https://www.amazon.com/Makita-XRH01Z-Li ... r=1-8&th=1
Or this: https://www.amazon.com/Hitachi-DH18DBLP ... =hi&sr=1-6

The Hitachi, at least it's predecessor model to this model attached, was a good tool, and better than most. I have not tried the Makita however, to be fair.
We used a lot of battery powered in the mine, but mostly to put in spads (for surveying), or mount a laser or electric panels. Basically, short holes, just a few inches deep.
Still, the battery models we did use, did perform well, just not like ones with a cord, hooked up to 'commercial' power. They are also not cheap.
I do have 100' #12, and #10 extension cords, so that's a way out.

Much depends on how many holes you need to drill, and what kind of hurry you are in, and, looking ahead, what battery tools you may want in the future. I'm down to two different flavors of battery powered tools now, which, makes a lot of sense. I had 5, and that can get a little spendy.

Do like I do on slow days.....push refresh, or enter the url....and go do something. A watched screen, never loads.....or something.... :)

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BadDog
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Re: Drilling holes in rocks - Help

Post by BadDog » Tue Jan 21, 2020 8:02 pm

Get a good quality 12ga 100' copper stranded "commercial grade" extension cord. I'm no EE, and haven't done the calcs, but in my experience, it'll be fine. I've got one on a reel (better than lugging a coil) that I use with my electric pruning chainsaw and with the rotary hammer shown. I've also run an old 9" angle grinder (60s inefficient heavy metal bodied monster) that I've used on that cord. Loaded up cleaning up flame cut plate, that thing's got to use more current than any rotary hammer. I've even used it with a concrete breaker (this one if I'm not mistaken) with no complaints.

It's never even gotten so that it was noticeably above ambient. Once you get it close with the heavy cord, a lighter cord might make up the difference if needed. It's not like you're going to be running 100% duty cycle. But, if I'm wrong and asking to die a painful death, there are those here who will straighten me out. :D
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pete
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Re: Drilling holes in rocks - Help

Post by pete » Tue Jan 21, 2020 8:21 pm

Good to hear your healing Bill. Split rocks? Ok since no one else has asked then how big, how hard and just how many? The drilled holes with the feathers and wedges will work up to some really big rock, but even with a hammer drill it's fairly slow going. It it's big enough and you've got a number to do? One licensed blaster and some det cord packed over with simple mud will get it done quick, fairly quiet and fairly cheap without much fly rock if you value your time at all. I've seen rock 1/2 the size of your house split with that method. Possibly over kill for what your wanting? :mrgreen: Maybe this will help a bit. https://www.youtube.com/watch?v=otiO_wKCwEc

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seal killer
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Re: Drilling holes in rocks - Help

Post by seal killer » Tue Jan 21, 2020 8:44 pm

pete--

Ha! I've got a lot of rocks! I want to make blocks for walls and stuff. I'm in no hurry.

The rocks (that I'll use for wall material) range from 30lbs to 300lbs. Then I've got some that weigh a thousand up to about a ton, or so. I won't cut those as they are fairly regular already and cutting them would be a shame.

It's pretty much all limestone. I do have some granite, but I am thinking of using those as is.

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seal killer
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Re: Drilling holes in rocks - Help

Post by seal killer » Tue Jan 21, 2020 8:57 pm

pete--

Good video. Thanks!

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warmstrong1955
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Re: Drilling holes in rocks - Help

Post by warmstrong1955 » Tue Jan 21, 2020 9:01 pm

FYI.....Limestone has a compressive strength of about 8000 PSI. Also, it's one of the most non-abrasive pieces of ground on the planet.
Granite.....18,000 PSI and up, and a whole lot more abrasive.....like....a LOT more.
The harder the rock, the more blow energy you need to drill it. If you don't don't have enough blow energy to break it, which is what you do to drill it, that energy (now reflective) goes right back into the bit/steel, and the hammer.
I can tell ya stories....although....on a much larger scale than a hammer drill.
There is your boring rock drilling tech of the day! ;)

Other Bill
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pete
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Re: Drilling holes in rocks - Help

Post by pete » Tue Jan 21, 2020 9:08 pm

Well then that TOH video should help. They neglected to point out that most rock has a grain structure a bit like wood. So it will break a lot easier in one direction than another if you can read the grain. And good thing your not in a hurry, even using 1,000 lb and up to multi ton rocks to build a large rock wall is really time consuming and much, much tougher than it looks. And worth mentioning, be careful about how high or large you build without decent drainage within the back fill behind the wall. I've seen a couple of large retaining walls made from 1 ton interlocking concrete blocks blow out just from too much rain or melting snow behind it.

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warmstrong1955
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Re: Drilling holes in rocks - Help

Post by warmstrong1955 » Tue Jan 21, 2020 9:13 pm

Once upon a time, I did this for a livin'..... https://www.youtube.com/watch?v=OCoiWpr-qj4
A lot like work.....
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pete
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Re: Drilling holes in rocks - Help

Post by pete » Tue Jan 21, 2020 9:38 pm

Really tough work and a filthy, wet & noisy job as well Bill. Anyone who's done that job has my respect.I've drilled exactly two vertical 55' x 10 3/4" blast holes about 35 years ago. Way cleaner, easier and quieter than those air powered jack legs, but it was still enough to decide to stay away from drilling rock as a living up to now. :-)

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