Drilling Hard Rock With Carbide

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SteveHGraham
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Re: Drilling Hard Rock With Carbide

Post by SteveHGraham »

There is a Youtube video of weighted straps flying through the air and taking the weights with them.
Every hard-fried egg began life sunny-side up.
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SteveHGraham
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Re: Drilling Hard Rock With Carbide

Post by SteveHGraham »

Today my wedges and feathers arrived. Where on earth does the term "feathers" come from? Anyway, I can only stand to work about 90 minutes in this heat, so I went out, made two cuts, and called it a day. I used a 5/8" Milwaukee carbide bit 18" in length.

I have to say that the difference between a hammer drill and a rotary hammer is like the difference between a .25 and a .44 Magnum. When I got started, the only 5/8" bit I had was for a hammer drill. I got out my Makita lithium drill, which drives a 1" auger through oak as if it were cheese, and after drilling for around a minute, I was only maybe 1.5" into the rock. I immediately went to Home Depot for an SDS+ bit, and I would say the rotary hammer penetrated over twice as fast.

Most of the rock was so hard it looked almost like opaque glass where it broke. The texture was inconsistent, however. Some is like sandstone, and there are even air-filled voids in it.

I am sorely tempted to buy whatever is the next size up from a $500 1-3/16" Makita rotary hammer. I want to know what the upper limit of 110V tools is. I rented a Hitachi demo hammer once, and it was a real pleasure to use. Makita sells a bigger rotary hammer with almost 4 times the impact energy. That would be fun.

Anyway, I put 4 holes in the rock, between the main mass and a sort of wing that extended toward the north, and after a few bops with a blacksmith's hammer, it cracked right off. Unfortunately, it was pinned in the ground, so I could not get it out without a lot of fuss. I moved toward the main body of the rock and made another cut using 5 wedges, and oddly, the piece that came off was easy to lift out of the hole, even though it was between the main rock and the little wing I couldn't move.

In the photo, you can see the cuts on the right side of the rock. One is a thin crack, and the other is a long, wide separation where I pulled out a piece of rock weighing maybe 30 pounds.

The tractor and strap failed to budge the main rock after this, so I am going to have to keep nibbling away.

Those wedges are pretty hilarious. Very easy to use. I have to thank Russ for the idea.
07 23 19 big rock in yard with wing broken off using wedges small.jpg
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Russ Hanscom
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Re: Drilling Hard Rock With Carbide

Post by Russ Hanscom »

I do not bother with feathers, although they probably promote longevity of the wedges. I just turn a taper on any convenient piece of scrap rod and beat it into the hole!
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SteveHGraham
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Re: Drilling Hard Rock With Carbide

Post by SteveHGraham »

These things are cheap on Amazon, and they come with O-rings to hold the feathers on. Pretty nifty.
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BadDog
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Re: Drilling Hard Rock With Carbide

Post by BadDog »

I would have expected the SDS+ rotary hammer to be roughly 10x quicker than the LXT hammer drill, particularly at that size bit. At least that's been my experience with the same tools working in hard concrete.

Good luck finding the limits of 110V in this respect.

I've used one of these a few years back to break out a 10" thick 3' x 24' slab of some sort of concrete that was so hard that my SDS+ Rotary hammer wouldn't really touch (about like your experience with the hammer drill). To make it worse, the section of slab that needed removal was between my house foundation and the pool deck. Previous fool (as opposed to the current fool) that owned this house decided to fill in a "flower bed" between the 2 slabs that was intended to provide the run-off for rain, with the result that every heavy rain we had water coming in on that side of the house. Anyway, that thing made short work out of the job, soon producing a bunch of roughly 12"x12" chunks that could be loaded and hauled like very heavy bricks. I could break up the chunks as fast as my son could load and haul a wheelbarrow to the access gate, and had to wait on him a few times. I would love to own one, by my tool addiction isn't quite advanced enough to justify ownership for VERY rare use when a 30 minute drive can borrow one for the cost of a 2 hours total round trip time (plus visit with a friend) .
Russ
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SteveHGraham
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Re: Drilling Hard Rock With Carbide

Post by SteveHGraham »

I can't tell you how much faster the rotary hammer was, since I didn't time it. I know the hammer drill would have been unpleasant to use, and the rotary hammer made the job pretty easy.

Interesting thing: there are now Chinese jackhammers available cheap. You can get one for $150. If it runs for 6 months, it's not a bad deal, and you can add a very cheap 3-year warranty.

I'm wondering if I should forget SDS-Max and get me a jackhammer. I don't know how easy it would be to operate on a rock, however. My rocks aren't flat concrete.
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liveaboard
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Re: Drilling Hard Rock With Carbide

Post by liveaboard »

I borrowed a Hilti rotary hammer drill from my pro builder neighbor; I rarely did masonry at that time.
Hilti broke on me so I had to get it repaired; cost me a pretty penny but them's the breaks sometimes.
A year later I needed it again, and as I'd paid for it I asked to use it again.
My neighbor told me it broke again, and now he uses Chinese 'disposable' hammer drills that cost 15% what a Hilti sells for.
So I bought one too. Now it needs a head bearing and I can't get it apart; should I care?
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SteveHGraham
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Re: Drilling Hard Rock With Carbide

Post by SteveHGraham »

I strained my back working on this crazy rock on Friday. Got pretty much healed by Monday. Strained my back again yesterday. Today I'm healed again.

I am fed up with this rock. I found a refurb 35-pound jackhammer for around a third off the new price, and I ordered it. Life is too short. A Chinese hammer would have cost half as much, but it would have been Chinese, and I think it would have been hard to sell for a decent price, so I went for a real company.

I may only use this thing two or three times before I sell it, but I don't care. I want my vengeance on the rock and its friends.
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SteveHGraham
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Re: Drilling Hard Rock With Carbide

Post by SteveHGraham »

Now I have a quandary: what kind of bit should I get? The chisel bit on my rotary hammer seems to work well. I can get pointed bits or chisel bits. I don't know how easy a pointed bit would be to control.
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Russ Hanscom
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Re: Drilling Hard Rock With Carbide

Post by Russ Hanscom »

Get one of each? You probably will need more than one.
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SteveHGraham
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Re: Drilling Hard Rock With Carbide

Post by SteveHGraham »

I decided to start with a narrow chisel bit. When I see what it does, maybe I'll know what else to get.

They make special bits for driving ground rods. That's pretty neat.
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SteveHGraham
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Re: Drilling Hard Rock With Carbide

Post by SteveHGraham »

I see scary stuff about silicon dust online. Do I need a respirator to use a jackhammer outdoors? I don't look forward to a respirator full of sweat.
Every hard-fried egg began life sunny-side up.
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