Drilling holes in rocks - Help

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seal killer
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Drilling holes in rocks - Help

Post by seal killer » Tue Jan 21, 2020 4:32 pm

All--

I am trying to learn how to split rocks. I have some feathers and wedges and a rotary hammer drill and some concrete bits with carbide tips. So far, I have no luck at all. I've only managed to get a hole about 3/8" deep in a piece of limestone. I've tried drilling using the 1/2" bit down to the 1/4" bit.

What am I doing wrong? Wrong bits? Wrong tips?

Thanks!
--Bill
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BadDog
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Re: Drilling holes in rocks - Help

Post by BadDog » Tue Jan 21, 2020 4:37 pm

Very much the wrong drill motor. You need a real Rotary-Hammer/Demo Motor. Your bits are intended to go into an SDS-Plus chuck, so I would look at the larger SDS-Plus tools. I have a Makita SDS+, and it's playing a whole different game from my little cordless hammer drill (same as yours). The latter is really only good for making small holes in soft masonry for hanging pictures and the like. With the right tool, things will go much MUCH better.

BTW, another step up is SDS-Max, which is starting to border on small jack hammer territory.
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Russ Hanscom
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Re: Drilling holes in rocks - Help

Post by Russ Hanscom » Tue Jan 21, 2020 5:29 pm

Yes, Get a real rotary hammer - most likely will be corded.

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seal killer
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Re: Drilling holes in rocks - Help

Post by seal killer » Tue Jan 21, 2020 5:31 pm

BadDog and Russ--

How's this one look?

https://www.homedepot.com/p/Makita-10-A ... /202517713

--Bill
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Re: Drilling holes in rocks - Help

Post by John Evans » Tue Jan 21, 2020 5:34 pm

Good to see you back at it Bill. Was wondering how you were recovering from your ladder indecent.
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seal killer
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Re: Drilling holes in rocks - Help

Post by seal killer » Tue Jan 21, 2020 5:49 pm

John--

Thanks!

I saw the surgeon two months and one day after the accident. He took new x-rays. After analyzing them, he told me that I had healed more in that time than he expected in four months or more. I've always healed very quickly.

Of course, I am still careful and there is everything from discomfort to real pain, especially in the mornings. After some exercise, I am good to go . . . slowly.

--Bill
ps You're right, it certainly was an in-descent.
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BadDog
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Re: Drilling holes in rocks - Help

Post by BadDog » Tue Jan 21, 2020 6:06 pm

That'll do it. I would arm-chair quarterback that anything SDS+ or above (in a name brand) would likely to well enough.

On something like this, especially if you have to make big deep holes in really hard rock, you want the biggest rotary/demo-hammer you can manage.

The down side is the bigger it gets, the bigger it gets. As in having to hold and manipulate. Easy enough drilling down, better even, but it gets correspondingly harder working as you go more horizontally. I'm currently trying to decide on rent (again) vs buy a modest sized jack hammer, and have the same issue. I don't need a bigger hammer, at least not but once or twice in a lifetime, but don't like coming up short when I need it, but don't want to lug (and store, and pay for) a monster when I very rarely need it.

Also, glad you are back on your feet!
Russ
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BadDog
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Re: Drilling holes in rocks - Help

Post by BadDog » Tue Jan 21, 2020 6:12 pm

This is what I got for an SDS+. However, I would swear it was classed as 1-1/8" when i bought it, not that it matters.

I chose it over one of the offset motor versions because I was specifically buying to work back in a tight space where I wanted the flexibility of the narrow profile. But for the most part, you can rotate the body to get into tight spaces up next to something, so not really a deciding factor.

Oh, and it's basically automatic in the bigger units, but if looking at smaller, always make sure to get one that has a hammer only mode without rotation.
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warmstrong1955
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Re: Drilling holes in rocks - Help

Post by warmstrong1955 » Tue Jan 21, 2020 6:17 pm

Welcome back Bill! Glad you are healing up well!

I'll skip all the boring stuff on how percussive rock drills work, and just say that the Makita at 4.6 ft lbs should do the trick in limestone and much more, and, they do make quality stuff.
The cheapy hammer drills do fine in concrete, but for real rock, best to just spend the money on something that will break it.

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seal killer
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Re: Drilling holes in rocks - Help

Post by seal killer » Tue Jan 21, 2020 6:32 pm

BadDog and Bill--

BadDog, weight is a big factor for me, especially right now. Plus, my wrist will probably be problematic for quite a while.

The reason I wanted cordless is because the rocks are not very close to power. There are probably a hundred tons that I've stacked about a hundred feet from power. I imagine that's too far for even a heavy duty extension cord.

So that means I'll have to haul them closer to the house. I can do that, it's just time consuming.

I could save some money by going with the SDS Plus you show. Maybe I could run it off one of my generators.

Bill, it is good to be back! However, my connection speed has gone from 1gb/s to too slow to measure. (Dish network.)

--Bill
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neanderman
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Re: Drilling holes in rocks - Help

Post by neanderman » Tue Jan 21, 2020 6:33 pm

I have a Bosch and it's one of the best investments I've made.
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carlquib
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Re: Drilling holes in rocks - Help

Post by carlquib » Tue Jan 21, 2020 6:42 pm

I'm a Hilti fan.I haven't used this particular model but it is similar to what I have. Hilti 228061 TE 7-C 120-volt Rotary Hammer Drill Package https://www.amazon.com/dp/B00UNBGPP0/re ... jEbG6BZMJG
Been using them since I was a kid in the fab shop. I would stay away from anything that uses the opposing steps to generate the percussive force. I went down that route and they don't work to drill anything very hard. I generally look for something that you can select drill, hammer/drill or just hammer. The hammer only setting will give you a clue to how the percusive force is generated. There are also cheaper versions out there or you can just rent if it is going to be a one time need. Once you have experienced a real hammer drill you won't want to go back to anything else.

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