anchor drilling

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anchor drilling

Postby bobby49 » Sep 28, 2018 12:36 pm

I recognize that most anchors are either 8mm, 10mm, or 12mm in diameter. There can be a variety of head types. What is the best portable drill to use for the hole? Obviously it is not going to be AC powered, but it could be powered by battery or by hand power.
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Re: anchor drilling

Postby trogman » Sep 29, 2018 11:57 am

I use a Bosch 18 V Rotary Hammer drill. But a lot of folks I know like Hiltis and DeWalt. Makita is good as well.
I think 18V is about the minimum, and I would definitely stick with ROTARY Hammer drills, as opposed to simple HAMMER drills, as they provide the percussion necessary to drill in hard rock.

The drill bits are pretty pricey, so I would shop around for the best deals. I've gotten pretty good deals on Ebay, especially buying bulk quantities. I've also figured out how to re-sharpen them, which is a big money-saver as well.

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Re: anchor drilling

Postby bobby49 » Sep 29, 2018 2:08 pm

I'm sure that this varies a lot with the type of rock. However, about how many holes can you drill on one battery charge? Is it necessary to have a whole pack full of extra batteries?
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Re: anchor drilling

Postby bobby49 » Sep 29, 2018 2:18 pm

Wow. Those hammer drills don't come cheap, do they?
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Re: anchor drilling

Postby trogman » Sep 30, 2018 7:47 am

bobby49 wrote:Wow. Those hammer drills don't come cheap, do they?


No, they don't. My Bosch cost $150 just for the drill, without any batteries. (looks they they have gone up quite a bit since then) The lithium batteries are very pricey, but a much better bang for your buck than the old NiCad ones. I paid $149 for a kit with two batteries and a charger; one battery was the 4.0 amp/hour, the other was a 2.0 Amp/hour.

As far as how many holes, that varies a lot with the size and the depth of the hole, as well as the rock type, etc. When drilling 1/2" holes in limestone, I can usually drill 8 to 10 holes to a depth of ~10". Keep in mind that I usually use my drill for micro-shaving, and not for setting bolts. Anchor bolts would usually only require a 3/8" hole, and you'd probably drill it ~3" deep. So you could expect a lot more life out of your battery. Still, it is always a good idea to have an extra battery on hand.
By the way, the 2.0 Amp/hour battery didn't seem to have a proportional amount of battery life to the 4.0, not sure why. At least that was my experience with the Bosch brand batteries.

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Re: anchor drilling

Postby bobby49 » Sep 30, 2018 1:39 pm

I'm confused. If you drill 3" deep, then why would you need to drill 10" deep?
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Re: anchor drilling

Postby trogman » Sep 30, 2018 5:45 pm

bobby49 wrote:I'm confused. If you drill 3" deep, then why would you need to drill 10" deep?


I mainly use my drill for micro-shaving, and I generally drill holes about 10" deep. Occasionally I will use it for anchor bolts, which only require a hole to be about 3" deep.

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Re: anchor drilling

Postby bobby49 » Oct 1, 2018 9:08 pm

If an anchor bolt hole will get the job done with 3", then why would you want to drill 10" for micro-shaving?
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Re: anchor drilling

Postby trogman » Oct 2, 2018 5:11 am

bobby49 wrote:If an anchor bolt hole will get the job done with 3", then why would you want to drill 10" for micro-shaving?


:laughing:

Completely different application. Micro-shaving is a technique we use to excavate and enlarge passages that are too small to enter.

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Re: anchor drilling

Postby bobby49 » Oct 4, 2018 2:19 am

Does anybody use anchors other than 10mm?
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Re: anchor drilling

Postby snoboy » Oct 6, 2018 4:57 pm

3/8" is very common, but close to 10 mm.
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Re: anchor drilling

Postby bobby49 » Oct 6, 2018 7:38 pm

Quick. Where is my micrometer?
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