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Posted by Edward Hennessey on May 9, 2008, 11:32 pm
nicklang907 wrote:
> On May 1, 7:32 pm, "Edward Hennessey"
>>> On Apr 30, 6:02 pm, "Edward Hennessey"
>>>> nicklang907 wrote:
>>>>> Hi,
>>
>>>>> I want to build stairs on our land, but need to drill into
>>>>> rock
>>>>> (granite i think) in order to make posts to connect the
>>>>> stairs
>>>>> to. My
>>>>> question is... is there a drilling tool (preferably as
>>>>> powered
>>>>> and
>>>>> portable) that will drill through rock and make a nice big
>>>>> hole?
>>
>>>> NL:
>>
>>>> Call your rental yards. Ask for Cobra, Berema or Pionjar
>>>> gasoline-powered drills.
>>>> Tell them what hole size you need to see if they stock the
>>>> bit.
>>>> If
>>>> you have granite, it should
>>>> be no problem. Plain quartz is an entirely different story.
>>>> Make
>>>> sure the unit starts
>>>> and runs nicely in the yard and take notes on any control
>>>> adjustments.
>>>> If you get a combination breaker/drill unit, be clear on the
>>>> selector control
>>>> and be positive it is FULLY seated in the selected position.
>>
>>>> Unless you want to bell mouth your holes, you will need to
>>>> have
>>>> a
>>>> flattened surface to start
>>>> your drilling. If that means chisel and grind or just plain
>>>> grinding for accuracy, that isn't a problem.
>>>> Begin your hole as perpendicular as possible, slowing down
>>>> the
>>>> rpm
>>>> on the drill and use an
>>>> assistant or your foot on the bit to help with accurate
>>>> placement.
>>>> If you want a really clean
>>>> job, start with a drill and a sledge to make a smaller,
>>>> shallow
>>>> pilot hole the bit will seat in.
>>
>>>> Once you are accurately seated, let out the rpm to a
>>>> manageable
>>>> range. Carefully pulling the
>>>> unit up and down every so often will help clear the drilled
>>>> spall
>>>> from the hole, making
>>>> for easier operation. Whatever you do, don't drill all the
>>>> way
>>>> through the rock. That would
>>>> not lead to a joyous result.
>>
>>>> Also, the usual caveats about a cartridge mask, eye
>>>> protection
>>>> and
>>>> ear muffs apply.
>>
>>
>>> Ed! You are a gentleman and a scholar!
>>
>> NL:
>>
>> You sure you got the right Ed?
>>
>>
>>
>>> Your response really led me in the right direction. I have a
>>> few more
>>> questions.
>>
>>> Is this a job for someone unexperienced like me? That is,
>>> should only
>>> people who really know what they are doing try this?
>>
>> If you were near me or another experienced operator, the more
>> holes you have
>> and the more precisely you need them positioned on irregular
>> rock
>> is something
>> you would balance against the cost of the rental, your
>> inexperience and mistakes
>> that may be troublesome to reverse. That said, this isn't brain
>> surgery. If you practice
>> on similar spare rock first, you should be able to handle
>> it--or
>> know you can't.
>>
>> Also, what
>>
>>> happens if I drill al lthe way through the rock?
>>
>> First, you don't want to for your installation. You want
>> to drill a bit deeper than the posts you are going to put in.
>> Stainless
>> posts would be nice. If you manage to poke through
>> with a long drill shaft, especially in harder rock, the drill
>> can get stuck or bent and the machine can toss you if you
>> don't
>> shut
>> it off when it binds and starts to overspeed.
>>
>> This is pretty much
>>
>>> bedrock, so I think it goes down for quite a while. Also,
>>> what
>>> if
>>> there is a quartz vein or something?
>>
>> Granite tends not to have big, metamorphosed quartz veins and
>> they
>> are
>> usually not terribly tough when present. The other kind of
>> white
>> granitic vein would be
>> feldspathic and feldspar is a very soft mineral. My concern for
>> whether you could
>> do this was basically pointed at solid quartz. If you go to the
>> library
>> and get out a rock/mineral field identification guide, you can
>> probably
>> figure out what rock type you have.
>>
>> I'm not sure if there is, but
>>
>>> perhaps I can't see it all... would this damage the drill or
>>> cause the
>>> drill to explode in my face?
>>
>> If your rental unit was gauging drill wear and you kept at some
>> resistant layer without progress, even with the carbide bit I
>> recommend, you might get
>> a wear charge. Otherwise, there is no danger.
>>
>> Finally, what is the difference between
>>
>>> a drill and a "breaker unit"?
>>
>> Some of the machines described are both jackhammers and drills.
>> The selector lever down near the chuck controls which function
>> is
>> operative. Many times the lever won't fully seat in the proper
>> position
>> unless you grab onto the drill shaft and use it to turn the
>> chuck
>> until the
>> gear mechanism is aligned. Don't force the lever. When things
>> align it will go in easily. But if you don't get it properly
>> seated, you
>> might get to buy the tool if the worst happens.
>>
>> These combination tools average about 70-80 pounds. In rock
>> like
>> you might have,
>> they will drill quickly and handling the machine in this
>> application is pretty
>> much a matter of being able to lift it.
>>
>> Jackhammering with them requires more operator strength. If
>> you're
>> in
>> shape, they won't push you around. Otherwise, they can be a bit
>> vigorous
>> for some people. If you have been eating your Spinach, you
>> might
>> even be
>> able to use the jackhammer to do preliminary rock removal at
>> difficult angles to make the
>> pads to receive your posts. It depends on how precise your
>> placement needs to
>> be. Diamond sawing and grinding followed by a dimpled pilot
>> hole
>> would be very clean. You could even put an outward bevel on the
>> pads to shed rain
>> after you make your dimpled hole with a star drill and small
>> sledge.
>> Small diamond saws are available for grinders.
>>
>> Lastly, if your holes are smaller--ask the rental guys what
>> size
>> holes their machines will make-- there
>> are Swedish and Japanese gas-powered drills out there that will
>> be
>> far easier to handle...and slower
>> on results. I've never used these smaller machines but Pionjar
>> made one and that is a good name.
>>
>>> Thanks so much for you expert help, Ed!
>>
>> You're welcome. Happy to help.
>>
>> Regards,
>>
>> Edward Hennessey
>
> Amazing... Thanks Ed! I am going to apply this knowledge now...
> I'll
> let you know how it turns out!
NL:
Good. Keep me posted. Best of luck to you.
Regards,
Edward Hennessey
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