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Drilling straight steel post holes into concrete slab using core drill ?

Drilling straight steel post holes into concrete slab using core drill ?

Old 11-20-18, 10:55 AM
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Drilling straight steel post holes into concrete slab using core drill ?

I am putting up nine steel post into my back yard that has new cured concrete. The steel post will be used to stabilize my privacy vinyl fence. Concrete was Poured about 90 days now. I started to drill a 2'' hole and once i put the pole in the hole I noticed that the pole wasn't straight. The problem that i am having is that the corner of my back yard has a pitch(so water drains into my drain line) So the core drill isn't stable and i don't want to drill additional holes into my new slab to anchor the core drill.

Another problem that i am having is, I drilled about 17'' into my slab and yet to hit dirt. I was told buy the fence company i bought my fence from that once I pass 12'' i can put quk set(not sure if i am spelling the brand right but it is quick set type of stuff fence guys use.) in the hole and place the steel pipe in and cut to length. i am aware that i have to go down 42'' into the ground once/ or if i hit dirt.

Any help will be great.
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Last edited by PJmax; 11-20-18 at 06:34 PM. Reason: enlarged tool picture
Old 11-20-18, 06:41 PM
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Welcome to the forums.

Usually when using a coring drill..... it sits flat on the concrete and drills a perpendicular hole. Are you saying that your concrete pad is not level with respect to the ground ?
If that's the case your going to have to make up some type of shim plate to hold the drill at the proper angle.

That is some thick concrete. Using Quikrete at 17" is fine. That's better than going into earth.
Old 11-21-18, 05:07 AM
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From your photo it looks like you got through the concrete and were into either another, older layer of concrete. Possibly with a void space or gravel in between.

If you want your holes to be vertical you need to true your coring drill like PJmax mentioned. Put a level vertically on the square post of the drill. Check it in both orientations and shim the base as needed to get the square post exactly vertical. I am glad to see that you rented the right tool for the job. This would be almost impossible and dangerous to do by hand.

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