What I learned about drilling concrete

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Bill Crowell

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I drilled sixteen 3/4"-diameter holes 5" deep into the concrete floor of my shop in order to bolt down my 4-post lift. (That is way overkill, I know, but it makes me feel good.)

First, because I knew nothing about concrete drilling, I tried a Makita hammer drill model HP2050 that uses straight-shank masonry bits. I had a really hard time drilling the holes because I couldn't keep the bits tight in the chuck, and then unit died after a couple of hours of use, so I got a refund from Home Depot and bought a Milwaukee model 5262-21 "SDS Plus" rotary hammer. This uses a so-called "SDS" bit that locks into the chuck "with authoritay", as they say on South Park.

I found the easiest way to do it was to first drill a 3/8" starter hole and then the 3/4" final diameter. It was pretty easy with the Milwaukee "SDS Plus". I only used one masonry bit of both sizes. The lift is attached with standard 3/4" male wedge-type concrete anchors, and they all tightened up as much as I could twist them. I put shims under the column pads in order to plumb them in.

I think I will also use the Milwaukee rotary hammer in the future to attach removable work fixtures to the floor with female wedge anchors while I am using them.
 
I use a long shank 3/16 masonry bit in a common drill to make my lead holes. Easier to keep my hole center where I want it.
 
I just got through doing the same thing on a friends 4 post last weekend. About 5 years ago, I bought a brand new Bosch SDS chuck hammer drill in an estate sale. I paid 20 bucks for it, but I probably have over 200.00 worth of bits now. The secret to a hammer drill is to start the hole with a some pressure & then just keep gentle pressure on the handle of the drill. Before I retired, I was using my drill at least 3-4 days a week at least 4-5 hours a day. I've worn out more bits than I have right now.
 
Just think years ago when all we had was this. It separated the men from the boys. Sometimes I catch myself dreaming of my dad standing behind me yelling "faster Steve faster" Put your weight into it Steve.

300px-Bohrwinde_und_Schraubendreherklinge.jpg
 
I have set a ton of concrete anchors in my career and on wedge type anchors in a floor I always drill the holes the full depth of the anchor plus an inch or so.
Then when the day comes to move whatever is anchored down just move it then drive the anchors down in the hole and patch with filler of your choice.
 
^^^^ Been there, done that on the 2 above posts. Does anyone remember the "Star" bit & a short handle maul to cut holes for wedge or lead anchors?
 
You guys must have been rich. We never had concrete. We had an oyster shell driveway.
 
^^^^ Been there, done that on the 2 above posts. Does anyone remember the "Star" bit & a short handle maul to cut holes for wedge or lead anchors?
Me and dad chiseled a hole through the basement wall for a chimney. Had to be 7 or 8 inch diameter. That was in the late 70’s.
 
Me and dad chiseled a hole through the basement wall for a chimney. Had to be 7 or 8 inch diameter. That was in the late 70’s.
I did the same on an 8" thick wall when I built a new house in '75... the guy that poured the walls put a plug in the wall for the sewer pipe...6' too low!

Wound up getting concrete bits in my eye and a serious burn from the same.

No rental outfits back then in the woods of the UP.
 
Just think years ago when all we had was this. It separated the men from the boys. Sometimes I catch myself dreaming of my dad standing behind me yelling "faster Steve faster" Put your weight into it Steve.

View attachment 1715559045

Yes, Oldman, that really built character, didn't it? The young whippersnappers today are totally spoiled by things like the SDS bull point bit. I did buy one of these, but haven't had a chance to use it yet. I am really looking forward to it, though:

chisel.jpg
 
I bought a HORRIBLE FREIGHT hammer drill that, surprisingly, works very well.

A couple months ago I caught my dumbass grandson in law trying to drill steel with it hammering away...
 
I have set a ton of concrete anchors in my career and on wedge type anchors in a floor I always drill the holes the full depth of the anchor plus an inch or so.
Then when the day comes to move whatever is anchored down just move it then drive the anchors down in the hole and patch with filler of your choice.

i always drill all the way through
that way, if i dont need that anchor anymore, i can pound it through

if it turns out i messed up and want it back where it was, i just pop a new anchor in
 
I, too, have a Bosch hammer drill. I use it to set gun safes up in concrete. I drill them slightly oversize, and put stainless all thread in a 2 part epoxy compound, and let it set for a day or two, then use grade 8 stainless hardware to bolt them down. 1 survived being rammed by a truck trying to make off with safe. The police followed the coolant trail to catch the bastards.
 
I frequently drill 1/2 inch holes for anchor bolts I use to winch cars into a given shop bay.

I've had no trouble using an 18v Porter Cable battery drill or a cheap Ryobi corded drill I bought used for $15, and I only use the one bit.

Must be a lot of additional load on 3/4 vs 1/2 or you got some dense concrete.
 
I have a Bosch, got it from my neighbor. It practically drills the holes all by itself, and I do a lot of concrete drilling. A guy I work with has an old Milwaukee, it’s slow, heavy and greasy as all heck. Ever since the Bosch showed up, that old Milwaukee has been relegated to the has been shelf at his shop.
 
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