Concrete core drills

[signcrafter]

I've needed to drill some bigger holes in concrete before and need to again. Renting is a pain and can get pretty expensive if you do it a few times. So I'm looking at options for purchasing my own to see if it's worth it or not.

I have a SDS drill that I could use these bits with, http://www.amazon.com/dp/B0000TZYHK/?tag=atomicindus08-20. But from what I've read they aren't good for rebar reinforced concrete, they are more for block walls. If I'm going to spend the money on a good bit I would like it to drill any type of concrete I might need it to.

Another option I've seen in my searching is using a 9" grinder and a core bit. Not sure how safe this one would be but I do have a 9" grinder if that will work. Anyone do any core drilling with a grinder?

My last option I ran across is these cheap drills on ebay, http://www.ebay.com/itm/NEW-BLUEROC...170984?hash=item280ae06928:g:fVQAAOxySFJSDTGh. Water feed for the bit cooling, 2 speed, and a clutch. Then the bits aren't that expensive. A 4" bit is under 100 bucks, http://www.ebay.com/itm/NEW-4-Diamo...796486?hash=item25b0ba68c6:g:Cj0AAMXQxKxSC8OR.

So for about 300 bucks I can get the setup to drill a 4" hole in reinforced concrete or block. I'm sure these aren't great drills and wouldn't hold up to everyday use but I'm guessing I might drill a dozen holes in my life. Then I can just pick up bits as needed. Just want to make sure they aren't complete garbage and a waste of money.

Looking for opinions on which route you would go? And I'm sure some will say "just keep renting" but I'd prefer to pick up my own setup. I don't mind spending 3-400 on something that will be able to drill core holes.

 

[BLJ]

Know suggestions on which drill to buy, but I will say this, dont use the grinder. No clutch will be q bad deal when it binds up.

 

[earlybirds]

I purchased a 2 1/2" concrete core bit (Amazon) for about $60 for drilling holes thru cement block walls and concrete floor when I ran my 2" PVC conduit for electric & data lines between the house and shop. The project took me several months of weekend work only. I think I drilled 8 holes over the course of the project, and it was nice to have the tool on hand when I needed it. I used a 4 1/2" angle grinder, and it easily handled the job. I saved a lot of money and time by NOT renting the core bit.

 

[The FIB]

I have been using the Spline Shank bits similar to the one in your first link, I have the whole set, 1" up to 5", as you stated they work great until you hit steel.
They will drill through rebar but it takes a looong time, not so good for the bit or drill.

Back when I was a construction electrician, if we were drilling through reinforced concrete, we would use this http://chicago.craigslist.org/chc/tls/5245448767.html , they can be used to drill vertical or horizontal holes, you can get diamond bits for them.
Be careful, they will drill through ANYTHING, including embedded rigid conduit and Pre-tensioned concrete cables.

 

[ISurvivednmu]

Bosch has some great corded rotary hammers, but their bits are not happy when they see any metal. Milwaukee has some good concrete bits that handle rebar well. I do have a rebar cutter for when needed also.

Bosch rotary hammer and Milwaukee bits. Unless you want cordless, then it is Dewalt or Milwaukee for the rotary hammer.

I am leaving out Hilti due to cost.

 

[firworks]

I just bought a 4 3/8" Bosch Speedcore bit and arbor and they were delivered yesterday. Planning on punching a hole in my wall tonight so I can report back on how those work at least if you're interested.

 

[signcrafter]

I just bought a 4 3/8" Bosch Speedcore bit and arbor and they were delivered yesterday. Planning on punching a hole in my wall tonight so I can report back on how those work at least if you're interested.

Would like to hear how it goes. Block wall or reinforced concrete? From what I've read those bits don't do well in concrete, mostly for block walls.

Bosch has some great corded rotary hammers, but their bits are not happy when they see any metal. Milwaukee has some good concrete bits that handle rebar well. I do have a rebar cutter for when needed also.

Bosch rotary hammer and Milwaukee bits. Unless you want cordless, then it is Dewalt or Milwaukee for the rotary hammer.

I am leaving out Hilti due to cost.

Do you have a link to the milwaukee bits that will work in my SDS max drill? What rebar cutter do you have?

I purchased a 2 1/2" concrete core bit (Amazon) for about $60 for drilling holes thru cement block walls and concrete floor when I ran my 2" PVC conduit for electric & data lines between the house and shop. The project took me several months of weekend work only. I think I drilled 8 holes over the course of the project, and it was nice to have the tool on hand when I needed it. I used a 4 1/2" angle grinder, and it easily handled the job. I saved a lot of money and time by NOT renting the core bit.

How did it go with the grinder? I'm a little apprehensive about using my grinder on a core bit since it doesn't have a clutch and seems like it would be a little awkward.

 

[firworks]

Would like to hear how it goes. Block wall or reinforced concrete? From what I've read those bits don't do well in concrete, mostly for block walls.

It's block wall. I'm drilling out a vent for a dryer in the laundry room of my house that was built in 1964.

 

[firworks]

I drilled the holes over the weekend. At least for hollow core block, the Bosch Speedcore bits work very well. It wasn't exactly fast going but I couldn't quite put as much force into it as I'd like to let the drill really hammer it since I was on a ladder and reaching. The holes it drilled were really clean and it actually didn't make too much of a mess either. It of course filled the air with dust but when I was done there was just a tiny pile of dust collected under and to the side a bit of the hole. The bit I used was 4-3/8".

 

[Rezeppa]

Use the grinder!!!! I work for an industrial construction company in the garage. We core drill constantly we have over 20 track units and 15-20 handheld and grinders. The 9 inch grinders and adapters work better than any other style hand held drill. The grinders spin quickly and seem to hold up against abuse. The drill will stop spinning from resistance before it will brake your wrist. A grinder is not like a drill with it doesn't have the same torque to spin your arm. I highly recommend just buying the adapters and bits I will post some information tomorrow. Now any hole over 4-6 inches wide and/or 4-6 inches deep are difficult to drill with a handheld unit. If your only drilling a few holes smaller than 8 inches it works quite well.

 

[LXCam]

SDS drives aren't designed for large holes, up to 1.5" is about all the reduced shank can take. Spline drives can take some punishment and you can get bits rated for the larger applications. I'd highly suggest a Milwaukee Thunderbolt.

Where are you located at, I was thinking about selling my coring equipment as I just don't need it anymore. I have everything up to 4"

 

[Rezeppa]

We mainly drill material harder than concrete like shotcrete and other forms of Refactory most has rebar and other forms of steal reinforcement. When cutting rebar and mesh you want to use carbide bits not diamond. So when drilling a 4 inch hole through 18 inches of concrete with rebar it is idea to have two bits a diamond and a carbide. When you fell the rebar switch to a carbide and vise versa.

 

[Alpine4x4]

We mainly drill material harder than concrete like shotcrete and other forms of Refactory most has rebar and other forms of steal reinforcement. When cutting rebar and mesh you want to use carbide bits not diamond. So when drilling a 4 inch hole through 18 inches of concrete with rebar it is idea to have two bits a diamond and a carbide. When you fell the rebar switch to a carbide and vise versa.

We use diamond bits 100% all day to core all our precast from 2"-36". Carbides not necessary unless you're cutting embedded plate or the like, a typical rebar or wire mesh cage is pretty easy to cut through with diamond.

As for the OP, your honest best option is to rent a true core drill and bit. We use a Husqvarna portable at work for small jobs and it works just fine.