Core Drill Bit???

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horsegoer

Senior Member
Location
NJ
Is this used for floor core drilling? It says hammer drill which I though was for walls. If drilling for a 3/4 conduit what size core would you use? 1" ? Also. how many uses do you usually get from a core bit before you have to replace it when using it. i know it probably depends on slab thickness...but approx. THanks.
 

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hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
You can also core with a hammer drill, but if you hit rebar you will stop or break break off the teeth on the bit. I have used those up to around two to three inches, i think you can get bigger though. I usually just rent it though.
 

horsegoer

Senior Member
Location
NJ
I would think something like a Rigid 98190 type bit would be used...but I guess you can use a kammer drill bit. THanks.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Is this used for floor core drilling? It says hammer drill which I though was for walls. If drilling for a 3/4 conduit what size core would you use? 1" ? Also. how many uses do you usually get from a core bit before you have to replace it when using it. i know it probably depends on slab thickness...but approx. THanks.

I have used these bits for drilling many foundation anchor holes for a couple of retrofits in more than one home. The four teeth should make for fast work compared to a two teeth.

This is a SDS shank for a tool that is only SDS hammer drill I suppose you hae one?
 

horsegoer

Senior Member
Location
NJ
I have used these bits for drilling many foundation anchor holes for a couple of retrofits in more than one home. The four teeth should make for fast work compared to a two teeth.

This is a SDS shank for a tool that is only SDS hammer drill I suppose you hae one?

Yes but do you use a hammer dril to core holes in a floor? I did not think so although i am sure it can be done. I thought you would always use the core bit such as the Rigid one I listed. Thanks.
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
You are drilling a 1 in hole in a concrete or gypcrete floor, you are not trying to make a core!
You probalby won't see a concrete core bit until you get to 2" or so. Why are you so concerned as to how the hole is made and what material is left over. The drill does not care if it a wall or a floor. You will need to know that when Down drilling you need to frequently clear the hole of debris in order to keep the bit from jamming up.
 

ddderek

Member
Core Drill Bit vs RotoHammer Bit

Core Drill Bit vs RotoHammer Bit

That is specifically a Rotary Hammer Drill Bit... It can be used for drilling holes in a floor, however the outside diameter of a 1" EMT conduit is 1 1/8" so I would not try drilling a 1" hole and getting it through!

You can get hundreds of holes with the proper bit using the proper drilling techniques... Tool abuse is the only thing that would drastically shorten its life... other than drillling into a live cicuit! :)

When you say CORE DRILL BIT, usually that refers to either a wet or dry coring bit with diamond tips and used by a specific coring machine.

We just bought a nice Milwaukee Coring machine that makes light work of going through concrete floors.

http://www.milwaukeetool.com/tools/...it-meter-box-and-diamond-coring-motor/4115-22

I don't know if this will show up as a link but you can copy and paste the above text to a browser window for the link to the Milwaukee Core Machine we bought. Home Depot had the best price on it.

Is this used for floor core drilling? It says hammer drill which I though was for walls. If drilling for a 3/4 conduit what size core would you use? 1" ? Also. how many uses do you usually get from a core bit before you have to replace it when using it. i know it probably depends on slab thickness...but approx. THanks.
 

horsegoer

Senior Member
Location
NJ
That is specifically a Rotary Hammer Drill Bit... It can be used for drilling holes in a floor, however the outside diameter of a 1" EMT conduit is 1 1/8" so I would not try drilling a 1" hole and getting it through!

You can get hundreds of holes with the proper bit using the proper drilling techniques... Tool abuse is the only thing that would drastically shorten its life... other than drillling into a live cicuit! :)

When you say CORE DRILL BIT, usually that refers to either a wet or dry coring bit with diamond tips and used by a specific coring machine.

We just bought a nice Milwaukee Coring machine that makes light work of going through concrete floors.

http://www.milwaukeetool.com/tools/...it-meter-box-and-diamond-coring-motor/4115-22

I don't know if this will show up as a link but you can copy and paste the above text to a browser window for the link to the Milwaukee Core Machine we bought. Home Depot had the best price on it.

Thanks so my question then is why do you switch to a core bit through floors at say 2+ inch and use other type bits for smaller holes in the floor ? Thanks
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Probably at the point of a core bit it is easier to cut a core then to pulverize the whole hole.
 

Smart $

Esteemed Member
Location
Ohio
Thanks so my question then is why do you switch to a core bit through floors at say 2+ inch and use other type bits for smaller holes in the floor ? Thanks
Design, functionality, availability... perhaps some other reasons.

If you are familiar with the use of high speed steel (HSS) drill bits vs. hole saws (or punches) for putting holes in sheet metal, the principles are the same. Would you put a 4" hole in sheet metal using a 4" HSS drill bit?
 

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Design, functionality, availability... perhaps some other reasons.

If you are familiar with the use of high speed steel (HSS) drill bits vs. hole saws (or punches) for putting holes in sheet metal, the principles are the same. Would you put a 4" hole in sheet metal using a 4" HSS drill bit?

Boy that would be some drill bit and the size of the drill motor to run it!:? I bet they make a drill bit that size for a monster size milling machine. However that is no hand tool. ;)
 

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
Hammer drilling is loud. Wet/dry coring is much less loud. SDS bit only go so large, you will need to change to big spline bits, cost high. Wet core no blow out and cut clean through steel. Look at Hilti TE5, TE72 the TE72 can drive ground rods too.
We use the hand held wet core drills, 99% of the time for walls or floors. We do have a big B&D stand wet drill too.
 

renosteinke

Senior Member
Location
NE Arkansas
Actually, core bits are available in sizes even smaller than 1".

That said .... look at the Bosch line of core drills. You buy the bit, the mandrel, and the pilot separately. Mandrels are availble in different lengths.

The core bits you would use to make holes for 1/2" conduit really isn't worth the fuss. For 3/4" pipe, it's a draw (core bit or drill). By 1" the core bits are clearly a better way to make the hole.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Thanks so my question then is why do you switch to a core bit through floors at say 2+ inch and use other type bits for smaller holes in the floor ? Thanks

You can see the price of the 1" bit, a 2", if available, would probably be 4x, not 2x as expensive. At that point I'd hire Concrete Cutters (a local firm) and have them do it. They did a 4" through my basement wall for the dryer vent for $200. (Yes, I know I could have just used my 3/8" bit and poked a gazillion holes through the wall, but this way I didn't even have to be there.) And a 2" hammer drill bit probably won't be very effective. The hammer drill is going to use a lot of energy just moving the bit around, let alone delivering energy to the wall.

Someone mentioned blow out. When you finally punch through with the hammer drill, it ain't pretty on the far side. Now if you're going into hollow core CMU, the ugly side is on the inside and who cares? But if you're going from inside the basement all the way through and the outside wall has a nice stucco finish on it, it won't for long! You can try having a helper push a piece of scrap 2x6 against the wall where you're going to exit (sure about that spot?), but that doesn't mitigate all the damage.
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
Is this used for floor core drilling? It says hammer drill which I though was for walls. If drilling for a 3/4 conduit what size core would you use? 1" ? Also. how many uses do you usually get from a core bit before you have to replace it when using it. i know it probably depends on slab thickness...but approx. THanks.

how big a hole you want? rotary core bits work better in concrete than dry core bits for a grinder.(5/8)
http://miyanagaamerica.com/products/core_drill/rotaryhammer.html
 

tyha

Senior Member
Location
central nc
That is specifically a Rotary Hammer Drill Bit... It can be used for drilling holes in a floor, however the outside diameter of a 1" EMT conduit is 1 1/8" so I would not try drilling a 1" hole and getting it through!

You can get hundreds of holes with the proper bit using the proper drilling techniques... Tool abuse is the only thing that would drastically shorten its life... other than drillling into a live cicuit! :)

When you say CORE DRILL BIT, usually that refers to either a wet or dry coring bit with diamond tips and used by a specific coring machine.

We just bought a nice Milwaukee Coring machine that makes light work of going through concrete floors.

http://www.milwaukeetool.com/tools/...it-meter-box-and-diamond-coring-motor/4115-22

I don't know if this will show up as a link but you can copy and paste the above text to a browser window for the link to the Milwaukee Core Machine we bought. Home Depot had the best price on it.
]


they dont make core bits under 1 - 1/2" (hilti doesnt anyway). go with the SDS Max 1 - 1/8" hammerdrill bit for 3/4 EMT conduit. 3/4 EMT OD 1-1/8" 1" EMT 1 - 3/8"
 

jusme123

Senior Member
Location
NY
Occupation
JW
Is this used for floor core drilling? It says hammer drill which I though was for walls. If drilling for a 3/4 conduit what size core would you use? 1" ? Also. how many uses do you usually get from a core bit before you have to replace it when using it. i know it probably depends on slab thickness...but approx. THanks.

...that's a picture of a DRILL bit, not a core bit. Core bits you do not use the hammer feature of a drill :rant:, that ruins them.
 

jusme123

Senior Member
Location
NY
Occupation
JW
You can see the price of the 1" bit, a 2", if available, would probably be 4x, not 2x as expensive. At that point I'd hire Concrete Cutters (a local firm) and have them do it. They did a 4" through my basement wall for the dryer vent for $200. (Yes, I know I could have just used my 3/8" bit and poked a gazillion holes through the wall, but this way I didn't even have to be there.) And a 2" hammer drill bit probably won't be very effective. The hammer drill is going to use a lot of energy just moving the bit around, let alone delivering energy to the wall.

Someone mentioned blow out. When you finally punch through with the hammer drill, it ain't pretty on the far side. Now if you're going into hollow core CMU, the ugly side is on the inside and who cares? But if you're going from inside the basement all the way through and the outside wall has a nice stucco finish on it, it won't for long! You can try having a helper push a piece of scrap 2x6 against the wall where you're going to exit (sure about that spot?), but that doesn't mitigate all the damage.


drill a 1/4" center hole all the way through, core half way one way, half way the other way. Both sides of wall will have a clean cut hole.
 
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