# Would you use this bit?



## Dorado (Feb 7, 2013)

Someone on some forum pointed me to the Bosch HCBG27 hammer drill bit when I asked about 1" bits for concrete. It was only about $17 on Amazon. A big box store has the newer HCBG27T for about $25. The newer one has ridges on the shank and I think the maximum RPM is listed as 1000 or more (better double check in store...specs not on Bosch's site). My old model has no ridges and it says:



> Max operating speed 600 RPM, At higher speeds the bit is likely to bend if allowed to rotate freely without contacting the work.


My drill's low speed is 0-1000. Is it safe and effective to use at 1000 RPM if I keep it in contact with the work going in and only let it spin "freely" while exiting the hole? Would you make sure the trigger is never fully pressed and hope the speed stays at 600 RPM max? I was looking forward to drilling within the next couple of hours and not I'm not sure I should. I'm leaning towards keeping it. I just have two or three holes planned for now.


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## oh'mike (Sep 18, 2009)

Use it-----when hammer drilling ,you will not be spinning the thing when it's not in the hole---

I like the Bosch Bits----lots of holes for the money---go get that hole drilled---Mike---good luck.


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## TheEplumber (Jul 20, 2010)

You said it has ridges and yours don't? Sounds like your drill is for SDS bits(dimpled shank) Might not fit your drill chuck, but they do make an adapter


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## Dorado (Feb 7, 2013)

It's just the PowerGrip shank. "Steel teeth that extend from the shank are designed to catch between the jaws of power tool chucks." I think it would fit a regular chuck, though I wouldn't be 100% confident the 1/2" bits would fit every 1/2" chuck. I guess I'll keep it.


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## woodworkbykirk (Sep 25, 2011)

if its a 1" diameter bit its defintiely a sds bit.. only sds hammers have the guts to drill a hole that large in concrete


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## Dorado (Feb 7, 2013)

The capacity of my drill (Bosch HD19-2) is 3/4" in concrete. They make a higher amp, lower RPM version with a 7/8" capacity, and I think it used to be rated at 1". They still make the 1" non-SDS bits for whatever reason. The package of my discontinued bit says it has a "Grip Tight" shank, whatever that means. This is the new version of my bit. Not SDS.


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## Dorado (Feb 7, 2013)

I chucked it pretty tight and it slipped in twist mode. I should have returned it. It caught a piece of steel mesh though. I'll cut it off and try again.

... It's working now, but I'm in an awkward position and pushing with my left hand (I'm a righty) inside a closet and it's vibrating. I don't have the nerve to try hammer mode yet. I'll continue tomorrow.


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## Dorado (Feb 7, 2013)

I bet the pilot hole is causing the vibration. Unless you can drill dead center through the pilot hole, maybe it's best not to make one.


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## TheEplumber (Jul 20, 2010)

Dorado said:


> I bet the pilot hole is causing the vibration. Unless you can drill dead center through the pilot hole, maybe it's best not to make one.


Maybe it's me but I've found the pilot holes allow the concrete around it to disintegrate sometimes- leaving small pebbles that jam your bit. If your drill's not forgiving you better get 2 hands on it to avoid twisting your wrist :thumbsup:


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## Dorado (Feb 7, 2013)

This was my first time drilling with a drill over 2.2 amps, and I was drilling a hole larger than recommended and nicking steel mesh, with my weak hand on the main handle. You bet I had two hands on it (my strong hand was on the removable handle). I'll drill a little more in twist mode. Maybe the hole will conform more to the shape of the bit. Then I'll try hammer.


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## TheEplumber (Jul 20, 2010)

Dorado said:


> This was my first time drilling with a drill over 2.2 amps, and I was drilling a hole larger than recommended and nicking steel mesh, with my weak hand on the main handle. You bet I had two hands on it (my strong hand was on the removable handle). I'll drill a little more in twist mode. Maybe the hole will conform more to the shape of the bit. Then I'll try hammer.


Your drill is smaller then what I'm used too so I don't know how it's acting but when I'm drilling concrete- I'm in hammer mode- nice and slow with slight steady pressure


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## jbfan (Jul 1, 2004)

You sure went to a lot of trouble to drill one hole that could have been done with 1/4 bit and a few holes.


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## joecaption (Nov 30, 2011)

I never would have tryed to drill that big a hole with out being in hammer mode.


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## Dorado (Feb 7, 2013)

I think the concrete is load bearing and I didn't like the idea of drilling a sloppy oversized hole with a 1/4" bit and chisel. I have to put 3/4" EMT in it. I tried drilling two parallel holes about 11" deep before I decided to use EMT and they ended joining each other at the end.


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## joecaption (Nov 30, 2011)

I hardly think a 1" hole is going to have any effect in a supporting wall,
Hole are made all the time for things like 4" drain pipes.


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## Dorado (Feb 7, 2013)

The drilling is going great. I had to use padded gloves in twist mode because the vibration was crazy. I put on fingerless weightlifting gloves with canvas gloves over them then tried hammer mode and I was comfortable and probably drilled an inch in 15 seconds. The things people were telling me about drilling a 1" hole with a hammer drill are wrong. If you just have a few 1" holes to drill, you don't even need a hammer drill. I drilled a 1/2" pilot hole which may have helped, and padded gloves are a must.


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