Question about Concrete Core Bits

Question about Concrete Core Bits

PostBy: 009to090 On: Fri Mar 27, 2009 4:00 pm

I own and have used many core bits before, but this is the first time I ever got any with a tapered shaft socket. The SDS+ shaft has a matching tapered shaft, that slides into the bit.
My question is: What holds it all together? Does the SDS+ shaft just spin the bit by friction? I know I could use a starter bit, right down the center of the shaft, but theres no threads anywhere for tightening the shaft to the bit.
These bits are:
Hitachi 725758 4-Inch x 4-Inch 8 Teeth Hollow Core Bit with 1:8 Internal Tapered Shank
and
Hitachi 725754 2-Inch x 4-Inch 8 Teeth Hollow Core Bit with 1:8 Internal Tapered Shank
the shank is:
Hitachi 725733 SDS Plus 4-1/2-Inch Long 1:8 Tapered Shank for Hollow Core Bits

Thanks.

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009to090
 
Stoker Coal Boiler: EFM 520 HighBoy
Hot Air Coal Stoker Stove: DVC-500 x 2
Coal Size/Type: Anthracite Rice

Re: Question about Concrete Core Bits

PostBy: RMA On: Fri Mar 27, 2009 5:04 pm

Matching machined tapers hold the bit it place. Similar to the Morse taper that hold most drill chucks in place
on a drill press.

Bob
RMA
 

Re: Question about Concrete Core Bits

PostBy: 009to090 On: Fri Mar 27, 2009 5:18 pm

RMA wrote:Matching machined tapers hold the bit it place. Similar to the Morse taper that hold most drill chucks in place
on a drill press.

Bob


Thanks Bob, I had that idea, since my drill press uses a tapered chuck. I just never saw it used on a bit before. I thought the vibes from my Hammer/Drill would knock it out and allow it to slip.
009to090
 
Stoker Coal Boiler: EFM 520 HighBoy
Hot Air Coal Stoker Stove: DVC-500 x 2
Coal Size/Type: Anthracite Rice


Re: Question about Concrete Core Bits

PostBy: whistlenut On: Fri Mar 27, 2009 7:58 pm

Actually the vibration helps hold then in place, too. Normally, there is a centering pilot bit that may be held in by a taper or a simple rubber o-ring, as Hilti does. Either way, they work great, last a long time and will be in your tool box for years.
Don't worry about them falling apart as you are coring, just keep enough water on the operation. By the way, Hitachi does a terrific job with there concrete hammers, drills, breakers. etc. Fair prices, very durable tools. Enjoy! :pepsi:
whistlenut
 
Stoker Coal Boiler: AA130's,260's, AHS130&260's,EFM900,GJ&VanWert
Hand Fed Coal Boiler: Franks Boiler,Itasca415,NYer130,Van Wert
Hot Air Coal Stoker Furnace: Yellow Flame
Hot Air Coal Stoker Stove: Alaska-4,Keystoker-2,
Hand Fed Coal Stove: Alaska,Gibraltor,Keystone,Vc Vigilant 2
Hand Fed Coal Furnace: Van Wert, NYer's, Ford,Jensen.
Coal Size/Type: Rice,Buck,Pea,Nut&Stove
Other Heating: Oil HWBB

Re: Question about Concrete Core Bits

PostBy: 009to090 On: Fri Mar 27, 2009 8:54 pm

whistlenut wrote:Actually the vibration helps hold then in place, too. Normally, there is a centering pilot bit that may be held in by a taper or a simple rubber o-ring, as Hilti does. Either way, they work great, last a long time and will be in your tool box for years.
Don't worry about them falling apart as you are coring, just keep enough water on the operation. By the way, Hitachi does a terrific job with there concrete hammers, drills, breakers. etc. Fair prices, very durable tools. Enjoy! :pepsi:


Great news! I was affraid of turning something this big, with just a friction connection. Yep, I got a pilot bit for it already.
I have a BoschHammer Model 11222EVs, that is fantastic. Its about 5 years old. And I have been taken for a ride or two, on my Milwaulkie Hole Hawg. :woot:
MORE POWER !!!!!
toothy toothy toothy toothy toothy
009to090
 
Stoker Coal Boiler: EFM 520 HighBoy
Hot Air Coal Stoker Stove: DVC-500 x 2
Coal Size/Type: Anthracite Rice

Re: Question about Concrete Core Bits

PostBy: Freddy On: Sat Mar 28, 2009 4:15 am

I wouldn't own a hole hawg! What an awful knuckle busting tool they are. Try a Dewalt 124 (and dewalt isn't generally my favorite tool). They have a clutch on low speed that works perfectly and on high speed they are long enough so you can easily hold a stall. Of course they are not a hammer drill, but to replace a hole hawg they are the answer.



http://cgi.ebay.com/NEW-DeWALT-DW124K-HD-1-2-Stud-Joist-Drill-Kit_W0QQitemZ110361436688QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item110361436688&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50
This link is broken, either the page no longer exists or there is some other issue like a typo.
Freddy
 
Stoker Coal Boiler: Axeman Anderson 130 (pea)
Hot Air Coal Stoker Stove: Reading piece o' junk in the barn (rice)
Coal Size/Type: Pea size, Superior, deep mined

Re: Question about Concrete Core Bits

PostBy: JB Sparks On: Sat Mar 28, 2009 6:36 am

Yeah, I hear ya on the holw hawg Freddy, I used to use the handles from my emt benders for the hawg side handles and comandere a couple of extra boys to hold on in case of a stall.
JB Sparks
 
Stove/Furnace Make: Harman - Chubby
Stove/Furnace Model: Harman: SF160 - Chubby Sr.