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Drills #4475211
07/31/17 05:01 AM
07/31/17 05:01 AM
Joined: Jan 2012
Posts: 208
NY
greasegunn Offline OP
greasegunn  Offline OP
Joined: Jan 2012
Posts: 208
NY
After struggling to drill out a broken stud on an exhaust flange Iím in the market for some better drills. Laying under the car is not my idea of fun so I want something that will zip through materials commonly found on automobiles as quickly as possible. Looks like the choices are High Speed Steel, cobalt, and carbide. Or maybe I should just buy inexpensive drills and treat them as throw aways? What are the pros and cons of each? For example I understand that carbide tends to be brittle. What is everyone else using with good success?

Re: Drills [Re: greasegunn] #4475224
07/31/17 05:31 AM
07/31/17 05:31 AM
Joined: Jul 2014
Posts: 68
Northern Illinois
Bumble_guy Offline
Bumble_guy  Offline
Joined: Jul 2014
Posts: 68
Northern Illinois
Cobolt is your friend


1981 Kenworth 1984 International 1996 chevy pickup 2000 GMC, skid steer ,2000 goergie boy motorhome 36f, 2006 Mustang GT Convertable
Re: Drills [Re: Bumble_guy] #4475237
07/31/17 05:46 AM
07/31/17 05:46 AM
Joined: Aug 2010
Posts: 5,940
Champlain/Hudson Valley
Kira Offline
Kira  Offline
Joined: Aug 2010
Posts: 5,940
Champlain/Hudson Valley
Is "Cobalt" that Home Depot store brand name or a type of steel alloy? serious question

Re: Drills [Re: greasegunn] #4475240
07/31/17 05:50 AM
07/31/17 05:50 AM
Joined: Mar 2014
Posts: 4
ohio
jjw6455 Offline
jjw6455  Offline
Joined: Mar 2014
Posts: 4
ohio
I struggled with that exact same stud on my Mazda 6, went through 3 or 4 bits and wasn't getting anywhere. Picked up a cobalt bit from the local store and it zipped through the stud in 30 seconds.

Re: Drills [Re: greasegunn] #4475245
07/31/17 05:57 AM
07/31/17 05:57 AM
Joined: Sep 2016
Posts: 1,418
Minnesota
bioburner Offline
bioburner  Offline
Joined: Sep 2016
Posts: 1,418
Minnesota
Cobalt is a type of steel, very expensive but ideal for drilling on hardened steel. Great for drilling out bolts before using a extractor or when drilling gun receivers for scope mounts and the metal is surface hardened or like the old Springfields just plain hard steel. The negative is that its brittle, so drill straight and get the surface center punched to prevent the tip from walking. Learn how to sharpen bits properly. 30 seconds at the grinding wheel putting a good point on can reduce efforts needed to drill.



97 Ford E350 D,99 F350 dually D
13 Scion Xb
12 Ford Transit Connect
06 Nissan Xterra
03 K1200 BMW
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Re: Drills [Re: greasegunn] #4475280
07/31/17 06:59 AM
07/31/17 06:59 AM
Joined: Nov 2006
Posts: 20,574
MA, Mittelfranken.de
Trav Offline
Trav  Offline
Joined: Nov 2006
Posts: 20,574
MA, Mittelfranken.de
Cobalt M42 jobber length bits and some smaller left handed ones for broken bolts and studs. For drilling through broken bolts I sometimes use solid carbide bits, you only need a few sizes but they are expensive an 1/8 and 1/4 will get you started with a pilot hole for most broken bolts then use the LH bit.

Last edited by Trav; 07/31/17 07:02 AM.

ASE L1, Master. Deutsch Meisterbrief.
Re: Drills [Re: Kira] #4475301
07/31/17 07:17 AM
07/31/17 07:17 AM
Joined: Aug 2011
Posts: 9,560
Boston, MA
HerrStig Offline
HerrStig  Offline
Joined: Aug 2011
Posts: 9,560
Boston, MA
Originally Posted By: Kira
Is "Cobalt" that Home Depot store brand name or a type of steel alloy? serious question
"Kobalt" is a Lowes brand.

Re: Drills [Re: greasegunn] #4475302
07/31/17 07:18 AM
07/31/17 07:18 AM
Joined: Oct 2010
Posts: 9,126
Virginia Beach
Astro14 Offline
Astro14  Offline
Joined: Oct 2010
Posts: 9,126
Virginia Beach
All cobalt bits are expensive.

I've got a whole set. Nothing better.

But even cobalt dulls. Get a drill doctor and keep them sharp.

You'll be amazed.

You don't need a King Kong drill, just good, sharp, bits.


32 Packard 15W40
02 Volvo V70 T5 0W40 M1
02 Volvo V70 XC 0W40 Edge
05 MB S600 0W40 M1
16 Tundra 1794 5W30 Pennzoil Ultra
Re: Drills [Re: greasegunn] #4475357
07/31/17 08:15 AM
07/31/17 08:15 AM
Joined: Nov 2008
Posts: 132
FL
9050lx Offline
9050lx  Offline
Joined: Nov 2008
Posts: 132
FL
Sears has a set they occasionally offer for a little over 30 bucks on sale.Probably chinese but they seem to work well.

Re: Drills [Re: jjw6455] #4475371
07/31/17 08:27 AM
07/31/17 08:27 AM
Joined: Jan 2012
Posts: 208
NY
greasegunn Offline OP
greasegunn  Offline OP
Joined: Jan 2012
Posts: 208
NY
Originally Posted By: jjw6455
I struggled with that exact same stud on my Mazda 6, went through 3 or 4 bits and wasn't getting anywhere. Picked up a cobalt bit from the local store and it zipped through the stud in 30 seconds.


As it turns out my issue was also on a Mazda 6 - the stud from the muffler that attached to the pipe had broken off. I needed to drill out the stud put in a nut and bolt.

Re: Drills [Re: Astro14] #4475372
07/31/17 08:28 AM
07/31/17 08:28 AM
Joined: Nov 2006
Posts: 20,574
MA, Mittelfranken.de
Trav Offline
Trav  Offline
Joined: Nov 2006
Posts: 20,574
MA, Mittelfranken.de
Try solid carbide, they are amazing at cutting through hardened metal and stay sharp a long time. Both the cobalt and carbide give cordless drills much better performance.
This will go through a broken bolt like a hot knife though butter.

http://www.ebay.com/itm/1-8-Solid-Carbid...4-/131380163688


ASE L1, Master. Deutsch Meisterbrief.
Re: Drills [Re: greasegunn] #4475396
07/31/17 08:57 AM
07/31/17 08:57 AM
Joined: Feb 2012
Posts: 3,870
NEUS
Bandito440 Offline
Bandito440  Offline
Joined: Feb 2012
Posts: 3,870
NEUS
Carbide is the proper choice here. Be sure to avoid chatter; they can be brittle.


'14 Grand Cherokee EcoDiesel
Rotella T6 5w-40 & OEM filter
Re: Drills [Re: greasegunn] #4475422
07/31/17 09:17 AM
07/31/17 09:17 AM
Joined: Sep 2014
Posts: 2,177
US-WA
Dyusik Offline
Dyusik  Offline
Joined: Sep 2014
Posts: 2,177
US-WA
+1 for cobalt, those bits are worth every penny.


95 Cherokee 190K DELO 10W30, XG8
07 IS250 103K Napa 10w30, FULL
04 YZF-R1 19K DELO 15w40, XG7317
99 HD XL1200S 21K VR1 20w50, NG1515
14 RX450h 35k PP MIX, NG7047
Re: Drills [Re: greasegunn] #4475671
07/31/17 01:37 PM
07/31/17 01:37 PM
Joined: Jul 2014
Posts: 68
Northern Illinois
Bumble_guy Offline
Bumble_guy  Offline
Joined: Jul 2014
Posts: 68
Northern Illinois
I don't know if you have Menards out by you but a set of cobalt bits by mastercraft 26 bucks ,work well


1981 Kenworth 1984 International 1996 chevy pickup 2000 GMC, skid steer ,2000 goergie boy motorhome 36f, 2006 Mustang GT Convertable
Re: Drills [Re: bioburner] #4475697
07/31/17 02:13 PM
07/31/17 02:13 PM
Joined: Dec 2016
Posts: 7,151
Waco, TX
Linctex Offline
Linctex  Offline
Joined: Dec 2016
Posts: 7,151
Waco, TX
Originally Posted By: bioburner
Cobalt is a type of steel, very expensive but ideal for drilling on hardened steel.


Correct, and I never waste my money on anything of lesser quality.


"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."
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