Drills

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After struggling to drill out a broken stud on an exhaust flange I’m 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?
 
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.
 
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.
 
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.
 
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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.
 
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.
 
Sears has a set they occasionally offer for a little over 30 bucks on sale.Probably chinese but they seem to work well.
 
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.
 
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.
 
i agree with the advice of learning to sharpen bits...thats a real relevation to successful drilling right there! a good drill/tap oil is helpful too..i like tap magic, nice product.
 
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