Drill bit set: Titanium ($20) vs cobalt ($30) <Pics>

[JEDI]

Titanium $20:
http://www.homedepot.com/h_d1/N-5yc...&keyword=titanium+drill+bit+set&storeId=10051

Cobalt $30:
http://www.homedepot.com/h_d1/N-5yc...Id=-1&keyword=cobalt+sdrill+bit&storeId=10051

Both have 1/2" bits.
Are the Cobalt ones worth the extra $10? (I'm drilling thru metal)

And is it just Cobalt coated?
(It doesnt tell me what grade Cobalt it is.)

 

[Lemon law]

Jedi, IMHO, it depends on what material you will be drilling and the drill speeds you will be using.

The advantage of a titanium nitride coating on a basic high speed steel drill, is that less material from the work diffuses onto the drill itself. But once the bit is resharpeed even once, much of the advantage is lost.

The advantage of a High speed steel drill with a high cobalt content, is that the cutting edge will be retain its hardness better at higher cutting edge temperatures. Very important if you are say using a 1/2" drill bit and a drill that spins the bit faster than 600 RPM when drilling mild steel. Get down to a 1/8" drill and the extra cobalt probably will do you little good.

 

[IronWing]

As Lemon law states, it depends on what you are drilling. In my wife's blacksmithing work the hardness of the steel will vary considerably across a single piece depending on how it was quenched. She pretty much only uses Thunderbits now as they have consistently held up over long term use.

 

[Howard]

Chances are, neither set is going to be high-quality. But, if you're drilling stainless steel, you'll want the cobalt.

 

[BoomerD]

Both sets are made in China...with Chinese quality materials.

https://www.americanmadedrillbits.com/

 

[Bubbaleone]

Titanium $20:
http://www.homedepot.com/h_d1/N-5yc...&keyword=titanium+drill+bit+set&storeId=10051

Cobalt $30:
http://www.homedepot.com/h_d1/N-5yc...Id=-1&keyword=cobalt+sdrill+bit&storeId=10051

Both have 1/2" bits.
Are the Cobalt ones worth the extra $10? (I'm drilling thru metal)

And is it just Cobalt coated?
(It doesnt tell me what grade Cobalt it is.)

From a machinist's perspective this is just misleading bullshit magic marketing to sucker in the uninformed consumer. There is no such thing as a titanium drill bit; titanium's metallurgical properties make it totally unsuitable as a cutting tool. It's actually just a conventional high-speed (M2 molybdenum series high speed steel alloy) drill, with a split-point 135 degree grind, which is a very good point design for drilling in steel.

What makes it superior is the gold colored Titanium Nitride (TiN) coating. TiN is an extremely hard, inert, thin film coating that is applied primarily to precision metal parts. It's the most common PVD (Physical Vapor Deposition) hard coating in use today. TiN has an ideal combination of hardness, toughness, adhesion and inertness. TiN is harder than cemented carbide and 3X harder than hard chrome.

A "cobalt" drill bit is M42 tool steel (M42 is a molybdenum series high speed steel alloy with an additional 8% cobalt), and is superior in stainless steel due to it's greater torsional rigidity and high red-hardness. A TiN coated cobalt drill is still superior to uncoated.

For the average user drilling in mild steel with a hand-held drill motor or a consumer grade drill press; the 135 degree split-point, TiN coated, high-speed steel drill bit is preferable both in performance and price.


.

 

[Howard]

From a machinist's perspective this is just misleading bullshit magic marketing to sucker in the uninformed consumer. There is no such thing as a titanium drill bit; titanium's metallurgical properties make it totally unsuitable as a cutting tool. It's actually just a conventional high-speed (M2 molybdenum series high speed steel alloy) drill, with a split-point 135 degree grind, which is a very good point design for drilling in steel.

What makes it superior is the gold colored Titanium Nitride (TiN) coating. TiN is an extremely hard, inert, thin film coating that is applied primarily to precision metal parts. It's the most common PVD (Physical Vapor Deposition) hard coating in use today. TiN has an ideal combination of hardness, toughness, adhesion and inertness. TiN is harder than cemented carbide and 3X harder than hard chrome.

A "cobalt" drill bit is M42 tool steel (M42 is a molybdenum series high speed steel alloy with an additional 8% cobalt), and is superior in stainless steel due to it's greater torsional rigidity and high red-hardness. A TiN coated cobalt drill is still superior to uncoated.

For the average user drilling in mild steel with a hand-held drill motor or a consumer grade drill press; the 135 degree split-point, TiN coated, high-speed steel drill bit is preferable both in performance and price.


.

Even people in the know just call them titanium bits... No sense wasting time sayin tee eye enn or titanium nitride.

 

[JEDI]

From a machinist's perspective this is just misleading bullshit magic marketing to sucker in the uninformed consumer. There is no such thing as a titanium drill bit; titanium's metallurgical properties make it totally unsuitable as a cutting tool. It's actually just a conventional high-speed (M2 molybdenum series high speed steel alloy) drill, with a split-point 135 degree grind, which is a very good point design for drilling in steel.

What makes it superior is the gold colored Titanium Nitride (TiN) coating. TiN is an extremely hard, inert, thin film coating that is applied primarily to precision metal parts. It's the most common PVD (Physical Vapor Deposition) hard coating in use today. TiN has an ideal combination of hardness, toughness, adhesion and inertness. TiN is harder than cemented carbide and 3X harder than hard chrome.

A "cobalt" drill bit is M42 tool steel (M42 is a molybdenum series high speed steel alloy with an additional 8% cobalt), and is superior in stainless steel due to it's greater torsional rigidity and high red-hardness. A TiN coated cobalt drill is still superior to uncoated.

For the average user drilling in mild steel with a hand-held drill motor or a consumer grade drill press; the 135 degree split-point, TiN coated, high-speed steel drill bit is preferable both in performance and price.


.

wait.. TiN coated M2 is better in performance to M35/M42 Cobalt bits (uncoated 143 degee split point) drilling thru steel?!

 

[Bubbaleone]

The more ductile M2 is better where drill bit flexing is likely to cause cutting edge chipping when using hand-held drill motors or non-rigid drill press spindles, as an example. In these uses, the cutting edge of M42 is more prone to chipping due to it's increased brittleness and lower ductility. In a rigid spindle machine tool, at the proper surface speed and feed rate for the material, then M42 is certainly superior, uncoated or not. I'm not comparing machine tool usage to the average homeowner using a DeWalt drill motor or Craftsman drill press, and who's not skilled in hand resharpening or owns a drill point grinder.


.

 

[Lemon law]

Chances are, neither set is going to be high-quality. But, if you're drilling stainless steel, you'll want the cobalt.

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I disagree with you Howard as a retired tool room machinist. Stainless steel can be an extra challenge to drill, but as just another steel alloy, its properties can vary all over the place.

But for the plain ole home do it your self-er, stainless steel presents a extra challenge for the uneducated do it yourself-er. As that group have a almost universal tendency to over
speed and underfeed when drilling stainless steel. As a result the drill is not fed enough, and the drill just skates on the surface. Causing the material being drilled to work harden. Meaning, unless the drill is not fed at least .002" inch per revolution for a 1/8" drill, or better yet, .004" or more per rev for a 1/2 inch drill, the surface of the material being drilled will simply work harden.

But in an Industrial mass production settings, with proper speeds and feeds, in general a TN coated drill will out perform a cobalt drill in stainless steel. Of course its also possible to buy M42 grade TN coated drills too. And for that matter, its also common to use carbide insert drills in diameters greater than 5/8". But forget that in a hand held drill.

 

[Howard]

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I disagree with you Howard as a retired tool room machinist. Stainless steel can be an extra challenge to drill, but as just another steel alloy, its properties can vary all over the place.

But for the plain ole home do it your self-er, stainless steel presents a extra challenge for the uneducated do it yourself-er. As that group have a almost universal tendency to over
speed and underfeed when drilling stainless steel. As a result the drill is not fed enough, and the drill just skates on the surface. Causing the material being drilled to work harden. Meaning, unless the drill is not fed at least .002" inch per revolution for a 1/8" drill, or better yet, .004" or more per rev for a 1/2 inch drill, the surface of the material being drilled will simply work harden.

But in an Industrial mass production settings, with proper speeds and feeds, in general a TN coated drill will out perform a cobalt drill in stainless steel. Of course its also possible to buy M42 grade TN coated drills too. And for that matter, its also common to use carbide insert drills in diameters greater than 5/8". But forget that in a hand held drill.

And what I think is going to happen is that the shitty coating on the shitty bit is going to wear out under the high pressures and feeds that you'd need to do useful drilling in SS, and then you're going to be wanting for the better hot hardness of the "cobalt".

They might start off with low feed/pressure, but most laypeople don't drill stainless, and the ones that do will try to figure out how to do it properly once they fail the first time.

 

[Lemon law]

And what I think is going to happen is that the shitty coating on the shitty bit is going to wear out under the high pressures and feeds that you'd need to do useful drilling in SS, and then you're going to be wanting for the better hot hardness of the "cobalt".

They might start off with low feed/pressure, but most laypeople don't drill stainless, and the ones that do will try to figure out how to do it properly once they fail the first time.

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Pardon me Howard, and in all due respects, I have seldom seen a bigger crock of hohhie about a factual matter. To start out with, a TN coating does not simply wear out, as the wear mechanism in a drill is not simply at only the cutting edge, when its often at the rake surfaces. Have you ever seen what happens to a properly ground drill after its drilled thousands of holes? The rake surfaces will be filled with hundreds of little black dots, caused by transference of material from the material being drilled into the rake surfaces. Which is what a TN coating is very good at preventing.

As I also doubt you understand anything about steel alloys. Maybe in a very simplistic sense someone can argue pure iron is a homogenous material, but as soon as carbon and other alloying materials are added, it becomes a micro crystalline layered material that is anything but homogenous. Even a medium carbon steel properly annealed becomes layers of pearlite and carbon due to the allotropic properties of the crystalline cubic properties of iron. That can crystallize into a body centered or face centered structure crystal depending on temperature. And that is only if the Steel is very slowly annealed which can risk grain growth. If it cooled too fast without a per say hardening effect from super rapid cooling, Katie bar the door as mill supplied output from basic oxygen processed scrap steel. As one lot of say 1020 steel could be very easy to machine, and the next lot could be almost 50 Rockwell C. Stainless steel is not the only bitch material to machine.

Then Howard, you have too much faith in the amateurs machinist ability to learn how to machine hard to machine materials. When metallurgical science and uniform alloys of steel is a 20'th century development that has taken a lot of research and effort.

 

[Howard]

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Pardon me Howard, and in all due respects, I have seldom seen a bigger crock of hohhie about a factual matter. To start out with, a TN coating does not simply wear out, as the wear mechanism in a drill is not simply at only the cutting edge, when its often at the rake surfaces. Have you ever seen what happens to a properly ground drill after its drilled thousands of holes? The rake surfaces will be filled with hundreds of little black dots, caused by transference of material from the material being drilled into the rake surfaces. Which is what a TN coating is very good at preventing.

As I also doubt you understand anything about steel alloys. Maybe in a very simplistic sense someone can argue pure iron is a homogenous material, but as soon as carbon and other alloying materials are added, it becomes a micro crystalline layered material that is anything but homogenous. Even a medium carbon steel properly annealed becomes layers of pearlite and carbon due to the allotropic properties of the crystalline cubic properties of iron. That can crystallize into a body centered or face centered structure crystal depending on temperature. And that is only if the Steel is very slowly annealed which can risk grain growth. If it cooled too fast without a per say hardening effect from super rapid cooling, Katie bar the door as mill supplied output from basic oxygen processed scrap steel. As one lot of say 1020 steel could be very easy to machine, and the next lot could be almost 50 Rockwell C. Stainless steel is not the only bitch material to machine.

Then Howard, you have too much faith in the amateurs machinist ability to learn how to machine hard to machine materials. When metallurgical science and uniform alloys of steel is a 20'th century development that has taken a lot of research and effort.

I have lots of experience using shitty TiN bits, and yes, they wear out at the cutting edges first. Then, you have what might hopefully be HSS underneath, and you can bet your ass nobody's going to be using any sort of coolant or oil to keep temperatures down. However, the TiN bit will of course do a better job vs cobalt if it stays intact.

I'm going to ignore your 2nd and 3rd paragraphs because they are completely off-topic and irrelevant (and I did understand the material in metallurgy (ME), thank you).

 

[PottedMeat]

Both sets are made in China...with Chinese quality materials.

https://www.americanmadedrillbits.com/

i can't tell with either of the two sets the OP posted, but

the Ridgid 14 pc cobalt set part# 6765 says 'manufactured in the usa from us or foreign materials'

http://www.pawnbroker.com/uploaded/2011-6-0/30a51e242D599d2D4f542D8cf82De4e43816bd94wz32D17.jpg

it seems you can get it off ebay for $25 shipped from a seller in idaho.



i've seen the name ridgid for years and always thought it was spelled and said 'RIGID' then i finally stare at the name and say where did that 'd' come from???