Difference between Cobalt and Carbide drill bits?

WinDancer

WinDancer

Joined
May 15, 1999
Messages
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Can someone explain the usability difference between Cobalt and Carbide drill bits?

Thanks,

Dave
 
Carbide bits can be used to drill already hardened steel. But they are brittle and tend to break if you're not real careful.

Cobalt bits are the greatest for drilling annealed ready to work steel. They will outlast high speed steel bits four to one so they are worth the little bit extra they cost.

Hope this helps.
 
Well it may not be much but here is a start for you. Cobalt is often added to "regular steel drilling" bits. It does improve cutting abilty considerably. The common amount of cobalt added is usually 8%. Silicon carbide can be a great cutter but is very brittle and is used in bits to drill very hard steels and also in masonary bits. The silicon carbibe bits are usually at least twice or more the cost of regular bits. Lots of care and good cutting fluids with reduced drilling speeds should be used with a reasonable, and controlled amount of pressure. Silicon carbibe drill bits in "true" fractional and numbered sizes also not commonly available. However, properly used in the applications necessary silicon carbide bits will drill very accurate holes. Frank Niro
 
I have used Cobalt bits for drilling 1084 ang 1095. I works fine as long as you use good cutting oil and make sure you don't drill too fast or it will dull the bit and make it really hard to drill anything with it.
 
Originally posted by Frank Niro
Well it may not be much but here is a start for you. Cobalt is often added to "regular steel drilling" bits. It does improve cutting abilty considerably. The common amount of cobalt added is usually 8%. Silicon carbide can be a great cutter but is very brittle and is used in bits to drill very hard steels and also in masonary bits. The silicon carbibe bits are usually at least twice or more the cost of regular bits. Lots of care and good cutting fluids with reduced drilling speeds should be used with a reasonable, and controlled amount of pressure. Silicon carbibe drill bits in "true" fractional and numbered sizes also not commonly available. However, properly used in the applications necessary silicon carbide bits will drill very accurate holes. Frank Niro
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Never heard of a Silicon Carbide drill bit, and I regrind machine tools on a regular basis!!

Carbide drill bits, end mills, ect. are all Tungsten Carbide, with a Cobalt binder (W, C, & CO), and are generally whats available.

Silicon Carbide is used in grinding wheels (green wheels), and in some grinding belts.

Other than clarifying the make-up of carbide tools, the rest is right on.
 
...the cobalt bits are about the best for general knifemaking work. They work well and stay sharper longer on just about any kind of steel I drill.

The titanium nitrite, high speed steel and such are, to me anyway, pretty much just cobalt wanna bees. They are ok for thin easy to drill stuff but for lasting sharpness and acurate hole drilling use the cobalt.

A good drill bit sharpener and a cobalt bit will make any drilling job easier.

;)

Brian
 
You might want to check out tungsten carbide, which can keep its sharp edges for a longer period of time:

Tungsten carbide is a type of steel mainly comprising of cobalt as well as tungsten carbide. The cobalt will act as a binder and help enhance shock resistance when drilling. The shock resistance provided will depend on the percentage of cobalt used to manufacture the product, and usually a small amount of wax will be added to hold the materials together. Tungsten carbide is a high-strength material and has a compression strength greater than many forged metals and alloys. This type of steel has a tensile strength ranging from 100,000 to 500,000 PSI.
Click to expand...

source: http://carbidedrillhq.com
 
ticker web on cobalt bits might not be ideal in certain situations compared to hss. cobalt bits are m35 & m42: 5 & 8% co respectively.
 
Oh my god... this thread... so much fail...
 
Chemistguy, are knifemakers sane? :)
Perhaps some one forgot to drill all the holes prior to heat treat?
That has never happened to anyone on this board, I'm sure. LOL
Fred
 
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