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Where to get Cobalt Drills?

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Plombob

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I lent someone my set of cobalt drills and now I need to replace half of them.

Anybody know a good source for reasonably priced cobalt drills?
 
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kf4zht

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The usual machinest places. I would try Enco, McMaster Carr, Zoro. I buy a lot of ebay, works good for either random lots of specific sizes.

So you lent someone the bits and now YOU need to replace some. Sounds like THEY need to replace them...
 
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AndyA

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Lowes has Dewalt drill bits in cobalt. The prices probably aren't as good as you could find online, but they're good for the day you break a bit and need to finish a project.
 
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ndoran

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here in Canada you can buy them at Canadian Tire and Princess Auto
 
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Plombob

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uart said:
Just wondering. Are they lost? broken? or just dull?
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The smaller ones are chewed up, the larger ones are blue and dull. Turns out they were drilling holes in stainless using a lot of pressure and high speed. :wtf:


Are there different kinds or grades of cobalt drills? I paid a lot more than $25 for this set of S-O drills thirty years ago. I can't imagine the Sears set is as good, or am I wrong?
 
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dirtydogintex

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Plombob said:
The smaller ones are chewed up, the larger ones are blue and dull. Turns out they were drilling holes in stainless using a lot of pressure and high speed. :wtf:


Are there different kinds or grades of cobalt drills? I paid a lot more than $25 for this set of S-O drills thirty years ago. I can't imagine the Sears set is as good, or am I wrong?
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IIRC SO has a lifetime warranty on their drill bits.

Wouldn't hurt to give'em a call....
 
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uart

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Plombob said:
The smaller ones are chewed up, the larger ones are blue and dull. Turns out they were drilling holes in stainless using a lot of pressure and high speed. :wtf:
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This thread reminds me of why I hate lending all but my most crappy tools.

Anyway, it sounds like they've had them so hot that they've lost some of their temper. I'd definitely be wanting to replace any that look at all abused. You might be able to get just a small set to replace the smaller ones, and replace the larger ones on a piece by piece basis if there aren't too many.
 
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neophyte

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Plombob said:
The smaller ones are chewed up, the larger ones are blue and dull. Turns out they were drilling holes in stainless using a lot of pressure and high speed. :wtf:


Are there different kinds or grades of cobalt drills? I paid a lot more than $25 for this set of S-O drills thirty years ago. I can't imagine the Sears set is as good, or am I wrong?
Click to expand...

There are different grades of Cobalt HSS. M35 and M42 are the most common alloys. M42 has a higher amount of Molybdenum. There are also different flute geometries depending on the alloy types the drill bits are meant to drill.

Are you sure the drill bits that are blued are actually ruined? Cobalt steel is supposed to take the type of heat that can turn regular steel blue. Also, one of the problems with drilling stainless is galling where metal transfers from the alloy being drilled to the cutting tool, which in term increases friction and heat. You might want to try regrinding the tips and check the drilling performance, at least on a couple.
 
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Plombob

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neophyte said:
There are different grades of Cobalt HSS. M35 and M42 are the most common alloys. M42 has a higher amount of Molybdenum. There are also different flute geometries depending on the alloy types the drill bits are meant to drill.

Are you sure the drill bits that are blued are actually ruined? Cobalt steel is supposed to take the type of heat that can turn regular steel blue. Also, one of the problems with drilling stainless is galling where metal transfers from the alloy being drilled to the cutting tool, which in term increases friction and heat. You might want to try regrinding the tips and check the drilling performance, at least on a couple.
Click to expand...

I assumed if the bit is blue, its lost the temper. I could try sharpening them.

What is the difference between the alloys?
 
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uart

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Plombob said:
I assumed if the bit is blue, its lost the temper. I could try sharpening them.

What is the difference between the alloys?
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M2 is your basic (good quality) HSS without cobalt. Approx 6% W (Tungsten), 5% Mo (Moly), 4% Cr (Chromium) and 2% V (Vanadium).

M35 is very similar to M2, but with the addition of approx 5% Co (Cobalt).

M42 contains higher levels of Mo and about 8% Co.

The Cobalt alloys are supposed give greater wear resistance and better tolerance of high temperature. So better for drilling hard materials, especially at higher rates of speed and feed.

The disadvantage of Co drills is that they're a bit more brittle and have less impact resistance than M2. Some Co drills also have a slightly thicker web to help try to mitigate this.
 
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neophyte

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Plombob said:
I assumed if the bit is blue, its lost the temper. I could try sharpening them.

What is the difference between the alloys?
Click to expand...

M42 Cobalt steel has a higher quantity of Molybdenum. Cobalt imparts higher hardness and significantly higher heat resistance to HSS, however with the extra hardness comes brittleness. Molybdenum is used to add toughness to steel. Some drill bits with a more open flute design are made from M7 high Molybdenum HSS to add extra toughness to compensate for the thinner flute geometry. The extra Molybdenum in the M42 HSS is likely used to offset the brittleness caused by the Cobalt.
 
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radgto

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dirtydogintex said:
yw

Apparently SO does warranty consumables.... like drill and driver bits, saw blades, taps and dies.... at least that's what a SO lady told me over the phone a coupla of months ago
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I've had them warranty about 15 drill bits, 3 easy outs and 3 taps just in the past year. No hassles at all, Did it over the phone since we don't have a SO truck at work.
Didn't even have to send the broken ones back
 
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Bigplum

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Do like I did, I bought a second hand snap on roll cab with jammed drawers ,
Got it home , got the drawers out and down in back were over 200 new 3.2 mm cobalt drills still in their packs plus some 10mm and 2mm packs ,
 
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Plombob

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I emailed Snap-On about replacing the bits, since some of you said they will do that:

"Warranty question: I purchased cobalt drill set, DBC215 years ago. I have my receipt. I recently heard from mechanic friends that Snap-On will replace drill bits. If this is true, I'd like to replace the drills that are worn out."



Snap-On's response:
The bits are consumable and would not be replaced.

Thank you,
Snap-on Tools
Click to expand...



I'm guessing that the guys who got them replaced went through the dealer and the dealer was doing it as a favor to a client?
 
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