Second try.. Left handed Cobalt or Carbide Drill supplier?

Anyone know of someone that carries left handed cobalt or carbide drills? Looking for a 3/8" jobber or screw length..
thanks
tom
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McMaster-Carr...
3474A23 Left-Hand Cobalt Steel Maintenance Length Bit 135 Deg, 3/8" Sz, 4-1/8" L O'all, 2.1" Drill Depth In stock at $13.42 Each
--
Ned Simmons

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On 3/3/2010 11:31 AM, Ned Simmons wrote:

Good find Ned.. I searched all over mcmaster and msc.. couldn't find a left hand cobalt at all.. I called msc and they could get me one via dropship from Irwin, but I would have had to buy 6 of them, and I couldn't see spending 100 bucks on something that I'm not sure will even work..
Just wondering, how did you come by that? I tried many different ways to get to a cobalt left hand drill, and only came up with HSS.
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wrote:

This doesn't answer your question, but it's an occasion to give my frequent sidebar on high speed steel. <g>
"Cobalt" tools are high speed steel tools. Several high-performance grades of HSS contain cobalt; 5% cobalt for M35 and T15, and 8% for M42. There's also a 10% cobalt version, M48. And the powder-metallurgy "bridge materials" (such as CPM Rex 121) contain even larger amounts. You won't see them on the retail market, except for gear hobs that cost like crazy.
It's M42 that's been nicknamed "cobalt." Some people cheat a bit and apply the term to M35 -- particularly importers of Asian tools.
But it's all high speed steel. If you're dealing with top-notch materials and tool suppliers, that *may* be why you kept coming up with HSS. They don't call it "cobalt." The term, used as the name for the tool material rather than for the alloy component, is used more frequently in the low end of the metalcutting business.
Here's an abbreviated table that shows the major grades of high speed steel, from a Chinese source. I haven't checked their characterization of AISI grades, so double-check if you want accurate information. One thing it doesn't show is the useless crap coming from China that shows up in discount stores. They call it "M50 equivalent," but it typically contains no tungsten at all. Regular M50 contains 0.25% tungsten. It's good for woodworking and for drilling aluminum. The "equivalent" is good for nothing much. <g>
http://www.diamondtoolselect.com/knowledge/a-comparison-table-of-different-high-speed-steel-hss-grade-standards /
--
Ed Huntress








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Ed sez, (snip, snip)
"Cobalt" tools are high speed steel tools. Several high-performance grades of HSS contain cobalt; 5% cobalt for M35 and T15, and 8% for M42. There's also a 10% cobalt version, M48. And the powder-metallurgy "bridge materials" (such as CPM Rex 121) contain even larger amounts. You won't see them on the retail market, except for gear hobs that cost like crazy. ..."
Great reply, Ed. Hopefully it will help the OP to get out of the "exact material" requirement rut and on to more productive, and enjoyable, metalworking.
Bob Swinney
wrote:

of HSS contain cobalt; 5% cobalt for M35 and T15, and 8% for M42. There's also a 10% cobalt version, M48. And the powder-metallurgy "bridge materials" (such as CPM Rex 121) contain even larger amounts. You won't see them on the retail market, except for gear hobs that cost like
This doesn't answer your question, but it's an occasion to give my frequent sidebar on high speed steel. <g>
crazy.
It's M42 that's been nicknamed "cobalt." Some people cheat a bit and apply the term to M35 -- particularly importers of Asian tools.
But it's all high speed steel. If you're dealing with top-notch materials and tool suppliers, that *may* be why you kept coming up with HSS. They don't call it "cobalt." The term, used as the name for the tool material rather than for the alloy component, is used more frequently in the low end of the metalcutting business.
Here's an abbreviated table that shows the major grades of high speed steel, from a Chinese source. I haven't checked their characterization of AISI grades, so double-check if you want accurate information. One thing it doesn't show is the useless crap coming from China that shows up in discount stores. They call it "M50 equivalent," but it typically contains no tungsten at all. Regular M50 contains 0.25% tungsten. It's good for woodworking and for drilling aluminum. The "equivalent" is good for nothing much. <g>
http://www.diamondtoolselect.com/knowledge/a-comparison-table-of-different-high-speed-steel-hss-grade-standards /
--
Ed Huntress








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On 3/4/2010 9:38 AM, Robert Swinney wrote:

I second that, great info Ed. Thanks.
I did know that Cobalt tooling was actually HSS with cobalt mixed in.. Only reason I was animate about getting cobalt or carbide is because I'm trying to drill out some nasty hard bolts, and I know damn well HSS would snap off in a heartbeat. Just trying to make a simple job a bit quicker.
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Ah, good. I post that from time to time, mostly as a help for the hobbyists who get snowed by the slang terms. I also pipe up when someone mentions "titanium" or "titanium-coated" or "tin-coated" tools (which actually are titanium-nitride-coated, or TiN-coated, tools). We're awash in jargon and slang.

I hope it works. But if ordinary M2 tools will snap, M42 tools will snap faster (and carbide will snap faster still). M42 is pretty brittle. Where it has an advantage is primarily in the higher temperatures at which you can run it, and also in its wear resistance. Those tools can be a bit harder, too (but not nearly as hard as carbide), which helps with hardened steel. But they do snap rather easily if your setup isn't rigid.
Good luck with your project.
--
Ed Huntress



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Snap off???
The generic "cobalt" screw machine length drills I bought from MSC dull almost as fast as M2 HSS in hardened steel that I can't anneal, like molded inserts in plastic car parts. I think I've resharpened one 3 or 4 times to drill out one small stuck bolt. That was drilling in a milling machine. The black ones especially are almost too brittle to use freehand on a rough fractured bolt.
Have you tried carbide masonry bits?
jsw
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I tried drilling such tough things. I recall a need to drill a Proto socket extension. HSS drill bits simply cannot handle this stuff, they dull and overheat. It was a good thing that I had carbide drill bits and a rigid machine to use them, that was the only way I could drill that socket extension.
i
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Warning - crude practical content - may offend the delicately inclined...
A handy, right there in the hardware store carbide bit is the roto-zip (and similar tools) tile bit. Having broken off a drill bit while end-drilling a stainless threaded rod (no rigid setup of any kind available for the purpose) I removed it, still without a ridgid setup of any kind, using the solid carbide tile bit in a Dremelish tool - and then kept going to drill the hole (with great care, but also with side clearance - which was OK for this particular hole).
I'll be happier and have more nice setups when the shop is done, but in the meantime, crude works sometimes.
--
Cats, coffee, chocolate...vices to live by

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wrote in message

Yup. Big carbides in M42. Heap brittle.

As I mentioned, the bit of extra hardness is not the primary virtue of M42. I'm not surprised that you didn't find a big difference in wear life versus M2 in hardened steel.

I wouldn't drill freehand with M42 bits. They're not tough enough for that.

I assume you're asking tnik? I haven't, but reading posts here from some people who have had success with them, I have in mind to give them a try when the occassion arises.
--
Ed Huntress


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Yes, the Original Poster. My $6.95/mo + freeware Internet access doesn't handle scrolling around the posting history very well when I have a reply in process. However it worked fine through the Northeast power outage this past weekend when my neighbors' Comcast was down.

I think you need a left-hand drill bit only when there is a good chance the broken bolt will unscrew. Otherwise right-hand bits work fine.
jsw
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On 3/4/2010 1:19 PM, Jim Wilkins wrote:

I have used masonry bits before.. They work pretty good, not as good as a carbide endmill tho. But in a pinch their great.

And you hit the nail on the head there Jim.. I wanted to try the left handed drill to see if maybe it would unscrew.
tom
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wrote:

Another alternative would be a standard, inexpensive, "EasyOut" (aka screw extractor) in a hole of the appropriate size drilled directly into the bolt.
Of course, if you're just interested in purchasing a left-hand carbide bit...
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wrote in message

They work very well when enlarging rivet holes in heat-treated knife tangs, etc.
When precision dimensions aren't necessary, they're a cheap way to deal with a one-off or very low volume task.
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wrote in message

Yeah, it makes sense. After all, it's just a carbide spade bit in a steel shank. If you sharpen it well, I can't see why it won't drill, more or less.
My problem is that I have lots of masonry bits, but few straight ones. <g> I usually have to whack them straight on an anvil before drilling masonry. I think I'll try it first with a new one.
--
Ed Huntress



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wrote in message

If you don't require a ROUND hole, then a bit of wobble...
After all, in the OP's case the key factor is to be able to insert an "Easy-Out" rather than do anything that's all that precise. <grin>
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tnik wrote:

I know a left-handed tool supplier: but I don't know if he sells left-handed tools.
KG
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Grind Cliffs head into a point, making it screw lose length.
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"Kirk Gordon" wrote...

Reminds me of my first job in a factory (wireman, progressed to prototype wireman in a few months, hated it and moved on)...
The "experienced" guys in the machine shop were always sending newbies to the stores for "sparks for the grinder", "left-handed ratchets" etc. I was sent for a "metric screwriver" so I popped over the road to the pub, came back with 25cc of vodka and 75cc of orange juice in a glass...
Dave H.
--
(The engineer formerly known as Homeless)

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