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Posted: 8/9/2017 5:24:45 PM EST
Got an Irwin "cobalt" in 5/32.

Package card says "For Hardened Steel"

Am I GTG?

Link Posted: 8/9/2017 5:31:50 PM EST
Originally Posted By ThePontificator:
Got an Irwin "cobalt" in 5/32.

Package card says "For Hardened Steel"

Am I GTG?

https://www.picclickimg.com/d/l400/pict/140787851340_/Irwin-3016024-3-8x5-Cobalt-HSS-J-L-Drill-Bit.jpg
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Should be good to go, just go slow.
Link Posted: 8/9/2017 5:59:50 PM EST
As mentioned, you'll be good with that.
Link Posted: 8/9/2017 7:16:16 PM EST
Just make sure you're holding a video camera in your free hand and you'll be golden
Link Posted: 8/9/2017 7:50:28 PM EST
Link Posted: 8/9/2017 9:07:03 PM EST
If you use a mill center drill countersink firstit really makes a difference when you go to drill the corresponding dimple. It keeps the bit from walking out of your center point.
Link Posted: 8/10/2017 12:03:38 AM EST
[Last Edit: 8/10/2017 12:05:08 AM EST by MaverickAA]
Nitride barrel is nothing unusual. Any new bit made for "steel" should be GTG.
The reason nitride gets a bad rep for drilling is because drillers cheap out and don't want to absorb the cost of the (minimally) increased wear in the bits (ahem,, I'm talking about YOU, ADCO).
I've done numerous nitride barrels, no sweat. Just use a decently sharp bit, no worries (cuts just like any other).
Keep in mind, nitride is only a few thou's deep, hardly anything a decent bit can't easily handle.
Link Posted: 8/13/2017 9:17:32 AM EST
Just use that bit, keep the tip submerged in a few drops of oil, preferably cutting oil, but even WD40 will do for this shallow cut. Go slow.

FWIW, I don't even dimple anymore. As long as you use true set screws, they have concave tips, not points. They flatten out against the barrel and leave a circle imprint, even on a nitride barrel I have. They grip very well.
Link Posted: 8/13/2017 10:12:40 AM EST
[Last Edit: 8/13/2017 10:14:42 AM EST by Tigwelder1971]
Link Posted: 8/13/2017 5:41:11 PM EST
Link Posted: 8/13/2017 8:28:32 PM EST
For dimpling I just kiss the spot with a Dremel cut off wheel at low speed to get through a bit then drill.
Link Posted: 8/13/2017 8:39:24 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By tobycreek:
For dimpling I just kiss the spot with a Dremel cut off wheel at low speed to get through a bit then drill.
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I would think one of the small round shape abrasive tools would be better, just do the whole process with one.
Link Posted: 8/15/2017 12:29:59 AM EST
[Last Edit: 8/15/2017 12:30:45 AM EST by caser]
I used a similar cobalt bit, on a Faxon barrel, it worked. But that nitride was harder than I expected.

Jobber length would have been better.
Link Posted: 8/15/2017 2:50:49 AM EST
FWIW, I don't even dimple anymore.
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The benefit of dimpling isn't just the dimple, it ensures that the rearmost set screw hole on the gas block is located perfectly in line with the gas port. With it in place, it makes it damned difficult to install a gas block incorrectly or not in line with the port.
Link Posted: 8/15/2017 4:13:58 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Mad-Machinist:
I just use carbide anytime I have to machine nitride.....
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I was just going to say that.
Carbide center drill works great, but you can still feel it.
Link Posted: 8/23/2017 7:41:34 PM EST
I agree with Gamma; a new Dremel bit that matches the profile of the dimple you're trying to make (conical, round, etc.) should be the most direct way to get this done.

For clarification, people advising "just go slow," are you saying "low RPMs" or "don't put much pressure on the bit"?
Link Posted: 8/25/2017 8:06:39 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By GHPorter:
I agree with Gamma; a new Dremel bit that matches the profile of the dimple you're trying to make (conical, round, etc.) should be the most direct way to get this done.

For clarification, people advising "just go slow," are you saying "low RPMs" or "don't put much pressure on the bit"?
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Don't put extra ressure on the bit, and keep submerged in cutting oil. Let the bit do the work.
Link Posted: 8/25/2017 3:40:46 PM EST
Not much to add to the good comments so far except that a pin punch helps keep your bit from drifting.
Also, I also use a carbide bit. Do use some kind of cutting oil and don't try to drill too quickly. (I use Kroil)
Link Posted: 8/26/2017 3:47:08 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By MS556:


Don't put extra ressure on the bit, and keep submerged in cutting oil. Let the bit do the work.
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That's what I was thinking, but thanks for the clarification.

What is the preferred cutting oil for nitrided steel, and what can one "get away with" if the preferred oil isn't readily available?

(These aren't really random questions - I am about 70% along in converting an inexpensive low profile gas block into an alignment jig, and I have a couple of barrels I may dimple too.)
Link Posted: 8/26/2017 6:35:43 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By GHPorter:

That's what I was thinking, but thanks for the clarification.

What is the preferred cutting oil for nitrided steel, and what can one "get away with" if the preferred oil isn't readily available?

(These aren't really random questions - I am about 70% along in converting an inexpensive low profile gas block into an alignment jig, and I have a couple of barrels I may dimple too.)
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Have you seen the new KAK dimpling jig? It is the best one so far and is cheap considering it comes with a good drill bit. It's almost not worth messing with making an old gas block into a jig.
Link Posted: 8/26/2017 7:50:13 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By QtrHorse:


Have you seen the new KAK dimpling jig? It is the best one so far and is cheap considering it comes with a good drill bit. It's almost not worth messing with making an old gas block into a jig.
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No, I hadn't. Good thing I hadn't spent much on the gas block I was going to convert...

That looks like an awesome tool. I guess I need one!
Link Posted: 8/27/2017 7:02:47 AM EST
and I just got an SLR jig from JoeBob.
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