# Drilling Tungsten Steel



## GrouseHiker (Mar 2, 2010)

The bolt on the Remington 597 is apparently tungsten steel for added weight. I'm trying to drill it with a small bit so I can tap and install a set screw. The high-speed-steel bits are barely cutting. The "attempt" at a hole is at the end of a machined slot. Could the tungsten steel have been hardened by the factory machining?


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## trial&error (Mar 2, 2010)

don't know about tungsten steel, but I know when machining stainless in the shop it becomes very hard and difficult to drill.


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## Gunplumber Mike (Mar 2, 2010)

Have you tried a carbide bit?


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## 1devildog (Mar 2, 2010)

A carbide might cut it, just remember to keep the speed SLOWWWWW, fast will burn up a bit in seconds. Although expensive, a dimond tip bit will drill it no problems what so ever.


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## GrouseHiker (Mar 2, 2010)

I almost clicked on the $7.50 carbide bit, but the things are so small (#53), I figured I would snap it. I know the carbide is a lot stiffer than HSS ($1.75), but I don't know if it's actually harder - to allow cutting harder materials.

I was hoping I would eventually break through some surface hardening and get to softer metal.

Added: I was doing the drilling by hand, since my drill press is not trued, will not chuck that small a bit, and seems to spin too fast.


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## Hammack (Mar 2, 2010)

Good luck, I don't know of a hand drill that will turn slow enough to not burn up a bit on hard metal.  A carbide bit is harder than a HSS.  Do you know what grade steel the bolt is?  I don't have a 592 but if it's tungsten carbide I don't think you will be drilling it.


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## GrouseHiker (Mar 2, 2010)

Hammack said:


> Good luck, I don't know of a hand drill that will turn slow enough to not burn up a bit on hard metal.  A carbide bit is harder than a HSS.  Do you know what grade steel the bolt is?  I don't have a 592 but if it's tungsten carbide I don't think you will be drilling it.



I've got this old Sears electric drill that will creep down to 0 rpm. I tried slow and fast with the HSS - barely a dent so far. Regarding the tungsten/steel bolt, I'm just repeating what I read on some forum about its composition; however, the bolt is VERY heavy for its size. I don't think it's carbide (I've stoned the face of the bolt a little), maybe just a tungsten alloy. I'll go ahead and order that tiny, solid-carbide bit (http://www.mcmaster.com/#2860a69/=61pl38) if you think it will cut better than the HSS.


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## miles58 (Mar 2, 2010)

David,

The bolt is not tungsten carbide.

It may well be very hard though.

Buy the carbide bit.  Take the chuck off your hand drill.  go to the hardware store and buy a bolt that fits the chuck.  screw the bolt into the chuck and cut it off, then chuck the bolt up in the drill press and run the carbide bit slow to drill the hole.  Don't be bashful with the oil to lube it when you drill the hole.

Dave


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## GrouseHiker (Mar 4, 2010)

The carbide bit worked like a charm. However, I guess it also made me overconfident - broke the tap off in the hole.

I got the broken piece of tap out. I'm writing this one off to a bad purchase decision. The carbon steel tap (~$5) shattered like glass. The HSS steel tap (~$9) has a lot more flexibility, and the twisting provides feedback on the stress it is seeing. The carbon steel tap was very rigid.

I've decided to upsize the set screw and get away from the tiny 1-72 threads.


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## miles58 (Mar 4, 2010)

GrouseHiker said:


> The carbide bit worked like a charm. However, I guess it also made me overconfident - broke the tap off in the hole.
> 
> I got the broken piece of tap out. I'm writing this one off to a bad purchase decision. The carbon steel tap (~$5) shattered like glass. The HSS steel tap (~$9) has a lot more flexibility, and the twisting provides feedback on the stress it is seeing. The carbon steel tap was very rigid.
> 
> I've decided to upsize the set screw and get away from the tiny 1-72 threads.



I have to give you this, you do provide some amusing threads to watch.

Dave


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## GrouseHiker (Mar 18, 2010)

Well I believe I reached the end of my rope on this little set screw project. The tungsten steel bolt is so hard, only carbide will cut it reliably. I finally got the hole drilled, but tapping threads was another story. Carbon steel, cobalt steel, and high speed steel wouldn't cut it. The cobalt vanadium tap got me a few threads cut before it snapped - and believe me I was VERY careful. Unfortunately, a 3-48 tap is not available in carbide. I would consider trying another cobalt vanadium tap if I could find one with a taper chamfer rather than a plug chamfer, but I don't think that exists either.

I probably have enough threads to hold a cut-down set screw, but it's not what I wanted. I'll just have to loctite it in and shorten it if necessary to get within my adjustment range.

I considered upsizing to 4-40, but I would run into clearance problems. Also, I'm not real excited about investing in a $100 carbide tap. So the bottom line: It was a learning experience, but not extremely successful.


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## kscoggins (Jul 11, 2010)

you could turn a plug tap into a taper with a grinder and some patience.


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## jfiliaul (Jul 28, 2014)

Here.. they do make a 3-48 Carbide Tap... Enjoy 
http://www.ebay.com/itm/like/201020096574?lpid=82
Not sure if thats a taper tap but this one DEF is!:
http://www.carbideemporium.com/cart...o&cPath=1531_1536_1751_1763&products_id=53622


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## Darkhorse (Jul 28, 2014)

I've machined all kinds of metal over my career as a toolmaker and I was taught young to look ahead, doing that I would not have attempted to drill something which I probably could not tap. You got the tap out. Good and shows skill as it can be tough. But what about next time? Breaking a 3-48 deep in a hole often can't be removed.
Just curious, why are you doing this? Help me visualize the purpose/problem/benefit.


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## hayseed_theology (Jul 28, 2014)

Darkhorse said:


> I've machined all kinds of metal over my career as a toolmaker and I was taught young to look ahead, doing that I would not have attempted to drill something which I probably could not tap. You got the tap out. Good and shows skill as it can be tough. But what about next time? Breaking a 3-48 deep in a hole often can't be removed.
> Just curious, why are you doing this? Help me visualize the purpose/problem/benefit.



This thread is over 4 years old.  GrouseHiker hasn't logged in 3.5 years.  You probably aren't gonna hear from him.


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## Darkhorse (Jul 28, 2014)

My wife says I never pay attention. Maybe she's right.


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