Good drill bits for drilling steel

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https://www.amazon.com/gp/aw/d/B001CZH2SK?vs=1 Looking for a good set of drill bits for drilling steel. My DeWalt Cobalt(probably Cobalt coated) have worked great for me in thin steel, soft metal or wood but just won't handle drilling out a broken bolt. Any thoughts on the ones in the link or other suggestions? I love Mac's warranty on bits but until my money tree starts growing in the yard I need to avoid making many tool truck purchases.
 
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Maybe read up on drill bits. Cobalt bits are an alloy not a coating. Titanium or black oxide are coatings. Titanium is harder than cobalt bits but cant be sharpened. Also the style of bit can determine how fast and efficient they are.
 

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Originally Posted By: Rand
Maybe read up on drill bits. Cobalt bits are an alloy not a coating. Titanium or black oxide are coatings. Titanium is harder than cobalt bits but cant be sharpened. Also the style of bit can determine how fast and efficient they are.
That explains a lot. Turns out I the DeWalt bits I have aren't Cobalt they're just gold colored.
 
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Go slow and keep oil on 'em. When you go fast & dry you anneal the tip and ruin things.
 
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I got jobber bits in Cobalt for pilot drilling bolts, gun recievers etc. Pilot drilling a bolt before tackling with a large high speed bit and a good amount of oil to help cool. May want to learn how to weld on a nut to the broken bolt. The heat helps break the bond of the bolt to the part and shot of penetrating oil helps shock it often times allowing to back it out without hardly any effort.
 
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The usual HSS (high speed steel) bits have always worked great for me. You have to match drill speed for the diameter of the bit. Small bit = higher RPM, large bit = slower. I don't usually use oil unless I'm using a dull bit, or drilling into something hardened, like a high grade bolt or something. Don't buy your bits at Walmart or Target.. Lowes/Home Depot can be hit or miss. Quality bits are usually found at your local construction store-- Whitecap, HD Supply, even Fastenal sells good ones. If it's cheap and has a fancy gold or other colored coating, you're buying garbage, in my experience. I've seen two good kinds: regular HSS, and the titanium and/or cobalt ones that cost a pretty penny. Both are good, the latter is better.
 
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Originally Posted By: 92saturnsl2
The usual HSS (high speed steel) bits have always worked great for me. You have to match drill speed for the diameter of the bit. Small bit = higher RPM, large bit = slower. I don't usually use oil unless I'm using a dull bit, or drilling into something hardened, like a high grade bolt or something. Don't buy your bits at Walmart or Target.. Lowes/Home Depot can be hit or miss. Quality bits are usually found at your local construction store-- Whitecap, HD Supply, even Fastenal sells good ones. If it's cheap and has a fancy gold or other colored coating, you're buying garbage, in my experience. I've seen two good kinds: regular HSS, and the titanium and/or cobalt ones that cost a pretty penny. Both are good, the latter is better.
Forgot to mention on steel, you want a shallow point. 118 is okay for normal carbon steel, 135 degrees is preferred for longer life, and any anything hardened.
 
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Originally Posted By: 92saturnsl2
The usual HSS (high speed steel) bits have always worked great for me. You have to match drill speed for the diameter of the bit. Small bit = higher RPM, large bit = slower. I don't usually use oil unless I'm using a dull bit, or drilling into something hardened, like a high grade bolt or something. Don't buy your bits at Walmart or Target.. Lowes/Home Depot can be hit or miss. Quality bits are usually found at your local construction store-- Whitecap, HD Supply, even Fastenal sells good ones. If it's cheap and has a fancy gold or other colored coating, you're buying garbage, in my experience. I've seen two good kids: regular HSS, and the titanium and/or cobalt ones that cost a pretty penny. Both are good, the latter is better.
I agree. All too often people say to "Go slow" when drilling. Not always true. As you said, drill speed or lathe RPM (really tool surface speed) is a function of bit diameter or material diameter in a lathe and also material. Also see lots of chatter about pilot holes. Well depending on the bit size and design, you may not need one. We had two Lawson reps come through the other day (two really good looking ladies who knew their stuff) and let us demo their Regency series bit. She specifically stated NOT to use pilot holes up to the 1/2" bit in their index as is would lead to chipping of the cutting edge. She also said she could tell who was using a pilot hole when it came time to warranty a bit. Due to the design of the point, you just drill and go. We were able to run a (approximately) 3/16" bit through the shoulder of one of their grade 9 bolts. No center punch, no pilot- just put the drill on and go. It made us believers- we ordered one of their indexes, which was really competitively priced!
 
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I had a nice set of DORMER bits in the UK that I used to drill stainless steel. (I had a boat.) Nothing else I used was as good. Dunno if they are sold in the US though.
 
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HUOT HSS AT 135 DEGREES. I have a full set of 1/6 to 1/2 and the sizes over 3/8, I centerless ground the shanks to 3/8'. I can use them in my Milwaukee 3/8 drill. I've had and used them for 35+ years. Ed
 
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Other than super expensive solid carbide drill bits M42 cobalt is the way to go not the cheaper M35. These are not the best but decent enough for the money. http://www.ebay.com/itm/29-Pc-Cobalt-Dri...725.m3641.l6368 Left handed http://www.ebay.com/itm/USA-Left-Hand-Drill-Bits-Drills-Screw-Extractor-EZOUT-Lifetime-Warranty-USA-MADE/171812561365?_trksid=p2047675.c100010.m2109&_trkparms=aid%3D2220072%26algo%3DSIC.MBE%26ao%3D1%26asc%3D39107%26meid%3D0c7d99097108483cb2f175e55c879934%26pid%3D100010%26rk%3D4%26rkt%3D6%26mehot%3Dpp%26sd%3D181713613940#rwid
 
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