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Author Topic: Good Drill Bits????  (Read 3888 times)
Highway Yacht
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« on: March 05, 2011, 12:43:47 PM »

Looking for recommendations on some good quality Drill Bits for drilling into steel. I'm drilling all the new rivet holes in my steel skins and the 1 1/2" tubular steel. I've tried a couple bits for hardend steel like Dewalt Bits and Cobalt Bits and dipped them in oil before every hole but they still seem to dull quickly. I'm using a small 1/8" bit as my pilot hole and that's the one that wears out the quickest. I've got like a 1000 holes to drill and would rather buy good bits that will last awhile instead of drilling 5 holes and tossing it. Anybody know of any good bits for drilling hardened steel??

Jimmy
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Gerry H
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« Reply #1 on: March 05, 2011, 12:53:23 PM »

Try Carbide, but watch your speed.
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« Reply #2 on: March 05, 2011, 12:55:56 PM »

Try Carbide, but watch your speed.

Carbide bits need to be used at a slow RPM??
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Ray D
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« Reply #3 on: March 05, 2011, 01:05:26 PM »

Get the drill doctor.  I put all new stainless skin on my bus and I drilled every hole with two drill bits, nothing special about them,  they were real short when completed though.  When you get the knack down for sharpening, how much pressure to put and correct drilling speed (I varied both pressure & my speed from slow to medium in spurts), they will stay sharp quite a while.

Ray D
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DaveG
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« Reply #4 on: March 05, 2011, 01:25:12 PM »

Try a "split point" bit, something like Fastenal's Black & Gold. Almost all 1/4" & 3/8" drill motors turn too fast for this type of drilling. Start with a good quality bit (not the most expensive) and control your speed and keep pressure on the bit...you want it cutting into the material, not just riding around and spinning on the material. Also, might want to be careful that your "pilot" hole is too close to the hole size you are drilling.
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Charley Davidson
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« Reply #5 on: March 05, 2011, 01:26:58 PM »

Your using mild steel unless it's stainless so just a jobber bit will/should do the job
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JackConrad
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« Reply #6 on: March 05, 2011, 01:29:25 PM »

Use a good lubricant such as WestLube. Overheating the tip of the bit is the fastest way to shorten bit life (other than breaking the bit).  Jack
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« Reply #7 on: March 05, 2011, 03:11:52 PM »

I would go to an industrial supply place and buy GOOD drill bits.Tell them what you are drilling. Dewalt stuff(almost all of it) is JUNK!!!
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Iceni John
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« Reply #8 on: March 05, 2011, 03:29:10 PM »

I agree that a Drill Doctor is a necessity.   I have to resharpen after two holes in stainless, and after every few holes in the 90,000 PSI steel that Crown used.   I used to buy US-made drill bits, but found they don't always last longer than some import ones.   I got a few bits recently from Ace Hardware, and they're surprisingly good for being Chinese.   I have two complete sets of HSS bits:  one set has 118-degree point angles for harder metals, and the other is 135-degree for aluminum and softer materials.   I also always use cutting oil, either Tapmatic or a sulphured oil, and this helps prolong the bits' life.

John

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« Reply #9 on: March 05, 2011, 03:38:29 PM »

I buy quality bits, run them around 800 rpm and use a lot of pressure.  The bits need to cut, it's when there is too little pressure that they heat up and dull.

HSS bits, I don't bother sharpening them.  i just toss them.

Brian
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« Reply #10 on: March 05, 2011, 05:25:50 PM »

I used split point cobalt drill bits when I did the 1,000 holes in my bus.  I found they drilled the fastest when run at a fairly high speed and they didn't seem to wear out any faster at a high speed.  I dipped them in oil several times per hole.
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« Reply #11 on: March 05, 2011, 05:52:29 PM »

sheeting bits have drill on each end . just swap ends and keep sharp. A 3/16th can be easily hand sharpened on a good bench grinder or if you don't feel confident use a drill doctor. As others have said heat is the enemy! I keep a jar of cheap vasoline and dip bits to help lubricate and cool. Just dip bit in jar at end of each hole.   Bob
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« Reply #12 on: March 05, 2011, 07:26:53 PM »

The trick as mentioned before is drill slow. If you rev that drill up it will eat the edge right off your bit. Make sure you have The Drill Doctor. It cost less for the Doctor than to buy enough bits to do the job. Have about 10 bits and at the end of the day sharpen them all and start fresh the next day.
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« Reply #13 on: March 05, 2011, 09:24:31 PM »

If you can find some of the old stepped bits that Boeing surplus used to sell, they are hard to beat. I still see them at lots of the swap meets although they sell for a lot more than Boeing used to get. I remember buying them for $2.00 a pound ten years ago. They seem to get 50 cents to a  buck for them now but that's still a bargain, I think. Anyway, I had great luck with them. Good luck, Hal   
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« Reply #14 on: March 05, 2011, 10:10:19 PM »

"dipping the bit in oil" will destroy the bit in short order.  Some materials will finish the job quicker but oil will always speed up the dulling.  You absolutely must use Drilling or taping "cutting oil".  I learned this from an old salt machinist more recently that i want to admit.  Now somebody please explain to me WHY cutting oil is so darn expensive considering the ingredients.

John
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« Reply #15 on: March 06, 2011, 08:55:20 AM »

My drill bits lasted about 80 holes each when used with plain oil so it must not have been too bad.  I bought a Drill Doctor, but none of the bits worked worth a darn after sharpening.  I gave up on the Drill Doctor and just bought a dozen or so bits for the project.

I know many people have great luck with the Drill Doctor but I just couldn't get it to work for me.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #16 on: March 06, 2011, 10:10:29 AM »

My drill bits lasted about 80 holes each when used with plain oil so it must not have been too bad.  I bought a Drill Doctor, but none of the bits worked worth a darn after sharpening.  I gave up on the Drill Doctor and just bought a dozen or so bits for the project.

I know many people have great luck with the Drill Doctor but I just couldn't get it to work for me.

I know from your post history that you are experienced and skilled.  Your knowing that the Drill Dr works gangbusters for others is your clue that you are not doing something correctly.  The sharpener is without equal in doing its job, really.  Sooooo many testimonials.  From your post I hear you asking for help like so many do in that you make a statement that you want refuted.  Yes, you can get it to work cause the "universe" is telling you so.  Some of the "magic" is closely" following the instructions TO THE LETTER.   The rest is a little tricky.....it involves the "feel" of doing it correctly and that can be elusive.  The quickest way to get that "feel" is to find a guy that can do this and spend every bit of TEN minutes with that "guru of sharpening" in a hands-on session.   Have him over or pack one of your dull 3/8 inch bits over to his place.  The price on the Drill Dr keeps going up and the device keeps shrinking and demand isn't falling off as far as I can tell.....it really works well Brian.    I have a friend that is a master at metal working and fabrication and he had one sitting in the corner for more than a year.  I asked why he never used it and he said he had NEVER been able to get it to work even once.  I pulled it out and sharpened a bit using the instructions, I had never touched one, and asked what the problem was in my own confusion.  He took another bit and screwed up the step that aligns the bit so that you get the angle of the cutting edge located properly and his bit had the cutting bevel ground on the bit exactly backwards.   Ah Ha, owwwww, so its supposed to be.....  5 minutes and he is a sharpening Guru too.   Great tool!  I now own my own.

HTH,

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
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« Reply #17 on: March 06, 2011, 10:32:42 AM »

My drill bits lasted about 80 holes each when used with plain oil so it must not have been too bad.  I bought a Drill Doctor, but none of the bits worked worth a darn after sharpening.  I gave up on the Drill Doctor and just bought a dozen or so bits for the project.

I know many people have great luck with the Drill Doctor but I just couldn't get it to work for me.

Cutting oil isn't all that cheap.  Every machine shop I have ever visited had cans of Cutting oil sitting at every drill press.  To me those are the experts and it is their "lie" that I am repeating and not my own.  But as far as "lies" about drill and such, I think they are highly quotable.  I have never gotten an answer from them as to "why" the stuff works.  Kerosene and turpentine work as a substitute but that was a odd source for that info so I don't know what is in the cutting oil and I haven't really researched it.  I have a hunch that using it becomes more critical as the size of the bit goes up but I don't know that either.  Her's my guess....oil makes a shield around the microscopic cutting edge and traps heat and softens the edge which "obligingly, wears of and dulls quickly.  Cutting oil is thin and carries the heat away.  Machinists pour water soluble oil mixed with water on their work and they direct the stream to the tool/material contact point and I think the water is the most important ingredient and the oil is a wetting agent.  I don't know but that is my reasoning.  Shouldn't be hard  to research and the board is capable of the answer I am certain.  You got 80 holes from a single drill bit but how many would it do if cutting oil were used?  Maybe none.  Dunno!
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
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« Reply #18 on: March 06, 2011, 11:15:23 AM »

I'm not saying you shouldn't use cutting oil.  I'm just relaying my experience with ordinary oil.  I didn't know any better at the time so I used what I had on hand.  I probably would have purchased and use cutting oil had I known at the time.
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« Reply #19 on: March 06, 2011, 11:58:15 AM »

Exactly my experience and I also got the cutting oil at the same point in my "career".  Whu Knu? Grin

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
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« Reply #20 on: March 06, 2011, 01:00:28 PM »

John Ed the water makes sense, which I actually learned from a Susi Chef. He had some beautiful chef knives and was running the fine stone under water. I thought he was cleaning it, but he said no he was sharpening it.
He said that water is the best cooling and sharpening agent to use for any metal or stainless steel instrument. I asked about oil and he mentioned that it protects the blade from being sharpened but will dull because of holding particles of itself around the blade and in the oil and dulls itself but that water cools better and has less friction. FWIW

Dave
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Ray D
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« Reply #21 on: March 06, 2011, 01:11:44 PM »

Cutting oil at the drill press, yes; hand drill, not very often.  For a hand drill the main purpose of the oil would be cooling and generally for a hand drill you are not going very deep, cooling the bit after each hole is what I do.  The lubricating property is not much use on a hand drill, it is hard to keep it wet enough & the lubricating property works best on threads, hack saws & drill presses, makes the tool work easier; and if you're getting any brown or blue cuttings, you are working the tool to hard.

Disclaimer:  This is how I was taught, not saying it is the correct way, it's my way.
Ray D
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robertglines1
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« Reply #22 on: March 06, 2011, 01:36:43 PM »

I mentioned vasoline in a earlier response. I use it to cool bit slowly to keep it from becoming brittle.  I have noted other responses and can see their advantages --cutting oil and like(thread oil)-- good discussion and a lesson learned. Bob
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« Reply #23 on: March 06, 2011, 01:48:31 PM »

I got a can of "Mitee" thread cutting oil free in a box of junk I mean goodies. I used it with a bit that drilled nicely without it on the previous hole but went dull instantly using the oil.
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« Reply #24 on: March 06, 2011, 03:14:28 PM »

I got a can of "Mitee" thread cutting oil free in a box of junk I mean goodies. I used it with a bit that drilled nicely without it on the previous hole but went dull instantly using the oil.


It was junk! Huh Tongue Grin Grin Grin


John the proof is in the pudd'n
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla
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« Reply #25 on: March 06, 2011, 06:23:59 PM »

Try this
http://www.browntool.com/Default.aspx?tabid=255&txtSearch=boeing+lubercant&List=1&SortField=ProductName%2cProductNumber&ProductID=1735
jlv
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Charley Davidson
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« Reply #26 on: March 06, 2011, 09:23:36 PM »

I got a can of "Mitee" thread cutting oil free in a box of junk I mean goodies. I used it with a bit that drilled nicely without it on the previous hole but went dull instantly using the oil.


It was junk! Huh Tongue Grin Grin Grin

You saying my free oil was not worth what I paid for it? Shocked Huh Roll Eyes Tongue
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Charley Davidson
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« Reply #27 on: March 07, 2011, 07:36:19 PM »

Surprisingly my favorite bits to use for mild steel that's 3/16 or less & I don't need a precision size is the multi/step bits from Harbor Freight. When I find them on sale  I buy them whether I need them or not. They last/perform very well
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« Reply #28 on: March 07, 2011, 07:59:09 PM »

As Jack says, "westlube". It's magic stuff; nothing better.  Amazing on stainless too...

And as junky as some Harbor freight stuff is, their drillmaster drill bits are really good.  A bit brittle but hard and long lived.
Their taps are pretty good too! Charley's right- their step bits are also really good items. They last a lonnnnng time with westlube!
« Last Edit: March 07, 2011, 08:02:02 PM by boogiethecat » Logged

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