# 3 & 4 flute drill bits



## iron man (Sep 25, 2014)

I use to use 3 & 4 flute drill bits when I worked in a machine shop they really worked well and where fairly accurate you had to drill a pilot hole but after that they really cut nice almost a finish as nice as a reamer. So I asked a local vender if he could get me a set he looked at me with a blank stare I could tell he did not have a clue. I started to look for them on-line and much to my surprise I found nothing am I the only one in this world that has used these?? Ray


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## Andre (Sep 25, 2014)

I used a Weldonite 3 flute CC endmill for counterboring once, it worked great and cut like a dream. Seems like sharpening a 4 flute drill by hand would be a nightmare getting all the grinds to the correct length.


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## Bill Gruby (Sep 25, 2014)

iron man said:


> I use to use 3 & 4 flute drill bits when I worked in a machine shop they really worked well and where fairly accurate you had to drill a pilot hole but after that they really cut nice almost a finish as nice as a reamer. So I asked a local vender if he could get me a set he looked at me with a blank stare I could tell he did not have a clue. I started to look for them on-line and much to my surprise I found nothing am I the only one in this world that has used these?? Ray



 As I see it you are still the only one that has used or even seen them. You wouldn't  happen to have a picture would you. I'm not saying they do not exist. only that I have never seen or heard of one. For counter boring I use a counterbore.

 "Billy G"


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## iron man (Sep 25, 2014)

Bill Gruby said:


> As I see it you are still the only one that has used or even seen them. You wouldn't  happen to have a picture would you. I'm not saying they do not exist. only that I have never seen or heard of one. For counter boring I use a counterbore.
> 
> "Billy G"



 After a long search I found this one not cheap and not a set..

http://www.amazon.com/Cleveland-Speed-Steel-Degree-Conventional/dp/B0026GWU0Y


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## Ebel440 (Sep 25, 2014)

I have some of the drills your talking about I think they are reamers though ill try to find one and take a picture


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## iron man (Sep 25, 2014)

There not reamers they are drill bits they really can get you out of trouble. Ray


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## LaVern (Sep 25, 2014)

When I was working in tool grinding we called them "Core Drills". We used an Oliver drill grinder to sharpen them and it was capable of sharpening 2, 3, and 4 flute drills. As I recall they were a bit tricky to get them set up right but after a few times of sharpening them you knew what to look for.  Anyhow if you are looking for some try "core drills".
LaVern


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## Ebel440 (Sep 25, 2014)

Sorry I meant I thought mine were reamers. I have always used them as reamers mine have a small pilot on the tip but may be the type of drill you are talking about


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## Bill Gruby (Sep 25, 2014)

If the pilot has no flutes and the body flutes look like an endmill what you have are Counterbores. The pilot follows the drilled hole to keep the C/Bore straight. They are not drills. See Below.

 "Billy G"


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## John Hasler (Sep 25, 2014)

If I understand your description I've got a three-flute version of that.  Looks much like an ordinary twist drill except that the tip is truncated (made that way, not ground off by someone) and a bit different from that on a twist drill.  I recall reading about four-flute ones but I can't recall where.


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## JeepsAndGuns (Sep 25, 2014)

Cobra carbide makes 3 flute drill bits, in solid carbide. Expensive little buggers!

http://www.lawsonproducts.com/Supertanium/Solid-Carbide-Drill-Bit-Kit/P7369.lp#
http://www.lawsonproducts.com/Supertanium/Cobra-Solid-Carbide-Drill-Bit/P58056.lp






I have a set of these that came with my smithy (bought used) for sale if anyone is interested.


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## John Hasler (Sep 25, 2014)

Is this what you mean?


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## Bill Gruby (Sep 25, 2014)

Because those drill bits have a raised edge doesn't give them an extra flute. Show me the business end that has three separate twisted flutes. I only see two on all of those. I am not doubting anyone but I want to see one.

 "Billy G"


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## 12bolts (Sep 25, 2014)

Bill the links that have been posted all specifically state they are 3 and 4 flute drills. Jeeps&Guns boxed set look like 3 flutes to me.

Cheers Phil


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## John Hasler (Sep 25, 2014)

LaVern said:


> When I was working in tool grinding we called them "Core Drills". We used an Oliver drill grinder to sharpen them and it was capable of sharpening 2, 3, and 4 flute drills. As I recall they were a bit tricky to get them set up right but after a few times of sharpening them you knew what to look for.  Anyhow if you are looking for some try "core drills".
> LaVern



The core drills I am familiar with are hollow and designed to extract a core sample from something.


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## John Hasler (Sep 25, 2014)

Bill Gruby said:


> Because those drill bits have a raised edge doesn't give them an extra flute. Show me the business end that has three separate twisted flutes. I only see two on all of those. I am not doubting anyone but I want to see one.
> 
> "Billy G"


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## Tony Wells (Sep 25, 2014)

They are core drills. Used to us them all the time to enlarge predrilled holes. I have a few now that I need once in a while. One is a fairly large 3 1/4" I believe. They will cut straight and on size if they are sharpened correctly. They are very rigid. I have some if pics are needed. No good for just punching holes. No drill point.

John, you are thinking of coring drills/bits. They are designed along the function of a trepann, to bring out a useable center core as a sample, for instance.


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## Bill Gruby (Sep 25, 2014)

OK now I know what you are referring to. Thank you for the pic. Tony nailed it. Core drills I have used but they do require a thru hole first. Sorry if I raised any confusion.

 "Billy G"


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## darkzero (Sep 26, 2014)

I have a couple. They're not core drills, well I don't think they are, I have used them without a through or pilot hole . These might not be exactly what the OP is talking about, these are probably some sort of specialty drills. They're solid carbide & I have only test used them on Ti 6-4. That's the only time I have used them, they did drill very nice but they load up with chips quicker than 2 flutes on deeper holes, they just sit in my tool box.


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## Tony Wells (Sep 26, 2014)

No, those aren't core drills. I'll put up some pics tomorrow. I'm sure many of you have seen or used them. They're not really common, but they do what they do pretty well. If you have a fairly deep or long part with a hole through, you can drill from both ends to the middle, then run the core drill all the way through to get a decent straight hole.


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## geryuri2 (Sep 26, 2014)

The drills in the above photo are center cutting, pretty unusual.  Core drills on the other hand are not (center cutting) they require an existing hole.  Classic first year machinist question "what is a core drill?" (A) It is used  to enlarge an existing hole, like one cored into a casting; hence the name.  They are extra rigid, to reduce wander due to the core in the casting not being precisely placed.


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## JeepsAndGuns (Sep 27, 2014)

As requested, heres a picture of the tips of the ones I have.


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## Terrywerm (Sep 27, 2014)

Thanks for this thread and responses, everyone!  I learned something new!


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