3 & 4 flute drill bits

[JeepsAndGuns]

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.

 

[John Hasler]

Is this what you mean?

 

[Bill Gruby]

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"

 

[12bolts]

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

 

[John Hasler]

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.

 

[John Hasler]

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"

 

[Tony Wells]

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.

 

[Bill Gruby]

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"

 

[darkzero]

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.

 

[Tony Wells]

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.