Three Flute Drill Bits

J

Jake M

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I've got a question about three flute drill bits. I've never played with them. I've had a nice set of "standard" drill bits picked for some time, made of kryptonite and all... The budget's coming together, but I'm starting to wonder about these three flute varietys, if you've ever used them.

Are they stout, or does the extra flute leave them weak/brittle? Is hand use an option?

Can these be sharpened by "normal" means?

Is there such thing as ?split point?, ?center cutting? with these things?

Bottom line, are these things worth messing with on a hobby/occasional use type basis?
 
I didn't know about those- makes a cleaner hole maybe, or they wander less?
 
Three fluted (core) drills are used for the most part for sizing cored holes in castings, they will also enlarge holes that have a keyway inside, they are as much a reamer than a drill. and usually result in a fairly accurate hole. They are not so much a hobby tool as a production tool, and would be difficult to sharpen accurately by hand. They are not made to drill a hole from solid metal.
 
benmychree said:
Three fluted (core) drills are used for the most part for sizing cored holes in castings, they will also enlarge holes that have a keyway inside, they are as much a reamer than a drill. and usually result in a fairly accurate hole. They are not so much a hobby tool as a production tool, and would be difficult to sharpen accurately by hand. They are not made to drill a hole from solid metal.
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The sudden advertising as push on these particular drills of various brands, by "internet algorithms", probably AI to at least some degree "for harder and tougher materials" sounds very intriguing, as that's what I'm after. What you say makes a lot more sense. They're not for "harder materials" as stated, they're for holes that are hard to drill.
 
Three, or four, flute drill bits are fantastic when you are breaking through into a curved surface. Think, drilling through a thick wall tube. They don't seize on break through the way a two flute bit will. I learned this after a tech where I worked got hurt when a bit seized in a work piece, and the fixture securing the part started rotating on the drill press platen. This was completely solved by adopted 3/4 flute drills for that particular operation.
 
To answer your last question (3F for general purpose hobby work): No. For regular general purpose work, the general purpose 2F, 118 degree work well. When you get into drilling details there are a lot of options and you can spend some pretty good coin. I have a couple regular revenue jobs come into my hobby shop that I bought special drill bits for each of those tasks - they are 20 to 40x the cost of a conventional drill bit - the performance is unbelievable (fast, good finish, spot on for size, extremely long tool life) - worth every penny. Yet if I’m just punching a hole in a piece of metal I grab a conventional drill bit and drill the hole.
 
Nesse1 said:
Three, or four, flute drill bits are fantastic when you are breaking through into a curved surface. Think, drilling through a thick wall tube. They don't seize on break through the way a two flute bit will. I learned this after a tech where I worked got hurt when a bit seized in a work piece, and the fixture securing the part started rotating on the drill press platen. This was completely solved by adopted 3/4 flute drills for that particular operation.
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Sounds like a good application for a 2 or 3 flute (maybe reverse spiral) center-cutting end mill.
 
Core drills rock for enlarging holes; surf fleabay for some in coarse steps. I use them on my lathe.
VERY round and precise holes, after hogging an eighth or more out

Sent from my SM-S911U using Tapatalk
 
MANY MOONS ago, I bought all the drills at a machine shop auction. They go by 64s from 1/4 to 1 1/2 up to a dozen of each size. Got a HUGE number of core drills in this lot most all dull. So, I almost never use them.

Hand sharpening don't work here, at least for me. (I am good at hand sharp 2 flute). Problem is getting all the flutes to cut even. leave one longer and you don't get the results core drills can do.

How do you get these drills sharpened?
 
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