3 Flute Drill Bits,Any Users

[Tundra Twin Track]

I got some of these NOS 3 flute drills a while back,used one for the first time yesterday and real impressed,the hole is very smooth.

[reggie_obe]

I've seen them used on cam driven screw machines. Hollow mills as well.

[projectnut]

They look like parabolic or high helix drills. They're primarily used for deep hole drilling to minimize having to peck to remove swarf. I have a set of fractionals up to 1/2" made by Chicago Latrobe. They work great. They're best used in a machine rather than a hand drill. The high helix tends to pull the drill into the work piece. They're easily controllable in a mill, but a bit harder with a hand drill.

[old mart]

Can they be used directly, or is a pilot hole required?
Are the illustrated ones solid carbide?

[Tundra Twin Track]

Can they be used directly, or is a pilot hole required?
Are the illustrated ones solid carbide?

I used them with no pilot hole and solid carbide.

[boslab]

Haven’t tried them, only the basic 4 flute core drills if got a few sizes of, not ream finish but not far off, needs a pilot hole unlike triflute I’ve been told, think I might invest in a few to try, just some basic sizes like 16mm clearance, plus they look cool
mark

[CarlByrns]

In smaller sizes, three flute drill bits were used to make/modify carburetor jets. They leave a nice round swirl-free hole.

[Tundra Twin Track]

Haven’t tried them, only the basic 4 flute core drills if got a few sizes of, not ream finish but not far off, needs a pilot hole unlike triflute I’ve been told, think I might invest in a few to try, just some basic sizes like 16mm clearance, plus they look cool
mark

I would have never bought these over the counter way to pricey for my shop,but scored them at garage sale.

[JoeLee]

I've seen them before but don't have any. I do have some 3 flute end mills.

JL.............

[Dunc]

Purchased set (1/16 - 3/8 inches) on sale @ local hardware store sale. supposed to [superlatives]... If there is a difference I fail to see it in either performance or results

[old mart]

I have just looked at a HSS three flute drill on ebay, and that type would need a pilot of 1/3 its diameter. Solid carbide drills give a better finish and hole size than steel drills, those three fluters must be awesome.

[boslab]

TTT is right, them things is very very pricey, oh well semi sharp Chinese decorative iron drill it’ll be, how sad, was looking forward to high tec drills
mark

[Tundra Twin Track]

TTT is right, them things is very very pricey, oh well semi sharp Chinese decorative iron drill it’ll be, how sad, was looking forward to high tec drills
mark

Mark I knew they were pricey,just talked to Kennametal Dealer $365 for the 5/8” and 1/2” $305,pretty happy paying $8 each for them lol!

[754]

They may be used for drilling cored holes in castings.. I mean their intended use..

[projectnut]

Sometimes you get lucky. I paid $65.00 for the 1/16- 1/2" (by 1/64 increments) set of Chicago Latrobe set I bought last year. They came from a company that buys out industrial businesses overstock, or inventory from closed businesses. They were simply listed as "High Speed Jobber Drill Set". I could see from the photos what they were, and the price was unbeatable.