unusual carbide tip drills ?

[Mark914]

i assume these are carbide tipped drills ? i have 2, i think they are old, at least 20-30 years. why is no flutes? most masonry type bits i see have spiral flutes. are these cheaper? what are they good for?

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[rsanter]

They look like metal drill bits for deep hole drilling
They are to be use in a mill or a drill press, not by hand

Bob

 

[Givl Reggin]

Looks like a star drill - you hit it with a hammer and turn it by hand.

 

[Provincial]

Look up "gun drill". They are used with coolant. The coolant flow flushes out the chips and keeps the bit lubricated and cool. Most of these were used in lathes with the drill bit not rotating, as it is held by a chuck in the tailstock.

In order to work correctly, most gun drill bits have a passage that leads from the held end of the drill up through the shank and opens at the working end. This is how the coolant is introduced in a way that carries the chips out the straight flutes.

 

[bobadame]

That looks like a gun drill for deep hole drilling. Coolant is fed through the center of the drill at high pressure, several hundred psi. I haven't seen one of those since the late 60's

 

[beerdog]

Is there a hole down the center?

 

[rodm1]

It's a hard steel drill for drilling after heat treat. If you need one you really have a problem. Run as fast as machine will go very low feed no coolant and just burn your way threw.

http://www.grainger.com/Grainger/B-A-Hard-Steel-Drill-Bit-4VYX3

 

[Mark914]

Thanks for the responses. No hole in the middle.
I think Rodm got it right. Looks just like the one in the link to Grainger