Ground drill bits

[AMCLS1]

I've always used Heller drill bits (mainly for the name) but I saw some Blue Spot hss drills in Tk maxx. Well for the money they are fantastic, they also do hss drills in individual sizes in tubes but they say half ground. What does that mean?

 

[Burnerman]

I do hope someone can jump in and help me here, but as I understand it, half ground drills are roll forged and then ground down as far as their flutes.
A fully ground drill is just that......ground along its entire length so that it's cutting diameter is seriously accurate.
These are the drills designated for such as the aircraft industry where tolerances are vital - to the likes of what we do, a half ground drill is fine.
They still use the same tip angles of 118 and 140 degrees ( I think that's correct) and fully ground drills have more cobalt content in their alloy.
Over to others!
John

 

[AMCLS1]

I do hope someone can jump in and help me here, but as I understand it, half ground drills are roll forged and then ground down as far as their flutes.
A fully ground drill is just that......ground along its entire length so that it's cutting diameter is seriously accurate.
These are the drills designated for such as the aircraft industry where tolerances are vital - to the likes of what we do, a half ground drill is fine.
They still use the same tip angles of 118 and 140 degrees ( I think that's correct) and fully ground drills have more cobalt content in their alloy.
Over to others!
John

Thanks for your help John.