[TowerTalk] Drill bits

[Larry McDavid]

"Dark" cutting oil usually means it is "sulfurized." Sulfurized cutting 
oil is good for machining steel and should work better even if hand 
drilling. "Light" cutting oil is not sulfurized and is not best for 
cutting steel.

My opinion is that you should be using a drill press, turning at low 
speed, well lubricated, with frequent drill extractions to remove chips 
and at moderate to strong cutting force. Don't let the drill spin freely 
as that will tend to work harden the material and make cutting more 
difficult. The goal of managing cutting speeds and feeds is to make sure 
enough material is removed to prevent work hardening but without 
excessive wear of the tool bits.

Unless you have a really big drill press, starting with a smaller drill 
bit, say 1/4-inch, will really help. Trying to do this with a hand drill 
will be pretty much hopeless, I think.

Larry W6FUB



Jim Miller KG0KP wrote:
> Finally, somebody who KNOWS about cutting oil...

-- 
Best wishes,

Larry McDavid W6FUB
Anaheim, CA  (20 miles southeast of Los Angeles, near Disneyland)