Drill bits for metal work.

[LD1]

...especially if it has to be done in the field with portable tools and power etc...

If I HAD to step bits (make a hole larger because going to oversized bolt, drilled wrong, etc), hand tools would be my LAST choice.

There is nothing easy about trying to use a 5/8 bit in an existing 1/2" hole. But is grabby, and good chance at breaking corners off bit.

If I had to drill a 1" hole with a portable drill motor, I'd pilot the web thickness, probably about 1/4 ", then I'd drill with the 1". It would be faster than multiple stepping, and alot easier on me, the tool, and the bit.

If you think multiple stepping is faster, it's probably because you are running too fast and burning your bits, and by stepping, you have enough contact pressure to overcome that and punch through anyway. Rather than try to burn through with a dull bit.

 

[/pine]

...If I had to drill a 1" hole with a portable drill motor, I'd pilot the web thickness, probably about 1/4 ", then I'd drill with the 1". It would be faster than multiple stepping, and alot easier on me, the tool, and the bit...

It was hypothetical...but if the object being bored was 1/2", 5/8" or 3/4" plate you are dead wrong on the time

 

[LD1]

It was hypothetical...but if the object being bored was 1/2", 5/8" or 3/4" plate you are dead wrong on the time

If you are using a 3/8 chuck, 4 amp drill motor......or a 20 year old 14.4v nicad cordless....then perhaps. Because neither would have enough power to still spin even with moderate pressure to form a chip.

And thus you must rely on the extreme tip pressure of just cutting a sliver off at a time. And no real danger about a gutless drill winding you up.

But use any quality ~10+ amp drill motor that has slow enough RPMS/gearing to lay on it and not stall.....Then no I am not wrong on the time.

 

[SPYDERLK]

Anyone in the trade long enough knows for a fact "it" can be a faster/easier technique...it was never about "learning" the theoretically correct way of doing anything...
On most commercial jobs...twist drills are considered as consumables...and most mechanics abuse them to save time...

Now if you're a (union card carrying) BTH machinist of course you are going to go by the manual...but everyone knows the fastest method...especially if it has to be done in the field with portable tools and power etc...

Honestly I do not recall a lot of threads/debates on the subject...but your argument is about the same as taking the guards off of angle grinders or disconnecting seat safety switches etc...there's nothing superior to your method...PERIOD

How do you prevent orbital chatter and grabbing when stepping up gradually. Do you modify the lead angle by "brassing" the bit to prevent grabbing? Are you often replacing or sharpening bits to remedy damage?