On Mon, August 27, 2018 2:54 pm, terry burge wrote:
<snip>
> I truly hate the job of drilling thru the mast. If I ever do
> that again I think I will start with a new set of drill bits every time.
<snip>
The trick to drilling Chrome Molly Mast (which is 4130 steel if you want
to get technical)
KEEP IT SLOW in RPM, and FEED HARD, and DON'T STOP <yes I'm shouting>
Here is the problem - if the 4130 gets hot, and then you STOP, the
material will self quench, and get HARD, and cutting oil can just make it
worse
Get yourself a good drill bit (Cobalt is good, but a good HSS bit will
do), and run the drill SLOWLY. For a 1/4" drill, 900 rpm is FAST, for a
3/8" 600 rpm is fast (aka figure 50 SFM or so), and keep the feed up - aka
you want to try and get .004-008" per revolution of the drill bit,
otherwise the tubing gets hard
AKA for your typical cordless drill, put it in low speed mode, and work
from there (Most top out 500-600 RPM)
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