(sorry, a little late)
To drill thru metal more effectively:
Start using a very small bit first. They will break thru fastest because
there is less metal surface to cut. Then, use a bit that is the next size
up or close to it. The next bit will then only have to cut a small amount
of metal on the side of the hole. This will keep your bits from dulling
quickly, as well as speeding up the whole process. Use each bit
progressively until you have the correct diameter.
Also, they make a special metal cutting bit that looks like a cone. It
does a similar thing, though, the front blade isnt always as small as
needed to get a good start. Also, they have limitations on angles,
depth, steps, and as I recall... do not work too good on very thick
work.
Saturate the bits, and even the spot you will drill, in cutting fluids,
or some sort of oil. The bits need to be cool as possible, and have a
nice smooth ride... else they will dull much faster. Clean out
scrap particles every few seconds from the pit (when drilling deep),
so as not to have to grind your bit against metal that is already cut.
If cutting very thick metals, your bits may get too hot. You should
douse them in a bucket of cold water every so often. This should
reduce the dulling as well. Some industrial cutters spray water
or some other coolent/lubricant while the machines are cutting.
NEVER use too much pressure. This will dull the bits VERY QUICKLY.
Use high speed, and med to light pressure. It takes time to carve
away at the metals.. but if you rush it, the cuttiing blade will
die.
If you notice that there has been no progress for a long time, that
means your bits front cutting surface is too dull and needs to be
sharpened or replaced (Drill Doctor works great!). Or, you have been
trying to cut with a bit that is too fat without using the
'progressive-size' drilling as I mentioned earlier.