Thread: Need advice on drill bits

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The guys are right about Cobalt bits.

5% Cobalt will do the job.
There is a 10% Cobalt out there, but far as I know it's for lathe cutting bits.

The Cobalts retain their edge longer than regular HSS (High Speed Steel).

Stay away from the Chinese carbon drill sets.

The 115 piece set that Denny W shows is the hot setup.
Every once in a while you'll find American made HSS in a 115 pc set and it's not too expensive.
Under $50. in most cases.

If you're trying to stretch your money, buy a set of 5% Cobalt's to 1/2" by 64th's.
Then a set of number and letter drills in HSS.

Usually the number and letter drills are used for tap holes and don't get used too much so a lesser quality tool will do the trick here.
You do want the fractional sizes in a good quality.

If things get tough, get a Carbide drill bit.
Buy them by each size as you need them.
Most times these will have to be mail ordered.

Biggest thing that makes drills last is proper cutting speed and proper cutting oil.

Drilling a pilot hole helps as well.
Just don't make the pilot hole so large that the big drill is cutting on extreme outer edge of the bit.
There's a lot of pressure there and if you have to do it take it slow and easy and use a sufficient quantity of cutting oil to carry the heat away.

Pilot holes improve accuracy to a considerable degree as well.